Neonatal neural organizing effects of exogenous corticosteroids on sexual differentiation of the brain in the female rat

Testosterone, deoxycorticosterone, or vehicle was administered neonatally to female Long-Evans rats. Parameters expressing the reproductive physiology and behavior of the adult animals were studied. It was found that neonatal administration of testosterone produced the expected "defeminization" and "masculinization" of the brain, affecting both the reproductive behavior and cyclicity of these females. In contrast, neonatal administration of the adrenal steroid did not affect cyclicity although it "defeminized" and "masculinized" sexual behavior, albeit to a lesser degree than testosterone. The results suggest a dichotomy in the neuroregulation of reproductive physiology and sexual behavior.