THE EFFECT OF DEXAMETHASONE ON THE ADRENAL-GLAND IN FETAL AND NEONATAL RATS

The development and regeneration of the adrenal glands were examined b y 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-o ld rats, zona fasciculata (ZF) and zona reticularis (ZR) were analyzed as one inner zone (IZ), while in 14-day-old animals they were analyze d 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 w ere visible to a certain degree up to the 14th neonatal day. Administr ation of Dx to pregnant rats induced a significant decrease of both ad renal weight and volume, as well as the volume of zona glomerulosa + c apsule (ZG + C) and IZ, both in fetuses and 3-day-old rats. This was d ue to a decrease in the number but not the volume of cortical cells. A lso, necrotic cortical cells, infiltrations and resorption zones accom panied by the presence of macrophages, giant cells and lymphocytes wer e observed. In 14-day-old animals, the degree of atrophic changes in t he 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 wa s 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 result s of the present study demonstrate that even a single Dx dose given to pregnant rat during the period critical for. the development of the h ypothalamo-pituitary-adrenal system in the fetuses leads to marked cha nges in the structure and function of-the fetal adrenal glands which a re partially maintained up to the 14th day of postnatal life. (C) 1995 Wiley-Liss, Inc.