Grant: Travel Awards - Institute Community Support

Adult neurogenesis involves the proliferation, differentiation, migration, and survival of neurons in the rodent dentate gyrus. Gonadal steroids have been shown to independently modulate these aspects of adult hippocampal neurogenesis. We previously reported that androgens, acting through the androgen receptor, increased the survival of neurons in the dentate gyrus of adult male rats. However, neither castration nor androgen replacement affected the proliferation of neurons suggesting androgens effects on neurogenesis were specifically related to cell survival. These previous studies, though, only examined the effects of androgens on neurogenesis in males. Thus, in the current study, we explored the effect of systemic injections of the androgen, dihydrotestosterone, on adult hippocampal neurogenesis in ovariectomized female rats. We replicated our previous finding in male rats as dihydrotestosterone increased the number of BrdU positive cells following 30 days of treatment. Additionally, castration and DHT treatment did not affect the number of Ki67 expressing neurons, suggesting androgens affect survival and not proliferation. Surprisingly, though, systemic DHT treatment did not increase the number of BrdU positive cells and did not affect the number of ki67 expressing cells in the dentate gyrus of females. Together, these data suggest androgens act in a sex dependent manner to increase adult hippocampal neurogenesis. Additionally, given the lack of an effect of DHT in females suggests the sex difference in response to androgens in adulthood may be organized during a perinatal critical period. The sex dependent effects of androgens on adult hippocampal neurogenesis may have implications for the treatment of neurological disorders that show sex-dependent changes and affect the hippocampus.