Abstract # 2228 Event # 84:

Scheduled for Friday, June 22, 2007 10:10 AM-10:25 AM: Session 8 (North Main Hall C/D) Symposium

Effects of Sex Hormones and Soy Isoflavones on Obesity and Insulin Resistance in Cynomolgus Monkeys

J. D. Wagner, L. Zhang, K. Kavanagh, S. B. Gray, M. R. Adams and J. R. Kaplan
Wake Forest University School of Medicine, Comparative Medicine Clinical Research Center, Medical Center Boulevard, Winston-Salem, North Carolina 27157-1040, USA
     The incidence of obesity and diabetes has been steadily increasing, particularly in older women. After menopause, both body weight and fat increase as do dyslipidemia and insulin resistance. Similar to women, there is an increase in weight gain and body fat after surgical menopause in cynomolgus monkeys (Macaca fascicularis). Estrogen therapy attenuates the weight gain and tends to improves insulin sensitivity. These effects may be partially explained by our recent findings that estrogen increases adiponectin concentrations, which have been associated with beneficial effects on fat and insulin sensitivity. Soy protein contains plant estrogens or isoflavones. We report here changes in insulin responses and differences between 61 male and 89 female cynomolgus monkeys (Macaca fascicularis) consuming diets for 16 months with the protein source from either soy with its isoflavones (“phytoestrogens”) at a human equivalent 140 mg isoflavone/day, or casein. ANOVA [a=0.05] showed females fed soy had a significantly lower plasma insulin response to a glucose challenge (as determined by area under the curve) compared to casein. In contrast, males fed soy showed a nonsignificant trend toward greater, insulin response than those fed casein. However, unlike estrogen therapy, soy consumption in both males and females significantly decreased adiponectin concentrations. Thus, consumption of phytoestrogens does not result in estrogen-like effects on adiponectin suggesting a different mechanism of action.