EXTRAHYPOTHALAMIC SEROTONERGIC MODIFICATION AFTER MASCULINIZATION INDUCED BY NEONATAL GONADAL-HORMONES

Exposure to gonadal steroids during the critical period exerts an organizational effect on the CNS. This hormonal effect could be mediated, at least in part, by neurotransmitters. Traditionally, the main place involved in the aminergic sexual differentiation has been the hypothalamus. The aim of this work was to examine the possible long-term effect of cerebral administration of testosterone or estradiol on sexual behavior and hypothalamic/extrahypothalamic monoaminergic systems in the adult rat. For this purpose, female Wistar rats were intraventricularly injected during the first 24 h of life with testosterone (T) or estradiol benzoate (EB) (200-mu-g/kg) (male and female control groups were vehicle treated) and sexual behavior and monoaminergic mediobasal hypothalamic, striatal, and limbic metabolism in adult rats were studied. Receptive behavior was not affected, whereas a masculinizing effect (% mounts) was observed in the animals treated with both gonadal hormones. Only testosterone-treated females showed a male-like serotonergic ratio in corpus striatum and limbic system. A possible extrahypothalamic serotonergic role could be suggested in the mechanisms of sexual differentiation.