Corticosterone-induced inhibition of sexual behavior
In a recent study,159 the effects of LBPs on male sexual behavior of young adult male Sprague–Dawley rats were investigated. Oral administration of 1 mg/kg or 10 mg/kg LBPs for 21 days significantly improved the male copulatory performance including increase of copulatory efficiency, increase of ejaculation frequency, and shortening of ejaculation latency. Furthermore, sexual inhibition caused by chronic corticosterone was prevented by administration of 40 mg/kg LBPs for 21 days. Simultaneously, treatment of rats with corticosterone suppressed neurogenesis in the subventricular zone and hippocampus in adult rats, which could be reversed by LBPs.159 In the subventricular zone, the number of BrdU-positive cells in the corticosterone-treated animals was significantly lower than LBP-treatment groups. The neurogenic effect of LBPs was also shown in vitro using mouse C17.2 neural stem cells derived from the cerebellum of neonatal mice and immortalized by retrovirus-mediated v-myc gene transfection. Corticosterone treatment suppressed the cell proliferation of C17.2 cell line, while co-incubation with 10 µg/mL LBP reversed the growth suppression. Blocking neurogenesis in male rats abolished the pro-sexual effect of LBPs. These results demonstrate the pro-sexual effect of LBPs on normal and sexually inhibited rats, and LBP may modulate sexual behavior by regulating neurogenesis.