GONADOTROPIN ANTAGONIST MODULATES COURTSHIP BEHAVIOR IN MALE RED-SIDED GARTER SNAKES, THAMNOPHIS-SIRTALIS-PARIETALIS

Behavioral studies were used to investigate the central effects of chi cken-I GnRH, chicken-II GnRH, and D-Phe(2,6),Pro(3)-GnRH, a GnRH antag onist, on the courtship behavior of male red-sided garter snakes, Tham nophis sirtalis parietalis. Intracerebroventricular (ICV) injections o f chicken-I or chicken-II GnRH had no effect on time spent courting or latency to court when experimental males were exposed to unmated fema les, or when experimental males were exposed to the female sex attract iveness pheromone. ICV injections of D-Phe(2,6),Pro(3)-GnRH caused a s ignificant decrease in latency to court when experimental males were e xposed to unmated females. When males injected with D-Phe(2,6),Pro(3)- GnRH were exposed to the female sex attractiveness pheromone, it cause d a significant increase in time spent courting compared to that in sa line-injected controls. D-Phe(2,6),Pro(3)-GnRH was not able to initiat e courtship behavior during the nonbreeding season, indicating that co urtship behavior is dependent on the interaction of multiple component s. This study does demonstrate that a hormone or neuropeptide can modu late sexual behavior in garter snakes. Copyright (C) 1996 Elsevier Sci ence Inc.