GLUCOCORTICOIDS AND INSULIN - COMPLEX INTERACTION ON BROWN ADIPOSE-TISSUE

Glucocorticoids and insulin effect long-term reciprocal changes in foo d intake and body weight. We tested the interactions of corticosterone and insulin on caloric efficiency, white adipose tissue (WAT) stores, and brown adipose tissue (BAT). Two experiments were performed: 1) ad renalectomized rats were treated with corticosterone with or without s treptozotocin-induced diabetes and 2) adrenalectomized, corticosterone -treated, diabetic rats were treated with insulin. By 4-5 days later, greater than or equal to 50% of the variance in caloric efficiency, pl asma triglycerides, and WAT stores was explained by regression of thes e variables on corticosterone (catabolic) and insulin (anabolic). When the ratio of the hormones was normal, but concentrations high, overal l gain of energy stores decreased and energy was redistributed to fat. Both hormones were anabolic on BAT lipid storage; the hormones played a complex role in the regulation of uncoupling protein (UCP) in BAT. Although corticosterone inhibited and insulin stimulated UCP, these ef fects were only evident in diabetics and with normoglycemia, respectiv ely. For BAT variables, less than or equal to 50% of the variance was explained by regression on corticosterone and insulin, suggesting that the effects of these hormones are mediated through an intermediate su ch as sympathetic nervous system input to BAT.