Effects of bombesin on the morphology and function of the rat adrenal cortex: comparison of the acute and chronic responses.

The acute and chronic effects of bombesin (BM) on the structure and function of rat adrenal cortex were investigated by morphometric and radioimmunological techniques. An intraperitoneal bolus injection of 2 micrograms/rat BM markedly raised plasma corticosterone (B) concentration (PBC). The intraperitoneal BM infusion (1 microgram/rat.h-1) for 1, 2 or 4 days evoked a notable increase in the number of adrenocortical cells, without inducing apparent changes in either PBC or B output by adrenal quarters. Since proliferation and expression of specialized functions are mutually exclusive states of cells, our findings suggest that the conspicuous stimulation of adrenocortical-cell proliferation evoked by BM infusion may be responsible for the apparent lack of effect of this treatment on B secretion.