Prostaglandin E₂ induces receptive behaviors in female Xenopus laevis

The object of this study was to examine the effects of exogenous and endogenous prostaglandin E₂ (PGE₂) on the sexual behavior of female South African clawed frogs, Xenopus laevis. Ticking and leg extension, which communicate sexual unreceptivity to males, were studied in intact, ovariectomized, and ovariectomized-oviductectomized females. Injection of nanomolar amounts of PGE₂ into the dorsal lymph sac significantly increased receptivity in intact, ovariectomized, and ovariectomized-oviductectomized females. The onset of the PGE₂ behavioral effect occurs within 30 sec to 3 min of injection for intact and ovariectomized females; for ovariectomized-oviductectomized females, the latency period for the effect ranges from 10-20 min. PGE₂ induced receptivity in doses as low as 0.03 μg/frog. Injection of the prostaglandin synthesis inhibitors, indomethacin and flurbiprofen (FBP), blocked chorionic gonadotropin- (HCG-) induced behavioral receptivity, suggesting that endogenous prostaglandin synthesis may have a role in regulating female sexual behavior. Flurbiprofen blockade of HCG-induced receptivity was reversed by PGE₂ administration, suggesting that FBP's effects are PG Synthesis-Specific.