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

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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, 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 < 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 < 0.001). Obese males had lower serum dihydrotestosterone levels than nonobese males (3.1 .+-. 0.7 vs. 5.6 .+-. 0.4 nmol/L; P < 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.