DECREASED POSTNATAL TESTOSTERONE AND CORTICOSTERONE CONCENTRATIONS INRATS FOLLOWING ACUTE INTERMITTENT PRENATAL HYPOXIA WITHOUT ALTERATIONS IN ADULT MALE SEX BEHAVIOR

The prenatal and postnatal testosterone surges in the male rat are ass ociated with neurobehavioral sexual differentiation of the brain. Both surges can be attenuated by maternal stress or other environmental fa ctors that activate the maternal and/or fetal hypothalamic/pituitary/a drenal (HPA) axis during the last week of gestation. Since hypoxia is known to activate the HPA axis, we studied its effect during gestation on sexual differentiation in the male rat. We examined the influence of intermittent hypoxic exposure during gestation with respect to the postnatal testosterone surge and corticosterone levels,;and subsequent development of adult reproductive and nonreproductive sexually dimorp hic behaviors. Plasma testosterone and corticosterone concentrations o f male neonates were measured after maternal exposure to acute, interm ittent, prenatal hypoxia (9% O-2 6 h/day from Day 15 to 21 of gestatio n). Relative to normoxic controls, acute, intermittent, prenatal hypox ia significantly attenuated the postnatal testosterone surge. Postpart um plasma corticosterone levels in these animals were also suppressed. In adulthood, prenatally hypoxic animals exhibited normal masculine s ex behavior. Lordosis behavior in response to estrogen and progesteron e priming was not significantly different between treatment groups. Sa ccharin preference, a nonreproductive, sexually dimorphic behavior, wa s not significantly influenced by prenatal hypoxic exposure. These res ults demonstrate that in the male acute intermittent prenatal hypoxia attenuates the postnatal testosterone surge. However, this reduction f ailed to result in significant alterations in the expression of sex re lated behaviors in adulthood.