Letteratura scientifica selezionata sul tema "Corpus luteum persistens"

Zusammenfassung Ziel der Untersuchung: Überprüfung der Wirksamkeit von DL-Cloprostenol vs. D-Cloprostenol in der Östrusinduktion bei Milchrindern. Probanden und Methoden: Das Probandenkollektiv umfasste 134 Rinder im Durchschnittsalter von 4,0 ± 0,5 Jahren (99 in Laktation, 35 Färsen). Vor alternierender Injektion zweier Cloprostenolpräparate (Gruppe A: DL-Cloprostenol, 500 μg, n = 70; Gruppe B: D-Cloprostenol, 150 μg, n = 64) wurde die Progesteronkonzentration im Serum bestimmt. Gynäkologische Kontrollen erfolgten 0–3 d post injectionem (p. inj.), wobei die als inseminationsfähig beurteilten Probanden (n = 123) am dritten Tag besamt wurden. Ergebnisse: In beiden Gruppen kam es bis zum dritten Tag p. inj. zu einer deutlichen Konsistenzänderung oder Regression der Corpora lutea (p ≤ 0,001). Die Lysis eines C. l. periodicum verlief bei Kühen markanter als bei Färsen (p ≤ 0,017). Insgesamt war D-Cloprostenol dem DL-Cloprostenol hier leicht überlegen. Am dritten Tag p. inj. wiesen 67,1% (A) bzw. 71,9% (B) der Probanden gut ausgeprägte Östrusanzeichen auf. Als inseminationsfähig wurden 94,3% (A) und 89,1% (B) der Tiere eingestuft. Ein geringer Präparateunterschied bestand hinsichtlich des Graviditätsresultates. Bei einem C. l. persistens verlief die Regression weniger progressiv als bei einem C. l. periodicum (p ≤ 0,024). Signifikante Wechselwirkungen zwischen den Einflussfaktoren Präparat und Indikation einerseits sowie für die übrigen gynäkologischen Kriterien andererseits ergaben sich nicht. Bei den Probanden mit prostaglandininduziertem Zyklus nach einem C. l. persistens lag die Graviditätsrate nach der 1. KB deutlich niedriger (31,9%) als bei Tieren nach Lysis eines C. l. periodicum (52,4%, p = 0,08). Schlussfolgerungen und klinische Relevanz: Der Einsatz von D-Cloprostenol erbringt im Wesentlichen die Resultate wie der von DL-Cloprostenol. Eine Überlegenheit konnte jedoch für die Progressivität der lytischen Wirkung des D-Cloprostenols festgestellt werden. Kühe mit C. l. persistens reagierten präparateunabhängig weniger intensiv als solche mit C. l. periodicum.

AbstractA detailed investigation was conducted to identify the main factors influencing the current poor reproductive performance in dairy herds in Northern Ireland. Nineteen herds were selected and a comprehensive database was established, comprising detailed information collected over a 2-year period. Milk progesterone monitoring (no.=1423 cows), based on twice weekly sampling, was included in this on-farm investigation. The mean interval from calving to commencement of luteal activity was 30·1 days and 13·4% (184/1378) of these cows had not commenced luteal activity by day 50post partum. In addition, there was a high incidence of abnormal progesterone profiles: delayed ovulation type I; 15·6% (242/1388), delayed ovulation type II; 11·7% (125/965), persistent corpus luteum type I; 19·4% (212/1121) and persistent corpus luteum type II; 11·9% (70/619). Delayed commencement of luteal activity and abnormal profiles were associated with reduced fertility performance manifested as increased interval to first AI service and ultimately prolonged calving interval. Delayed commencement of luteal activity and abnormal progesterone profiles, with the exception of ‘delayed ovulation type II’ profiles, were not associated with lower conception rates. Assistance at calving was associated with delayed commencement of luteal activity. Delayed commencement of luteal activity and delayed ovulation types I and II profiles were associated with indicators of nutritional stress and poorer production performance in early lactation. Retained foetal membranes were strongly associated with prolonged luteal phases (persistent corpus luteum types I and II profiles). While hormonal therapy may prove useful in treating cows with abnormal milk progesterone profiles, the prevention and treatment of associated diseases and the implementation of good management practices are likely to be more rewarding.

Abstract. Oxytocin (OT), progesterone and prostaglandin F2α (PGF2α) concentrations were measured in the utero-ovarian vein (UOV) of ewes which displayed persistence of the corpus luteum (CL). During the period of expected luteolysis, the frequency of OT and PGF2α pulses in the UOV was significantly (P < 0.005 for both) lower in ewes with persistent CLs, compared with ewes that underwent normal luteal regression. In contrast, the amplitude of both OT and PGF2α pulses was similar in both groups of animals. It is suggested that persistence of the CL resulted from a decreased PGF2α pulse frequency, which may have arisen from a decreased frequency of stimulation by OT. In two persistent CL ewes, however, it appeared that a failure at the level of the uterus may have contributed to the observed decrease in PGF2α release. Although a PGF2α analogue (Lutalyse) infusion into the uterine vein of two ewes with persistent CLs failed to induced luteolysis, it did stimulate a large release of OT into the UOV. This suggests that persistent CLs maybe more resistant to PGF2α and, that at day 22 post-oestrus, these CLs are capable of releasing large quantities of OT into the UOV.

ABSTRACT The characteristics of the binding of 125I-labelled human GH (hGH) and ovine prolactin (oPRL) were studied in the ovine corpus luteum. Although oPRL is the homologous ligand for sheep lactogenic receptors, its binding was significantly and consistently lower than that of 125I-labelled hGH. This was not due to iodination damage of oPRL since: (1) 125I-labelled oPRL tracers which bound poorly relative to 125I-labelled hGH in the ovine corpus luteum were equipotent in the pig and rat corpus luteum, (2) the differences between 125I-labelled hGH and oPRL binding persisted with tracers of equivalent biopotency and (3) the iodination procedure affected neither oPRL bioactivity in the Nb2 tumour assay nor its binding activity with ovine corpus luteum receptors. Ovine luteal receptors were specific for lactogenic hormones. The specific binding of 125I-labelled hGH or oPRL could be inhibited completely by incubation with either unlabelled hormone, with similar potencies. However, oGH inhibited binding only at much higher concentrations, consistent with its known contamination with oPRL. Moreover, 125I-labelled oGH was not bound specifically to sheep luteal tissue. Fractionation of sheep luteal homogenates on sucrose density gradients (with or without cell-surface membrane perturbation by digitonin) demonstrated that binding of 125I-labelled hGH and 125I-labelled oPRL peaked in the same regions of the gradients, coincident with a number of luteal cell-surface membrane markers. We conclude that the marked discrepancy between the binding of hGH and oPRL tracers by sheep luteal tissue was not due to iodination damage of oPRL, binding of 125I-labelled hGH to somatogenic receptors or differential binding to luteal cell-surface versus intracellular receptors. J. Endocr. (1987) 113, 365–374

Tissue inhibitors of metalloproteinases (TIMPs) are potential regulators of tissue remodeling in the ovary. The aim of the present study was to examine the localization and temporal regulation of TIMP-4 protein in the mouse ovary. An induced superovulation model (eCG/hCG) was employed in immature mice to evaluate TIMP-4 protein expression profiles in ovaries collected during the follicular phase, the pre ovulatory period, and the luteal lifespan. Immunofluorescence results indicated that TIMP-4 protein was localized to theca of both antral and preovulatory follicles and adjacent ovarian stroma. After the initiation of luteinization with hCG, TIMP-4 was observed within the luteinizing granulosa cells and persisted throughout the lifespan of the corpus luteum. In the cycling ovary, TIMP-4 signaling localized to corpus luteum from previous estrous cycles, the theca of preovulatory follicles, and appeared to be lower in newly forming corpus luteum. Western analysis further showed that the levels of TIMP-4 increased significantly during the luteinization process of granulosa cells, but no significant change was found among all corpus luteum stages. A putative regulatory mechanism of TIMP-4 expression was identified utilizing an in vitro model. Treatment of cultured granulosa cells with hCG significantly augmented TIMP-4 protein expression levels. Together our data indicate that the luteinization process of granulosa cells is associated with up-regulation of TIMP-4 and that TIMP-4 might play an essential role in maintenance of the luteal function during the whole lifespan of corpus luteum.

ABSTRACT Northern analysis and in-situ hybridization were used to follow the development of relaxin gene expression in the newly forming corpus luteum (CL) after ovulation and throughout luteal development. Alkaline phosphatase (AP) was used as a marker of theca-derived lutein cells and the relationship between AP-positive and relaxin mRNA-containing cells was assessed. Ovaries from prepubertal pigs treated with pregnant mares serum gonadotrophin (PMSG)/human chorionic gonadotrophin (hCG) were collected during the periovulatory period and at various times during 19 days after ovulation. In addition, CL from cyclic pigs on days 10 and 16 were used to monitor relaxin gene expression in small and large luteal cells. Northern analysis revealed that relaxin gene expression increased with CL development in the PMSG/hCG-treated pig, reaching maximal levels at around day 14 post-ovulation. Thereafter, as the CL regressed, the level of relaxin mRNA declined. In CL from cyclic pigs at day 10 of the cycle, only small luteal cells expressed relaxin mRNA. However, by day 16 of the cycle, large luteal cells were the source of relaxin gene expression. In-situ hybridization studies revealed that in the early CL (up to 30 h post-ovulation), the relaxin gene transcript was observed in cells along the margins of the CL and in the core of the infolding follicle wall corresponding to the AP-positive, luteinized theca cell layer. As luteinization progressed, the theca and granulosa cell layers could no longer be distinguished morphologically (from 54 h after ovulation until day 9). However, the pattern of relaxin hybridization persisted along the periphery in bands of cells penetrating the CL, and coincided with areas of AP staining, indicating that the theca lutein cells were the site of relaxin gene expression. At day 14, relaxin hybridization and AP staining were distributed throughout the luteal tissue. With CL regression both AP staining and relaxin hybridization declined. This pattern of relaxin hybridization in the CL of the gonadotrophin-primed pig was identical to that observed in cyclic pigs on days 10 and 16 of the cycle. These findings indicate that theca interna cells retain their ability to express the relaxin gene following ovulation and luteinization. In the early CL, the small theca-derived lutein cells are the source of relaxin transcript. However, as the CL becomes fully differentiated, the large granulosa-derived lutein cells acquire the capacity to express the relaxin message.

ABSTRACT There is inconclusive evidence that oxytocin acts directly on the corpus luteum and affects steroidogenesis. Since any such action would probably be mediated by oxytocin receptors, these should be present in luteal tissue. In this study, homogenates of corpora lutea from both pregnant and non-pregnant ewes were examined for oxytocin receptors by radio-receptor assay. Specific oxytocin binding was not observed in luteal tissue during the oestrous cycle. However specific binding was found in the corpora lutea of pregnant ewes; appearing at a fetal head length of approximately 0·65 cm (about 30 days of pregnancy) and persisting to a head size of 11 cm, the largest size examined in this study. The affinity (Kd) of the receptor was calculated as 2·9 ± 0·3 nmol/l (s.e.m.; n = 9), a value similar to that obtained for the uterus. The receptor number ranged from a low of 8·7± 3·2 fmol/mg protein (n = 6) at a head size of <0·65 cm, to a maximum of 40·1 ± 6·5 fmol/mg protein (n = 25) at a head size of 2·5–3·75 cm. These values were lower than our estimate of 588 ± 39 fmol/mg protein (n = 5) for the uterus. It is concluded that a direct action of oxytocin on the corpus luteum is possible but only after the first month of pregnancy and not in the corpus luteum of the oestrous cycle. Journal of Endocrinology (1989) 121, 117–123

The distribution of gelatinases/matrix metalloproteinases-2 and -9 (MMP-2 and MMP-9) and tissue inhibitor of metalloproteinase-1 (TIMP-1) in neonatal and gonadotropin-primed immature rat ovaries was studied by immunofluorescent microscopy. Immature female Long-Evans rats were primed with 15 IU pregnant mare's serum gonadotropin (PMSG) in 100 microliters PBS. Two days later, to induce ovulation, the rats were injected with human chorionic gonadotropin (hCG, 5 IU/100 microliters PBS). The animals were killed at appropriate times and the ovaries removed and processed for cryostat or paraffin sectioning. Ovaries were also obtained from 7-day-old neonatal rats and processed as above. In the neonatal rat ovary, MMP-2 was present in the follicle and in the ovarian surface epithelium. MMP-9 was not detectable in the neonatal ovary. TIMP-1 was present in the oocyte and in the surface epithelium. In the PMSG-primed ovary, MMP-2 was present in the granulosa and thecal cells of the ovary. MMP-9 distribution, however, was restricted to the interstitial and thecal cells. TIMP-1 was mainly present in the blood vessels and thecal cells, with minor staining in the granulosa cells. In the developing corpus luteum, luteal and endothelial cells were positive for MMP-2. MMP-9 localization was restricted to the plasma membrane of the luteal and interstitial cells. TIMP-1 was clearly observed in the luteal capillaries and, to a lesser extent, in the luteal cell plasma membrane. This distribution of MMP-2, MMP-9, and TIMP-1 in the corpus luteum persisted throughout the life span of the corpus luteum. The spatial and temporal distribution of the gelatinases and TIMP-1 suggests unique roles for these proteins in the rat ovary.

The article considers the unique, not described in the domestic scientific and educational literature, the dishormonal pathology of the reproductive sphere of goats. The disease is characterized by prolonged anaphrodisia, the persistence of one or more functionally active corpus luteum in the ovaries and hydrometra - volumetric increase in the size of the uterus due to effusion of sterile serous fluid into its cavity. Hydrometra is a leading diagnostic sign of the disease. The research aimed to analyze the data of foreign literature on epidemiology, pathophysiology, diagnostics, and therapy of false pregnancy (hydrometra) in goats. Based on the analysis of foreign literature data, the epidemiological characteristics of the disease were determined. It was found that the hydrometra is a fairly common pathology and is recorded on average in 4.2% of goats. The risk group includes goats aged 6...8 years and older. A hereditary (familial) predisposition of milk goats to the development of hydrometra was revealed. Iatrogenic factors also have a significant effect on the frequency of incidence: hormonal treatment of goats during and/or out the estrous season with progestins alone or in combination with gonadotropin in the serum of mares. The etiology of pseudopregnancy, as well as the cause-effect relationship between the persistence of the corpus luteum and the development of hydrometra have not been fully established. Retention of the corpus luteum always precedes and accompanies the development of hydrometra. Spontaneous regression of the persistent corpus luteum leads to interruption of pseudopregnancy and emptying of hydrometra. Violation of the external regulation with prostaglandin of the functional activity of the corpus luteum, apparently, plays a pivotal role in the pathogenesis of the disease. According to the profile of progesterone in the blood, it was found that the duration of false pregnancy is an average of 150.3±23.5 days. Visual echography is the main diagnostic method of false pregnancy. The diagnosis of the disease is based on the detection of hypoechoic fluid in the uterine cavity in the absence of placentas and fetuses in the uterus. Prostaglandin therapy is a pathogenetically substantiated and quite effective method of treating hydrometra.

Measurements of ovarian, corpus luteum, follicles of Lithuanian Black and White and German Black and White breed cows made by ultrasound scanner were revised. Effect of different factors, such as age, breed and season determining persistence of corpus luteum was statistically evaluated. Validation of treatment efficacy of persistent corpus luteum was carried out based on testing of progesterone concentration in peripheral blood plasma.

Persistent corpus luteum (PCL) is one cause of infertility in mares. However, its nature is poorly understood. Furthermore, role of oxytocin during luteolysis is not clear. A series of experiments were conducted (1) to characterize PCL and to compare PCL with interovulatoryintervals (IOIs) and (2) to evaluate the role of oxytocin during luteolysis. The induction of PCL was also attempted using a PGF2α secretion inhibitor. Oxytocin was used to induce luteolysis. Progesterone (P4) concentration decreased in IOI and PCL until Day 14 postovulation and then diverged, whereas PGFM concentration did not differ between groups. Transient P4 depressions were observed during PCL. Before the end of luteolysis P4 concentration was less in PCL than IOI. Inhibition of PGF2α secretion caused a 1-day increase in the length of the luteal phase. Oxytocin caused a P4 decrease within 8-hours and a PGFM increase within 1- hour after infusion and induced partial luteolysis; Controlo da luteólise na égua Resumo: O corpo lúteo persistente (PCL) é uma causa de infertilidade em éguas, no entanto a sua origem não é conhecida. Além disso, o papel da oxitocina na luteólise na égua não está claro. Foram realizados estudos para (1) caracterizar o PCL e comparar o PCL com intervalos-entreovulações fisiológicos (IOI) e (2) determinar o papel da oxitocina na luteólise. A indução do PCL foi tentada através da inibição da secreção de PGF2α. A oxitocina foi utilizada para induzir a luteólise. A progesterona (P4) diminuiu em éguas com IOI e PCL até ao dia 14 pósovulação divergindo entre grupos posteriormente; a PGFM não diferiu entre grupos. Foram observadas diminuições transitórias de P4 na presença de PCL. Antes da luteólise a P4 era menor em éguas com PCL comparado com IOI. A inibição da secreção de PGF2α aumentou em 1 dia a duração da fase lútea. A oxitocina diminuiu a P4 em 8 horas e aumentou a PGFM em 1 hora após o início da infusão, causando luteólise parcial.

Em programas de transferência de embriões, as perdas embrionárias após a inovulação têm sido relacionadas com uma capacidade reduzida do corpo lúteo (CL) em secretar progesterona (P4), uma vez que este hormônio prepara o endométrio para a implantação e a manutenção da prenhez. Assim, o objetivo deste trabalho foi estudar a eficácia da utilização de dispositivo intravaginal contendo progesterona (CIDR®) por 14 dias em receptoras de embrião, para a indução de folículos persistentes e formação de CLs maiores do que aqueles formados com a utilização de CIDR® por 8 dias. Duzentas e setenta e oito novilhas Bos taurus x Bos indicus foram divididas em 4 grupos. As receptoras do Grupo 1 (G1, n = 70) receberam 2,0 mg de BE + 50 mg de P4 por via intramuscular (IM) no dia da colocação do CIDR® (D0), oito dias depois (D8), o dispositivo foi retirado e foi aplicado um análogo da prostaglandina F2 alfa (PGF2 alfa - 0,53 mg de Cloprostenol Sódico) IM pela manhã. No D9, foi aplicado 0,5 mg de BE IM e o D17 foi o dia da inovulação. Os animais do Grupo 2 (G2, n = 71) receberam 2,0 mg de BE + 50 mg de P4 no dia da colocação do CIDR® (D0), todavia, esses animais receberam 2 aplicações de PGF2 alfa, uma no início do tratamento e outra 5 dias depois. Nestes animais, o CIDR® foi mantido por 14 dias; assim, no D15 foi aplicado 0,5 mg de BE e o dia da inovulação, foi o D23. No Grupo 3 (G3, n = 67), o tratamento foi semelhante ao do G2, no entanto a PGF2 alfa foi aplicada uma única vez, 5 dias após o início do tratamento. No Grupo 4 (G4, n = 70), o tratamento foi semelhante ao do G2, tendo os animais recebido 2 aplicações de PGF2 alfa, uma no dia da colocação do CIDR® e outra no dia da retirada. A avaliação ultrassonográfica dos ovários foi realizada um dia após a retirada do CIDR® e no dia da inovulação, quando foram colhidas amostras de sangue para dosagem de P4. O diâmetro médio do folículo dominante (FD) foi maior nos grupos G2, G3 e G4 quando comparado com o grupo G1. A área do CL, a concentração plasmática de P4 e a taxa de aproveitamento foram maiores nos grupos G2 e G3 que no grupo G1, enquanto o grupo G4 não diferiu estatisticamente dos demais. A taxa de concepção nos grupos G2 e G3 foi inferior àquela do grupo G1, mas não diferiu entre o grupo G4 e os demais. A taxa de prenhez não apresentou diferença estatística entre os grupos. Esses resultados sugerem que a utilização de CIDR® por tempo prolongado, quando associada à aplicação de PGF2 alfa no início do tratamento, é eficaz na formação de folículos persistentes, que resultam em CLs aumentados e com maior capacidade de secretar P4 . No entanto, ao contrário do esperado, a taxa de concepção foi reduzida nos grupos em que o tratamento visava a formação de folículos persistentes.
Embryo losses in cattle embryo transfer programs have been related to a corpus luteum (CL) inability to secrete progesterone (P4), necessary to endometrial preparation for embryo implantation and pregnancy maintenance. Thus the objective of this experiment was to evaluate the efficacy of a treatment with progesterone-releasing intravaginal devices (CIDR®) for a period of 14 days in order to induce the formation of a persistent follicle and a CL of larger diameter than the ones produced during the conventional 8 days CIDR® treatment. Two hundred seventy-eight cross-bred Bos taurus x Bos indicus heifers were randomly allocated in four groups. Heifers in Group 1 (G1, n = 70) received 2.0 mg estradiol benzoate (EB) + 50 mg of P4 at the moment of CIDR® insertion (D0), a 0.53 mg injection of cloprostenol (PGF2 alfa analogous) at the time of CIDR® removal (D8) and 0.5 mg EB on D9. On D17 animals received a frozen/thawed embryo by direct transfer. Heifers in Group 2 (G2, n = 71) received a CIDR® device combined with 2.0 mg of EB + 50 mg of P4 (D0). Animals of this group received 2 injections of PGF2 alfa, one on D0 and the other on D5. The CIDR® was removed on D14. A 0.5 mg injection of EB was administered on D15. The treatment in Group 3 (G3, n = 67) was similar to G2, except by the fact that a single injection of PGF2 alfa was administered on D5. Treatment performed on animals of Group 4 was similar to the one performed on G2. However, animals of this group received two injections of PGF2 alfa, one at the time of CIDR® insertion and the other at the moment of it?s removal. Ovarian ultrasonography was performed on the day after CIDR® removal and at the day of embryo transfer. Blood samples for P4 analysis were also collected on the day of embryo transfer. Mean diameter of the dominant follicle was larger in heifers in G2, G3 and G4 when compared to G1. The CL area, plasma progesterone concentrations and recipient selection rate was greater in G2 and G3 than in G1, but G4 was not different of the other groups. Conception rates were lower in G2 and G3 when compared to G1. No differences between groups were found regarding to the pregnancy rates. These results suggest that a CIDR® long-term treatment, when associated with PGF2 alfa in the beggining of the treatment is efficient to stimulate the formation of a persistent follicle, resulting in a larger CL which provides higher P4 concentration. However, the induction of a persistent follicle had a negative effect on the conception rates which was not expected.