The influence of dexamethasone treatment of pregnant rats on the development of chromaffin tissue in their offspring during the fetal and neonatal period

Abstract

The aim of these examinations was to determine the influence of dexamethasone (Dx)-treatment of gravid females, on day 16 of gestation on the development of medullary chromaffin tissue of their fetuses and neonatal offspring. In conducting these investigations we used stereological as well as spectrofluorimetric measurements, in 20-day-old fetuses and 1-, 3-, 5-, 7-, 9-, 11-, 13- and 14-day-old neonatal rats. Single Dx-treatment (1.5 mg/kg bw) of the dams led to a significant decrease in body and adrenal weight of their fetuses and neonatal offspring, and also reduction of the medullary volume and the number of chromaffin cells during the entire period examined as a result of decreased cell proliferation in the fetal and early neonatal period (till the 5th day of age). The proliferative activity of the chromaffin cells was evaluated through the mitotic index after applying the cytostatic vincristine-sulphate. During the second neonatal week the mitotic index showed significantly higher values in comparison with the corresponding controls, which indicates that there is regeneration and recovery of the adrenal gland medulla. Adrenaline content in the adrenal gland tissue of offspring of Dx-treated dams was significantly reduced only on the 1st neonatal day. Thus, the change in blood glucocorticoid level of pregnant females after a single Dx injection during the period critical for development of the hypothalamo-pituitary-adrenal system in fetuses affects the development and kinetics of medullar chromaffin cell division.

Prenatal Glucocorticoids: Short-Term Benefits and Long-Term Risks

“…The influence of a single dexamethasone treatment given to gravid females resulted in the decreased volume of adrenal medulla and the number of chromaffin cells that persisted during the fetal and neonatal period. Decreased proliferation of chromaffin cells during the fetal and early neonatal period was followed by significantly higher values in relation to controls during the second neonatal week, indicating the capacity of the adrenal gland medulla to recover [185]. Multiple dexamethasone doses applied during pregnancy exert a more potent inhibitory effect.…”

Maternal Perinatal Undernutrition has Long-Term Consequences on Morphology, Function and Gene Expression of the Adrenal Medulla in the Adult Male Rat

“…It is therefore plausible that the perinatal environment during critical periods of life such as gestation and lactation may modify the maturation of the adrenal medulla, with subsequent permanent changes in both the structure and the function of adrenomedullary cells. Putative noxious signals such as hypoxia, glucocorticoid hormones and placental restriction profoundly affect chromaffin cell development in several species (30–32). Using a model of prenatal maternal 50% food restriction diet (FR50), we have demonstrated that maternal undernutrition during the last week of gestation and lactation also markedly impairs the neuroendocrine differentiation of chromaffin cells in male rat at weaning (33).…”