Effect of bombesin on the structure and function of the rat adrenal cortex

Intact and dexamethasone-treated adult female Wistar rats were infused (Alzet osmotic minipumps) with bombesin (0.75 micrograms/rat per day) for 7 days. Bombesin depressed body weight and capacity of adrenal homogenate to secrete corticosterone; the latter effect was reflected in intact rats by a drop in serum corticosterone level. Bombesin had no effect on pituitary and serum adrenocorticotropic hormone (ACTH) concentration and serum aldosterone level. In intact animals, infusion of bombesin resulted in lowering of the number of parenchymal cells in adrenal cortex connected with the hypertrophy of glomerulosa and fasciculata cells. Moreover, bombesin lowered basal corticosterone secretion by isolated rat adrenocortical cells; however, neuropeptide applied did not change the response of isolated cells to ACTH stimulation. The data obtained clearly demonstrate inhibitory effect of bombesin on basal corticosterone secretion by the rat adrenal cortex.