Direct and indirect influences of a 14 days oestradiol-17 beta treatment on the endocrine pancreas of the female rat.

The relationship between the hyperinsulinism induced by 14-days oestradiol treatment and the trophic action of this hormone on the endocrine pancreas was studied. The possible interference of the adrenal glands in these effects of oestradiol was investigated using comparisons between adrenalectomized and/or ovariectomized rats. Oestradiol increased the dry weight of the islets of Langerhans and enhanced total incorporation of [3H] leucine into newly synthetized proteins during a glucose stimulation independently of the presence of the adrenal glands. Conversely, the presence of the adrenal glands was necessary for the expression of the enhancing actions of oestradiol such as the production of insulin hypersecretion, increased insulin biosynthesis and a higher proportion of light granules inside the B cells. These results were in favour of a direct trophic role of oestradiol on the endocrine pancreas, but also of an indirect role of this hormone in the stimulation of the insulin secretion and biosynthesis, mediated by glucocorticoids.