AJP - Endocrinology and Metabolism, Vol 245, Issue 2 194-E199, Copyright © 1983 by American Physiological Society
Hypothalamic hyperinsulinemia and obesity: role of adrenal glucocorticoids
B. M. King, A. R. Banta, G. N. Tharel, B. K. Bruce and L. A. Frohman
The effects of adrenalectomy on the obesity and hyperinsulinemia induced by
ventromedial hypothalamic (VMH) lesions were studied in female rats. Plasma
insulin and glucose levels were assayed after a 4-h fast and 17 min after
the initiation of a meal (6 ml sweetened milk in 7 min). The development of
hypothalamic obesity was prevented by prior adrenalectomy and restored by
administration of corticosterone. Adrenalectomy abolished both the basal
and postabsorptive hyperinsulinemia observed in sham-adrenalectomized rats
with VMH lesions. Corticosterone treatment of adrenalectomized animals
enhanced both basal and postabsorptive insulin levels, but adrenalectomized
rats with VMH lesions were hyperinsulinemic compared with animals with sham
lesions only under the postabsorptive condition. Postabsorptive glucose
levels were unaffected by either the lesion or adrenal ablation. The
results support our previous conclusion that postabsorptive
hyperinsulinemia is of greater importance than is basal hyperinsulinemia in
the pathogenesis of hypothalamic obesity. Although the results are
consistent with a stimulatory role of corticosterone on food intake
mediating the postabsorptive hyperinsulinemia, a primary effect on CNS loci
involved with the regulation of insulin secretion is also possible.
