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

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.