Prenatal ethanol exposure induces a sexually dimorphic effect on daily water consumption in prepubertal and adult rats.

Previous studies have shown that female rats consume significantly more water than males on a weight basis. Because exposure to alcohol during the last week of gestation is associated with incomplete behavioral defeminization in male rats, we examined daily water intake in fetal alcohol-exposed (FAE) males and females. Time-pregnant multiparous Sprague-Dawley dams were administered an ethanol liquid diet containing 35% ethanol-derived calories from day 14 through parturition. At 80 days of age, daily water consumption of FAE males and female litter representatives was measured for 7 days. FAE males, but not females, consumed significantly more water than their pair-fed counterparts. Subsequent experiments determined that the increased water consumption in FAE males is present prepubertally, persists into mature adulthood, and is not influenced by prenatal or postnatal castration. Chronic estrogen treatment induced large increases in water consumption, but consumption of FAE males remained elevated over elevated pair-fed male consumption, indicating that pituitary sensitivity to estrogen was not increased in FAE males. Morphometric studies of hypothalamic nuclei containing vasopressin cells revealed no long-term effects of prenatal ethanol exposure on the volume of the supraoptic nucleus or paraventricular nucleus in males, nor was an effect observed in the ventromedial nucleus measured as a control. In FAE females, the volume of the paraventricular nucleus was significantly smaller than chow-fed controls. Whereas baseline plasma and pituitary arginine vasopressin (AVP) levels of FAE animals and pair-fed controls were not significantly different, AVP content was significantly reduced in the septal/bed nucleus region in brains of FAE animals of both sexes. Overall, these data indicate that prenatal ethanol exposure increases male water consumption in the absence of alterations in basal plasma AVP.