Ovarian-adrenal interactions in regulation of endocrine pancreatic function in the rat

The interference of adrenal hormones with the oestradiol-induced modifications of endocrine pancreatic function remains controversial. For this reason, we compared sham-operated, ovariectomized and adrenalectomized-ovariectomized female rats. In each group, control and 17-beta-oestradiol-treated rats (0.1 mg/day for 14 days) were studied, the latter group being compared with similar rats treated with corticosterone (0.4 mg/day). Oestradiol treatment induced hypoglycaemia and hyperinsulinism in basal and glucose-stimulated states, and hypoglucagonaemia. The presence of adrenal glands was necessary for the full expression of oestradiol effects on pancreatic islet B cells: in adrenalectomized-ovariectomized rats, oestradiol treatment induced an unexpected decrease in insulin response to intravenous glucose, and in pancreatic insulin content. Corticosterone treatment partly restored the oestradiol-induced rise of plasma insulin, and restored the B cell response to intravenous glucose. A permissive action of glucocorticoids may be a prerequisite for the effect of oestrogens on B cells. Since oestrogens by themselves augment the plasma corticosterone level, the insulinotropic effect of oestrogens may be partly mediated by the increase in endogenous corticosteroids. In contrast, oestradiol seems to suppress islet A cell function.