ETHANOL EXPOSURE DURING THE LAST WEEK OF GESTATION IN THE RAT - INHIBITION OF THE PRENATAL TESTOSTERONE SURGE IN MALES WITHOUT LONG-TERM ALTERATIONS IN SEX BEHAVIOR

In utero ethanol exposure decreases the prenatal testosterone (T) surg e in male rats. To determine the functional significance of this suppr ession. we measured sex behavior in adult litter representatives of pr egnant rats that were administered a fortified liquid diet containing 35% ethanol-derived calories from day 15 of gestation through parturit ion. Control dams were pair-fed an isocaloric liquid diet with the eth anol calories replaced by sucrose. Results from the behavioral studies showed that gonadally intact fetal alcohol-exposed (FAE) males exhibi ted little masculine sex behavior in the first of four weekly sessions . However, their behavior in the subsequent three tests was indistingu ishable from pair-led controls. Lordosis quotients in the same males f ollowing castration and estrogen and progesterone treatment were under 10%. In castrated FAE females, no effects of prenatal ethanol exposur e were observed in masculine behaviors following androgen replacement or feminine sex behaviors following estrogen and progesterone replacem ent. Additional studies measured the duration of prenatal ethanol expo sure necessary to inhibit the prenatal T surge in order to determine w hether the inhibition was due to a direct effect of the drug. Results revealed an inhibition of the surge in males exposed to ethanol from d ays 14 through 20 of pregnancy. days 14 through 16 of pregnancy, or da ys 17 through 20 of pregnancy. A normal surge of T was observed on day s 18-19 of gestation in cont;ol fetuses. These findings indicate that ethanol does not have to be present in blood at the time of the surge to have an inhibitory effect. They also reveal that the surge can be i nhibited with as little as 2436 h of ethanol exposure prior to its nor mal appearance on day 18 of gestation. In spite of this inhibition of the prenatal T surge, the behavioral results indicate that normal masc ulinization and defeminization of sex behavior occurs in FAE males exp osed to ethanol after the beginning of the period of differentiation o f the hypothalamus and testes. (C) 1998 Elsevier Science Inc.