Effects of maternal ethanol consumption in rats on basal and rhythmic pituitary - adrenal function in neonatal offspring

Abstract

Neonatal corticoid treatment delays development of the circadian rhythm of plasma corticosterone in rats. We therefore sought to determine whether fetal or neonatal exposure to ethanol, a substance which activates the hypothalamo - pituitary - adrenal axis, produces similar effects. Subjects were the offspring of dams fed a 5.0% w/v ethanol-containing liquid diet or pair-fed an isocaloric control diet during gestation weeks two and three or during postnatal week one. At birth (day 1), the fetal ethanol-exposed pups had significantly higher brain and plasma corticosterone levels than the pair-fed or normal controls; brain and body weights were unaffected. By day 3, brain and plasma corticosterone titers in the fetal ethanol-exposed pups declined to the levels of the pair-fed and normal controls, although brain weights were significantly reduced. Significantly higher p.m. than a.m. levels of plasma corticosterone first occurred on day 18 both in the fetal ethanol-exposed pups and in the pair-fed and normal controls. Thus, despite its causing elevated corticosterone levels at birth, fetal exposure to ethanol did not affect the onset of the pituitary - adrenal circadian rhythm. On the other hand, exposure to ethanol during the first neonatal week delayed the onset of the pituitary - adrenal rhythm from day 18 to day 21. However, even greater delays occurred in the neonatal pair-fed controls, suggesting that the delays following neonatal exposure were due to nutritional deficits rather than to alcohol per se. The developmental and long-term influences of elevated corticoid levels at birth in fetal ethanol-exposed rats on other aspects of pituitary - adrenal function remain to be determined.