Animal Model Of Diet-induced Obesity Research Articles

Regarding “Selection and Recall Bias in a Case–Control Study of Lifetime Alcohol Intake and Breast Cancer Risk”

We previously reported that oral delivery of salmon calcitonin (sCT) improved energy and glucose homeostasis and attenuated diabetic progression in animal models of diet-induced obesity (DIO) and type 2 diabetes, although the glucoregulatory mode of action was not fully elucidated. In the present study we hypothesized that oral sCT as pharmacological intervention 1) exerted anti-hyperglycemic efficacy, and 2) enhanced insulin action in DIO-streptozotocin (DIO-STZ) diabetic rats. Diabetic hyperglycemia was induced in male selectively bred DIO rats by a single low dose (30 mg/kg) injection of STZ. Oral sCT by gavage was delivered as once-daily administration with lead-in (2 mg/kg) and maintenance (0.5 mg/kg) dose of oral sCT for a total of 21 days. Food intake, body weight, blood glucose, HbA1c, glucose and insulin tolerance test, and parameters of insulin sensitivity were investigated. Plasma glucoregulatory hormones and pancreatic insulin content were analyzed. Oral sCT treatment induced a pronounced anorectic action during the 7 days lead-in period and markedly reduced food intake and body weight in conjunction with improved glucose homeostasis. During the maintenance period, oral sCT normalized food intake and attenuated weight loss, albeit sustained glycemic control by reducing fasting blood glucose and HbA1c levels compared to those of vehicle-treated rats at the end of study. Notably, plasma levels of insulin, glucagon, leptin and adiponectin were unaltered, albeit insulin action was enhanced in conjunction with protection of pancreatic insulin content. The results of the present study indicate that oral sCT exerts a novel insulin-sensitizing effect to improve glucose metabolism in obesity and type 2 diabetes.

The discovery and optimization of pyrimidinone-containing MCH R1 antagonists

Optimization of a series of constrained melanin-concentrating hormone receptor 1 (MCH R1) antagonists has provided compounds with potent and selective MCH R1 activity. Details of the optimization process are provided and the use of one of the compounds in an animal model of diet-induced obesity is presented.

α2-Heremans-Schmid Glycoprotein/ Fetuin-A Is Associated With Insulin Resistance and Fat Accumulation in the Liver in Humans

The alpha(2)-Heremans-Schmid glycoprotein (AHSG; fetuin-A in animals) impairs insulin signaling in vitro and in rodents. Whether AHSG is associated with insulin resistance in humans is under investigation. In an animal model of diet-induced obesity that is commonly associated with hepatic steatosis, an increase in Ahsg mRNA expression was observed in the liver. Therefore, we hypothesized that the AHSG plasma protein, which is exclusively secreted by the liver in humans, may not only be associated with insulin resistance but also with fat accumulation in the liver. Data from 106 healthy Caucasians without type 2 diabetes were included in cross-sectional analyses. A subgroup of 47 individuals had data from a longitudinal study. Insulin sensitivity was measured by a euglycemic-hyperinsulinemic clamp, and liver fat was determined by (1)H magnetic resonance spectroscopy. AHSG plasma levels, adjusted for age, sex, and percentage of body fat, were higher in subjects with impaired glucose tolerance compared with subjects with normal glucose tolerance (P = 0.006). AHSG plasma levels were negatively associated with insulin sensitivity (r = -0.22, P = 0.03) in cross-sectional analyses. Moreover, they were positively associated with liver fat (r = 0.27, P = 0.01). In longitudinal analyses, under weight loss, a decrease in liver fat was accompanied by a decrease in AHSG plasma concentrations. Furthermore, high AHSG levels at baseline predicted less increase in insulin sensitivity (P = 0.02). We found that high AHSG plasma levels are associated with insulin resistance in humans. Moreover, AHSG plasma levels are elevated in subjects with fat accumulation in the liver. This is consistent with a potential role of AHSG as a link between fatty liver and insulin resistance.

Gene-diet interactions in obesity

A considerable amount of research on the genetics of obesity has been reported in the past few years. Despite evidence that genetic factors play a significant role in the etiology of this nutritional disease and the increasing number of obesity genes identified, relatively little is known about the role of genes in the response of obesity phenotypes to alterations in energy balance or diet composition. This is especially true for dietary fat, which is known to be associated with obesity at the population level. The aim of this review was to summarize the evidence currently available about the role of gene-nutrient interactions in human obesity. Evidence from both genetic epidemiology and molecular epidemiology studies suggests that genetic factors are involved in determining the susceptibility to gaining or losing fat in response to diet or the risk of developing some of the comorbidities generally observed in obese individuals. Recent evidence suggests that quantitative trait loci identified from animal models of diet-induced obesity could influence body fat in humans. Despite the limited number of studies, the evidence on gene-diet interactions in obesity is convincing. More research is needed to identify the genes responsible for these interaction effects, and the use of animal models of diet-induced obesity represents a promising approach. Finally, data on children are needed to allow assessment of the tracking of nutrient intake between childhood and adulthood. In addition, gene-diet interactions in children need to be investigated to determine whether the genes involved are the same as those found in adults.