Treatment of pregnant females with dexamethasone influences postnatal development of the adrenal medulla

Abstract

In the light of the mutual dependence between the adrenal cortex and medulla, the aim of this work was to examine whether glucocorticoid treatment of pregnant rats affects the development of the adrenal medulla of their offspring in the postnatal period. Pregnant rats were treated with dexamethasone (Dx) in a daily dose of 0.3 mg Dx/kg b.w. during days 16-20 of gestation. The structure and function of the adrenal medulla of their 14-day-old offspring were estimated on the basis of the morphometric parameters of the gland, chromaffin cell mitotic index and adrenal gland adrenaline content. Stereological analysis was carried out at the light microscopic level, the mitotic index was determined by counting the number of metaphase arrested chromaffin cells following the administration of vincristine-sulphate, whereas adrenaline content in the adrenal gland was measured fluorimetrically. Plasma ACTH concentrations of the offspring were also determined by RIA. Long term Dx treatment of pregnant rats caused a significant decrease of the total volume of adrenal chromaffin tissue in the 14-day-old offspring as well as a reduction in the number of chromaffin cells and the average cell and nuclear volumes. The proliferative activity of the chromaffin cells was also lower than in the control offspring. These changes were accompanied by a significantly reduced adrenaline content in the adrenals. The results of this work show that glucocorticoid excess during the period of pregnancy when the fetal adrenal medulla is formed has a strong inhibitory effect on the adrenal medulla of the offspring at the age of 14 days.