Obesity in Male and Female Rhesus Monkeys: Fat Distribution, Glucoregulation, and Serum Androgen Level*

Abstract

Obese (n = 8) and nonobese (n = 6) adult rhesus monkeys (Macaca mulatta) were assessed in terms of body size and distribution of body fat, glucose tolerance, and serum lipid, insulin, and androgen levels. The weights of the obese monkeys were more than 2 SD above the mean for their sex, while the nonobese monkeys averaged less than 0.25 SD from the mean. Obese males and females had excess body fat located predominantly in the abdominal region; abdominal circumference was highly correlated with total body fat, as estimated by the isotope dilution method (r = 0.98; P less than 0.001). Obese monkeys of both sexes had fasting hyperinsulinemia, greater insulin response to iv glucose administration, and marginally impaired glucose tolerance. Obese males had delayed maximal insulin response to glucose administration. Fasting serum triglycerides also were elevated in the obese monkeys (0.95 +/- 0.08 vs. 0.47 +/- 0.05 mmol/L; P less than 0.001). Obese males had lower serum dihydrotestosterone levels than nonobese males (3.1 +/- 0.7 vs. 5.6 +/- 0.4 nmol/L; P less than 0.01). Nonobese females had approximately 2-fold higher serum dehydroepiandrosterone sulfate levels than the other groups. We conclude that obese male and female rhesus monkeys have patterns of fat distribution and glucoregulatory abnormalities similar to those of humans with upper body obesity. The contribution of differences in androgen metabolism to the development of obesity and its complications in rhesus monkeys remain to be defined.

Prenatal androgen excess negatively impacts body fat distribution in a nonhuman primate model of polycystic ovary syndrome

“…In contrast, women only do so when BMI reaches overweight or obese categories. 20 Since maximal BMI values in our control females reach over 40 kg/m 2 ( Figure 1a), well short of the obese range for female rhesus monkeys in our colony, 21 the lack of association between visceral fat and BMI in control females in this study would be consistent with the absence of obesity. EPA females also exhibit a significant correlation between Ib and total body fat, total abdominal fat and visceral fat, agreeing with data from PCOS women showing an increase in visceral fat with fasting serum insulin levels.…”

Insulin Signaling and Insulin Sensitizing in Muscle and Liver of Obese Monkeys: Peroxisome Proliferator-Activated Receptor Gamma Agonist Improves Defective Activation of Atypical Protein Kinase C

“…Insulin resistance and obesity, accompanied by dyslipidemia, have been well documented in rhesus monkeys with metabolic syndrome (8,9,17,22,23,32,33,41,43,67,68,84). Calorie restriction and calorie restriction mimetic agents have been demonstrated in rhesus monkeys to reverse or prevent these metabolic disorders (13,21,24,42,45,46,50,60,64).…”

A Comparison of Dual‐Energy X‐Ray Absorptiometry and Somatometrics for Determining Body Fat in Rhesus Macaques

“…Traditional methods (e.g., body weight, skinfold thickness), often used to assess body composition in nonhuman primates (4,(8)(9)(10)(11)(12), have inherent shortcomings due in part to assumptions and measurement errors inherent to them. These somatometric measurement errors have been examined for over a decade (13)(14)(15)(16)(17)(18)(19)(20).…”

“…More component-specific techniques, such as tritiated water dilution (4,9,10) and DXA (7,22,23), have the power to separate fat and lean tissue, and have also been used for the assessment of body composition in nonhuman primates.…”