Articles de revues : « Hormone proteine »

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Niessen, René W. L. M., Birgit A. Pfaffendorf, Augueste Sturk, Roy J. Lamping, Marianne C. L. Schaap, C. Erik Hack et Marjolein Peters. « The Influence of Insulin, ß-Estradiol, Dexamethasone and Thyroid Hormone on the Secretion of Coagulant and Anticoagulant Proteins by HepG2 Cells ». Thrombosis and Haemostasis 74, n^o 02 (1995) : 686–92. http://dx.doi.org/10.1055/s-0038-1649798.

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SummaryAs a basis for regulatory studies on the influence of hormones on (anti)coagulant protein production by hepatocytes, we examined the amounts of the plasma proteins antithrombin III (AT III), protein C, protein S, factor II, factor X, fibrinogen, and prealbumin produced by the hepatoma cell line HepG2, into the culture medium, in the absence and presence of insulin, β-estradiol, dexamethasone and thyroid hormone. Without hormones these cells produced large amounts of fibrinogen (2,452 ± 501 ng/mg cell protein), AT III (447 ± 16 ng/mg cell protein) and factor II (464 ± 31 ng/mg cell protein) and only small amounts of protein C (50 ± 7 ng/mg cell protein) and factor X (55 ± 5 ng/mg cell protein). Thyroid hormone had a slight but significant effect on the enrichment in the culture medium of the anticoagulant protein AT III (1.34-fold) but not on protein C (0.96-fold) and protein S (0.91-fold). This hormone also significantly increased the amounts of the coagulant proteins factor II (1.28-fold), factor X (1.45-fold) and fibrinogen (2.17-fold). Insulin had an overall stimulating effect on the amounts of all the proteins that were investigated. Neither dexamethasone nor ß-estradiol administration did substantially change the amounts of these proteins.We conclude that the HepG2 cell is a useful tool to study the hormonal regulation of the production of (anti)coagulant proteins. We studied the overall process of protein production, i.e., the amounts of proteins produced into the culture medium. Detailed studies have to be performed to establish the specific hormonal effects on the underlying processes, e.g., transcription, translation, cellular processing and transport, and secretion.

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De Feo, Pierpaolo. « Hormonal regulation of human protein metabolism ». European Journal of Endocrinology 135, n^o 1 (juillet 1996) : 7–18. http://dx.doi.org/10.1530/eje.0.1350007.

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De Feo P. Hormonal regulation of human protein metabolism. Eur J Endocrinol 1996:135:7–18. ISSN 0804–4643 This review focuses on the effects of hormones on protein kinetics in humans. Most of the recent knowledge on the regulation of protein metabolism in humans has been obtained by tracing protein kinetics in vivo, using labelled isotopes of essential or non-essential amino acids. This technique allows the rates of the whole-body protein synthesis and breakdown to be estimated together with amino acid oxidation and the fractional synthetic rates of mixed muscle proteins or of single plasma proteins. Changes induced within these parameters by hormonal administration or endocrine diseases are also discussed. Hormones, on the basis of their net effect on protein balance (protein synthesis minus protein breakdown), are divided into two categories: those provided with an anabolic action and those with a prevalent catabolic action. The effects on protein metabolism of the following hormones are reviewed: insulin, growth hormone, IGF-I, adrenaline, androgens, estrogens, progesterone, glucagon, glucocorticosteroids, thyroid hormones. The review concludes with a report on the effects of multiple hormonal infusions on whole-body protein kinetics and a discussion on the potential role played by the concomitant increase of several hormones in the pathogenesis of protein wasting that complicates stress diseases. Pierpaolo De Feo, DIMISEM, Via E. Dal Pozzo, 06126 Perugia, Italy

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Richardson, Samantha J., Julie A. Monk, Caroline A. Shepherdley, Lars O. E. Ebbesson, Frank Sin, Deborah M. Power, Peter B. Frappell, Josef Köhrle et Marilyn B. Renfree. « Developmentally regulated thyroid hormone distributor proteins in marsupials, a reptile, and fish ». American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 288, n^o 5 (mai 2005) : R1264—R1272. http://dx.doi.org/10.1152/ajpregu.00793.2004.

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Thyroid hormones are essential for vertebrate development. There is a characteristic rise in thyroid hormone levels in blood during critical periods of thyroid hormone-regulated development. Thyroid hormones are lipophilic compounds, which readily partition from an aqueous environment into a lipid environment. Thyroid hormone distributor proteins are required to ensure adequate distribution of thyroid hormones, throughout the aqueous environment of the blood, and to counteract the avid partitioning of thyroid hormones into the lipid environment of cell membranes. In human blood, these proteins are albumin, transthyretin and thyroxine-binding globulin. We analyzed the developmental profile of thyroid hormone distributor proteins in serum from a representative of each order of marsupials ( M. eugenii; S.crassicaudata), a reptile ( C. porosus), in two species of salmonoid fishes ( S. salar; O. tshawytsch), and throughout a calendar year for sea bream ( S. aurata). We demonstrated that during development, these animals have a thyroid hormone distributor protein present in their blood which is not present in the adult blood. At least in mammals, this additional protein has higher affinity for thyroid hormones than the thyroid hormone distributor proteins in the blood of the adult. In fish, reptile and polyprotodont marsupial, this protein was transthyretin. In a diprotodont marsupial, it was thyroxine-binding globulin. We propose an hypothesis that an augmented thyroid hormone distributor protein network contributes to the rise in total thyroid hormone levels in the blood during development.

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Campbell, Kenneth L., Nurit Haspel, Cassandra Gath, Nuzulul Kurniatash, Indira (Nouduri) Akkiraju, Naomi Stuffers et Uma Vadher. « Protein hormone fragmentation in intercellular signaling : hormones as nested information systems ». Biology of Reproduction 104, n^o 4 (5 janvier 2021) : 887–901. http://dx.doi.org/10.1093/biolre/ioaa234.

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Abstract This study explores the hypothesis that protein hormones are nested information systems in which initial products of gene transcription, and their subsequent protein fragments, before and after secretion and initial target cell action, play additional physiological regulatory roles. The study produced four tools and key results: (1) a problem approach that proceeds, with examples and suggestions for in vivo organismal functional tests for peptide–protein interactions, from proteolytic breakdown prediction to models of hormone fragment modulation of protein–protein binding motifs in unrelated proteins; (2) a catalog of 461 known soluble human protein hormones and their predicted fragmentation patterns; (3) an analysis of the predicted proteolytic patterns of the canonical protein hormone transcripts demonstrating near-universal persistence of 9 ± 7 peptides of 8 ± 8 amino acids even after cleavage with 24 proteases from four protease classes; and (4) a coincidence analysis of the predicted proteolysis locations and the 1939 exon junctions within the transcripts that shows an excess (P < 0.001) of predicted proteolysis within 10 residues, especially at the exonal junction (P < 0.01). It appears all protein hormone transcripts generate multiple fragments the size of peptide hormones or protein–protein binding domains that may alter intracellular or extracellular functions by acting as modulators of metabolic enzymes, transduction factors, protein binding proteins, or hormone receptors. High proteolytic frequency at exonal junctions suggests proteolysis has evolved, as a complement to gene exon fusion, to extract structures or functions within single exons or protein segments to simplify the genome by discarding archaic one-exon genes.

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Corbacho, AM, G. Martinez De La Escalera et C. Clapp. « Roles of prolactin and related members of the prolactin/growth hormone/placental lactogen family in angiogenesis ». Journal of Endocrinology 173, n^o 2 (1 mai 2002) : 219–38. http://dx.doi.org/10.1677/joe.0.1730219.

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Prolactin, growth hormone and placental lactogen are members of a family of polypeptide hormones which share structural similarities and biological activities. Numerous functions have been attributed to these hormones, among which stand out their recently discovered effects on angiogenesis, the process by which new blood vessels are formed from the pre-existing microvasculature. Prolactin, growth hormone and placental lactogen, along with two non-classical members of the family, proliferin and proliferin-related protein, can act both as circulating hormones and as paracrine/autocrine factors to either stimulate or inhibit various stages of the formation and remodeling of new blood vessels, including endothelial cell proliferation, migration, protease production and apoptosis. Such opposing actions can reside in similar but independent molecules, as is the case of proliferin and proliferin-related protein, which stimulate and inhibit angiogenesis respectively. The potential to exert opposing effects on angiogenesis can also reside within the same molecule as the parent protein can promote angiogenesis (i.e. prolactin, growth hormone and placental lactogen), but after proteolytic processing the resulting peptide fragment acquires anti-angiogenic properties (i.e. 16 kDa prolactin, 16 kDa growth hormone and 16 kDa placental lactogen). The unique properties of the peptide fragments versus the full-length molecules, the regulation of the protease responsible for specific protein cleavage, the selective expression of specific receptors and their associated signal transduction pathways are issues that are being investigated to further establish the precise contribution of these hormones to angiogenesis under both physiological and pathological situations. In this review article, we summarize the known and speculative issues underlying the effects of the prolactin, growth hormone and placental lactogen family of proteins on angiogenesis, and address important remaining enigmas in this field of research.

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Puzianowska-Kuznicka, Monika, Eliza Pawlik-Pachucka, Magdalena Owczarz, Monika Budzińska et Jacek Polosak. « Small-Molecule Hormones : Molecular Mechanisms of Action ». International Journal of Endocrinology 2013 (2013) : 1–21. http://dx.doi.org/10.1155/2013/601246.

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Small-molecule hormones play crucial roles in the development and in the maintenance of an adult mammalian organism. On the molecular level, they regulate a plethora of biological pathways. Part of their actions depends on their transcription-regulating properties, exerted by highly specific nuclear receptors which are hormone-dependent transcription factors. Nuclear hormone receptors interact with coactivators, corepressors, basal transcription factors, and other transcription factors in order to modulate the activity of target genes in a manner that is dependent on tissue, age and developmental and pathophysiological states. The biological effect of this mechanism becomes apparent not earlier than 30–60 minutes after hormonal stimulus. In addition, small-molecule hormones modify the function of the cell by a number of nongenomic mechanisms, involving interaction with proteins localized in the plasma membrane, in the cytoplasm, as well as with proteins localized in other cellular membranes and in nonnuclear cellular compartments. The identity of such proteins is still under investigation; however, it seems that extranuclear fractions of nuclear hormone receptors commonly serve this function. A direct interaction of small-molecule hormones with membrane phospholipids and with mRNA is also postulated. In these mechanisms, the reaction to hormonal stimulus appears within seconds or minutes.

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Borsellino, Giovanni, Arturo Buonaguidi, Mario Baroni, Gaetano Elli, Augusta Sonato, Silvano Poma, Stefania Rescalli et Roberto Mondina. « Plasma Steroid Transport in Subjects with Tumors of Hormonal Target Organs : A Review ». Tumori Journal 78, n^o 3 (juin 1992) : 155–58. http://dx.doi.org/10.1177/030089169207800302.

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Tumors derived from a hormonal target organ are assumed to be stimulated by the same hormone that stimulates the normal target tissue. In spite of attempts to acquire direct indications of a correlation between hormones and cancer, none have been definitive because studies of total and free hormone levels have given contradictory results. For this reason, attention has shifted to the study of plasma binding and transport of hormones, that is, of the proteins responsible for modulation of the hormone effect and thus of hormone bioavailability. The data reviewed indicate that in-depth study of the transport and binding system of sex steroids would give new information about the endocrine characteristics of cancer patients.

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Cordeiro, Aline, Luana Lopes Souza, Marcelo Einicker-Lamas et Carmen Cabanelas Pazos-Moura. « Non-classic thyroid hormone signalling involved in hepatic lipid metabolism ». Journal of Endocrinology 216, n^o 3 (7 janvier 2013) : R47—R57. http://dx.doi.org/10.1530/joe-12-0542.

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Thyroid hormones are important modulators of lipid metabolism because the liver is a primary hormonal target. The hypolipidaemic effects of thyroid hormones result from the balance between direct and indirect actions resulting in stimulation of lipid synthesis and lipid oxidation, which favours degradation pathways. Originally, it was believed that thyroid hormone activity was only transduced by alteration of gene transcription mediated by the nuclear receptor thyroid hormone receptors, comprising the classic action of thyroid hormone. However, the discovery of other effects independent of this classic mechanism characterised a new model of thyroid hormone action, the non-classic mechanism that involves other signalling pathways. To date, this mechanism and its relevance have been intensively described. Considering the increasing evidence for non-classic signalling of thyroid hormones and the major influence of these hormones in the regulation of lipid metabolism, we reviewed the role of thyroid hormone in cytosolic signalling cascades, focusing on the regulation of second messengers, and the activity of effector proteins and the implication of these mechanisms on the control of hepatic lipid metabolism.

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Meier, V. S., et B. Groner. « The nuclear factor YY1 participates in repression of the beta-casein gene promoter in mammary epithelial cells and is counteracted by mammary gland factor during lactogenic hormone induction. » Molecular and Cellular Biology 14, n^o 1 (janvier 1994) : 128–37. http://dx.doi.org/10.1128/mcb.14.1.128.

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Expression of the beta-casein milk protein gene in the mammary epithelial cell line HC11 is primarily regulated at the transcriptional level. A 338-bp segment of promoter sequence 5' of the transcription start site is sufficient to confer inducibility by the lactogenic hormones insulin, glucocorticoid hormone, and prolactin. Positively and negatively acting promoter elements and specific DNA binding proteins have been identified. The binding of the mammary gland factor MGF to a site between -80 and -100 is indispensable for hormonal induction of transcription. Binding of MGF activity to DNA is greatly enhanced by the action of the lactogenic hormones. Repression of transcription in the uninduced state is mediated by a promoter element located adjacent to the MGF binding site at positions -110 to -150. This repressor element consists of two interacting protein binding sites. A nuclear factor that binds specifically to the proximal site between positions -110 and -120 has been characterized and found to be identical with the nuclear factor YY1 (delta, NF-E1). YY1 does not bind to the distal site. The simultaneous mutation in the proximal and the distal sites results in high, hormone-independent transcription. This finding suggests that YY1 plays a functional role in the repression and acts in conjunction with a second DNA binding protein. Comparison of YY1 DNA binding activity in uninduced and hormone-induced cells showed that relief of repression is not mediated by changes in the concentration or binding affinity of YY1. Infection of HC11 cells with a YY1-expressing recombinant retrovirus resulted in overexpression of YY1 but did not suppress hormonal induction. The addition of purified MGF decreased YY1 binding to its DNA recognition site in vitro. This finding indicates that MGF regulates the DNA binding activity of YY1 and thereby may cause the relief of transcriptional repression.

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Meier, V. S., et B. Groner. « The nuclear factor YY1 participates in repression of the beta-casein gene promoter in mammary epithelial cells and is counteracted by mammary gland factor during lactogenic hormone induction ». Molecular and Cellular Biology 14, n^o 1 (janvier 1994) : 128–37. http://dx.doi.org/10.1128/mcb.14.1.128-137.1994.

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Expression of the beta-casein milk protein gene in the mammary epithelial cell line HC11 is primarily regulated at the transcriptional level. A 338-bp segment of promoter sequence 5' of the transcription start site is sufficient to confer inducibility by the lactogenic hormones insulin, glucocorticoid hormone, and prolactin. Positively and negatively acting promoter elements and specific DNA binding proteins have been identified. The binding of the mammary gland factor MGF to a site between -80 and -100 is indispensable for hormonal induction of transcription. Binding of MGF activity to DNA is greatly enhanced by the action of the lactogenic hormones. Repression of transcription in the uninduced state is mediated by a promoter element located adjacent to the MGF binding site at positions -110 to -150. This repressor element consists of two interacting protein binding sites. A nuclear factor that binds specifically to the proximal site between positions -110 and -120 has been characterized and found to be identical with the nuclear factor YY1 (delta, NF-E1). YY1 does not bind to the distal site. The simultaneous mutation in the proximal and the distal sites results in high, hormone-independent transcription. This finding suggests that YY1 plays a functional role in the repression and acts in conjunction with a second DNA binding protein. Comparison of YY1 DNA binding activity in uninduced and hormone-induced cells showed that relief of repression is not mediated by changes in the concentration or binding affinity of YY1. Infection of HC11 cells with a YY1-expressing recombinant retrovirus resulted in overexpression of YY1 but did not suppress hormonal induction. The addition of purified MGF decreased YY1 binding to its DNA recognition site in vitro. This finding indicates that MGF regulates the DNA binding activity of YY1 and thereby may cause the relief of transcriptional repression.

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Fetissov, Sergueï O., Romain Legrand et Nicolas Lucas. « Bacterial Protein Mimetic of Peptide Hormone as a New Class of Protein- based Drugs ». Current Medicinal Chemistry 26, n^o 3 (26 mars 2019) : 546–53. http://dx.doi.org/10.2174/0929867324666171005110620.

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Specific peptide molecules classified as hormones, neuropeptides and cytokines are involved in intercellular signaling regulating various physiological processes in all organs and tissues. This justifies the peptidergic signaling as an attractive pharmacological target. Recently, a protein mimetic of a peptide hormone has been identified in Escherichia coli suggesting the potential use of specific bacterial proteins as a new type of peptide-like drugs. We review the scientific rational and technological approaches leading to the identification of the E. coli caseinolytic protease B (ClpB) homologue protein as a conformational mimetic of α-melanocyte-stimulating hormone (α-MSH), a melanocortin peptide critically involved in the regulation of energy homeostasis in humans and animals. Theoretical and experimental backgrounds for the validation of bacterial ClpB as a potential drug are discussed based on the known E. coli ClpB amino acid sequence homology with α-MSH. Using in silico analysis, we show that other protein sources containing similar to E. coli ClpB α-MSH-like epitopes with potential biological activity may exist in Enterobacteriaceae and in some Brassicaceae. Thus, the original approach leading to the identification of E. coli ClpB as an α-MSH mimetic protein can be applied for the identification of mimetic proteins of other peptide hormones and development of a new type of peptide-like protein-based drugs.

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Carlson, Anne A., Marta B. Manser, Andrew J. Young, Andrew F. Russell, Neil R. Jordan, Alan S. McNeilly et Tim Clutton-Brock. « Cortisol levels are positively associated with pup-feeding rates in male meerkats ». Proceedings of the Royal Society B : Biological Sciences 273, n^o 1586 (5 décembre 2005) : 571–77. http://dx.doi.org/10.1098/rspb.2005.3087.

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In societies of cooperative vertebrates, individual differences in contributions to offspring care are commonly substantial. Recent attempts to explain the causes of this variation have focused on correlations between contributions to care and the protein hormone prolactin, or the steroid hormone testosterone. However, such studies have seldom considered the importance of other hormones or controlled for non-hormonal factors that are correlative with both individual hormone levels and contributions to care. Using multivariate statistics, we show that hormone levels explain significant variation in contributions to pup-feeding by male meerkats, even after controlling for non-hormonal effects. However, long-term contributions to pup provisioning were significantly and positively correlated with plasma levels of cortisol rather than prolactin, while plasma levels of testosterone were not related to individual patterns of pup-feeding. Furthermore, a playback experiment that used pup begging calls to increase the feeding rates of male helpers gave rise to parallel increases in plasma cortisol levels, whilst prolactin and testosterone levels remained unchanged. Our findings confirm that hormones can explain significant amounts of variation in contributions to offspring feeding, and that cortisol, not prolactin, is the hormone most strongly associated with pup-feeding in cooperative male meerkats.

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Gordeladze, Jan O., Per W. Johansen, Ruth H. Paulssen, Eyvind J. Paulssen et Kaare M. Gautvik. « G-Proteins : implications for pathophysiology and disease ». European Journal of Endocrinology 131, n^o 6 (décembre 1994) : 557–74. http://dx.doi.org/10.1530/eje.0.1310557.

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Gordeladze JO, Johansen PW, Paulssen RH, Paulssen EJ, Gautvik KM. G-Proteins: implications for pathophysiology and disease. Eur J Endocrinol 1994;131:557–74. ISSN 0804–4643 This article focuses on the involvement of G-proteins in neuroendocrine secretion, cell growth and phenotype alterations. The current concept of hormonal activation of the GTPase cycle, as well as the molecular diversity of G-protein families and receptor * G-protein * effector coupling, are described. Also described are certain G-proteins as possible proto-oncogenes and how point mutations and frame shift mutations alter G-protein function and determine the characteristics of various endocrine diseases. The article outlines in detail how receptors and G-proteins interact in prolactin and growth-hormone-secreting pituicytes, how G-proteins are involved in the growth and differentiation of preadipocytes and osteoblasts. All in all, it seems that hormonal activation through G-proteins is modulated through direct intra- and inter-signalling system cross-talk at the plasma membrane level (short-term) and through interactions on the level of transcription (HREs) from tyrosine kinases, steroid-like hormones and metabolic pathways. Pharmacological intervention to treat diseases where G-proteins are involved should take both long and short-term regulatory phenomena into consideration. JO Gordeladze, Institute of Medical Biochemistry, University of Oslo, PO Box 1112, Blindern, 0317 Oslo, Norway

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Jayachandran, Muthuvel, et Virginia M. Miller. « Ovariectomy upregulates expression of estrogen receptors, NOS, and HSPs in porcine platelets ». American Journal of Physiology-Heart and Circulatory Physiology 283, n^o 1 (1 juillet 2002) : H220—H226. http://dx.doi.org/10.1152/ajpheart.00950.2001.

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Platelets participate in normal and pathological thrombotic processes. Hormone replacement in postmenopausal women is associated with increase risk for thrombosis. However, little is known regarding how platelets are affected by hormonal status. Nitric oxide (NO) modulates platelet functions and is modulated by hormones. Therefore, the present study was designed to determine how loss of ovarian hormones changes expression of estrogen receptors and regulatory proteins for NO synthase (NOS) in platelets. Estrogen receptors (ERα and ERβ), NOS, heat shock proteins 70 and 90 (HSP70 and HSP90), caveolin-1, -2, and -3, calmodulin, NOS activity, and cGMP were analyzed in a lysate of platelets from gonadally intact and ovariectomized female pigs. Expression of ERβ and ERα receptors, endothelial NOS (eNOS), HSP70, and HSP90 increased with ovariectomy. NOS activity and cGMP also increased; calmodulin was unchanged. Caveolins were not detected. These results suggest that ovarian hormones influence expression of estrogen receptors and eNOS in platelets. Changes in estrogen receptors and NOS could affect platelet aggregation in response to hormone replacement.

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Liddle, R. A. « Regulation of cholecystokinin secretion by intraluminal releasing factors ». American Journal of Physiology-Gastrointestinal and Liver Physiology 269, n^o 3 (1 septembre 1995) : G319—G327. http://dx.doi.org/10.1152/ajpgi.1995.269.3.g319.

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Ingested nutrients stimulate secretion of gastrointestinal hormones that are necessary for the coordinated processes of digestion and absorption of food. One of the most important hormonal regulators of the digestive process is cholecystokinin (CCK). This hormone is concentrated in the proximal small intestine and is secreted into the blood on the ingestion of proteins and fats. The physiological actions of CCK include stimulation of pancreatic secretion and gallbladder contraction, regulation of gastric emptying, and induction of satiety. Therefore, in a highly coordinated manner CCK regulates the ingestion, digestion, and absorption of nutrients. The manner by which foods affect enteric hormone secretion is largely unknown. However, it has recently become apparent that two CCK-releasing factors are present in the lumen of the proximal small intestine. One of these factors, known as monitor peptide, has been chemically characterized. Monitor peptide is produced by pancreatic acinar cells and is secreted by way of the pancreatic duct into the duodenum. On reaching the small intestine, monitor peptide interacts with CCK cells to induce hormone secretion. A CCK-releasing factor of intestinal origin has been partially characterized and is responsible for stimulation of CCK secretion after 1) ingestion of protein or fats, 2) instillation of protease inhibitors into the duodenum, or 3) diversion of bile-pancreatic juice from the upper small intestine. Together, these releasing factors provide positive and negative feedback mechanisms for regulation of CCK secretion. This review discusses the physiological observations that have led to the chemical characterization of the CCK-releasing factors and the potential implications of this work to other hormones of the gastrointestinal tract.

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Pradhananga, Sarbendra, et Jon R. Sayers. « Natural synthesis : Biologics, biosimilars and biobetters in protein hormone therapy ». Biochemist 34, n^o 1 (1 février 2012) : 10–15. http://dx.doi.org/10.1042/bio03401010.

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Hormone therapies have been used since the early 20th Century and belong to a group of drugs that has recently become known as ‘biologics’. Biologics are medicinal products that have been produced by biological processes as opposed to chemically synthesized drugs. The term biologics spans a wide range of products that include therapeutics such as organs, tissue, cells, blood or blood components, vaccines and proteins. This ‘proteins’ subgroup can be further subdivided into therapeutics such as antibodies, enzymes and hormones. The first hormone therapeutics were extracted from human or animal sources; however, with the advent and development of cloning and protein production technologies from the late-20th Century onwards, protein hormone therapeutics are now produced by recombinant DNA technology.

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Tena-Sempere, Manuel, et Ilpo Huhtaniemi. « Sex in the brain : How the brain regulates reproductive function ». Biochemist 31, n^o 2 (1 avril 2009) : 4–7. http://dx.doi.org/10.1042/bio03102004.

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Reproductive functions are maintained by a complex hormonal regulatory network called the hypothalamic–pituitary–gonadal (HPG) axis, which is under the hierarchical control of a network of neurohormones that ultimately modulate the synthesis and pulsatile release of the decapeptide gonadotropin-releasing hormone (GnRH) by specialized neural cells distributed along the mediobasal hypothalamus. This neuropeptide drives the production of the two gonadotropic hormones of the anterior pituitary gland, luteinizing hormone (LH) and folliclestimulating hormone (FSH), which are released into the circulation and regulate specific functions of the ovary and testis. In turn, hormones produced by the gonads feed back to the hypothalamic– pituitary level to maintain functional balance of the HPG axis, through negative and positive (only in females) regulatory loops. In this article, we review the main hormonal regulatory systems that are operative in the HPG axis with special emphasis on recent developments in our knowledge of the neuroendocrine pathways governing GnRH secretion, including the identification of kisspeptins and G-protein-coupled receptor 54 (GPR54) as major gatekeepers of puberty onset and fertility.

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Chowdhary, Sumaira, Shaugfta Aara, Masarat Nazeer et Musadiq Allaqband. « Thyroid Function Tests in Preeclampsia ». International Journal Of Medical Science And Clinical Invention 5, n^o 3 (13 mars 2018) : 3606–9. http://dx.doi.org/10.18535/ijmsci/v5i3.09.

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Background: The thyroid hormones are protein-bound in the serum, and only 0.02% of T4 and 0.2% of T3 are free, biologically active hormones. 45–70% of thyroid hormones are bound to thyroxine-binding globulin (TBG), and the rest to transthyretin and albumin. Familial conditions, estrogen treatment and pregnancy may have effects on the concentrations of the binding proteins, leading to changes in thyroid hormone fractions until a new equilibrium is reached. Materials and Methods.Thyroid function tests were performed by chemiluminescent microparticle immunoassay (CMIA) for the quantitative determination of thyroid hormones (Total T3, Total T4 and TSH) .In human serum and plasma values were presented as mean ± standard deviation. Student t’ test was used to compare hormonal levels. The corresponding value of 'p' was obtained from the standard table of critical 't' values at the appropriate degree of freedom. Statistical significance was considered as p<0.05. Conclusion. The findings of present study indicate that as the severity of preeclampsia increases the level of TSH increases with corresponding decrease in T3, T4.

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Brennan, Amelia J., Julie A. Sharp, Elie Khalil, Matthew R. Digby, Sonia L. Mailer, Christophe M. Lefèvre et Kevin R. Nicholas. « A population of mammary epithelial cells do not require hormones or growth factors to survive ». Journal of Endocrinology 196, n^o 3 (4 janvier 2008) : 483–96. http://dx.doi.org/10.1677/joe-07-0537.

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Hormonal stimulation of mammary explants mimics many of the biochemical changes observed during lactogenesis. Previous studies using eutherian species conclude that mammary explants require addition of exogenous macromolecules to remain hormone responsive in culture. The present study examines the survival of mammary explants from the wallaby and mouse using milk protein gene expression as a functional marker of lactation and cell viability. Mammary explants from pregnant tammars and mice showed that milk protein gene expression was significantly elevated after 3 days of culture with lactogenic hormones. The subsequent removal of exogenous hormones from the media for 10 days resulted in the down-regulation of milk protein genes. Surprisingly, mammary explants remained hormone responsive and expression of milk protein genes was re-induced after a second challenge with lactogenic hormones. Furthermore, the alveolar architecture was maintained. Global functional microarray analysis showed that classic involution markers were not differentially expressed, although two stress-induced survival genes were significantly up-regulated. We report that a population of mammary epithelial cells have an intrinsic capacity to remain viable and hormone responsive for extended periods in chemically defined media without any exogenous macromolecules. We propose that the mammary explant culture model uncouples the first phase of involution, as milk accumulation that normally provides involution stimuli is absent in this culture model allowing a population of cells to survive.

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Gittoes, Neil J. L., Christopher J. McCabe, Julie Verhaeg, Michael C. Sheppard et Jayne A. Franklyn. « Thyroid Hormone and Estrogen Receptor Expression in Normal Pituitary and Nonfunctioning Tumors of the Anterior Pituitary1 ». Journal of Clinical Endocrinology & ; Metabolism 82, n^o 6 (1 juin 1997) : 1960–67. http://dx.doi.org/10.1210/jcem.82.6.3969.

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Abstract Nonfunctioning tumors (NFTs) of the anterior pituitary often express elevated levels of the glycoprotein hormone α-subunit, which, under normal physiological conditions, is under negative feedback control by thyroid and gonadal steroid hormones. We postulate that inappropriately elevated levels of expression of α-subunit in the face of normal levels of these target organ hormones may reflect an abnormality of thyroid hormone receptors (TRs) and/or gonadal steroid receptors in NFTs. Using immunocytochemistry and Western blotting we have examined TR and estrogen receptor (ER) protein expression in normal human anterior pituitary glands and NFTs. Pretranslational expression of these receptors was examined using semiquantitative reverse transcriptase-PCR. Expression of all TR variant and ER proteins was reduced in pituitary tumors compared with that in normal pituitaries. The expression of messenger ribonucleic acids encoding the TRβ1 and TRβ2 isoforms and ER was also significantly reduced in tumors compared with normal tissues, although there was no difference between tumors and normals in the level of expression of TRα1 and α2 messenger ribonucleic acids. We suggest that reduced expression of TRs and ER may account for inappropriate expression of the glycoprotein hormoneα -subunit gene in some NFTs and may contribute to uncontrolled tumor growth.

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Banks, William A. « Brain Meets Body : The Blood-Brain Barrier as an Endocrine Interface ». Endocrinology 153, n^o 9 (1 septembre 2012) : 4111–19. http://dx.doi.org/10.1210/en.2012-1435.

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The blood-brain barrier (BBB) separates the central nervous system (CNS) from the peripheral tissues. However, this does not prevent hormones from entering the brain, but shifts the main control of entry to the BBB. In general, steroid hormones cross the BBB by transmembrane diffusion, a nonsaturable process resulting in brain levels that reflect blood levels, whereas thyroid hormones and many peptides and regulatory proteins cross using transporters, a saturable process resulting in brain levels that reflect blood levels and transporter characteristics. Protein binding, brain-to-blood transport, and pharmacokinetics modulate BBB penetration. Some hormones have the opposite effect within the CNS than they do in the periphery, suggesting that these hormones cross the BBB to act as their own counterregulators. The cells making up the BBB are also endocrine like, both responding to circulating substances and secreting substances into the circulation and CNS. By dividing a hormone's receptors into central and peripheral pools, the former of which may not be part of the hormone's negative feed back loop, the BBB fosters the development of variable hormone resistance syndromes, as exemplified by evidence that altered insulin action in the CNS can contribute to Alzheimer's disease. In summary, the BBB acts as a regulatory interface in an endocrine-like, humoral-based communication between the CNS and peripheral tissues.

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Clapp, Carmen, Stéphanie Thebault, Michael C. Jeziorski et Gonzalo Martínez De La Escalera. « Peptide Hormone Regulation of Angiogenesis ». Physiological Reviews 89, n^o 4 (octobre 2009) : 1177–215. http://dx.doi.org/10.1152/physrev.00024.2009.

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It is now apparent that regulation of blood vessel growth contributes to the classical actions of hormones on development, growth, and reproduction. Endothelial cells are ideally positioned to respond to hormones, which act in concert with locally produced chemical mediators to regulate their growth, motility, function, and survival. Hormones affect angiogenesis either directly through actions on endothelial cells or indirectly by regulating proangiogenic factors like vascular endothelial growth factor. Importantly, the local microenvironment of endothelial cells can determine the outcome of hormone action on angiogenesis. Members of the growth hormone/prolactin/placental lactogen, the renin-angiotensin, and the kallikrein-kinin systems that exert stimulatory effects on angiogenesis can acquire antiangiogenic properties after undergoing proteolytic cleavage. In view of the opposing effects of hormonal fragments and precursor molecules, the regulation of the proteases responsible for specific protein cleavage represents an efficient mechanism for balancing angiogenesis. This review presents an overview of the actions on angiogenesis of the above-mentioned peptide hormonal families and addresses how specific proteolysis alters the final outcome of these actions in the context of health and disease.

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Kharrazian, Datis, Martha Herbert et Aristo Vojdani. « Immunological Reactivity Using Monoclonal and Polyclonal Antibodies of Autoimmune Thyroid Target Sites with Dietary Proteins ». Journal of Thyroid Research 2017 (2017) : 1–13. http://dx.doi.org/10.1155/2017/4354723.

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Many hypothyroid and autoimmune thyroid patients experience reactions with specific foods. Additionally, food interactions may play a role in a subset of individuals who have difficulty finding a suitable thyroid hormone dosage. Our study was designed to investigate the potential role of dietary protein immune reactivity with thyroid hormones and thyroid axis target sites. We identified immune reactivity between dietary proteins and target sites on the thyroid axis that includes thyroid hormones, thyroid receptors, enzymes, and transport proteins. We also measured immune reactivity of either target specific monoclonal or polyclonal antibodies for thyroid-stimulating hormone (TSH) receptor, 5′deiodinase, thyroid peroxidase, thyroglobulin, thyroxine-binding globulin, thyroxine, and triiodothyronine against 204 purified dietary proteins commonly consumed in cooked and raw forms. Dietary protein determinants included unmodified (raw) and modified (cooked and roasted) foods, herbs, spices, food gums, brewed beverages, and additives. There were no dietary protein immune reactions with TSH receptor, thyroid peroxidase, and thyroxine-binding globulin. However, specific antigen-antibody immune reactivity was identified with several purified food proteins with triiodothyronine, thyroxine, thyroglobulin, and 5′deiodinase. Laboratory analysis of immunological cross-reactivity between thyroid target sites and dietary proteins is the initial step necessary in determining whether dietary proteins may play a potential immunoreactive role in autoimmune thyroid disease.

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Kraemer, William J., Nicholas A. Ratamess et Bradley C. Nindl. « Recovery responses of testosterone, growth hormone, and IGF-1 after resistance exercise ». Journal of Applied Physiology 122, n^o 3 (1 mars 2017) : 549–58. http://dx.doi.org/10.1152/japplphysiol.00599.2016.

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The complexity and redundancy of the endocrine pathways during recovery related to anabolic function in the body belie an oversimplistic approach to its study. The purpose of this review is to examine the role of resistance exercise (RE) on the recovery responses of three major anabolic hormones, testosterone, growth hormone(s), and insulin-like growth factor 1. Each hormone has a complexity related to differential pathways of action as well as interactions with binding proteins and receptor interactions. Testosterone is the primary anabolic hormone, and its concentration changes during the recovery period depending on the upregulation or downregulation of the androgen receptor. Multiple tissues beyond skeletal muscle are targeted under hormonal control and play critical roles in metabolism and physiological function. Growth hormone (GH) demonstrates differential increases in recovery with RE based on the type of GH being assayed and workout being used. IGF-1 shows variable increases in recovery with RE and is intimately linked to a host of binding proteins that are essential to its integrative actions and mediating targeting effects. The RE stress is related to recruitment of muscle tissue with the glandular release of hormones as signals to target tissues to support homeostatic mechanisms for metabolism and tissue repair during the recovery process. Anabolic hormones play a crucial role in the body’s response to metabolism, repair, and adaptive capabilities especially in response to anabolic-type RE. Changes of these hormones following RE during recovery in the circulatory biocompartment of blood are reflective of the many mechanisms of action that are in play in the repair and recovery process.

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Copping, Susan, et Peter G. H. Byfield. « The role of thyroid hormone autoantibodies in serum transport ». Acta Endocrinologica 121, n^o 4 (octobre 1989) : 551–59. http://dx.doi.org/10.1530/acta.0.1210551.

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Abstract. Eleven sera known to contain thyroid hormone autoantibodies were analysed by reverse-flow electrophoresis for the equilibrium distribution of thyroid hormones between these autoantibodies and the three normal binding proteins found in serum. The binding properties of the autoantibodies determined in vitro did not necessarily predict their contribution to transport in serum of T4 and T3. Some could both bind in vitro and transport in serum. Others were able to bind both hormones but transported only one. However, some autoantibodies could be specific, binding and transporting one hormone only. In some sera, the autoantibody was the dominant transport protein having drawn hormone from thyroxine-binding globulin which is normally the most important. The autoantibodies were not saturated even in euthyroid individuals, indicating that they bind hormone reversibly and are a part of an equilibrium system.

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Veletza, S. V., K. V. Nichols, I. Gross, H. Lu, D. W. Dynia et J. Floros. « Surfactant protein C : hormonal control of SP-C mRNA levels in vitro ». American Journal of Physiology-Lung Cellular and Molecular Physiology 262, n^o 6 (1 juin 1992) : L684—L687. http://dx.doi.org/10.1152/ajplung.1992.262.6.l684.

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We have studied hormonal regulation of the surfactant protein C (SP-C) in fetal 18-dah rat lung explants. SP-C mRNA was detected in Northern blots with a specific rat SP-C cDNA probe and quantified by densitometry. Treatment of the explants with dexamethasone resulted in a dose-dependent increase of the SP-C mRNA level. Transcriptional assays have shown that the regulation of SP-C mRNA by dexamethasone involves a transcriptional step. Administration of the cAMP analogues, 8-bromoadenosine 3',5'-cyclic monophosphate (8-BrcAMP) or dibutyryl adenosine 3',5'-cyclic monophosphate (DBcAMP), produced a dose-dependent increase of SP-C mRNA levels, with maximum stimulation observed at 200 microM. The thyroid hormone T3 had no effect on SP-C mRNA levels, whether administered alone or in combination with dexamethasone. Variation in the effects of the above hormones on three surfactant protein mRNAs, SP-A, SP-B and SP-C, indicates that the hormonal regulation of the surfactant proteins is a complex process and that each gene is, in part, differentially regulated.

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Carlsson-Bostedt, L., N. Frölander, S. Edén, T. Stigbrand et B. von Schoultz. « Effects of oestrogen and human growth hormone on pregnancy-associated plasma proteins in the rat ». Acta Endocrinologica 116, n^o 2 (octobre 1987) : 299–304. http://dx.doi.org/10.1530/acta.0.1160299.

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Abstract. The serum concentrations of pregnancy-associated murine protein-1 (PAMP-1), acute phase α2macroglobulin, albumin, transferrin, and complement factor 3(C3) were followed in male rats during continuous infusions of oestradiol-17β and human growth hormone. Three different patterns of protein response could be distinguished. A distinct acute phase response without any additive influence of the given hormones was recorded for α2-macroglobulin, whereas the levels of albumin, transferrin and C3 were virtually unaffected throughout the experiment. Growth hormone gave a rapid and pronounced increase of PAMP-1 levels, whereas the response to oestradiol of this 'steroid-sensitive' protein was significantly weaker and delayed. It is suggested that the apparent oestrogenic influence on certain pregnancy-associated plasma proteins is mediated via growth hormone.

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Toth, Michael J., Cynthia K. Sites, Dwight E. Matthews et Peter R. Casson. « Ovarian suppression with gonadotropin-releasing hormone agonist reduces whole body protein turnover in women ». American Journal of Physiology-Endocrinology and Metabolism 291, n^o 3 (septembre 2006) : E483—E490. http://dx.doi.org/10.1152/ajpendo.00600.2005.

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The age-related decline in fat-free mass is accelerated in women after menopause. The role of ovarian hormone deficiency in the regulation of fat-free mass, however, has not been clearly defined. To address this question, we examined the effect of ovarian hormone suppression on whole body protein metabolism. Whole body protein breakdown, oxidation, and synthesis were measured using [13C]leucine in young, healthy women with regular menstrual patterns before and after 2 mo of treatment with gonadotropin-releasing hormone agonist (GnRHa; n = 6) or placebo ( n = 7). Protein metabolism was measured under postabsorptive and euglycemic-hyperinsulinemic-hyperaminoacidemic conditions. Ovarian suppression did not alter whole body or regional fat-free mass or adiposity. In the postabsorptive state, GnRHa administration was associated with reductions in protein breakdown and synthesis ( P < 0.05), whereas no change in protein oxidation was noted. Under euglycemic-hyperinsulinemic-hyperaminoacidemic conditions, a similar reduction ( P < 0.05) in protein synthesis and breakdown was noted, whereas, protein oxidation increased ( P < 0.05) in the placebo group. Testosterone, steroid hormone precursors, insulin-like growth factor I, and their respective binding proteins were not altered by GnRHa administration, and changes in these hormones over time were not associated with GnRHa-induced alterations in protein metabolism, suggesting that changes in protein turnover are not due to an effect of ovarian suppression on other endocrine systems. Our findings provide evidence that endogenous ovarian hormones participate in the regulation of protein turnover in women.

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Moore, H. P., et R. B. Kelly. « Secretory protein targeting in a pituitary cell line : differential transport of foreign secretory proteins to distinct secretory pathways. » Journal of Cell Biology 101, n^o 5 (1 novembre 1985) : 1773–81. http://dx.doi.org/10.1083/jcb.101.5.1773.

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The mouse pituitary cell line, AtT-20, packages the adrenocorticotropic hormone (ACTH) in secretory vesicles and releases it when the cell is stimulated with secretagogues. These cells have the capacity, after transfection with the appropriate DNA, to package heterologous peptide hormones into the regulated secretory vesicles (Moore, H. P. H., M. D. Walker, F. Lee, and R. B. Kelly, 1983, Cell, 35:531-538). To test if other secreted proteins prefer a different route to the surface, we have transfected AtT-20 cells with DNAs coding for a fragment of a membrane protein, the vesicular stomatitis virus G protein from which the membrane spanning domain has been deleted (Rose, J. K., and J. E. Bergmann, 1982, Cell, 17:813-819). We found that the secreted vesicular stomatitis virus G proteins were not transported to the regulated secretory vesicles. Instead they preferentially exited the cell by the constitutive pathway previously found in these cells (Gumbiner, B., and R. B. Kelly, 1982, Cell, 28:51-59). In contrast, human growth hormone transfected into the cells by the same procedure was transported to the regulated pathway with a similar efficiency as the endogenous hormone ACTH. Transport of the secreted G protein to the regulated pathway, if it occurs at all, is at least 30-fold less efficient than peptide hormones. We conclude that the transport machinery in AtT-20 cells must selectively recognize different secreted proteins and sort them into distinct secretory pathways.

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Webb, C. F., et M. Wallis. « A comparison of lactogenic receptors from rat liver and Nb2 rat lymphoma cells by using cross-linking techniques ». Biochemical Journal 250, n^o 1 (15 février 1988) : 215–19. http://dx.doi.org/10.1042/bj2500215.

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Lactogenic receptors were analysed with the use of the cross-linking agent disuccinimidyl suberate to attach covalently 125I-labelled ovine prolactin or human growth hormone to binding sites from (1) liver from pregnant rats and (2) the rat-derived Nb2 lymphoma cell line. Analysis by SDS/polyacrylamide-gel electrophoresis of the proteins cross-linked to labelled hormone in rat liver indicated a major specifically-labelled complex with an Mr of 68,000-72,000, when run under reducing or non-reducing conditions. With Nb2 cells a major specifically-labelled complex with an Mr of 97,000-110,000 was identified, but only when electrophoresis was run using reducing conditions. Assuming one hormone molecule (Mr 22,000-24,000) per hormone-receptor complex, then the receptor proteins have an Mr of 44,000-50,000 for rat liver and 73,000-88,000 for the Nb2 cells. For both cell types the receptors were of lactogenic specificity; lactogenic hormones competed for binding whereas somatogenic hormones did not. These studies suggest that the lactogenic receptors in rat liver membranes and Nb2 cells differ in two respects. Firstly, the Mr of the labelled receptor protein in Nb2 cells is greater than that of the corresponding receptor protein in rat liver membranes; secondly, the Nb2 cell receptor appears to exist as a disulphide-linked oligomer whereas the receptor in rat liver membranes does not.

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Dale, Elizabeth, Miriam Davis et Denise L. Faustman. « A role for transcription factor NF-κB in autoimmunity : possible interactions of genes, sex, and the immune response ». Advances in Physiology Education 30, n^o 4 (décembre 2006) : 152–58. http://dx.doi.org/10.1152/advan.00065.2006.

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Sex hormones have long been implicated in autoimmune diseases because women account for 80% of cases. The mechanism of hormonal action in autoimmunity is unknown. Drawing on genetic studies of autoimmune disease, this article discusses how both genes and sex hormones may exert their effects through the same general mechanism, dysregulation of transcription factor NF-κB, an immunoregulatory protein. Gene and hormone alterations of the NF-κB signaling cascade provide a unifying hypothesis to explain the wide-ranging human and murine autoimmune disease phenotypes regulated by NF-κB, including cytokine balance, antigen presentation, lymphoid development, and lymphoid repertoire selection by apoptosis.

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Ząbczyńska, Marta, Kamila Kozłowska et Ewa Pocheć. « Glycosylation in the Thyroid Gland : Vital Aspects of Glycoprotein Function in Thyrocyte Physiology and Thyroid Disorders ». International Journal of Molecular Sciences 19, n^o 9 (17 septembre 2018) : 2792. http://dx.doi.org/10.3390/ijms19092792.

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The key proteins responsible for hormone synthesis in the thyroid are glycosylated. Oligosaccharides strongly affect the function of glycosylated proteins. Both thyroid-stimulating hormone (TSH) secreted by the pituitary gland and TSH receptors on the surface of thyrocytes contain N-glycans, which are crucial to their proper activity. Thyroglobulin (Tg), the protein backbone for synthesis of thyroid hormones, is a heavily N-glycosylated protein, containing 20 putative N-glycosylated sites. N-oligosaccharides play a role in Tg transport into the follicular lumen, where thyroid hormones are produced, and into thyrocytes, where hyposialylated Tg is degraded. N-glycans of the cell membrane transporters sodium/iodide symporter and pendrin are necessary for iodide transport. Some changes in glycosylation result in abnormal activity of the thyroid and alteration of the metabolic clearance rate of hormones. Alteration of glycan structures is a pathological process related to the progression of chronic diseases such as thyroid cancers and autoimmunity. Thyroid carcinogenesis is accompanied by changes in sialylation and fucosylation, β1,6-branching of glycans, the content and structure of poly-LacNAc chains, as well as O-GlcNAcylation, while in thyroid autoimmunity the main processes affected are sialylation and fucosylation. The glycobiology of the thyroid gland is an intensively studied field of research, providing new data helpful in understanding the role of the sugar component in thyroid protein biology and disorders.

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Branvold, D. J., D. R. Allred, D. J. Beckstead, H. J. Kim, N. Fillmore, B. M. Condon, J. D. Brown, S. N. Sudweeks, D. M. Thomson et W. W. Winder. « Thyroid hormone effects on LKB1, MO25, phospho-AMPK, phospho-CREB, and PGC-1α in rat muscle ». Journal of Applied Physiology 105, n^o 4 (octobre 2008) : 1218–27. http://dx.doi.org/10.1152/japplphysiol.00997.2007.

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Expression of all of the isoforms of the subunits of AMP-activated protein kinase (AMPK) and AMPK activity is increased in skeletal muscle of hyperthyroid rats. Activity of AMPK in skeletal muscle is regulated principally by the upstream kinase, LKB1. This experiment was designed to determine whether the increase in AMPK activity is accompanied by increased expression of the LKB1, along with binding partner proteins. LKB1, MO25, and downstream targets were determined in muscle extracts in control rats, in rats given 3 mg of thyroxine and 1 mg of triiodothyronine per kilogram chow for 4 wk, and in rats given 0.01% propylthiouracil (PTU; an inhibitor of thyroid hormone synthesis) in drinking water for 4 wk (hypothyroid group). LKB1 and MO25 increased in the soleus of thyroid hormone-treated rats vs. the controls. In other muscle types, LKB1 responses were variable, but MO25 increased in all. In soleus, MO25 mRNA increased with thyroid hormone treatment, and STRAD mRNA increased with PTU treatment. Phospho-AMPK and phospho-ACC were elevated in soleus and gastrocnemius of hyperthyroid rats. Thyroid hormone treatment also increased the amount of phospho-cAMP response element binding protein (CREB) in the soleus, heart, and red quadriceps. Four proteins having CREB response elements (CRE) in promoter regions of their genes (peroxisome proliferator-activated receptor-γ coactivator-1α, uncoupling protein 3, cytochrome c, and hexokinase II) were all increased in soleus in response to thyroid hormones. These data provide evidence that thyroid hormones increase soleus muscle LKB1 and MO25 content with subsequent activation of AMPK, phosphorylation of CREB, and expression of mitochondrial protein genes having CRE in their promoters.

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Starkov, A. A. « “Mild” Uncoupling of Mitochondria ». Bioscience Reports 17, n^o 3 (1 juin 1997) : 273–79. http://dx.doi.org/10.1023/a:1027380527769.

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Recently, it was proposed that the thyroid hormone-mediated uncoupling in mitochondria is involved in the cellular defence system against free radicals (Skulachev V.P. (1996) Quart. Rev. Biophys. 29:169–202). This phenomenon was named “mild” uncoupling. It was postulated to be a protein-mediated process controlled by several factors. The data reported during the past 40 years, pointing to the protein-mediated uncoupling mechanism in mitochondria, are reviewed in a context of hypothetical properties of “mild” uncoupling. The mechanism of “mild” uncoupling is suggested to be the following: (a) mitochondria possess protein(s) that regulate the proton permeability of inner mitochondrial membrane; (b) these proteins are regulated by binding of an unidentified low-molecular-weight endogenous compound with properties resembling those of the most active artificial uncouplers like FCCP and SF6847; (c) the interaction of this compound with its target protein(s) is modulated by a thyroid hormone in a positive (i.e. enhancing the proton permeability) way and by sex steroid hormones in a negative way; (e) endogenous fatty acids can attenuate the influence of both thyroid and steroid hormones.

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Cella, Nathalie, Bernd Groner et Nancy E. Hynes. « Characterization of Stat5a and Stat5b Homodimers and Heterodimers and Their Association with the Glucocortiocoid Receptor in Mammary Cells ». Molecular and Cellular Biology 18, n^o 4 (1 avril 1998) : 1783–92. http://dx.doi.org/10.1128/mcb.18.4.1783.

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ABSTRACT The lactogenic hormones, i.e., prolactin and glucocorticoids, act in concert to stimulate transcription factors responsible for hormone-dependent milk protein gene expression. In the mammary gland, prolactin activates Stat5a and Stat5b and glucocorticoids activate the glucocorticoid receptor (GR). Immunoprecipitation experiments revealed that in mammary cells, Stat5a, Stat5b, and the GR are physically associated in vivo. The association is not dependent on lactogenic hormone treatment and is evident at all stages of mammary gland development. Immunodepletion experiments indicated that a fraction of GR and Stat5 proteins are not associated, suggesting that there are different intracellular pools of these proteins. Lactogenic hormone treatment of HC11 mammary cells resulted in tyrosine phosphorylation of Stat5a and Stat5b, dimerization, and rapid nuclear translocation of both Stat5 proteins. Following hormone treatment, Stat5a-Stat5b heterodimers were detected by their coimmunoprecipitation. In addition, immunodepletion experiments followed by gel shift analyses revealed the presence of active Stat5a and Stat5b homodimers. In mammary cells, Stat5b homodimers are less abundant than Stat5a homodimers. Although the GR does not bind the Stat5 DNA binding site directly, it could be detected with the Stat5-DNA complex. These results suggest that glucocorticoids affect milk protein gene expression via association of the GR with Stat5. Thus, there is a functional coupling between Stat-dependent and nuclear hormone receptor-dependent gene transcription.

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Simon, Francis R., John Fortune, Mieko Iwahashi, Ishtiaq Qadri et Eileen Sutherland. « Multihormonal regulation of hepatic sinusoidalNtcpgene expression ». American Journal of Physiology-Gastrointestinal and Liver Physiology 287, n^o 4 (octobre 2004) : G782—G794. http://dx.doi.org/10.1152/ajpgi.00379.2003.

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Bile acids are efficiently removed from sinusoidal blood by a number of transporters including the Na+-taurocholate-cotransporting polypeptide (Ntcp). Na+-dependent bile salt uptake, as well as Ntcp, are expressed twofold higher in male compared with female rat livers. Also, estrogen administration to male rats decreases Ntcp expression. The aims of this study were to determine the hormonal mechanism(s) responsible for this sexually dimorphic expression of Ntcp. We examined castrated and hypophysectomized rats of both sexes. Sex steroid hormones, growth hormone, thyroid, and glucocorticoids were administered, and livers were examined for changes in Ntcp messenger RNA (mRNA). Ntcp mRNA and protein content were selectively increased in males. Estradiol selectively decreased Ntcp expression in males, whereas ovariectomy increased Ntcp in females, confirming the importance of estrogens in regulating Ntcp. Hypophysectomy decreased Ntcp mRNA levels in males and prevented estrogen administration from decreasing Ntcp, indicating the importance of pituitary hormones. Although constant infusion of growth hormone to intact males reduced Ntcp, its replacement alone after hypophysectomy did not restore the sex differences. In contrast, thyroid hormone and corticosterone increased Ntcp mRNA in hypophysectomized rats. Sex differences in Ntcp mRNA levels were produced only when the female pattern of growth hormone was administered to animals also receiving thyroid and corticosterone. Thyroid and dexamethasone also increased Ntcp mRNA in isolated rat hepatocytes, whereas growth hormone decreased Ntcp. These findings demonstrate the essential role that pituitary hormones play in the sexually dimorphic control of Ntcp expression in adult rat liver and in the mediation of estrogen effects.

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Kim, Keewan, Samrawit F. Yisahak, Carrie J. Nobles, Victoria C. Andriessen, Elizabeth A. DeVilbiss, Lindsey A. Sjaarda, Ahoud Alohali, Neil J. Perkins et Sunni L. Mumford. « Low Intake of Vegetable Protein is Associated With Altered Ovulatory Function Among Healthy Women of Reproductive Age ». Journal of Clinical Endocrinology & ; Metabolism 106, n^o 7 (18 mars 2021) : e2600-e2612. http://dx.doi.org/10.1210/clinem/dgab179.

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Abstract Context Diets high in plant-based protein have gained popularity due to increasing health concerns regarding consumption of animal products. Though links between intakes of certain protein-rich foods and reproductive disorders have been suggested, the relationship of overall animal and vegetable proteins with reproductive hormones among reproductive-aged women is unknown. Objective To evaluate the associations between the intake of dietary protein with reproductive hormones and sporadic anovulation among reproductive-aged women. Design A prospective cohort study, 2005–2007. Setting University at Buffalo, western New York, United States. Participants A total of 259 premenopausal women (18–44 years) without dietary restrictions. Main Outcome Measure(s) Serum reproductive hormones were determined up to 8 times per cycle for 2 cycles. Protein intake was assessed the day prior to hormone assessment at 4 visits/cycle using 24-hour recalls. Results Overall, 84% of participants met the recommended dietary allowance for total protein set for reproductive-aged women. Neither total nor animal protein intake were associated with reproductive hormones or anovulation. However, vegetable protein intake in the lowest tertile was associated with lower luteal phase progesterone (-18.0%, 95% confidence interval [CI] -30.2, -3.6), higher follicle-stimulating hormone (3.8%, 95% CI 0.2, 7.6), and a higher risk of anovulation (risk ratio [RR] 2.53, 95% CI 1.21, 5.26), compared with the middle tertile. Nuts and seeds were the only protein-rich foods associated with an elevated risk of anovulation (RR 2.12, 95% CI 1.17, 3.85). Conclusions Findings suggest that among women who meet the recommended dietary allowance for total protein, low intake of vegetable, but not animal, protein may disturb normal ovulatory function.

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O'Shea, PJ, et GR Williams. « Insight into the physiological actions of thyroid hormone receptors from genetically modified mice ». Journal of Endocrinology 175, n^o 3 (1 décembre 2002) : 553–70. http://dx.doi.org/10.1677/joe.0.1750553.

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Thyroid hormones exert a range of developmental and physiological actions in all vertebrates. Serum concentrations of L-thyroxine (T4) and 3,5,3 -L-triiodothyronine (T3) are maintained by a negative feedback loop involving T3-inhibition of hypothalamic thyrotrophin releasing hormone (TRH) and pituitary thyroid stimulating hormone (TSH) secretion, and by tissue specific and hormone-regulated expression of the three iodothyronine deiodinase enzymes that activate or metabolise thyroid hormones. T3 actions are mediated by two T3-receptors, TRalpha and TRbeta, which act as hormone-inducible transcription factors. The TRalpha (NR1A1) and TRbeta (NR1A2) genes encode mRNAs that are alternatively spliced to generate 9 mRNA isoforms (TRalpha1, alpha2, alpha3, Deltaalpha1, Deltaalpha2, beta1, beta2, beta3 and Deltabeta3), of which four (TRalpha1, alpha2, beta1 and beta2) are known to be expressed at the protein level in vivo. The numerous TR mRNAs are expressed widely in tissue- and developmental stage-specific patterns, although it is important to note that levels of mRNA expression may not correlate with receptor protein concentrations in individual tissues. The TRalpha2, alpha3, Deltaalpha1 and Deltaalpha2 transcripts encode proteins that fail to bind T3 in vitro. These non-binding isoforms, in addition to TRDeltabeta3 which does bind hormone, may act as dominant negative antagonists of the true T3-binding receptors in vitro, but their physiological functions and those of the TRbeta3 isoform have not been determined. In order to obtain a new understanding of the complexities of T3 action in vivo and the role of TRs during development, many mouse models of disrupted or augmented thyroid hormone signalling have been generated. The aim of this review is to provide a picture of the physiological actions of thyroid hormones by considering the phenotypes of these genetically modified mice.

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Patel, Amiya Kumar. « Dose dependent interactions between estradiolâ€17Î² and triiodothyronine with reference to different physiological and biochemical parameters on liver tissue of common Indian Toad (Bufo melanostictus) ». South Asian Journal of Experimental Biology 2, n^o 3 (15 juillet 2012) : 79–89. http://dx.doi.org/10.38150/sajeb.2(3).p79-89.

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To study the dose dependent interaction between two chemically differentand functionally distinct hormones i.e. estradiolâ€17β and triâ€iodothyronine(T3), six different animal groups of common Indian toad (Bufo melanostictus)were injected intramuscularly each with single dose of individual treatment[Estradiolâ€17β (Eâ€40 and Eâ€80); T3 (Tâ€20 and Tâ€40), and combination dose (Eâ€40+Tâ€20 and Eâ€80+Tâ€40)]. The data clearly demonstrated the interaction between these two hormones with respect to different physiochemical parameters in the liver tissue, such as alkaline phosphates activity, oxygen consumption rate, lipid, cholesterol, RNA, DNA, protein, free amino acid, totalsugar and ascorbic acid content with respect to different days after treatment(0, 1, 5 and 10) as well as different doses of hormonal treatments, individuallyand in combination. The comparative study indicated the dose dependenthormoneâ€hormone interaction between estradiolâ€17β and T3 hormone with respect to synergistic effect on oxygen consumption rate, fluctuation in lipid and cholesterol content, antagonistic effect of T3 on activation of the transcriptional apparatus to synthesize RNA, free amino acid metabolism, antagonistic effect on protein metabolism suggesting the protein catabolic or anabolic nature of T3, the permissive effect of estradiolâ€17β upon T3 on sugar content in liver tissue of toad.

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Wu, WenWen, Hiroshi Kamma, Masachika Fujiwara, Yukiko Yano, Hiroaki Satoh, Hisatoh Hara, Tohru Yashiro, Ei Ueno et Yuji Aiyoshi. « Altered Expression Patterns of Heterogeneous Nuclear Ribonucleoproteins A2 and B1 in the Adrenal Cortex ». Journal of Histochemistry & ; Cytochemistry 53, n^o 4 (avril 2005) : 487–95. http://dx.doi.org/10.1369/jhc.4a6295.2005.

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Several proteins implicated in hormonogenesis of the adrenal cortex have alternatively spliced isoforms, which respond differently to adrenocorticotropic hormone (ACTH). Heterogeneous nuclear ribonucleoproteins A2 and B1 are among the abundant pre-mRNA-binding proteins involved in alternative splicing. We examined the expression of A2 and B1 in normal adrenal cortex and tumors. B1 was variably expressed in the zona fasciculata-reticularis, although A2 was diffusely expressed in the three zones. B1 was more abundant in compact cells than clear cells, and B1 expression was frequent in the zona reticularis, which consists mainly of compact cells. In three kinds of cortical adenomas autonomously producing hormones, B1 was generally overexpressed and there were no significant differences among them. In cortisol-producing tumors, non-tumor parts of the cortex, which were generally atrophic due to low ACTH, had less B1 protein than normal adrenals. These results suggested a correlation between B1 expression and the hormonal activity responding to ACTH. In vitro ACTH stimulation induced a biphasic expression of B1 in an H295R cortical carcinoma cell line, and it paralleled hormonogenesis. Conclusively, B1 expression varied in relation to the hormonal activity responding to the ACTH, and it may provide a key to elucidating the splicing mechanisms involved in hormonogenesis.

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Khan, H., LG Jiang, GN Jayashree, TA Yarney et MR Sairam. « Recognition of follicle stimulating hormone (alpha-subunit) by a recombinant receptor protein domain coded by an alternately spliced mRNA and expressed in Escherichia coli ». Journal of Molecular Endocrinology 19, n^o 2 (1 octobre 1997) : 183–90. http://dx.doi.org/10.1677/jme.0.0190183.

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To assess the functional significance of putative proteins encoded by alternately spliced mRNA of the sheep testicular FSH receptor, a short form cDNA comprising of the first four exons (117 residues mature protein) was engineered for expression in Escherichia coli. The expressed protein of molecular mass 15 kDa was purified to homogeneity and verified by reaction with an antibody against a synthetic peptide sequence unique to the amino (N)-terminal region FSH receptor. The purified FSH receptor domain protein bound 125I-labeled hFSH in a ligand blot on polyvinylidine difluoride membranes. Further analyses by slot blot revealed high affinity of the immobilized protein with significant reaction at 10 pmol. As the immobilized receptor protein also reacted with structurally related hormones (125I-labeled LH/125I-labeled human chorionic gonadotropin), we confirmed that interaction most probably occurred via the common alpha-subunit of these glycoprotein hormones. Our results reveal that this N-terminal portion of the FSH receptor contain(s) major site(s) for hormone recognition that could be mediated via the alpha-subunit. A rabbit antibody to the receptor inhibited FSH action in receptor bearing cells, revealing the utility of such recombinant FSH receptor protein(s) for modulation of hormone action.

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Engels, J. W., J. Glauder, H. Müllner, D. Tripier, E. Uhlmann et W. Wetekam. « Enzymatic amidation of recombinant (Leu27) growth hormone releasing hormone-Gly45 ». "Protein Engineering, Design and Selection" 1, n^o 3 (1987) : 195–99. http://dx.doi.org/10.1093/protein/1.3.195.

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LeBlanc, Sacha, Erik Höglund, Kathleen M. Gilmour et Suzanne Currie. « Hormonal modulation of the heat shock response : insights from fish with divergent cortisol stress responses ». American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 302, n^o 1 (janvier 2012) : R184—R192. http://dx.doi.org/10.1152/ajpregu.00196.2011.

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Acute temperature stress in animals results in increases in heat shock proteins (HSPs) and stress hormones. There is evidence that stress hormones influence the magnitude of the heat shock response; however, their role is equivocal. To determine whether and how stress hormones may affect the heat shock response, we capitalized on two lines of rainbow trout specifically bred for their high (HR) and low (LR) cortisol response to stress. We predicted that LR fish, with a low cortisol but high catecholamine response to stress, would induce higher levels of HSPs after acute heat stress than HR trout. We found that HR fish have significantly higher increases in both catecholamines and cortisol compared with LR fish, and LR fish had no appreciable stress hormone response to heat shock. This unexpected finding prevented further interpretation of the hormonal modulation of the heat shock response but provided insight into stress-coping styles and environmental stress. HR fish also had a significantly greater and faster heat shock response and less oxidative protein damage than LR fish. Despite these clear differences in the physiological and cellular responses to heat shock, there were no differences in the thermal tolerance of HR and LR fish. Our results support the hypothesis that responsiveness to environmental change underpins the physiological differences in stress-coping styles. Here, we demonstrate that the heat shock response is a distinguishing feature of the HR and LR lines and suggest that it may have been coselected with the hormonal responses to stress.

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Hooley, R., SJ Smith, MH Beale et RP Walker. « In vivo Photoaffinity Labelling of Gibberellin-Binding Proteins in Avena fatua Aleurone ». Functional Plant Biology 20, n^o 5 (1993) : 573. http://dx.doi.org/10.1071/pp9930573.

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It is generally accepted that specific recognition between plant hormones and proteins involved in their biosynthesis, metabolism, transport and perception are of profound importance in the hormonal regulation of plant growth and development. The identification and detailed characterisation of hormone-binding proteins which perform these functions is an important component of research that aims to understand plant hormone action. In this report the development of photoaffinity reagents for gibberellin (GA)-binding proteins is reviewed, and their use as probes with which to identify and characterise GA-binding proteins in Avena fatua aleurone is described. In vivo GA-photoaffinity labelling of aleurone layers, using the new photoaffinity probe GA4-17-sulfoxyethyl-p-azido-[125I]-iodosalicylate, leads to the covalent attachment of this reagent to numerous aleurone polypeptides. Biologically active and inactive GAs used as competitors during in vivo GA-photoaffinity labelling help discriminate between specific and non-specific binding. The biologically active GA4 and GA4-17-yl-1′- (1′-thia)propan-3′-ol-4-azido-5-iodosalicylate compete for photoaffinity labelling of a 60 kDa aleurone polypeptide, while the inactive GAs does not. These GA-photoaffinity labelling characteristics suggest that the 60 kDa aleurone polypeptide may interact specifically with active GAS. This is the first report to identify a specific GA-binding protein in aleurone. We suggest that this specific interaction observed in vivo, under conditions where the aleurone cells are responding to the GA-photoaffinity probe by expressing α-amylase genes, may be of significance in the perception and action of GA in this tissue.

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Suneja, Manish, Daryl J. Murry, John B. Stokes et Victoria S. Lim. « Hormonal regulation of energy-protein homeostasis in hemodialysis patients : an anorexigenic profile that may predispose to adverse cardiovascular outcomes ». American Journal of Physiology-Endocrinology and Metabolism 300, n^o 1 (janvier 2011) : E55—E64. http://dx.doi.org/10.1152/ajpendo.00438.2010.

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To assess whether endocrine dysfunction may cause derangement in energy homeostasis in patients undergoing hemodialysis (HD), we profiled hormones, during a 3-day period, from the adipose tissue and the gut and the nervous system around the circadian clock in 10 otherwise healthy HD patients and 8 normal controls. The protocol included a 40-h fast. We also measured energy-protein intake and output and assessed appetite and body composition. We found many hormonal abnormalities in HD patients: 1) leptin levels were elevated, due, in part, to increased production, and nocturnal surge in response to daytime feeding, exaggerated. 2) Peptide YY (PYY), an anorexigenic gut hormone, was markedly elevated and displayed an augmented response to feeding. 3) Acylated ghrelin, an orexigenic gut hormone, was lower and did not exhibit the premeal spike as observed in the controls. 4) neuropeptide Y (NPY), a potent orexigenic peptide, was markedly elevated and did not display any circadian variation. 5) Norepinephrine, marginally elevated, did not exhibit the normal nocturnal dip. By contrast, α-melanocyte-stimulating hormone and glucagon-like peptide-1 were not different between the two groups. Despite these hormonal abnormalities, HD patients maintained a good appetite and had normal body lean and fat mass, and there was no evidence of increased energy expenditure or protein catabolism. We explain the hormonal abnormalities as well as the absence of anorexia on suppression of parasympathetic activity (vagus nerve dysfunction), a phenomenon well documented in dialysis patients. Unexpectedly, we noted that the combination of high leptin, PYY, and NPY with suppressed ghrelin may increase arterial blood pressure, impair vasodilatation, and induce cardiac hypertrophy, and thus could predispose to adverse cardiovascular events that are the major causes of morbidity and mortality in the HD population. This is the first report attempting to link hormonal abnormalities associated with energy homeostasis to adverse cardiovascular outcome in the HD patients.

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HENDRY, KAY A. K., AMANDA J. MacCALLUM, CHRISTOPHER H. KNIGHT et COLIN J. WILDE. « Effect of endocrine and paracrine factors on protein synthesis and cell proliferation in bovine hoof tissue culture ». Journal of Dairy Research 66, n^o 1 (février 1999) : 23–33. http://dx.doi.org/10.1017/s0022029998003288.

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Laminitis is a major cause of lameness in dairy cattle, and is widely attributed to a defect in the horny tissue that gives the hoof its mechanical strength. Defective horn is associated with, and may be preceded by, impaired keratin deposition in the hoof epidermis. The cause of abnormal keratin deposition is not easily identified but, like epidermal keratinization in other tissues, is likely to be controlled by hormones and the paracrine action of locally produced growth factors. The hormonal regulation of keratin synthesis and cell proliferation in the bovine hoof was studied using tissue explants in organ culture. As the highest incidence of laminitis is in early lactation, the study focused on insulin, cortisol and prolactin, three hormones implicated in lactogenesis and galactopoiesis. Incubation of tissue explants for 24 h in medium containing insulin (10–5000 ng/ml) stimulated protein synthesis measured by incorporation of 35 S-labelled amino acids. Histochemical examination showed that insulin binding co-localized with the site of protein synthesis. Insulin also stimulated DNA synthesis, an index of cell proliferation, which was measured by incorporation of [3H]methyl thymidine. Cortisol (10–5000 ng/ml) decreased protein synthesis, whereas prolactin (10–5000 ng/ml) had no significant effect on protein or DNA synthesis. Epidermal growth factor (10–200 ng/ml), a potent inhibitor of keratinization in other tissues, stimulated protein synthesis compared with untreated controls. Epidermal growth factor binding was located microscopically to the germinal and differentiating epidermal layers. SDS-PAGE and fluorography showed that the population of proteins synthesized in the presence of any hormone or growth factor combination did not differ from that in untreated controls and included the keratins involved in horn deposition. The results show that bovine hoof keratinization is under endocrine and growth factor control, and suggest that systemic changes in lactogenic hormones may act to inhibit keratin deposition.

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Nicholls, P. K., C. A. Harrison, L. O'Donnell et P. G. Stanton. « 148. HORMONAL REGULATION OF miRNA IN THE TESTIS ». Reproduction, Fertility and Development 21, n^o 9 (2009) : 66. http://dx.doi.org/10.1071/srb09abs148.

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Acute suppression of circulating reproductive hormones (FSH and testosterone) inhibits sperm release (spermiation) (1), although the molecular mechanisms of spermiation failure are poorly understood. Micro-RNAs (miRNAs) are small non-coding RNAs that regulate protein expression, and are essential for normal spermatogenesis. Recent studies suggest that miRNAs are exquisitely sensitive to hormonal control by FSH, LH and testosterone (2–4). This suggests that hormonal regulation of miRNAs in the testis following acute hormonal suppression may contribute to spermiation failure. Therefore, we hypothesised that gonadotrophin regulated miRNAs control spermiation outcome. We used array analysis to show that miRNA expression is hormonally regulated by FSH and testosterone in our rat in vivo model of spermiation failure and also in primary rat Sertoli cells by. qPCR validation revealed that miR-7b, -23a, -30c, -125b, -148b, -197, -483, -592, and -690 are all hormonally sensitive testicular miRNAs. Bioinformatic analyses of potential gene targets of these miRNAs predicted numerous protein components localised in the testicular tubulobulbar complex (TBC). The TBC is a podosome-like structure found between Sertoli cells and adjacent germ cells in the testis, and is thought to internalise intact inter-cellular structures and regulate spermatid head shape prior to spermiation. WASP, a TBC protein that regulates actin filament dynamics, contained a conserved binding site for miR-690 within its 3'UTR. Increased miR-690 expression following hormone suppression corresponded to a decrease in WASP protein expression in vivo and in vitro. In addition, transfection of miR-690 into HEK293T cells down-regulated WASP protein. Our results suggest that following hormone suppression, miR-690 is stimulated in the Sertoli cell, thereby inhibiting WASP protein expression. We conclude that miRNA-mediated disruption of TBC integrity potentially regulates spermatid disengagement. This study describes new molecular mechanisms in the testis that may control spermiation outcome of potential significance in male hormonal contraception.

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Hansen, Mette. « Female hormones : do they influence muscle and tendon protein metabolism ? » Proceedings of the Nutrition Society 77, n^o 1 (29 août 2017) : 32–41. http://dx.doi.org/10.1017/s0029665117001951.

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Due to increased longevity, women can expect to live more than one-third of their lives in a post-menopausal state, which is characterised by low circulating levels of oestrogen and progesterone. The aim of this review is to provide insights into current knowledge of the effect of female hormones (or lack of female hormones) on skeletal muscle protein turnover at rest and in response to exercise. This review is primarily based on data from human trials. Many elderly post-menopausal women experience physical disabilities and loss of independence related to sarcopenia, which reduces life quality and is associated with substantial financial costs. Resistance training and dietary optimisation can counteract or at least decelerate the degenerative ageing process, but lack of oestrogen in post-menopausal women may reduce their sensitivity to these anabolic stimuli and accelerate muscle loss. Tendons and ligaments are also affected by sex hormones, but the effect seems to differ between endogenous and exogenous female hormones. Furthermore, the effect seems to depend on the age, and as a result influence the biomechanical properties of the ligaments and tendons differentially. Based on the present knowledge oestrogen seems to play a significant role with regard to skeletal muscle protein turnover. Therefore, oestrogen/hormonal replacement therapy may counteract the degenerative changes in skeletal muscle. Nevertheless, there is a need for greater insight into the direct and indirect mechanistic effects of female hormones before any evidence-based recommendations regarding type, dose, duration and timing of hormone replacement therapy can be provided.

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Somogyi, Virág, Tamás L. Horváth, István Tóth, Tibor Bartha, László Vilmos Frenyó, Dávid Sándor Kiss, Gergely Jócsák, Annamária Kerti, Frederick Naftolin et Attila Zsarnovszky. « Bisphenol A influences oestrogen- and thyroid hormone-regulated thyroid hormone receptor expression in rat cerebellar cell culture ». Acta Veterinaria Hungarica 64, n^o 4 (décembre 2016) : 497–513. http://dx.doi.org/10.1556/004.2016.046.

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Thyroid hormones (THs) and oestrogens are crucial in the regulation of cerebellar development. TH receptors (TRs) mediate these hormone effects and are regulated by both hormone families. We reported earlier that THs and oestradiol (E2) determine TR levels in cerebellar cell culture. Here we demonstrate the effects of low concentrations (10–10 M) of the endocrine disruptor (ED) bisphenol A (BPA) on the hormonal (THs, E2) regulation of TRα,β in rat cerebellar cell culture. Primary cerebellar cell cultures, glia-containing and glia-destroyed, were treated with BPA or a combination of BPA and E2 and/or THs. Oestrogen receptor and TH receptor mRNA and protein levels were determined by real-time qPCR and Western blot techniques. The results show that BPA alone decreases, while BPA in combination with THs and/or E2 increases TR mRNA expression. In contrast, BPA alone increased receptor protein expressions, but did not further increase them in combination with THs and/or E2. The modulatory effects of BPA were mediated by the glia; however, the degree of changes also depended on the specific hormone ligand used. The results signify the importance of the regulatory mechanisms interposed between transcription and translation and raise the possibility that BPA could act to influence nuclear hormone receptor levels independently of ligand–receptor interaction.

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Gencheva-Angelova, Irena I., Adelaida L. Ruseva et Juli I.Pastuhov. « Laboratory Assessment of Thyroid Function in Patients with Proteinuria ». Journal of Biomedical and Clinical Research 10, n^o 2 (1 décembre 2017) : 126–29. http://dx.doi.org/10.1515/jbcr-2017-0020.

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Summary Significant losses of functional proteins such as hormones and hormone-binding proteins are seen in patients suffering from proteinuria. Studies have reported loss of thyroid hormones and thyroxine-binding globulin in the urine. There is evidence that subclinical hypothyroidism is six times more common in patients with proteinuria than in healthy people. The parameters of the effect of proteinuria on thyroid function have not been fully studiedyet.We investigated 74 patients with qualitatively established proteinuria, of whom 34 men and 40 women, without diagnosed thyroid disease. The average age of the patients was 60.9 years. We tested 20 free controls for free thyroxine (FT4), thyroid stimulating hormone (TSH), creatinine and albumin in serum, and the quantity of urine protein. The mean results found for TSH were higher in the patients with proteinuria than in those of the controls (2.719 mU/l vs 1.78 mU/l). For FT4, the mean result in the patients with proteinuria was 17.04 pmol/l vs 16.39 pmol/l. in the controls. A correlation was sought between TSH and FT4 levels and all the laboratory parameters we tested. Patients with proteinuria had higher TSH levels, probably due to the loss of thyroid hormones in the urine. However, these losses cannot lead to clinically proven hypothyroidism.

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