Prostaglandin F2 alpha, sexual behavior and ovarian estrogen synthesis in garter snakes (Thamnophis sirtalis parietalis).

1. High levels of prostaglandin F2 alpha (PGF2 alpha; 10-18 ng) were detected in copulatory material removed from the cloacae of female Thamnophis sirtalis parietalis immediately after mating. 2. In vitro, ovarian fragments treated with PGF2 alpha secreted significantly more estrogen than control fragments. 3. Together these results suggest that a post-mating surge in estrogen secretion that occurs in this species may be influenced by a substantial rise in PGF2 alpha that occurs after mating. 4. These findings are consistent with the hypothesis that post-mating elevations in plasma levels of PGF2 alpha in females are derived from male copulatory material.