AJP - Regulatory, Integrative and Comparative Physiology, Vol 268, Issue 1 142-R149, Copyright © 1995 by American Physiological Society
Glucocorticoids and insulin: reciprocal signals for energy balance
A. M. Strack, R. J. Sebastian, M. W. Schwartz and M. F. Dallman
Department of Physiology, University of California, San Francisco 94143.
Signals that regulate long-term energy balance have been difficult to
identify. Increasingly strong evidence indicates that insulin, acting on
the central nervous system in part through its effect on neuropeptide Y
(NPY), inhibits food intake. We hypothesized that corticosteroids and
insulin might serve as interacting, reciprocal signals for energy balance,
acting on energy acquisition, in part through their effects on hypothalamic
NPY, as well as on energy stores. Because glucocorticoids also stimulate
insulin secretion, their role is normally obscured. Glucocorticoids and
insulin were clamped in adrenalectomized rats with steroid replacement and
streptozotocin-induced diabetes. Glucocorticoids stimulated and insulin
inhibited NPY mRNA and food intake. Glucocorticoids inhibited and insulin
increased energy gain as determined by the change in body weight. When
adrenalectomized diabetic rats were treated, corticosterone stimulated and
insulin inhibited food intake, and, respectively, inhibited and increased
overall energy gain. More than 50% of the variance was explained by
regression analysis of the two hormones on food intake and body weight.
Thus glucocorticoids and insulin are major, antagonistic, long-term
regulators of energy balance. The effects of corticosterone and insulin on
food intake may be mediated, in part, through regulation of hypothalamic
NPY synthesis and secretion.
