Sexual orientation in male rats prenatally exposed to ethanol.

Previous studies have shown that prenatal ethanol exposure causes feminization of the male offspring, as evidenced by display of female sexual response (lordosis), when mounted by a stud male. In the present study we examined whether or not the feminization induced by prenatal ethanol exposure also affected a different aspect of sexually motivated behavior, namely, the approach towards a receptive female normally displayed by male rats. The testing apparatus consisted of an open-field arena with two small boxes in which were placed the stimulus animals, in one box a male rat, in the other a receptive female. The partition between the stimulus and the experimental animals consisted of a metal net allowing both animals to see and smell each other without actual physical contact. The tendency to approach the receptive female or the male was assessed by the proportion of the observation period the experimental male spent near the receptive female or the male rat, respectively. The experiment was performed on the adult male offspring of mothers consuming a liquid diet containing 5% ethanol, giving rise to a daily ethanol intake of about 14 g/kg. One group of control mothers was given a liquid diet without alcohol but isocaloric with the alcohol-containing diet. Another control group had free access to water and lab chow. The results showed that male offspring of both control groups devoted 29% of the observation period near the receptive female as compared to 13% near the male. The ethanol-exposed males on the other hand devoted as much time, 20%, to the male as to the receptive female.(ABSTRACT TRUNCATED AT 250 WORDS)