ALTERED ADULT SEXUAL-BEHAVIOR IN THE MALE-RAT FOLLOWING CHRONIC PRENATAL HYPOXIA

The last week of gestation is a critical period for the sexual differe ntiation of the brain in the rat. Exposure to prenatal stress during t his period has been shown to demasculinize and/or feminize adult male sexual behavior. Many of the neurochemical and endocrine responses to hypoxia are similar to that observed under stressful conditions such a s restraint stress. Therefore, we examined the postnatal consequences on reproductive and nonreproductive sexually dimorphic behaviors in ma le offspring of dams exposed to chronic hypoxia during the last week o f gestation. In addition, we examined sensorimotor development in offs pring of both sexes. Pregnant Sprague-Dawley dams were exposed to cont inuous hypoxia (10.5% O2 from gestational day 15 to 21). Offspring wer e weaned at 22 days of age and group housed. Behavioral tests were con ducted with littermate representatives. In adulthood, male rats prenat ally exposed to hypoxia had significantly delayed initiation latencies of masculine sexual behavior and decreased number of ejaculations, bu t did not display a significant increase in feminine sex behavior pote ntials. Developmentally, animals exposed to prenatal hypoxia did not d iffer significantly from controls with respect to day of eye or ear op ening, or the in times of righting reflex, negative geotaxis or cliff avoidance. Wire hanging latencies in hypoxic exposed animals were sign ificantly greater than controls around the time of eye opening, but di d not differ at earlier or later ages. A significant effect of hypoxia was detected on stride length at 95 days of age, but other aspects of gait patterns were similar to controls. No group differences in gait patterns were observed at 17 or 45 days of age. In addition, no signif icant differences were observed in open field activity, circadian loco motor activity, saccharin preference, or Morris water maze test. This hypoxia regimen did not influence the occurrence of the prenatal or po stnatal surge of plasma testosterone. Overall, these results provide s ome evidence that, in males, mild, chronic prenatal hypoxia may result in incomplete masculinization of adult reproductive behavior in the a bsence of overt changes in perinatal testosterone surges.