Adipose Tissue Of Male Rats Research Articles

Tributyltin-induced visceral adiposity is associated with impaired redox balance in white adipose tissue of male rats

Tributyltin (TBT) is an organotin compound that has several adverse health effects, including the development of obesity. Although obesity is strongly associated with adipose redox imbalance, there is a lack of information on whether TBT promotes a pro-oxidative environment in WAT. Thus, adult male Wistar rats were randomly exposed to either vehicle (ethanol 0.4%) or TBT (1000 ng/kg) for 30 days. Body and fat pad masses, visceral fat morphology, lipid peroxidation, protein carbonylation, redox status markers, and catalase activity were evaluated. TBT promoted increased adiposity and visceral fat, with hypertrophic adipocytes, but did not alter body mass and subcutaneous fat. ROS production and lipid peroxidation were elevated in TBT group, as well as catalase protein expression and activity, although protein oxidation and glutathione peroxidase protein expression remained unchanged. In conclusion, this is the first study to demonstrate that subacute TBT administration leads to visceral adipose redox imbalance, with increased oxidative stress. This enlights the understanding of the metabolic toxic outcomes of continuous exposure to TBT in mammals.

Hypolipidemic effect of dill seed (Anethum graveolens L.) essential oil on lipid profile and peroxisome proliferator-activated receptor- γ expression in hyperlipidemic male rats

Herbal medicines have been suggested for the treatment of hyperlipidemic disorders. The hypolipidemic activities of dill essential oil on lipid profile and peroxisome proliferator-activated receptor-γ (PPARγ) expression in adipose tissue were studied in male rats with hyperlipidemia. The effects were studied and compared of dill essential oil and atorvastatin on serum lipid profile and aspartate aminotransferase (AST), alanine aminotransferase (ALT) levels, histopathological damage of liver and PPARγ gene expression in the adipose tissue of male rats with hyperlipidemia. The treatment with dill decreased body weight, serum cholesterol, triglyceride, LDL-C, ALT and AST levels, histopathological damage to the liver and PPARγ expression of adipose tissue, and increased serum HDL-C levels in experimental hyperlipidemic rats compared to the hyperlipidemic control rats, both significantly. The plant and atorvastatin improved hyperlipidemia, attenuated liver tissue damage and down-regulated PPARγ expression. So, dill could be defined as an excellent candidate for treatment of hyperlipidemia.

Effect of Aerobic Training and Cinnamon on Expression of Resistin Gene in Adipose Tissue of Male Rats Fed with a High-Fat Diet

Background: The pathogenesis of obesity is very complex, and a number of factors are involved in its occurrence. To treat or control obesity and diabetes, various treatment methods, such as the use of natural and synthetic drugs or lifestyle modifications, are recommended for obese people. Exercise is an active lifestyle that can have beneficial effects on obese people. Due to people's concerns about the side effects of chemical drugs, including drug resistance, today in medicine, the use of herbal compounds with different properties, including cinnamon, has been considered by everyone. Objectives: In the current work, simultaneous application of cinnamon extract (CE) and aerobic practices were studied on the expression of the resistin gene (RG) in adipose tissue of male rats on a high-fat diet. Methods: The influence of 5 days a week of aerobic exercise for 6 weeks, along with a simultaneous high-fat diet (as an emulsion with the rate of 150 mL in excess of the routine diet) and consumption of CE (200 mg/kg), were studied. The expression of the RG in adipose tissue of male rats that received a high-fat diet in their daily food was assessed. Independent variables of the present study included performing 6 weeks of aerobic exercise, consumption of CE, and high-fat diet as the underlying variables. The mRNA expression of the proteins was evaluated using real-time PCR. The effect of variables on between-group and within-group changes was assessed using a one-way analysis of variance and the Bonferroni test. Results: Different patterns, including high-fat diet, cinnamon, and combinations of high-fat diet/cinnamon, high-fat diet/aerobic exercise, and high-fat diet/aerobic exercise, were significant on resistin in adipose tissue. Conclusions: The best results in terms of mitigating the adverse effects of diet on the expression of RG were observed for a combination of six weeks of exercise and CE. Therefore, the simultaneous utilization of aerobic exercise and CE is recommended.

The effect of endurance training combined with adenosine on the gene expression of UCP-1 and MAPK p38 in subcutaneous adipose tissue of male Wistar rats fed a high -fat diet

Background: Strategies to increase energy expenditure are an attractive approach to reduce excess fat storage and body weight to improve metabolic health. The aim of the present study was to investigate the effects of endurance training combined with adenosine injection on the gene expression of UCP-1 and MAPK p38 in the subcutaneous adipose tissue of male rats fed a high-fat diet. Materials and Methods: Forty rats were randomly divided into 4 groups: 1. normal control, 2. high-fat diet (HFD) control, 3. HFD + adenosine, and 4. HFD + endurance training + adenosine. After 13 weeks of HFD, 12 weeks of endurance training on a moderate-intensity treadmill was performed. UCP-1 and MAPK p38 mRNA levels were measured by RT-PCR. Results: A significant increase in UCP-1 was observed with in HFD + endurance training + adenosine and HFD + adenosine compared to normal and HFD controls. A significant decrease in MAPK p38 was also observed with HFD + endurance training + adenosine and HFD + adenosine compared to HFD. Conclusion: Endurance training and adenosine are likely activators of UCP-1 gene expression and can be used as effective lipolytic agents in obesity. The MAPK p38 pathway increases glucose uptake by insulin and also induces oxidative phosphorylation in mitochondria following a healthy diet and aerobic activity.

(-)-Epicatechin increases apelin/APLNR expression and modifies proteins involved in lipid metabolism of offspring descendants of maternal obesity

Several studies have shown the beneficial effects of (-)-epicatechin (Epi) in metabolic profile and that this flavanol is a biased ligand of the apelin receptor. The apelinergic system is expressed in adipocytes and has been related to obesity and metabolic disorders. The study aim was to evaluate the effect of Epi on apelin, on its receptor and on proteins involved in lipolysis, lipogenesis, and adipogenesis in the retroperitoneal adipose tissue of male rats descended from obese mothers. We evaluated the effect of Epi in the retroperitoneal adipose tissue of four groups of male offspring, analyzing mRNA expression and protein levels of apelin and its Apj receptor. We also analyzed, by Western Blot, the levels of AMPKα, ACC, C/EBPα, ATGL, Fas, and FABP4 of the AP2 proteins. Epi significantly elevated apelin mRNA expression and protein levels as well as its Apj receptor. Besides, the flavanol significantly promoted AMPKα phosphorylation with the concomitant reduction of Fas, and the increase of the ATGL protein. In contrast, there was an increase in the inactive phosphorylated form of ACC and a decrease in the phosphorylated active form of C/EBPα. Similarly, Epi treatment induced a reduction in the fatty acid-binding protein 4 in the C+Epi and MO+Epi groups.In conclusion, Epi increases the expression of the apelinergic system and the active phosphorylated form of AMPKα; likewise, it modifies the expression level or active form of proteins involved in lipolysis, lipogenesis and adipogenesis in the retroperitoneal adipose tissue of male offspring of obese mothers.

Early unhealthy eating habits underlie morpho-functional changes in the liver and adipose tissue in male rats.

Early-life consumption of high-fat and sugar-rich foods is recognized as a major contributor for the onset of metabolic dysfunction and its related disorders, including diabetes and nonalcoholic fatty liver disease. The lifelong impact of early unhealthy eating habits that start at younger ages remains unclear. Therefore, to better understand the effects of diet, it is essential to evaluate the structural and functional changes induced in metabolic organs and potential mechanisms underlying those changes. To investigate the long-term effects of eating habits, young male rats were exposed to high-sugar and high-energy diets. After 14weeks, body composition was assessed, and histopathological changes were analyzed in the liver and adipose tissue. Serum biochemical parameters were also determined. Expression of inflammatory markers in the liver was evaluated by immunohistochemistry. Our results revealed that serum levels of glucose, creatinine, aspartate transaminase (AST), alanine transaminase (ALT), and lipid profile were increased in rats red high-sugar and high-energy diets. Histopathological alterations were observed, including abnormal hepatocyte organization and lipid droplet accumulation in the liver, and abnormal structure of adipocytes. In both unhealthy diet groups, hepatic expression of Toll-like receptor4 (TLR4), cyclooxygenase2 (COX-2), and E-selectin were increased, as well as a biomarker of oxidative stress. Together, our data demonstrated that unhealthy diets induced functional and structural changes in the metabolic organs, suggesting that proinflammatory and oxidative stress mechanisms trigger the hepatic alterations and metabolic dysfunction.

The effect of Berberine on obesity through browning of the inguinal white adipose tissue of male rats

Background: Obesity increases the risk of many diseases. White adipose tissue (WAT) browning is being targeted in the treatment of obesity. Berberine (BR) is a plant alkaloid, used mainly in treatment of diarrhea. Studies revealed that BR improves some metabolic disorders in obese but the browning effect of BR on WAT is not fully investigated.Aim of the work: Testing the possible impact of BR on browning of inguinal WAT (iWAT) of adult male albino rats, and to study its possible ameliorating effect on the obesity associated disturbed lipid profile.Materials and methods: Forty-eight adult male albino rats were divided into two main groups; normally fed diet group (NFD) and high fat diet group (HFD). Normal fat diet group was subdivided into three subgroups. Normal fat diet control group (NFDc) received no treatment. Normal fat diet-berberine low dose (NFD+BRL) group received 5mg/kg body weight (b.w) BR, and normal fat diet-berberine high dose (NFD+BRH) group received 10mg/kg b.w berberine. High fat diet group was subdivided into three subgroups: High fat diet control group (HFDc), high fat diet-berberine low dose (HFD+BRL) group and high fat diet-berberine high dose (HFD+BRH) group. Results: Berberine promoted adipocyte browning in the iWAT, where the beige adipocytes were revealed. In addition, browning markers expression in iWAT; UCP1, PGC-1α and CIDEA increased. Also, BR ameliorated the disturbed lipid profile in HFD group.Conclusion: Berberine showed to be a safe browning agent which also improved the dyslipidemia occurred in HFD group. Berberine high dose showed better results than the lower dose. Thus, we believe that BR has excellent potential as an effective safe anti-obesity agent.

Long-term nitrate administration increases expression of browning genes in epididymal adipose tissue of male type 2 diabetic rats

Expression of browning genes are lower in both humans and animals with type 2 diabetes (T2D). This study aims at determining effects of long-term nitrate administration on protein and mRNA levels of uncoupling protein 1 (UCP1), peroxisome proliferator activated receptor gamma (PPAR-γ), and PPAR-γ coactivator 1 alpha (PGC1-α) in epididymal adipose tissue (eAT) of rats with T2D. Male Wistar rats were divided into 4 groups (n = 6/group): Control, diabetes, control + nitrate (CN), and diabetes + nitrate (DN). T2D was induced using high fat diet combined with a low-dose of streptozotocin (30 mg/kg body weight). Sodium nitrate was administrated at a dose of 100 mg/L for 6 months in nitrate-treated rats. Fasting serum glucose and insulin concentrations were measured at months 0 (i.e. at start of the protocol), 3, and 6. At month 6, protein and mRNA levels of UCP1, PPAR-γ, and PGC1-α were measured in eAT samples. In addition, tissue concentration of cyclic guanosine monophosphate (cGMP) was measured and histological analyses were done at month 6. In rats with T2D, 6-month administration of nitrate decreased serum glucose and insulin concentrations by 13% and 23%, respectively and increased cGMP level by 85%. Rats with T2D had lower mRNA and protein levels of PPAR-γ (62%, P < 0.0001 and 18%, P = 0.0472), PGC1-α (49%, P = 0.0019 and 21%, P = 0.0482), and UCP1 (35%, P = 0.0613 and 30%, P = 0.0031) in eAT; 6-month nitrate administration restored these decreased levels to near control values. In addition, nitrate increased adipocyte density by 193% and decreased adipocyte area by 53% in rats with T2D. In conclusion, long-term low-dose nitrate administration increased mRNA and protein expressions of browning genes in white adipose tissue of male rats with T2D; these findings partly explain favorable metabolic effects of nitrate administration in diabetes.

High-dose Nandrolone Decanoate induces oxidative stress and inflammation in retroperitoneal adipose tissue of male rats

The non-therapeutic use of the androgenic anabolic steroid Nandrolone Decanoate is popular due to its effects on physical performance and body composition, especially for its lipolytic and anabolic effects associated. However, high doses of such drugs are often associated with a series of pathologies related to unbalanced redox homeostasis, which, in turn, can be linked to inflammation. The oxidative stress onset could deregulate the secretion of cytokines, evidencing a dysfunctional adipocyte. Thus, the aim of this study was to investigate the effect of supraphysiological doses of Nandrolone Decanoate on redox homeostasis of retroperitoneal fatpad of male rats and its relationship with cytokines-based inflammatory signaling. Hydrogen peroxide production was assessed in the retroperitoneal fat pad of adult male rats which received either 10 mg kg of Nandrolone Decanoate or only a vehicle. Also, catalase, superoxide dismutase and glutathione peroxidase activities were measured, together with total reduced thiols and protein carbonylation, as well as IL-1β, TNF-α, and IL-6 local levels. High doses of Nandrolone Decanoate caused an increase in the hydrogen peroxide production, together with lower activities of the antioxidant enzymes and lower levels of total reduced thiol. There were also higher protein carbonylation and greater levels of IL-1β, TNF-α, and IL-6 in the treated group compared to control group. Therefore, it was possible to verify that high doses of Nandrolone Decanoate cause oxidative stress and induce higher inflammatory signaling in retroperitoneal fat pad of male rats.

Convergent neuronal projections from paraventricular nucleus, parabrachial nucleus, and brainstem onto gastrocnemius muscle, white and brown adipose tissue in male rats.

When energy balance is altered by aerobic exercise, starvation, and cold exposure, for example, there appears to be coordination of the responses of skeletal muscle, white adipose (WAT), and brown adipose (BAT) tissues. We hypothesized that WAT, BAT, and skeletal muscle may share an integrated regulation by the central nervous system (CNS); specifically, that neurons in brain regions associated with energy balance would possess neuroanatomical connections to permit coordination of multiple, complementary responses in these downstream tissues. To study this, we used trans-neuronal viral retrograde tract tracing, using isogenic strains of pseudorabies virus (PRV) with distinct fluorescent reporters (either eGFP or mRFP), injected pairwise into male rat gastrocnemius, subcutaneous WAT and interscapular BAT, coupled with neurochemical characterization of specific cell populations for cocaine- and amphetamine-related transcript (CART), oxytocin (OX), corticotrophin releasing hormone (CRH) and calcitonin gene-related peptide (CGRP). Cells in the paraventricular (PVN) and parabrachial (PBN) nuclei and brainstem showed dual projections to muscle + WAT, muscle + BAT, and WAT + BAT. Dual PRV-labeled cells were found in parvocellular, magnocellular and descending/pre-autonomic regions of the PVN, and multiple structural divisions of the PBN and brainstem. In most PBN subdivisions, more than 50% of CGRP cells dually projected to muscle + WAT and muscle + BAT. Similarly, 31-68% of CGRP cells projected both to WAT + BAT. However, dual PRV-labeled cells in PVN only occasionally expressed OX or CRH but not CART. These studies reveal for the first time both separate and shared outflow circuitries among skeletal muscle and subcutaneous WAT and BAT.

Effects of Sleeve Gastrectomy on the Metabolic Profile and on the Expression of Renin-Angiotensin System in Adipose Tissue of Obese Rats.

Sleeve gastrectomy (SG) has been used as a multipurpose surgical procedure for the treatment of obesity. The present study aimed to assess the effects of SG on the metabolic and inflammatory profile and renin-angiotensin system (RAS) expression in the white adipose tissue of male rats with obesity induced by a high-fat diet. Male Wistar rats were treated with a standard diet or high-fat diet and submitted to SG or sham surgery. The glycemic and lipid profiles and gene expression of inflammatory markers and RAS components in adipose tissue were evaluated. SG led to weight loss, decreased adiposity (p < 0.01) and a reduction in plasma glucose (p < 0.05), C-peptide (p < 0.05), insulin (p < 0.001) and total cholesterol (p < 0.05) levels. In addition, SG led to a decrease in the expression of tumor necrosis factor-alpha (TNF-α) (p < 0.01), interleukin- 6 (IL-6) (p < 0.001), angiotensinogen (AGT) (p < 0.001) and angiotensin converting enzyme (ACE) (p < 0.05) and increased the expression of angiotensin converting enzyme 2 (ACE2) (p < 0.05) in white adipose tissue. No statistically significant differences were observed for AT1 (p = 0.10) and Mas (p = 0.22) receptors. This study showed that SG leads to weight loss and improves metabolic parameters. Changes in the expression of RAS components and of inflammatory molecules in adipose tissue seem to play a role the before beneficial effects of the SG.

Nutritional and exercise interventions variably affect estrogen receptor expression in the adipose tissue of male rats

Energy-dense food consumption and lack of physical activity are implicated in the development of the current obesity epidemic. The role of estrogen in adiposity and fuel partitioning is mediated mainly though the estrogen receptor α (ERα) isoform. We hypothesized that nutritional adaptation and exercise training, either individually or combined, could impact ERα expression in adipose tissue relative to glucose tolerance. Seventy-two Wistar rats were submitted to a high-fat, high-sucrose (HF-HS) diet for 16weeks. The first phase of our study was to investigate the effect of an HF-HS diet on whole-body glucose tolerance, as well as on body composition and ERα expression in different adipose tissues. Second, we investigated the effect of switching to a well-balanced diet, with or without exercise training for 8 weeks, on those same parameters. After the first part of this study, HF-HS–fed rats were fatter (8%) than control rats. Despite a decrease in glucose tolerance, ERα expression in adipose tissues was not significantly altered by an HF-HS diet. The return to a well-balanced diet significantly increased ERα expression in perirenal and epididymal adipose tissue, but there was no effect of diet or exercise training on whole-body glucose tolerance. The present findings suggest that diet is a powerful modulator of ERα expression in adipose tissue, as nutritional modulation after an HF-HS diet strongly affects ERα expression, particularly in perirenal and epididymal adipose tissue. However, ERα expression in adipose tissue does not appear to be associated with whole-body glucose tolerance.

A change of hormonal regulation of adenylyl cyclase in epididymal adipose tissue of rats with experimental models of diabetes mellitus

One of the key causes of diabetes mellitus (DM) and its complications are hormonal disturbances in functioning of hormonal signaling systems, including the adenylyl cyclase signaling system (ACSS). The goal of this work was to study the functional state and hormonal sensitivity of ACSS in the epididymal adipose tissue of male rats in the 7-month model of mild type 1 DM (DM1), in the 18-month neonatal model of type 2 DM (DM2), and in the taken for comparison model of the 30-day acute DM1. It is shown for the first time that in adipocytes from the epididymal fat of rats with the studied DM models the basal AC activity and its stimulation by forskolin were decreased, which indicates a weakening of the catalytic function of the enzyme adenylyl cyclase (AC). Stimulation of AC by guanine nucleotides in DM changed to the lesser extent, which speaks in favor of preservation of functions of heterotrimeric G(s)-proteins in the epididymal fat. In rats with DM1 the sensitivity of AC of adipocytes to agonists of β-adrenergic receptors (β-AR), activators of lipolysis, remained practically unchanged, while in animals with DM2 the AC stimulating effects of β-AR-agonists were reduced or completely blocked, like in the case of β3-AR-agonist BRL-37344 and CL-316243. In adipocytes of rats with DM1 the AC inhibitory effect of N6-cyclopentyladenosine, agonist of type 1 adenosine receptors (Aden1R), an inhibitor of lipolysis, was attenuated, whe- reas in DM2 this effect was completely preserved. Thus, in the epididymal adipose tissue of rats with DM1 the antilipolytic AC cascades including Aden1R were decreased and the stimulation of AC by β-AR-agonists was preserved, whereas in rats with DM2 the β-AR-mediated AC cascades activating lipolysis were reduced, but Aden1R-mediated AC cascades inhibiting lipolysis did not change. The changes of hormonal regulation of ACSS in adipocytes from the epididymal fat lead to disturbances of the metabolic status of animal with DM1 and DM2 and should be considered in the diagnostics and treatment of DM and its complications.

Cultured 3T3L1 adipocytes dispose of excess medium glucose as lactate under abundant oxygen availability

White adipose tissue (WAT) produces lactate in significant amount from circulating glucose, especially in obesity;Under normoxia, 3T3L1 cells secrete large quantities of lactate to the medium, again at the expense of glucose and proportionally to its levels. Most of the glucose was converted to lactate with only part of it being used to synthesize fat. Cultured adipocytes were largely anaerobic, but this was not a Warburg-like process. It is speculated that the massive production of lactate, is a process of defense of the adipocyte, used to dispose of excess glucose. This way, the adipocyte exports glucose carbon (and reduces the problem of excess substrate availability) to the liver, but the process may be also a mechanism of short-term control of hyperglycemia. The in vivo data obtained from adipose tissue of male rats agree with this interpretation.

The Response of Lipolytic Activity in Adipose Tissue to Saturated Fat

Introduction: Obesity has become a major problem in the modern world; it is affected genetically and by lifestyle and dietary habits as consuming fast food meals enriched with high saturated fat (SF). Since obesity is associated with multi co-morbidities like dyslipidemia, hypertension, and metabolic syndrome, this work studied the effect of diet rich in saturated fat on body weight, blood pressure, lipid profile, glycemic state and lipolytic activity of adipose tissue in male rats. Materials and Methods: Twenty male rats of an average body weight 192.4 g were divided equally into two groups, control group (Cgp) fed commercial rat chow and experimental group (SFgp) fed 10% saturated fat to induce obesity. After 3 months the body weight, blood pressure, fasting blood glucose, insulin level, and lipid profile of both groups were measured and the lipolytic activity of adipose tissue was assessed. Results: Rats fed saturated fat for 3 months showed significant increase in body weight, systolic blood pressure, TG, Cholesterol, LDL, fasting blood glucose and insulin levels with a significant decline in HDL. Lipolytic activity of SC tissue in the presence of adrenaline decreased significantly while in the presence of insulin it increased significantly. It showed a significant increase in the presence of adrenaline and insulin in visceral adipose tissue. A p value less than 0.05 was considered statistically significant. Conclusion: Consumption of diet rich in saturated fat in male rats induced obesity that is associated with hypertension, dyslipidemia, hyperglycemia and insulin resistance. The adipose tissue of obese male rats showed a significant decrease in lipolytic activity of SC with a significant rise in the corresponding value in visceral adipose tissue.

High‐fat diet feeding induces sex‐dependent changes in inflammatory and insulin sensitivity profiles of rat adipose tissue

The aim of the study was to determine, in rats of both sexes, the effect of HF diet feeding on the expression of adipokines involved in inflammatory status and insulin sensitivity and on the levels of proteins involved in lipid handling of retroperitoneal adipose tissue. Eight-week-old Wistar rats of both sexes were fed a control diet (2.9% w/w fat) or an HF diet (30% w/w fat) for 14 weeks. Adiponectin, peroxisome proliferator-activated receptor γ and inflammatory marker mRNA levels were analyzed by real-time polymerase chain reaction. Levels of insulin receptor, glucose transporter 4, carnitine palmitoyltransferase 1, fatty acid synthase, hormone-sensitive lipase and lipoprotein lipase were determined by Western blot. HF diet feeding did not induce hyperphagia or body weight gain but did promote an increase in adiposity although only in male rats. HF diet impaired glucose tolerance and the expression of inflammatory and insulin sensitivity markers in adipose tissue of male rats, but not in female rats. Male rats seem to be more prone to disorders associated with an unbalanced composition of the diet, even in the absence of hyperphagia. In contrast, female rats counteract excessive fat intake by improving their ability to use lipid fuels, which limits adiposity and maintains insulin sensitivity.

Effect of Insulin Resistance on Lipolytic activity of Adipose Tissue in Male Rats

Background: The excess usage of fructose as a sweetener has raised the incidence of insulin resistance among the population which is associated with dyslipedemia, hypertension and obesity. This work studied the effect of induced insulin resistance on body weight, blood pressure, lipid profile, glycemic state and lipolytic activity of adipose tissue in male rats. Methods: Twenty male rats of 129.4 g average body weight (BW) were divided equally into two groups. Both had free access to water. The control group had pure water; the experimental group had water mixed with 25% of fructose to induce insulin resistance. After 3 months body weight, blood pressure, fasting blood glucose, insulin levels, lipid profile of both groups were measured and lipolytic activity of adipose tissue was assessed. Results: Rats given fructose for 3 months showed significant increase in BW, systolic blood pressure, triglyceride, Cholesterol, low density lipoprotein, fasting blood glucose and insulin levels with a significant decline in highdensity lipoprotein. Lipolytic activity of subcutaneous (SC) and visceral adipose tissue in presence of adrenaline increased significantly which runs in parallel with the results obtained in presence of insulin as it showed a significant rise in both SC and visceral adipose tissue. Data were considered statistically significant at alpha level of 5%. Conclusion: Insulin resistance induced in male rat by high fructose consumption showed a significant rise in BW and is associated with hypertension and dyslipidemia with significant rise in lipolytic activity of both SC and visceral adipose tissue. DOI: http://dx.doi.org/10.3126/njms.v1i2.6602 Nepal Journal of Medical Sciences. 2012;1(2): 68-73

A soyabean diet does not modify the activity of brown adipose tissue but alters the rate of lipolysis in the retroperitoneal white adipose tissue of male rats recovering from early-life malnutrition

Nutritional recovery with a soyabean diet decreases body and fat weights when compared with a casein diet. We investigated whether the reduced adiposity observed in rats recovering from early-life malnutrition with a soyabean diet results from alterations in lipid metabolism in white adipose tissue (WAT) and/or brown adipose tissue (BAT). Male rats from mothers fed either 17 or 6% protein during pregnancy and lactation were maintained on 17% casein (CC and LC groups), 17% soyabean (CS and LS groups) or 6% casein (LL group) diets over 60d. The rats maintained on a soyabean diet had similar relative food intakes, but lower body and retroperitoneal WAT weights and a reduced lipid content in the retroperitoneal WAT. The insulin levels were lower in the recovered rats and were elevated in those fed a soyabean diet. Serum T3 concentration and uncoupling protein 1 content in the BAT were decreased in the recovered rats. The thermogenic capacity of the BAT was not affected by the soyabean diet. The lipogenesis rate in the retroperitoneal WAT was similar in all of the groups except for the LL group, which had exacerbated lipogenesis. The enhancement of the lipolysis rate by isoproterenol was decreased in white adipocytes from the soyabean-recovered rats and was elevated in adipocytes from the soyabean-control rats. Thus, in animals maintained on a soyabean diet, the proportions of fat deposits are determined by the lipolysis rate, which differs depending on the previous nutritional status.

Effects of Gonadectomy on Glucocorticoid Metabolism in Obese Zucker Rats

Glucocorticoids are metabolized by 11beta-hydroxysteroid dehydrogenase 1 (11betaHSD1) and the A-ring reductases (5alpha- and 5beta-reductases). Dysregulation of these enzymes has been reported in liver and adipose tissue in obese humans and animals, potentially leading to altered intracellular glucocorticoid concentrations and compensatory activation of the hypothalamic-pituitary-adrenal axis. This dysregulation of glucocorticoid metabolism in obesity is poorly understood. We hypothesized that changes in glucocorticoid metabolism in obesity are mediated by alterations in androgen action. Steroid metabolism was studied in obese and lean male Zucker rats (age 10 wk, 10 animals per group) 4 wk after gonadectomy or sham surgery. Oral glucose tolerance tests were performed, and activities and abundances of mRNAs for steroid metabolizing enzymes were quantified in liver and adipose tissue. Gonadectomy did not consistently alter weight gain, glucose intolerance, or hyperinsulinemia in obese animals. Gonadectomy increased adrenal mass (P < 0.05), suppressed 11betaHSD1 activity and/or mRNA in liver and adipose, increased 5alpha-reductase 1 mRNA in liver (P < 0.05), and increased 5beta-reductase activity only in obese animals (P < 0.05). Differences in hepatic 11betaHSD1 mRNA expression and adipose activity between lean and obese animals were normalized by gonadectomy, whereas obese gonadectomized animals maintained elevated liver 5alpha-reductase and had an exaggerated elevation of 5beta-reductase activity. We conclude that androgens tonically increase 11betaHSD1 in liver and adipose tissue in male rats and contribute to the dysregulation of 11betaHSD1 in obesity. By contrast, androgens tonically suppress hepatic A-ring reductases in male rats and do not contribute to dysregulation of these enzymes in obesity.

Effects of dietary monosaccharides on sympathetic nervous system activity in adipose tissues of male rats.

Dietary carbohydrate activates the sympathetic nervous system (SNS). As the mechanisms underlying this response are not fully characterized, studies were undertaken to compare SNS responses to ingestion of glucose, fructose, and galactose. SNS activity was examined using techniques of [(3)H]norepinephrine ([(3)H]NE) turnover in brown and white fat. In addition, gene expression for several sympathetically related proteins was also analyzed in these tissues. [(3)H]NE turnover in interscapular brown adipose tissue (IBAT) and retroperitoneal fat increased in response to glucose and fructose in the diet, whereas [(3)H]NE turnover in epididymal fat did not respond to either monosaccharide. Galactose feeding, by contrast, decreased [(3)H]NE turnover in IBAT, but increased it in epididymal, though not retroperitoneal, fat. Expression of GLUT4 was more abundant in IBAT and retroperitoneal fat from glucose- and fructose-fed animals than from diet- or galactose-fed rats. Chemical sympathectomy abolished the GLUT4 response in retroperitoneal fat, but was without effect on GLUT4 in epididymal fat. These studies are consistent with activation of a neural pathway by oral glucose or fructose, leading to SNS activation in IBAT and retroperitoneal fat and enhanced GLUT4 expression.