The acute and chronic effects of bornbesin
(BM) on the structure and function of rat adrenal
cortex were investigated by rnorphornetric and
radioirnrnunological techniques. An intraperitoneal bolus
injection of 2 yglrat BM rnarkedly raised plasma
corticosterone (B) concentration (PBC). The intraperitoneal
BM infusion (1 yg/rat.h-l) for 1, 2 or 4
days evoked a notable increase in the nurnber of
adrenocortical cells, without inducing apparent changes
in either PBC or B output by adrenal quarters. Since
proliferation and expression of specialized functions are
rnutually exclusive states of cells, our findings suggest
that the conspicuous stirnulation of adrenocortical-cell
proliferation evoked by BM infusion may be responsible
for the apparent lack of effect of this treatrnent on B
secretion