Dissertations / Theses on the topic 'Diet-induced'

Obesity results from expansion of white adipose tissue. The inability of white adipose tissue to adequately store lipids leads to ectopic deposition of lipids in non-adipose tissue that can lead to systemic insulin resistance. It is well known that insulin resistance correlates with inflammation of adipose tissue in obese animals and humans. Decreasing inflammation in the adipose tissue has been proven as a therapeutic strategy for improvement of insulin sensitivity in vivo. Numerous factors secreted by immune cells, including macrophages, have been suggested as regulating adipose tissue insulin sensitivity. In the first part of my thesis, I describe the role of one such factor, CD40 in adipose tissue inflammation. The CD40-CD40L dyad acts as co-stimulation in the interaction of antigen-presenting cells, such as macrophages and dendritic cells, with effector cells, such as T cells, in adaptive immunity. We found that CD40 knockout mice were smaller but surprisingly more insulin resistant and glucose intolerant compared to wild-type mice when fed a high fat diet. Consistent with their metabolic phenotype, knockout mice displayed increased adipose tissue inflammation with infiltration of immune cells including macrophages and T cells. Consistent with increased inflammation, CD40 knockout adipose tissue displayed decreased lipid storage. Deficiency of CD40 also led to increased lipid deposition in liver, which may be due to increased lipid release into circulation from the adipose tissue as well as increased lipid synthesis in the liver. CD40 knockout mice had increased hepatic insulin resistance and increased gluconeogensis despite decreased hepatic inflammation. These findings suggest that CD40 is a novel regulator of adipose tissue inflammation in diet-induced obesity. In the second part of this thesis we examined perivascular adipose tissue and brown adipose tissue for the presence of inflammation. In contrast to visceral adipose tissue, macrophage infiltration was absent in perivascular and brown adipose tissue as defined by reduced F480+ cells by flow cytometry and immunohistochemistry. We also found that perivascular adipose tissue was similar to brown adipose tissue as shown by gross morphology and gene expression pattern. Inflammatory gene expression was not increased in brown or perivascular adipose tissue in obese mice as determined by microarray gene expression analysis. These findings suggest that perivascular adipose tissue is more similar to brown adipose tissue than white adipose tissue and that both perivascular and brown adipose tissue are resistant to inflammation. We conclude that, (1) CD40 protects against adipose tissue inflammation in diet-induced obesity, (2) the CD40 knockout mouse is an interesting model of hepatic steatosis with decreased inflammation and (3) perivascular adipose tissue is almost identical to brown adipose tissue in obese mice and that both are resistant to inflammation.

The studies in this thesis aimed to develop and characterise a rodent model of meal feeding that would mimic aspects of human eating behaviour, leading to the overconsumption of calories and ultimately to obesity. In seeking to identify potential mechanisms that might be involved in the initiation of meals, a palatable scheduled feeding regime was utilised to induce a substantial food intake over short periods of time in rodents. This was done by providing scheduled access to a palatable diet for a 2h-period each day without imposed caloric restriction during the remainder of the day. Initially, the effects of different palatable diets were examined. Three of the four palatable diets resulted in a rapid adaptation of feeding behaviour and induced the consumption of large, binge-type meals in both Sprague Dawley rats and C57BL/6 mice. Candidate gene expression analysis by in-situ hybridisation during the two hour period leading up to scheduled feeding suggested that homeostatic neuropeptide systems in the hypothalamus did not have a major role in driving the consumption of these meals. Further characterisation of the scheduled feeding model revealed that palatable scheduled feeding does not lead to a relative hypophagic phase or an increase in pre-meal secreted gut hormones in anticipation of the scheduled meals. Interestingly, schedule-fed animals exhibited food anticipatory activity during the same period. In addition, scheduled-fed animals displayed only a mild obese phenotype but their metabolic health was adversely affected. Again using in-situ hybridisation, candidate gene expression was assessed during the scheduled feeding period itself, revealing a relationship with adiposity level but not with immediate feeding behaviour. Finally, in a ‘hypothesis-free' approach, gene expression was analysed by microarray at the point of initiation of scheduled feeding, with no apparent changes in gene expression levels. In conclusion, palatable scheduled feeding in mice and rats induces large, binge-type meals that appear not to be directly regulated by homeostatic neuropeptides in the hypothalamus. Investigations into forebrain candidate gene expression by in-situ hybridisation suggested that measuring mRNA levels might not be the optimal analytical approach to demonstrate an involvement of the reward-related signalling system. Alternative strategies for identifying meal feeding mechanisms in the palatable scheduled feeding model could focus on approaches such as neurotransmitter release.

Thesis (Honors paper)--Florida State University, 2008.<br>Advisor: Debra Ann Fadool, Ph.D., Florida State University, College of Arts and Sciences, Dept. of Biological Science. Includes bibliographical references.

CTRP3 is a secreted plasma protein of the C1q family that helps regulate hepatic gluconeogenesis and is downregulated in a diet-induced obese state. However, the role of CTRP3 in regulating lipid metabolism has not been established. Here, we used a transgenic mouse model to address the potential function of CTRP3 in ameliorating high-fat diet-induced metabolic stress. Both transgenic and wild-type mice fed a high-fat diet showed similar body weight gain, food intake, and energy expenditure. Despite similar adiposity to wild-type mice upon diet-induced obesity (DIO), CTRP3 transgenic mice were strikingly resistant to the development of hepatic steatosis, had reduced serum TNF-α levels, and demonstrated a modest improvement in systemic insulin sensitivity. Additionally, reduced hepatic triglyceride levels were due to decreased expression of enzymes (GPAT, AGPAT, and DGAT) involved in triglyceride synthesis. Importantly, short-term daily administration of recombinant CTRP3 to DIO mice for 5 days was sufficient to improve the fatty liver phenotype, evident as reduced hepatic triglyceride content and expression of triglyceride synthesis genes. Consistent with a direct effect on liver cells, recombinant CTRP3 treatment reduced fatty acid synthesis and neutral lipid accumulation in cultured rat H4IIE hepatocytes. Together, these results establish a novel role for CTRP3 hormone in regulating hepatic lipid metabolism and highlight its protective function and therapeutic potential in attenuating hepatic steatosis.

Relatively few studies have examined the effects of psychostimulants in obese subjects. Using the dietary obese rat model, the present experiments determined the reductions in food intake (hypophagia) and increases in locomotion (hyperlocomotion) induced by cocaine in diet-induced obese prone (DIO-prone) rats and diet resistant prone (DR-prone) rats as well as diet-induced obese (DIO) rats and diet resistant (DR) rats. In Experiment 1, thirty-six male Sprague-Dawley rats were given intra-peritoneal (i.p.) injections of cocaine (0, 10, 20, and 30 mg/kg) immediately prior to placement into locomotor chambers outfitted with a food source and a water source for a 60-minute test period. In Experiment 2, the same rats were exposed to a high-fat diet, and were subsequently divided into groups according to the extent of the weight gain (high weight gainers œ DIO group, low weight gainers œ DR group, and residual weight gainers œ MIX group). The rats were retested for reactivity to cocaine using conditions similar to those in Experiment 1. Rats injected with cocaine prior to high-fat exposure (Experiment 1) showed a dose dependent suppression of food intake, as well as a dose dependent increase in locomotor activity, with DR-prone rats exhibiting an enhanced degree of cocaine-induced hypophagia, as well as cocaine-induced hyperlocomotion as compared to the other groups. In Experiment 2, DIO rats exhibited a suppression of food intake after injection of 10 mg/kg cocaine, as well as an increase in locomotor activity that was significantly greater than noted in the other groups. When the results of Experiment 1 were analyzed as a function of prospective body weight gain (as opposed to placement into distinct groups), reactivity to cocaine decreased as body weight gain increased. In contrast, after high-fat exposure and weight gain, increased body weight gain was associated with an increased magnitude of suppression in food intake after cocaine administration. Similar patterns of differential cocaine sensitivity were observed for cocaine hyperlocomotion in Experiment 2. These studies indicate that although the propensity to develop obesity is associated with a diminished cocaine response, cocaine reactivity is enhanced after the induction of obesity.

Thesis (Ph. D.)--Illinois State University, 1999.<br>Title from title page screen, viewed July 24, 2006. Dissertation Committee: Steven A. Juliano (chair), Wayne A. Riddle, Scott K. Sakaluk, Charles F. Thompson, Douglas W. Whitman. Includes bibliographical references (leaves 126-133) and abstract. Also available in print.

Thesis (Ph. D.)--University of Missouri-Columbia, 2007.<br>The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on October 16, 2007) Vita. Includes bibliographical references.

Obesity and drug abuse share common neural circuitries including the mesocoticolimbic and striatal dopamine reward system. In the current study, a rat model of diet-induced obesity (DIO) was used to determine striatal dopamine function, impulsivity and motivation as neurobehavioral outcomes and predictors of obesity. For the outcome study, rats were randomly assigned a high-fat (HF) or a low-fat (LF) diet for 8 wk. Following the 8-wk HF-diet exposure, rats were segregated into obesity-prone and obesity-resistant groups based on maximum and minimum body weight gain, respectively, and neurobehavioral outcomes were evaluated. For the predictor study, neurobehavioral antecedents were evaluated prior to an 8-wk high-fat diet exposure and were correlated with subsequent body weight gain. Striatal D2 receptor density was determined by in vitro kinetic analysis of [3H]raclopride binding. DAT function was determined using in vitro kinetic analysis of [3H]dopamine uptake, methamphetamine-evoked [3H]dopamine overflow and no net flux in vivo microdialysis. DAT cell-surface expression was determined using biotinylation and Western blotting. Impulsivity and food-motivated behavior were determined using a delay discounting task and progressive ratio schedule for food-reinforcers, respectively. Relative to obesity-resistant, obesity-prone rats exhibited 18% greater body weight, 42% lower striatal D2 receptor density, 30% lower total DAT expression, 40% lower in vitro and in vivo DAT function, 45% greater extracellular dopamine concentration, and 2-fold greater methamphetamine-evoked [3H]dopamine overflow. Obesity-prone rats exhibited higher motivation for food, but were less impulsive relative to obesity-resistant rats. Neurobehavioral antecedents of DIO included greater motivation for high-fat reinforcers in rats subsequently shown to be obesity-prone relative to obesity-resistant. Impulsivity, DAT function and extracellular dopamine concentration did not predict the DIO-phenotype. Thus, motivation for food is linked to both initiation and maintenance of obesity. Importantly, obesity results in decreased striatal DAT function, which may underlie the maintenance of compulsive food intake in obesity.

Discovery of cheap, nontoxic and readily available antiatherosclerotic drugs is an extraordinary challenge in this modern world. Atherosclerosis and cardiovascular diseases have been predicted to be the leading cause of death by the year 2030. Hence, this thesis was designed to search for plant (s) with anti-atherogenic properties, investigate its possible side effects and extrapolate its likely mechanism(s) of action. An ethnobotanical survey was employed in identification of locally important plants used for the management and treatment of cardiovascular diseases and its predisposing factors in Nkonkobe Municipality, Eastern Cape in South Africa. Information on the names of plants, their parts used and methods of preparation was collected through a questionnaire which was administered to herbalists, traditional healers and rural dwellers. The most frequently used plant (Rhizomes of Tulbaghia violacea Harv.) was investigated for toxicity using brine shrimp lethality (in vitro) and in vivo toxicity test (acute and subchronic) on rats to determine safety dosage. The in vitro antioxidant and free radical scavenging activity of the plant was investigated using models such as 1,1-diphenyl-2- picrylhydrazyl (DPPH), superoxide anions, hydrogen peroxide (H2O2), nitric oxide (NO), 2,2’- azinobis [3-ethylbenzothiazoline-6-sulfonic acid] diammonium salt (ABTS), lipid peroxidation inhibition and the ferric reducing agent. Phytochemical content and the effect of oral administration of fresh methanolic extract rhizomes of Tulbaghia violacea (250, 500 mg/kg. bwt/day) on Lipid peroxidation (TBARS), serum and tissue antioxidant enzymes in normal, hypercholesterolemic and diet induced atherogenic rats were also assessed. More so, the potential of the extract (250 and 500 mg/kg. bwt) to protect against atherogenic diet (4 percentage cholesterol 1 pecentage cholic acid and 0.5 percentage thiouracil) induced fatty streaks formation, dyslipidemia, oxidative stress and endothelial dysfunction was also investigated. Ethnobotanical study revealed that 19 plant species are used for the treatment of heart related diseases in the Municipality. 53 percentage of the plants mentioned were used for the management of chest pain, 47 percentage for high blood pressure, 42 percent for heart disease, 16 percentage for stroke and 11 percentage for the treatment of hypercholesterolemia. Tulbaghia violacea was repeatedly mentioned as the plant species used for the treatment of high blood pressure and predisposing factors in the study area. The brine shrimp cytotoxicity test revealed that fresh, dried methanolic extracts and essential oil of the T. violacea exhibited a high degree of cytotoxic activity with IC50 values of 18.18 (fresh) and 19.24 (dried) μg/ml. An IC50 value of 12. 59 μg/ml was obtained for the essential oil of the plant. The low cytotoxicity values obtained, suggested that rhizome of T. violacea may serve as a potential source of antimicrobial and anticancer agents. In vivo acute study of single oral administration of 5g/kg dose does not produce mortality or significant behavioral changes during 14 days observation. In the sub-chronic study, the extract (250, 500 mg/kg/bwt/ day) administered for a period of 28 days showed no mortality or morbidity. The weekly body and organ weight of the rats showed no significant differences between the control and the rats treated with the extract. The extract at all doses does not show any effect on of biomarkers of liver or renal damage. However, a significant decrease in the activity of ƔGT was observed in the extract treated groups. Hematological evaluation revealed that oral administration of fresh methanolic extracts of rhizomes of T. violacea does not cause anaemia or leucocytosis in the animals. Furthermore, histopathology results of the internal organs revealed no detectable inflammation. These results demonstrated that the rhizome extract of T. violacea was potentially safe for consumption orally even in chronic concentration. In vitro antioxidant evaluation showed that the essential oil, fresh and dried methanolic extracts exhibited potent antioxidant activities in a concentration dependent manner. Phytochemical investigation reveals that the fresh and the dry extract of RTV are rich in flavonoid, flavonol, phenols, tannin and proanthocyanidin, while the essential oil contained dimethy disulfide, dimethyl trisulfide, (methyl methylthio) methyl, 2,4-dithiapentane (11.35 percent) and (methylthio) acetic acid, 2- (methylthio) ethanol, 3-(methylthio) - and propanenitrile (7.20 percent). The fresh extract had higher radicals scavenging activity than the essential oil or dried extract, with 50 percentage inhibition of DPPH, hydrogen peroxide and lipid peroxidation at a concentration of 35.0 ± 0.12, 19.3 ± 0.11 and 17.9 ± 0.15 μg/ml respectively. Oral administration of methanolic extract of RTV in 125, 250 and 500 mg/kg to female Wistar rats significantly inhibited reduction of glutathione (GSH), superoxide dismutase (SOD) and catalase (CAT). The extracts also inhibited (p< 0.05) lipid peroxidation in normal, high cholesterol and diet induced atherosclerosis fed rats in a dose dependant manner. Also the extract (250 and 500 mg/kg/bwt/day) caused a significant (p<0.05) improvement in body weight of treated animals compared with untreated hypercholesterolemia control rats. The extracts also protected significantly (p<0.05) against atherogenic diet induced liver damage or fatty streaks formation in the aorta as revealed by histological examination. The anti-cholesterolemia and anti-atherosclerotic activities of the extract compared favorably well with standard drugs Gemfibrozil and Atorvastatin respectively. Conclusively, rhizomes of T. violacea possess significant anti-atherogenic activity and its mechanism of action(s) may be due to its antioxidant and anti-hypercholesterolemia properties. The results of this study also suggested that rhizome of T. violacea is relatively safe for human consumption and it may be used as an alternative to garlic.

Background: Heart Failure (HF) is characterized by impaired cardiac function with symptoms of dyspnea, fatigue and exercise intolerance. Western diet (WD), a diet high in saturated fats and sugars, causes systemic increase in IL-18, a cytokine elevated in HF, which induces abnormal myocardial structure and diastolic dysfunction. IL-18 binding protein(IL-18BP) binds IL-18, preventing the binding to the IL-18-receptor. We investigated a therapeutic intervention using recombinant-murine IL-18BP to improve the WD-induced cardiomyopathy in C57BL/6J mice. Methods: Echocardiography with pulse-wave Doppler and tissue imaging was performed to assess cardiac function. Oral glucose tolerance test was performed to assess metabolic parameters and IL-18 plasma levels were quantified with ELISA. Results: WD-fed mice had worsened isovolumetric relaxation time (IVRT) and myocardial performance index (MPI), indicating cardiac dysfunction. Daily intraperitoneal injections of 0.5mg/kg IL-18BP for two weeks, significantly improved both IVRT and MPI. Conclusions: IL-18BP treatment improves cardiac function in a model of WD-induced cardiomyopathy.

Ageing and obesogenic diets are two prominent problems in the developed world, as both lead to an increase in body mass and insulin resistance, which can then result in further pathophysiologies, such as type 2 diabetes, cancer and cardiovascular disease. Protein tyrosine phosphatase 1B (PTP1B) contributes to development of body weight gain and insulin resistance through negatively regulating leptin and insulin signalling, respectively. Liver-specific ptp1b deletion from birth improves insulin sensitivity, lipid metabolism and decreases endoplasmic reticulum (ER) stress. However, as a therapy in humans, PTP1B inhibition would target pre-diabetic and diabetic adults; therefore, we investigated the effects of liver-specific inhibition of PTP1B in adult, insulin resistant, obese mice. Restricting the amount of the essential amino acid, methionine, five-fold in the diet, decreases body weight, adiposity and improves insulin sensitivity in young mice. In order to delineate if this would be a feasible treatment in adulthood, we administered the diet to 12-month-old mice with age-induced obesity and insulin resistance and compared its effects to those in 2-month-old mice. As hepatic ptp1b deletion and methionine restriction (MR) both improve hepatic insulin signalling, we investigated if the combined treatment could have additive effects compared to MR alone on whole-body glucose homeostasis. To examine if the effects of MR are methionine-specific or if they would occur with restriction of other EAAs, we compared leucine restriction (LR) to MR in adult mice. Overall, hepatic PTP1B inhibition in adult mice reversed high-fat diet (HFD) -induced glucose intolerance, hepatic lipid accumulation and ER stress. MR administered to 12-month-old adult mice reversed the metabolic effects of ageing back to levels measured in healthy, young, 2-month-old mice. The combination of MR and hepatic ptp1b deletion from birth had no further beneficial effect in male mice, but possibly an additional effect in female mice. MR produced stronger beneficial metabolic effects than LR in mice, suggesting methionine-specific mechanisms may play a role.

The ability of ionizing radiation to enhance colon carcinogenesis and the role of diet in this process has not been documented. We hypothesized that radiation would enhance the formation of aberrant crypt foci, ACF, known precursor lesions to colon cancer, by suppressing apoptosis and upregulating proliferation in colonocytes. Diets contained a combination of fish oil or corn oil and either pectin or cellulose. We exposed 40 male Sprague-Dawley rats to 1 Gy ionizing radiation (1 GeV Fe) 10 d prior to injection with AOM. Colons were resected at the promotion stage of carcinogenesis (7 wk post initial injection) and assayed for ACF and apoptosis. Radiation treatment increased (P=0.0327) the incidence of high multiplicity ACF (foci with four or more aberrant crypts) and decreased (P=0.0340) the apoptotic index compared to non-irradiated rats. Radiation also resulted in an increase (P<0.0001) in the proliferative index compared to the nonirradiated rats. The fish oil containing diets resulted in fewer (P=0.0002) high-multiplicity ACF compared to the corn oil treatment. Dietary pectin significantly increased (P=0.0204) the apoptotic index compared to cellulose treatment. These data suggest that ionizing radiation can work synergistically with AOM and increase the formation of high-multiplicity ACF, upregulate cellular proliferation and decrease apoptosis in colonocytes. The data also suggest that diets containing fish oil and pectin may protect against colon cancer by increasing apoptosis and reducing the formation of high multiplicity ACF.

Biochemical theories postulate that deficient serotonergic functioning may be etiologically related to affective illness and aggressive behavior. In Study I mood and aggressivity were measured in thirty-six normal male subjects before and after ingestion of a Tryptophan Depleted, Tryptophan Loaded or Balanced amino acid mixture. While no differences in aggressivity were found, the Tryptophan Depleted group scored significantly higher at posttest on the MAACL Depression Scale than the control groups and demonstrated selective attention for dysphoric themes. In Study II a Balanced or Tryptophan Depleted amino acid mixture was administered to eighty normal male subjects prior to placing them in either a positive or negative environment, with or without instructions concerning the potential amino acid effects. The tryptophan depleted group became significantly more depressed than the control group regardless of environmental condition or instructional set. These findings suggest that lowered tryptophan may result in a central serotonergic dysfunction which is causally related to depressive affect and possibly to the pathogenesis of clinical forms of depression.

Dietary manipulations and their pharmacological outcomes have been increasingly studied in neurodegenerative diseases. However, a systematic comparison among different methods in validated animal models of Alzheimer's disease is made necessary due to several different approaches applied in recent studies. Moreover, despite the large body of evidence on the effects of calorie restriction (CR) and ketogenic diets (KDs) on amyloid pathology, no consistent data is available on the effects of calorie restriction, ketogenic diet or ketone supplements on tau pathology in transgenic models of AD. Moreover, the ketogenic diet used in our studies was custom made with low carbohydrate content and rich in medium chain triglyceride (MCT) oils, known to be rapidly metabolized in the liver, resulting in sustained peripheral ketosis. Chapter 1 tested the ability of KD to induce significant ketosis in a mouse model of amyloid deposition. We showed that, despite the mild ketosis induced, KD fed APP mice presented subtle behavioral improvement shown as faster learning in the radial arm water maze, making less errors than APP mice kept on a control diet. Additionally, we observed decreased Aβ immunoreactivity in the anterior cortex of KD fed versus control fed APP mice, despite the lack of changes in congophilic deposits. Due to the mild ketosis induced, a modified ketogenic diet was devised with decreased maltodextrin content and showed greater peripheral levels of β-hydroxybutyrate. Chapter 2 investigated the effects of a ketogenic diet in two transgenic mouse models of Alzheimer's pathology. Interestingly, we found that both transgenic lines, regardless of diet, weighed less than nontransgenic mice, despite their elevated food intake. The reduced body weight may, in part, be explained by the increased locomotor activity shown by both transgenic lines in both the open field and y-maze. Moreover, KD fed mice performed significantly better on the rotarod compared to mice on the control diet independent of genotype. We did not observed KD-induced changes in spatial or associative memory in the radial arm water maze or contextual fear conditioning, respectively. Furthermore, immunohistochemical levels of amyloid, tau, astrocytic and microglial markers showed no differences between animals fed KD or the control diet. Chapter 3 studied the effects of calorie restriction on a mouse model of tau deposition. We show here that 35% body weight reduction in Tg4510 mice did not prevent increased locomotor activity in the open field, previously reported in chapter 2. Similarly, CR did not affect motor performance or spatial memory assessed by the rotarod and radial arm water maze, respectively. Interestingly, CR Tg4510 mice showed improved short-term memory tested by the novel object recognition despite spending a minimal percentage of the trial time interacting with the objects presented. However, this improvement was not observed when the test was modified to replace the objects with mice. In this case, we noticed that nontransgenic mice spent most of the trial time interacting with the novel mouse whereas Tg4510 mice spent roughly the same amount of time at any of the areas in the test chamber. Moreover, no changes in histopathological or biochemical levels of tau, astrocytic, microglial or synaptic markers were observed. Chapter 4 sought to investigate alternative approaches to inducing ketosis in the brain by either administering BHB intracerebroventricularly (i.c.v.) or by using the acetoacetate (AcAc) diester as a dietary supplement in mice. We observed that i.c.v administration of BHB in 20 months old APP mice did not affect body weight or food intake. Consistent with the lack of effects on behavioral performance, amyloid and congophilic load were not different between APP mice infused with either saline or BHB. We also found that enteral administration of AcAc diester was well tolerated and induced peripheral ketosis for at least 3 hours. Acute ketosis, however, was not sufficient to attenuate behavioral deficits in old APP mice. Chronic dietary supplementation with AcAc was tested in control tet mice and was shown to effectively induce ketosis in mice fed a diet with normal contents of carbohydrates. Nonetheless, we observed that AcAc-induced ketosis was not significantly greater than levels induced by the ketogenic diet tested in our lab. Considering that KD did not rescue behavioral or histopathological features of either amyloid or tau depositing mouse models, we anticipated that dietary supplementation with AcAc would not likely modify the phenotype of the same mouse models tested previously. Taken together, our findings show that our custom made ketogenic diet was effective in inducing and sustaining ketosis and may play an important role in enhancing motor performance in mice. However, the lack of changes on the cognitive and histopathological phenotype of the models studied suggests that KD may not be a disease modifying therapeutic approach to AD. Moreover, calorie restriction showed inconsistent effects on behavioral and histopathological outcomes of a mouse model of tauopathies. Furthermore, dietary supplementation with acetoacetate diester was successful in inducing peripheral ketosis to the same extend as a ketogenic diet even in the context of normal carbohydrate intake, suggesting that it may be of therapeutic interest for diseases of hypometabolism but not a disease modifying therapy in mouse models of Alzheimer's pathology.

<p> Neuropathy, a debilitating complication of diabetes, has primarily been attributed to poor glycemic control, but has recently been associated with obesity and the metabolic syndrome in nondiabetic individuals. A robust body of evidence indicates that a high-fat diet can induce signs of neuropathy in mice but the pathogenesis of high fat diet-induced neuropathy remains unknown. </p><p> <b>PURPOSE:</b> To determine if neuronal inflammation is a potential initiating mechanism for the development of mechanical hypersensitivity and nerve fiber changes (signs of neuropathy) in high fat fed mice. <b>METHODS: </b> Male C57Bl/6 mice were randomized to a standard (Std, 15% kcal from fat) or high fat diet (HF, 54% kcal from fat) for 2, 4, or 8 wks (n = 11-12 per group). Lumbar dorsal root ganglia were harvested and inflammatory mediators (IL-1&alpha;, IL-1&beta;, IL-2, IL-3, IL-4, IL-5, IL-6, IL-10, IL-12p70, IL-17, MCP-1, IFN-&gamma;, TNF-&alpha;, MIP-1&alpha;, GMCSF, RANTES) were quantified using a Multiplex ELISA and normalized to total protein. Neuropathy was characterized by the von Frey test for mechanical sensitivity at wk 0 and every other week thereafter. Hindpaw foot pad skin was harvested at end study and used to quantify intraepidermal nerve fiber density (IENFD) and pain-sensing (TrkA) nerve fibers via immunohistochemistry. <b>RESULTS:</b> After 8 wks, HF had greater bodyweight (33.3 &plusmn; 1.0 vs. 26.7 &plusmn; 0.5 g, p &lt; 0.001), fasting blood glucose (160.3 &plusmn; 9.4 vs. 138.5 &plusmn; 3.4 mg/dl, p &lt; 0.05) and insulin (3.58 &plusmn; 0.46 vs. 0.82 &plusmn; 0.14 ng/ml, p &lt; 0.001) compared to Std. IL-1&alpha;, RANTES and IL-5 were higher in HF compared to Std after 2 wks and 4 wks, respectively (IL-1&alpha;: 4.8 &plusmn; 1.3 vs. 2.9 &plusmn; 0.6 pg/mg, p &lt; 0.05; RANTES: 19.6 &plusmn; 2.2 vs. 13.3 &plusmn; 1.2 pg/mg p &lt; 0.05; IL-5: 5.8 &plusmn; 0.7 vs. 3.1 &plusmn; 0.5 pg/mg, p &lt; 0.05 ). IENFD and TrkA fiber density were also higher in HF vs. Std after 4 wks (IENFD: 39.4 &plusmn; 1.2 vs. 32.2 &plusmn; 1.3 fibers/mm, p &lt; 0.001; TrkA: 30.4 &plusmn; 1.8 vs. 22.4 &plusmn; 1.3 fibers/mm). There were no significant differences in hindpaw sensitivity for Std vs. HF at any time point. <b>CONCLUSION:</b> Increased inflammatory mediators preceded and accompanied an increase in a specific population of pain sensing nerve fibers (TrkA) in the hindpaw footpad of high fat fed mice. Diets high in fat may increase neuronal inflammation and initiate nerve fiber changes responsible for painful neuropathy in nondiabetic and diabetic individuals.</p><p>

Thesis (M.S.)--University of North Carolina at Chapel Hill, 2008.<br>Title from electronic title page (viewed Dec. 11, 2008). "... in partial fulfillment of the requirement for the degree of Master of Science in the Department of Nutrition." Discipline: Nutrition; Department/School: Public Health.

Non-alcoholic fatty liver disease (NAFLD) results from accumulation of fat in liver, so-called steatosis. Fatty liver may lead to the development of inflammation (steatohepatitis). This study analysed the role of high fat diet, Vitamin D, and complement properdin in mouse models of high fat diet. Properdin knockout mice, and properdin wild type mice on LDLR-/- and LDLR+/+ background were fed a high fat –high sugar diet or Western (high fat) diet. Body weight, fat pad weight, liver histopathology, immunohistochemistry were analysed. Hepatic expression of candidate genes (TNF-α, srebp-1c, TLR4, HMGCR, SR-B1, PPAR-y) was performed by qPCR. ELISA was used to quantify serum insulin, Adiponectin, MDA. Liver function test, endotoxin, complement activation, Western blot were evaluated. in vivo results showed that a high fat–high sugar diet and so-called Western diet led to the development steatosis, inflammation, and properdin has a role in the prevention of obesity, and metabolic syndrome diseases. Vitamin D given to mice fed high fat –high sugar diet led to the prevention of obesity, and associated complications. Exercising mice combined with supplemented Vitamin D had a better effect to prevent metabolic syndrome diseases. in vitro results shown that DHA, Vitamin D, and Allicin had anti-inflammatory roles by reducing TNF-α to LPS stimulation.

Ad libitum high-fat diet (HFD)-induced obesity leads to insulin resistance in skeletal muscle, altered gene expression, and altered growth signaling, all of which contributes to pathological changes in metabolism. Liver kinase B1 (LKB1) is an important metabolism regulator. The purpose of this dissertation was to understand how knocking out LKB1 influences HFD induced adaptations in mouse skeletal muscle. To do so, control and skeletal muscle LKB1 knock-out (LKB1-KO) mice were put on either standard diet (STD) or HFD for 1 week or 14 weeks, or put on the HFD for 14 weeks and then switched to STD for 1 week (switched diet). The major differences in adaptation in the LKB1-KO mice include: 1) lower fasting blood glucose levels but impaired glucose tolerance compared to WT mice (although conflicting results are generated if the data is not normalized to fasting blood glucose levels), 2) altered expression of 16 HFD-induced genes, and 3) decreased muscle weight. The lower fasting blood glucose in LKB1-KO mice was likely due to elevated serum insulin levels, and the impaired glucose tolerance was associated with decreased phosphorylation of TBC1D1, an important regulator of insulin stimulated glucose uptake. 16 potential important target genes (metabolism, mitochondrial, cytoskeleton, cell cycle, cell-cell interactions, enzyme, ion channel) were identified in the context of HFD feeding and LKB1-KO. These genes were quantified by RT-PCR and grouped according to changes in their patterns of expression among the different groups. Among several other interesting changes in gene expression, the muscle growth-related protein, Ky was not affected by short-term HFD, but increased after long-term HFD, and did not decrease after switched diet, showing that its expression may be an important long-term adaptation to HFD. LKB1-KO promoted anabolic signaling through increasing t-eIF2α and eIF4E expression, and promoted protein degradation through increasing protein ubiquitination. Because the degradation is the main effect and lead to muscle weight decrease. The effect of HFD and/or LKB1-KO on the LKB1-AMPK system was also determined. The results showed that knocking-out LKB1 decreased AMPK activity, decreased nuclear distribution for AMPK α2 and increased AMPK α1 expression. Long-term HFD increased t-AMPK expression in LKB1-KO mice, decreased the cytoplasm p-AMPK and nuclear p/t-AMPK ratio in CON mice. Together the findings of this dissertation demonstrated HFD induced glucose/insulin tolerance, while LKB1-KO had a controversial effect on glucose/insulin sensitivity. Both HFD and LKB1-KO affect AMPK expression and cellular location, while LKB1-KO also affects AMPK activity. LKB1-KO promoted protein degradation through ubiquitination in skeletal muscle.

Oxidative stress attributable to the activation of a Nox2-containing NADPH oxidase is involved in dietary obesity-associated cardiovascular diseases. However, the mechanism of Nox2 activation in dietary obesity remains unclear. In this project age-matched apolipoprotein E knockout (ApoEKO) and Nox2/ApoE double knockout (D-KO) mice were used to investigate high-fat diet (HFD)-induced obesity-related metabolic disorders, Nox2 activation, endothelial and adipose tissue dysfunction. Compared to NCD, HFD ApoEKO mice developed insulin resistance, increased systemic oxidative stress and vascular dysfunction which was accompanied by increased Nox2 expression, activated mitogen-activated protein kinase (MAPK) and attenuated Akt/endothelial nitric oxide synthesis (eNOS) pathways. Akt was decreased, vascular cell adhesion molecule-1 was increased and macrophages were recruited indicating endothelial cell activation and inflammation, attenuating the phosphatidylinositol-3-kinase/Akt/eNOS branch in favour of the MAPK. In vitro experiments showed that in response to high glucose/insulin challenge, ApoEKO aortas increased significantly the levels of Nox2 expression, activation of stress signalling pathways and the cells were senescent. Finally, the relationship of Nox2-derived reactive oxygen species due to obesity and adipose tissue dysfunction was examined for the first time in ApoEKO mice. It was found that adipose tissue in obesity is infiltrated by macrophages and intercellular adhesion molecule-1 is increased. Insulin receptor is decreased whereas ERK phosphorylation is increased and eNOS phosphorylation is decreased suggesting impaired insulin signalling. Uncoupled protein-1 levels also decreased. Nox2/ApoE D-KO mice did not exhibit any of the delirious effects of HFD/ insulin resistance and were protected from adipose tissue inflammation. In conclusion, this project demonstrated a crucial role for metabolic disorders in systemic Nox2 activation, inflammation, endothelial dysfunction and insulin receptor function in HFD ApoEKO mice. Also, it provides novel insights into mechanisms underlying adipose tissue dysfunction. Therefore, Nox2 targeting may represent an effective therapy to preserve endothelial and adipose tissue function and improve global metabolism in dietary obesity.

In recent years there has been an explosion in the rates of obesity, defined as a body mass index greater than 30kg/ m2, and associated cardiovascular disease. Alterations in peripheral glucocorticoid metabolism have been suggested to play a role in the development of obesity. Obesity occurs in both sexes, but the risk of associated metabolic disturbance and vascular dysfunction is greater in men. Although there is no accepted definition of obesity in rodents, the term is used to describe animals with a significant increase in fat pad mass often achieved by feeding a high fat diet. Although animal models of obesity have been useful in delineating potential mechanisms linking obesity with its metabolic and vascular sequelae, most studies have been in male animals and, thus, have not addressed sex differences. Additionally, emerging evidence shows that obesity during pregnancy is associated with increased cardio-metabolic and vascular disease in offspring, although the processes underlying such ‘programming’ effects are unclear. This thesis addresses the hypothesis that exposure to postnatal, or maternal obesity will alter both metabolism and vascular function in mice. Male and female mice maintained on a high fat and sugar diet from 5 weeks of age had increased adipose tissue deposition in adulthood. However there were striking sex differences in glucose homeostasis, mRNA levels and glucocorticoid metabolism, with males being more severely affected. Treatment of male mice with 17β-estradiol ameliorated a number of the effects of the high fat diet, including weight gain and altered glucose homeostasis; additionally estradiol altered glucocorticoid metabolism in the adipose so that it resembled that of females. Suprisingly, given the changes in metabolism, obesity in adult mice produced only small changes in vascular function and did not alter vascular remodelling following injury. The effects of maternal obesity were studied using male offspring aged 3 and 6 months. The offspring of obese mothers had similar body weight, adiposity, plasma lipid and plasma hormone concentrations to controls. In contrast, exposure to obesity in utero was associated with receptor specific changes in agonist-mediated contraction and decreased endothelium-dependent relaxation in male offspring. Despite these changes in vascular function, no alterations in blood pressure or vascular remodelling following injury were present. These results demonstrate that the more profound changes in glucose-insulin homeostasis associated with obesity in male humans can be recapitulated in rodent models and imply that estradiol plays a role in protecting the metabolism of female mice, potentially by alteration of glucocorticoid metabolism. Despite altered metabolism in postnatal obesity vascular function remained normal suggesting metabolic and vascular dysfunction are not intrinsically linked. Conversely, maternal obesity did not cause any overt changes in offspring metabolism but caused vascular dysfunction implying these parameters can be programmed independently.

Thesis (M.S.)--University of California, San Diego, 2008.<br>Title from first page of PDF file (viewed January 5, 2009). Available via ProQuest Digital Dissertations. Includes bibliographical references (p. 43-46).

Background Maternal diet and gestational diabetes have important implications for offspring health and disease. The fat mass and obesity associated gene (FTO) has the strongest relationship to increased body fat mass in humans, potentially via its effect on appetite and insulin sensitivity. Leptin plays a key role in regulating energy intake and expenditure, including appetite and hunger. Our hypothesis was that the expression of the Fto and leptin gene is influenced by the quality of carbohydrate in the maternal diet. Aim To compare glucose metabolism and mRNA expression of the Fto, leptin and other appetite-regulating genes in hypothalamic, adipose and/or other tissues of offspring of female mice fed high vs. low GI starch diets throughout pregnancy. Female C57BL/6 mice were randomly assigned to a low GI, high GI diet, or standard chow from 4 weeks of age and then mated with males who were fed the standard chow. In Study 1, male pups were weaned at the end of postnatal week 4 and divided into 2 subgroups, one following the chow diet and one their mother’s diet until 20 weeks of age. At week 20, the pups were sacrificed for tissue collection. In Study 2, female mice were sacrificed at gestation day 16-18 and placentas recovered. Tissues were analysed for gene expression and histological findings. Results Fto gene expression in the hypothalamus of offspring fed high GI starch from conception to postnatal week 20 was 2.5-fold higher than those fed low GI starch for the same time period (p = 0.01). Placental Fto gene expression was 3.8-fold higher in mothers fed the high GI starch diet vs. the low GI diet (p = 0.0003). By contrast, both early life and life-long exposure to a high GI diet were associated with lower Fto gene expression in white muscle. In the visceral adipose tissue, leptin gene expression was 3.3-fold higher in offspring exposed to the low GI diet from conception to week 20 and 4.4-fold higher in the offspring exposed to the low GI diet in early life. Plasma levels of the ‘hunger’ hormone ghrelin were significantly lower in offspring who received the low GI diet throughout life, while levels of the ‘satiety’ hormone leptin were higher. The co-expression of hypothalamic appetite genes AGRP/NPY and POMC/CART was also differentially regulated by the nature of the dietary carbohydrates. In this study, differences in diet, gene expression and hormone levels were not accompanied by differences in phenotype. Conclusion Carbohydrate quality, specifically the GI and/or rate of starch digestion in maternal diets, can differentially regulate the expression of the Fto and leptin gene in offspring tissues even in the absence of phenotypic differences. The nature of the dietary carbohydrates can regulate the co-expression of AGRP/NPY and POMC/CART in the hypothalamus. The findings imply that epigenetic changes induced in early life underlie observed differences in fat mass and insulin resistance in previous studies of high vs. low GI feeding. It is possible that changes in the nature of the carbohydrate in human diets may explain in part the current epidemic of obesity in children and adults.

Phenotypic plasticity is favored in heterogeneous environments in which alternative phenotypes can exploit alternative resources. However, it’s not clear whether phenotypic plasticity is useful in environments that become more homogenous over an organism’s life cycle. I studied a population of grasshopper Melanoplus differentialis that experiences high resource diversity as nymphs but low resource diversity as adults to determine if individuals can undergo diet-induced morphological plasticity in head shape to increase biting ability and ingestion of hard diets. Insects on a soft diet were larger and had greater bite force than those on a hard diet. Head structures related to chewing ability changed shape with mass, heads became taller and narrower. Scaling relationships among body parts suggested that there wasn’t evidence for tradeoff in allocation to chewing vs. locomotor performance. Results are consistent with the idea that essential adult feeding morphology constrains the advantage of plasticity in feeding structures among nymphs.

Type 2 Diabetes Mellitus (T2DM) is the metabolic disorder that accounts for the presence of hyperglycemia within insulin resistance (IR). The International Diabetes Federation estimated in 2013 that 382 million people (8.3% of world society ) had diabetes and that this number is set to rise beyond 592 million people in the next 22 years. T2DM accounts for 90% of people with diabetes (WHO 1999). Obesity is considered a major risk factor for developing T2DM over time. The World Health Organization (WHO) stated in 2014 that more than 1.9 billion adults were overweight and of these, over 600 million were obese (body mass index (BMI) > 30 kg/m2). Besides healthcare costs, WHO projects that diabetes will be the 7th leading cause of death in 2030 (Mathers & Loncar 2006). Once T2DM is diagnosed, the first therapeutic approach is by lifestyle counselling consisting of an increase in physical activity and changes in the patient dietary habits. The aim of this project is to study and integrate the metabolic responses that regulate systemic glucose homeostasis. We are not aware of other works describing in a holistic way the different metabolic processes regulating glucose homeostasis in different tissues that play an important role during the development and onset of diet-induced T2DM. With this approach, we will gain more insight and a better knowledge of the metabolic alterations taking place during an obese state induced by high-fat diet, as well as assess the degree of reversibility that can be reached by undergoing a lifestyle intervention, known as “metabolic plasticity”. For this purpose a diet-induced obese animal model of T2DM is used. To achieve the presented aims, a phenotypical and funcional study is performed at systemic level in order to complete a more experimental and detailed approach afterwards in each of the studied tissues: pancreas, white adipose tissue, liver, oxidative and glycolytic skeletal muscle, and hypothalamus. This experimental approach encompasses tissue-specific-functional analysis, gene expression studies, protein content determination and signalling, metabolomics and RNAseq. Likewise, systems biology tools have been developed and have allowed to measure several correlations as well as perform different types of multivariant analysis with the studied parameters. Three experimental groups are defined representing the metabolic stages of interest: control group (Ctrl); pathologic group (HFD, that mimic diet-induced T2DM after 16 wks on HFD; and in which animals showed overweight, and fasting hyperglycemia and hyperinsulinemia); and a third group (Int) that follows a lifestyle intervention consisting of caloric restriction, modification of the fatty acid source and carbohydrates in the diet, and the performance of an exercise training programme. The diet-induced obese experimental group (HFD group) reported the typical physiological features of the pathological state: overweight, fasting hyperglycemia, hyperinsulinemia and hyperleptinemia, increase in fat mass and volume, increase of white adipose tissue, liver and pancreas weight, increase of liver and oxidative skeletal muscle triglycerice levels, glucose intolerance, insulin resistance, increase in beta-cell mass along with hypertrophic enlarged islets and dysfunction in glucose-stimulated insulin secretion in vivo and in vitro, and a diminishment in oxygen consumption, heat production and scapular temperature. Lifestyle intervention was enough to revert most of the disruptions reported in the pathological group. However, certain irreversibility degree was still observed in particular studied parameters: (1) alteration in fasting glucose and glucose-stimulated insulin secretion in vivo, (2) increment in pancreatic beta-cell area, (3) affectation in the epididymal white adipose tissue with inflammation and immune cell infiltration, as well as (4) mitochondria dysfunction, already observed in the pathological state. Taken all this together, we can conclude that the pathological state left a certain degree of metabolic irreversibility does not allow a total recovery of the phenotype across the different tissues studied, at least with this type of intervention and timings. The development and application of systems biology tools have allowed the study the irreversibility degree in an integrative mode, the correlations among certain parameters at a multiorganic level, the gene expression patterns of complexes described from a protein-protein interaction (PPI) network. These strategies and computational approaches have led to the identification of most of the altered tissues and metabòlic pathways in the different states under study.<br>La Diabetes Mellitus del tipus 2 (DM2) és una malaltia que es caracteritza per uns nivells elevats de glucosa i insulina circulants ocasionats per un estat de resistència a la insulina. Segons la International Diabetes Federation, el 2013 382 milions de persones van ser diagnosticades de diabetes (8.3% de la població mundial), i d’acord amb les prediccions aquesta xifra augmentarà fins els 592 milions en els pròxims 22 anys. La DM2 explica el 90% dels casos de diabetes (WHO 1999). L’obesitat és un factor de risc per la DM2 i avui en dia suposa una epidèmia: el 2014 la OMS va xifrar en 1.9 bilions la població adulta amb sobrepès i 600 milions amb obesitat. A part del cost econòmic que suposa per a la societat, la OMS va projectar que el 2013 la DM2 serà la setena causa de mort al món (Mathers & Loncar 2006). Un cop diagnosticada, la primera aproximació en l’assessorament al pacient amb DM2 o en un estat de risc consisteix en una intervenció en l’estil de vida: incrementant l’activitat física i portant a terme una dieta equilibrada i saludable. Aquest projecte té com a objectiu l’estudi i la integració de les respostes metabòliques responsables de regular l’homeostasi de la glucosa a nivell sistèmic. Avui en dia, no existeix cap treball que descrigui de forma holística els diferents processos metabòlics que regulen l’homeostasi de la glucosa en tots els teixits que juguen un paper determinant durant el desenvolupament de la DM2 associada a l’obesitat. D’aquesta manera, es pretén guanyar coneixement sobre les alteracions metabòliques que tenen lloc en un estat d’obesitat induït per una dieta rica en greixos, i així mateix valorar el grau de reversibilitat que es pot assolir mitjançant una intervenció en l’estil de vida, al que ens referim com a “plasticitat metabòlica”. Utilitzem un model animal d’obesitat i DM2 induïda per una dieta alta en greixos. Per aconseguir els objectius plantejats inicialment es realitza un estudi fenotípic i funcional a nivell sistèmic per més tard realizar una aproximació experimental més exhaustiva en cadascun dels teixits d’interès: pàncrees, teixit adipós blanc, fetge, múscul esquelètic oxidatiu i glicolític, i hipotàlem. Aquesta aproximació experimental engloba anàlisis funcionals-teixit específic, estudis d’expressió gènica, determinació del contingut proteic i les vies de senyalització, metabolòmica i RNAseq. Així mateix, s’han desenvolupat eines de biologia de sistemes que han permès calcular diferents correlacions i fer diferents tipus d’anàlisis multivariant amb tots els paràmetres estudiats. Es defineixen tres grups experimentals d’animals que concreten els estats metabòlics d’interès: grup control (Ctrl); grup patològic (HFD) (que simula la DM2 induïda per la dieta grassa durant 16 setmanes, i en què els animals tenen sobreprès i la glucosa i insulina circulants elevades en dejú); i un tercer grup que segueix una intervenció en l’estil de vida (Int) que consisteix en restricció calòrica, una modificació de la font d’àcids grassos i hidrats de carboni de la dieta, juntament amb la realització d’un programa d’exercici. El grup experimental d’obesitat induïda per una dieta grassa (grup HFD) presenta les característiques fisiològiques pròpies de l’estat patològic: sobrepès, hiperglucèmia, hiperinsulinèmia i hiperleptinèmia en dejú, augment de la massa i el volum de greix, augment del pes del teixit adipós blanc, el fetge i el pàncrees, augment dels nivells de triglicèrids en fetge i múscul oxidatiu, intolerància a la glucosa, resistència a la insulina, augment de la massa de cèl·lula beta en el pàncrees juntament amb illots hipertròfics engrandits i disfunció de la secreció d’insulina estimulada per glucosa in vivo i in vitro, i disfunció del consum d’oxigen, generació de calor i temperatura escapular. La intervenció va ser suficient per revertir gran part de les alteracions observades en el grup patològic. No obstant, encara s’observa cert grau d’irreversibilitat en determinats paràmetres estudiats: (1) alteració de la glucosa en dejú i la resposta insulínica davant d’un estímul de glucosa in vivo, (2) increment en l’àrea de cèl·lula beta pancreàtica, (3) afectació en el teixit adipós blanc epididimal amb la presència d’inflamació i infiltració de cèl·lules immunes, així com (4) disfunció mitocondrial, ja observats en l’estat patològic. Amb tot, podem concloure que l’estat patològic deixa un cert grau d’irreversibilitat metabòlica no permetent així una recuperació total del fenotip en tots els teixits estudiats, almenys, amb aquest tipus d’intervenció i aquests períodes de temps. El desenvolupament i l’aplicació d’eines de biologia de sistemes han permès estudiar el grau de reversibilitat d’una manera integrada, les correlacions entre paràmetres concrets a nivel multiorgànic, el patró d’expressió gènica de complexes descrits en una xarxa de protein-protein-interaction (PPI). Aquestes estratègies computacionals han permès identificar aquells teixits i vies metabòliques més alterades en els diferents estats estudiats.