7 alpha -Hydroxypregnenolone regulates diurnal changes in sexual behavior of male quail

In the Japanese quail, 7 alpha -hydroxypregnenolone, a previously undescribed avian neurosteroid, is actively produced in the brain. 7 alpha -Hydroxypregnenolone acts as a novel neuronal activator to stimulate locomotor activity of quail. Therefore, in this study, we determined whether 7 alpha -hydroxypregnenolone changes the expression of sexual behavior in Japanese quail. We first measured diurnal changes in sexual behavior of male quail exposed to a long-day photoperiod. We found that sexual behavior of male quail was high in the morning when endogenous 7 alpha -hydroxypregnenolone level is high. Subsequently, we centrally administered 7 alpha -hydroxypregnenolone in the evening when endogenous 7 alpha -hydroxypregnenolone level is low. In the 30min after intracerebroventricular (ICV) injection, 7 alpha -hydroxypregnenolone dose dependently increased the frequency of sexual behavior of male quail. However, 7 beta -hydroxypregnenolone, a stereoisomer of 7 alpha -hydroxypregnenolone, did not effect on the frequency of sexual behavior of male quail. In addition, to confirm the action of 7 alpha -hydroxypregnenolone on sexual behavior, male birds received an ICV injection of ketoconazole, an inhibitor of cytochrome P450s, and behavioral experiments were performed in the morning. Ketoconazole significantly decreased the frequency of sexual behavior of male quail, whereas administration of 7 alpha -hydroxypregnenolone to ketoconazole-treated males increased the frequency of their sexual behavior. These results indicate that 7 alpha -hydroxypregnenolone regulates diurnal changes in sexual behavior of male quail.