Overnutrition, ectopic lipid and the metabolic syndrome

Male Mice Lacking NLRX1 Are Partially Protected From High-Fat Diet-Induced Hyperglycemia

Nod-like receptor (NLR)X1 is an NLR family protein that localizes to the mitochondrial matrix and modulates reactive oxygen species production, possibly by directly interacting with the electron transport chain. Recent work demonstrated that cells lacking NLRX1 have higher oxygen consumption but lower levels of adenosine triphosphate, suggesting that NLRX1 might prevent uncoupling of oxidative phosphorylation. We therefore hypothesized that NLRX1 might regulate whole-body energy metabolism through its effect on mitochondria. Male NLRX1 whole-body knockout (KO) mice and wild-type (WT) C57BL/6N controls were fed a low-fat or a high-fat (HF) diet for 16 weeks from weaning. Contrary to this hypothesis, there were no differences in body weight, adiposity, energy intake, or energy expenditure between HF-fed KO and WT mice, but instead HF KO mice were partially protected from the development of diet-induced hyperglycemia. Additionally, HF KO mice did not present with hyperinsulinemia during the glucose tolerance test, as did HF WT mice. There were no genotype differences in insulin tolerance, which led us to consider a pancreatic phenotype. Histology revealed that KO mice were protected from HF-induced pancreatic lipid accumulation, suggesting a potential role for NLRX1 in pancreatic dysfunction during the development diet-induced type 2 diabetes mellitus. Hence, NLRX1 depletion partially protects against postabsorptive hyperglycemia in obesity that may be linked to the prevention of pancreatic lipid accumulation. Although the actual mechanisms restoring glucose and insulin dynamics remain unknown, NLRX1 emerges as a potentially interesting target to inhibit for the prevention of type 2 diabetes mellitus.

Expression enhancement in brown adipose tissue of genes related to thermogenesis and mitochondrial dynamics after administration of pepsin egg white hydrolysate

Pepsin egg white hydrolysate enhanced mitochondria proliferation on brown adipose tissue and thermogenesis. Reduced body weight and adiposity were observed.

Anti-obesogenic and hypolipidemic effects of a glucagon-like peptide-1 receptor agonist derived from the saliva of the Gila monster

INTRODUCTION

Glucagon-like peptide-1 (GLP-1) receptor (R) agonists are a class of incretin mimetic drugs that have been used for the treatment of type 2 diabetes mellitus and also considered strong candidates for the treatment of obesity. The original prototypical drug in this class is the exenatide, a synthetic peptide with the same structure as the native molecule, exendin-4, found in the saliva of the Gila monster (Heloderma suspectum suspectum lizard).

OBJECTIVES

To identify and compare the anti-obesogenic, antidyslipidemic and antidiabetogenic effects of agonism in GLP-1R by exenatide on two distinct models of obesity: induced by hypothalamic injury (MSG) or high-calorie diet (DIO).

METHODS

To obtain MSG, neonatal rats were daily subcutaneously injected with 4 g monosodium glutamate/kg, for 10 consecutive days. To obtain DIO, 72-75 days old rats received hyperlipid food and 30% sucrose for drinking up to 142-145 days old. Untreated healthy rats with the same age were used as control. General biometric and metabolic parameters were measured.

RESULTS

MSG was characterized by decreased naso-anal length, food and fluid intake, plasma protein and glucose decay rate per minute after insulin administration (K_ITT), as well as increased Lee index (body mass^0.33/naso-anal length), mass of retroperitoneal and periepididymal fat pads, glycemia, triglycerides (TG), LDL and VLDL. Exenatide ameliorated K_ITT and food and fluid intake, and it also restored glycemia in MSG. DIO was characterized by glucose intolerance, increased body mass, Lee index, fluid intake, mass of retroperitoneal and periepididymal fat pads, glycemia, glycated hemoglobin (HbA1c), TG, VLDL and total cholesterol, as well as decreased food intake and K_ITT. Exenatide restored glycemia, HbA1c, TG, VLDL, total cholesterol and body mass, and it also ameliorated food and fluid intake, K_ITT and mass of retroperitoneal fat pad in DIO.

CONCLUSIONS

The hypothalamic injury and the high-calorie diet induce dyslipidemia and glycemic dysregulation in addition to obesity in rats. The usual therapeutic dose of exenatide in humans is antidiabetogenic in both these obesity models, but is anti-obesogenic and hypolipidemic only in diet-induced obesity. Agonists of GLP-1R are promising anti-obesogenic and antidyslipidemic drugs in the early stages of the obesity, in which the integrity of the nervous system was unaffected.

Metabolic Syndrome: An Evolving Clinical Construct

Metabolic syndrome (MetS), a clustering of metabolic risk factors, identifies individuals at increased risk of diabetes and cardiovascular disease (CVD). Measurement of waist circumference, high-density lipoprotein-cholesterol, triglycerides, blood pressure and fasting blood glucose are easily obtained in the clinic. At any level of low-density lipoprotein-cholesterol, presence of MetS increases the risk of adverse CVD outcomes including bothatherosclerotic CVD and atrial fibrillation. The MetS construct should focus the clinician on recommending behavioral lifestyle modification as this improves all of its components. The challenge, however, has been the lack of a standardized approach to achieve effective and sustained lifestyle modification in clinical practice. We briefly review various approaches useful to the clinician in counseling such patients. These include group lifestyle programs and emerging mobile technology. Technology alone may not be sufficient, but as an adjunct has the promise to improve low rates of behavioral change currently seen with traditional programs.