5-Alpha-Reductase 2 Inhibition Impairs Brain Defeminization of Male Rats: Reproductive Aspects

The study investigated the role of the 5alpha-reductase 2 (5alpha-R2) metabolic pathway in brain sexual differentiation of male rats by inhibiting it with finasteride from gestational day 19 to postnatal day 5. The results showed that while sexual maturation and copulatory potential were unaffected, finasteride-treated males exhibited increased pre-implantation loss in mating, likely due to abnormally shaped sperm. Despite normal male sexual behavior, 53% of these males displayed homosexual behavior when pretreated with estradiol, indicating incomplete brain defeminization. The study concluded that 5alpha-R2 is crucial for brain sexual differentiation, producing essential metabolites that work with estradiol and protecting the brain from estradiol's excess effects.