Ostarine does not enhance the metabolic effect of exercise in obese rats.

Overweight and obesity are associated with severe metabolic disorders and an increased risk of cardiovascular diseases. It is a known fact that physical activity has a positive effect on metabolic parameters, and also reduces the risk of diseases such as diabetes. Some products can enhance the rate of lipolysis and help in improving fat loss. One of these are selective androgen receptor modulators (SARMs) which act as anabolic agents and are also believed to aid in fat-burning. In this study, we investigated whether 30 days of ostarine administration could potentially improve metabolic parameters using the rat model of obesity combined with exercise. We assessed the levels of biochemical and hormonal parameters in serum samples as well as insulin sensitivity indices of tissues. There were significant changes in the metabolic parameters with exercise. However, we did not find any additive effects of ostarine and exercise on most of the parameters tested. Similar results were obtained from the analysis of gene expression and the concentration of leptin and adiponectin. Our results indicated that ostarine had a lowering effect on cholesterol concentration in the serum (P<0.05). Moreover, when combining ostarine and exercise, additive changes were only observed in the levels of total and HDL cholesterol. No significant change was observed in the metabolic parameters of obese rats with the use of ostarine at the dose of 0.4 mg/kg body weight. Since ostarine is known to enhance performance, further research on its effects is needed.

Neuropeptide B promotes differentiation of rodent white preadipocytes into mature adipocytes.

Neuropeptide B (NPB) modulates energy homeostasis and metabolism through activation of NPBWR1 and NPBWR2 in humans and NPBWR1 in rodents. Recently, we reported that NPB promotes adipogenesis in rat brown preadipocytes. In the present study, we evaluated the effects of NPB on proliferation and differentiation into mature adipocytes of white rat preadipocytes and 3T3-L1 cells. We found the expression of NPBWR1 and NPB on mRNA and protein level in rat white preadipocytes and 3T3-L1 cells. NPB increased expression of mRNA and protein production of adipogenic genes (PPARγ, C/EBPß, CEBPα and FABP4) in rat preadipocytes and 3T3-L1 cells during the differentiation process. Furthermore, NPB stimulated lipid accumulation in rat preadipocytes and 3T3-L1 cells. In addition, we found that NPB promotes phosphorylation of p38 kinase in rat preadipocytes and 3T3-L1 cells. NPB failed to stimulate expression of proadipogenic genes in the presence of p38 inhibitor. NPB failed to modulate viability and proliferation of rat preadipocytes and 3T3-L1 cells. Taken together, we report that NPB promotes differentiation of rodent preadipocytes via p38-dependent mechanism. NPB does not modulate viability and proliferation of rat preadipocytes and 3T3-L1 cells.

The role of the orexin (hypocretin) system in controlling energy homeostasis, endocrine system, and reproduction in pigs and other living organisms.

Orexins A (OXA) and B (OXB) (hypocretin 1 and 2) are neuropeptides produced in the brain and peripheral tissues. Biological activities of orexins are mediated through activation of two G-protein coupled receptors termed as orexin 1 receptor (OX1R) and orexin 2 receptor (OX1R). Orexin system (OXA, OXB, OX1R, OX2R) was implicated in controlling sleep, energy expenditure, appetite, reproduction as well as metabolism and energy homeostasis. In this review, we summarize the current knowledge regarding the role of the orexin system in controlling porcine physiology. Particularly, we review and discuss evidence indicating that in pig and other living organisms, orexins and their receptors modulate the energy homeostasis, reproduction as well as functions of peripheral tissues including the pancreas, adrenal glands, gastro-intestinal tract and adipose tissue.

Obesity is associated with increased level of kisspeptin in mothers' blood and umbilical cord blood - a pilot study.

OBJECTIVE: Kisspeptin (KP) is a major regulator of reproductive functions. It has also been shown to be involved in the metabolic changes associated with obesity. According to the well-established concept of prenatal programming, environmental factors can influence physiological and behavioral systems at the early stages of development. Thus, we hypothesized that in pregnant women, obesity can be associated with alterations in the levels of KP. We also assumed that the observed changes in obese mothers' blood (MB) would be reflected in the umbilical cord blood (CB). MATERIALS AND METHODS: We collected MB and CB from obese and nonobese women and analyzed the differences in metabolic and hormonal profiles, including KP concentration, using commercially available assays. RESULTS: We found that the level of KP was increased in the MB and CB of obese patients compared to nonobese subjects (p<0.05). A strong correlation was observed between the concentration of KP in MB and CB (r=0.8343; p<0.01). Moreover, we detected that the differences in the adipokine profile observed in the MB were not reflected in CB. CONCLUSIONS: Our results indicate that blood KP concentration can serve as a valuable marker in pregnant women. However, further studies are needed to understand the alterations of this peptide in obese pregnant woman and their potential effects on offspring.

Adropin suppresses insulin expression and secretion in INS-1E cells and rat pancreatic islets.

Adropin is a peptide hormone which is produced in brain and peripheral tissues such as liver. It was found that adropin modulates lipid and glucose homeostasis by interacting with hepatocytes and myocytes. Adropin enhances insulin sensitivity and alleviates hyperinsulinemia in animal models with high-fat diet-induced insulin resistance. However, it is unknown whether adropin regulates insulin secretion and proliferation of beta cells. Therefore, we studied the effects of adropin on insulin secretion in INS-1E cells as well as isolated pancreatic islets. Furthermore, we assessed the influence of adropin on insulin mRNA expression, cell viability and proliferation in INS-1E cells. Pancreatic islets were isolated from male Wistar rats. mRNA expression was evaluated using real-time PCR and cell viability by MTT assay. Cell replication was measured by BrdU incorporation and insulin secretion by RIA. We found that adropin suppresses insulin mRNA expression in INS-1E cells. Moreover, adropin attenuates glucose-induced insulin secretion in INS-1E cells as well as in isolated pancreatic islets. In addition, using INS-1E cells we found that adropin suppresses glucose-induced cAMP production. However, adropin fails to modulate INS-1E cell viability and proliferation. In summary, we found adropin suppresses insulin mRNA expression and secretion, without affecting beta cell viability or proliferation.

The role of orexin in controlling the activity of the adipo-pancreatic axis.

Orexin A and B are two neuropeptides, which regulate a variety of physiological functions by interacting with central nervous system and peripheral tissues. Biological effects of orexins are mediated through two G-protein-coupled receptors (OXR1 and OXR2). In addition to their strong influence on the sleep-wake cycle, there is growing evidence that orexins regulate body weight, glucose homeostasis and insulin sensitivity. Furthermore, orexins promote energy expenditure and protect against obesity by interacting with brown adipocytes. Fat tissue and the endocrine pancreas play pivotal roles in maintaining energy homeostasis. Since both organs are crucially important in the context of pathophysiology of obesity and diabetes, we summarize the current knowledge regarding the role of orexins and their receptors in controlling adipocytes as well as the endocrine pancreatic functions. Particularly, we discuss studies evaluating the effects of orexins in controlling brown and white adipocytes as well as pancreatic alpha and beta cell functions.

Orexin A but not orexin B regulates lipid metabolism and leptin secretion in isolated porcine adipocytes.

It is well known that orexins are involved in the metabolism and endocrine function of rodent adipocytes, but there are no data on other animal species, including pigs. Therefore, in this study, we tested the hypothesis that orexin A (OxA) and orexin B (OxB) modulate the metabolism and endocrine functions of isolated porcine adipocytes and adipose tissue explants. Moreover, we characterized the possible mechanism of OxA action in porcine adipocytes. According to the results, both orexin receptor 1 and orexin receptor 2 were expressed in the porcine adipose tissue. We found that OxA suppressed the release of glycerol from porcine adipocytes both in the absence (basal lipolysis; P < 0.05) and in the presence (stimulated lipolysis; P < 0.05) of isoproterenol. Orexin A increased basal and insulin-stimulated glucose uptake (P < 0.05), as well as it enhanced the rate of glucose incorporation into lipids with insulin (stimulated lipogenesis; P < 0.01) or without insulin (basal; P < 0.05). We have also shown that OxA stimulated the mRNA expression of glucose transporter 4 (P < 0.05) and its translocation into the plasma membrane (P < 0.01). Moreover, OxA upregulated the mRNA expression of leptin in isolated porcine adipocytes (P < 0.05) and increased the secretion of leptin (P < 0.05). We have also demonstrated one of the possible mechanisms of OxA action in adipocytes. In the presence of extracellular-signal-regulated kinase 1 and 2 (ERK1/2) inhibitor, the effect of OxA was not detectable in porcine adipocytes, which indicates that this peptide increased cell viability via ERK1/2 pathway (P < 0.05). However, OxB did not show any effect on the metabolism and endocrine functions of porcine adipocytes. In summary, we have shown for the first time that OxA has a significant impact on the intensity of lipolysis, glucose uptake, lipogenesis, as well as on the expression and secretion of leptin. Therefore, we conclude that OxA but not OxB regulates lipid metabolism in porcine adipose tissue and that this regulation is partly mediated via ERK1/2 pathway. The action of orexins should be further explored to better understand their role in the regulation of adiposity in pigs.

Serum levels of spexin and kisspeptin negatively correlate with obesity and insulin resistance in women.

Spexin (SPX) and kisspeptin (KISS) are novel peptides relevant in the context of regulation of metabolism, food intake, puberty and reproduction. Here, we studied changes of serum SPX and KISS levels in female non-obese volunteers (BMI<25 kg/m(2)) and obese patients (BMI>35 kg/m(2)). Correlations between SPX or KISS with BMI, McAuley index, QUICKI, HOMA IR, serum levels of insulin, glucagon, leptin, adiponectin, orexin-A, obestatin, ghrelin and GLP-1 were assessed. Obese patients had lower SPX and KISS levels as compared to non-obese volunteers (SPX: 4.48+/-0.19 ng/ml vs. 6.63+/-0.29 ng/ml; p<0.001, KISS: 1.357+/-0.15 nmol/l vs. 2.165+/-0.174 nmol/l; p<0.01). SPX negatively correlated with BMI, HOMA-IR, insulin, glucagon, active ghrelin and leptin. Positive correlations were found between SPX and QUICKI index, McAuley index, serum levels of obestatin, GLP-1 and adiponectin and orexin-A Serum KISS negatively correlated with BMI, HOMA-IR, serum levels of insulin, glucagon, active ghrelin and leptin. KISS positively correlated with QUICKI index, McAuley index and adiponectin. In summary, SPX and KISS show negative correlations with obesity, insulin resistance indices, and hormones known to affect insulin sensitivity in females. Both, SPX and KISS could be therefore relevant in the pathophysiology of obesity and insulin resistance.

TRPV4 regulates insulin mRNA expression and INS-1E cell death via ERK1/2 and NO-dependent mechanisms.

TRPV4 is a Ca2+-permeable, nonselective cation channel. Recently, TRPV4 was implicated in controlling peripheral insulin sensitivity, insulin secretion and apoptosis of pancreatic beta cells. Here, we characterize the role and potential mechanisms of TRPV4 in regulating insulin mRNA expression and cell death in insulin producing INS-1E cells and rat pancreatic islets. TRPV4 protein production was downregulated by siRNA. Intracellular calcium level was measured using Fluo-3 AM. Gene expression was studied by real-time PCR. Phosphorylation of extracellular signal-regulated kinase (ERK1 and ERK2) was detected by Western blot. Nitric oxide (NO) production was assessed by chemiluminescent reaction. Reactive oxygen species (ROS) level was analysed using a fluorogenic dye (DCFDA). Cell death was evaluated by determination of cytoplasmic histone-associated DNA fragments. Downregulation of TRPV4 neither affected insulin mRNA expression nor INS-1E cell growth. By contrast, pharmacological TRPV4 activation by 100nmol/l GSK1016790A increased Ca2+ levels in INS-1E cells and enhanced insulin mRNA expression after 1 and 3h, whereas a suppression of insulin mRNA expression was detected after 24h incubation. GSK1016790A increased ERK1/2 phosphorylation and NO production but not ROS production. Pharmacological blockade of ERK1/2 attenuated GSK1016790A-induced insulin mRNA expression. Inhibition of NO synthesis by l-NAME failed to affect insulin mRNA expression in GSK1016790A treated INS-1E cells. Furthermore, inhibition of NO production attenuated GSK1016790A-induced INS-1E cell death. In pancreatic islets, 100nmol/l GSK1016790A increased insulin mRNA levels after 3h without inducing cytotoxicity after 24h. In conclusion, TRPV4 differently regulates insulin mRNA expression in INS-1E cells via ERK1/2 and NO-dependent mechanisms.

Chronic orexin-A (hypocretin-1) treatment of type 2 diabetic rats improves glucose control and beta-cell functions.

Orexin regulates food intake and energy expenditure. Here, we test the ability of orexin-A (OXA, hypocretin-1) at improving metabolic control in type 2 diabetic animals and elaborate potential mechanisms of action. Rats with experimentally induced type 2 diabetes by a combination of streptozotocin injection and high-fat diet feeding were chronically infused with OXA. In vitro experiments were conducted on isolated pancreatic islets, primary adipocytes and insulin secreting INS-1E cells. OXA improved glucose control, enhanced insulin sensitivity and attenuated pancreatic ß-cell loss in type 2 diabetic rats. Ex vivo, apoptotic death of pancreatic islets isolated from OXA-treated type 2 diabetic animals as well as the impairment of glucose-stimulated insulin secretion were attenuated, as compared to islets derived from vehicle-treated rats. OXA reduced plasma tumor necrosis factor-α (TNF-α) and non-esterified fatty acids (NEFA) levels in type 2 diabetic rats. OXA decreased palmitate- and TNF-α-induced apoptosis of INS-1E cells. OXA improves glucose control by enhancing insulin sensitivity and protecting ß-cells from apoptotic cell death in type 2 diabetic animals.