Hormonal protection of gender-related peculiarities of testosterone metabolism in the brain of prenatally stressed rats.

OBJECTIVES: Prenatal stress results in demasculinization and feminization of sexual behavior in adult male rats. Earlier the preventive effect of testosterone replacement of an androgen deficiency in male fetuses during exposure to stress has been demonstrated. Nevertheless the neuroendocrine mechanisms underlying hormonal protection of the brain sexual differentiation are not clear.

MATERIAL AND METHODS: Time-mated rats were undergone to 1 h strict immobilization during days 15 to 21 of gestation. Another group of stressed dams was injected with testosterone propionate on the 17th, 19th and 21st gestational days subcutaneously (5 mg/kg b.w.) 30 min prior to restraining. Aromatase and 5alpha-reductase activities were determined in the preoptic area and medial basal hypothalamus of 10-day old offspring.

RESULTS: Aromatase activity in the preoptic area declined in affected with prenatal stress males and reached the normal female level. It completely restored in prenatally stressed males under influence of prenatal testosterone replacement. 5alpha-reductase activity decreased in the preoptic area of prenatally stressed females. In those pretreated with testosterone propionate, 5alpha-reductase activity was significantly elevated above normal level.

CONCLUSIONS: The data obtained demonstrate a preservation of aromatase activity in the preoptic area of males resulted from testosterone replacement. Presumably testosterone exerts its protective effect on the male sexual behavior by prevention of neurochemical feminization of the brain preoptic area and, perhaps, due to some other mechanisms.