Impaired corticosteroid production by isolated adrenocortical cells of hypercholesterolemic rabbits

The effect of dexamethasone on the adrenal gland in fetal and neonatal rats

The development and regeneration of the adrenal glands were examined by stereological and morphological methods in 20-day-old fetal, as well as 3-day- and 14-day-old neonatal male rats born to dams treated with dexamethasone (Dx) on day 16 of gestation. In the fetuses and 3-day-old rats, zona fasciculata (ZF) and zona reticularis (ZR) were analyzed as one inner zone (IZ), while in 14-day-old animals they were analyzed separately. Single Dx treatment (1.5 mg/kg b.w.) of the dams led to atrophic changes in the adrenal cortex of the fetuses. These changes were visible to a certain degree up to the 14th neonatal day. Administration of Dx to pregnant rats induced a significant decrease of both adrenal weight and volume, as well as the volume of zona glomerulosa + capsule (ZG + C) and IZ, both in fetuses and 3-day-old rats. This was due to a decrease in the number but not the volume of cortical cells. Also, necrotic cortical cells, infiltrations and resorption zones accompanied by the presence of macrophages, giant cells and lymphocytes were observed. In 14-day-old animals, the degree of atrophic changes in the adrenal cortex was reduced. Changes were observed only in ZR which was decreased in volume resulting from both a significant decrease of the volume and number of cortical cells. Then number of macrophages was somewhat increased, while giant cells were not present. However, the total number of parenchyma cells in ZG was increased, pointing to the possibility of renewal of cortical cells within this zone. The results of the present study demonstrate that even a single Dx dose given to pregnant rat during the period critical for the development of the hypothalamo-pituitary-adrenal system in the fetuses leads to marked changes in the structure and function of the fetal adrenal glands which are partially maintained up to the 14th day of postnatal life.

Lipoprotein receptors and steroidogenesis in adrenocortical cells

Steroid-producing tissues require a continuous supply of cholesterol for hormone synthesis. In the majority of the steroidogenic tissues the cholesterol is imported via the receptor-mediated uptake of lipoproteins, and therefore the influence on the lipoprotein receptors provides an additional level for the regulation of hormone synthesis. Hormones regulating the adrenocortical activity exert both short- and long-term action, and thus they may control the interactions of the major cholesterol delivery particles--low- (LDLs) and high-density lipoproteins (HDLs)--and their receptors in short- and long-term action, possibly modulating the signal transduction in the former case and the number and distribution in the latter. The LDL and HDL pathway and the signal transduction mechanism is briefly reviewed. Data are discussed concerning short- and long-term action of hormones (alpha-MSH and ACTH, respectively) on the HDL3 receptors of isolated adrenocortical cells. Short-term treatment with alpha-MSH and long-term treatment with ACTH increased the binding of HDL3 to zona glomerulosa and fasciculata cells, respectively, while both treatments increased the hormone production in the presence of HDL. The lipoprotein receptors were frequently found on the microvilli of adrenocortical cell membranes.