Luteinizing hormone-releasing hormone (LHRH) is known to influence sexual behavior in many vertebrate taxa, but there have been no systematic studies on the role of LHRH in sexual behavior of turtles. We tested the hypotheses that exogenous LHRH analogues would induce sexual behavior of male Four-eyed turtle, Sacalia quadriocellata. We examined this by challenging males with intramuscular injections of mammalian luteinizing hormone-releasing hormone analogue (LHRH-A), human chorionic gonadotropin (HCG), or a combination of the two, and subsequently exposing them to sexually receptive females for behavioral observation. Our data show that the injection of only HCG could not, while that of only LHRH-A could, facilitate sexual behavior along with testicular recrudescence and spermatogenesis in S. quadriocellata. The injection of both LHRH-A and HCG would induce more drastic sexual behavior of the animals than that of LHRH-A alone, indicating HCG enhances the effects of LHRH-A induced sexual behavior. However, different pharmacological dosages of LHRH-A (0.5 mg, 1 mg, 2 mg per 100 g bodyweight) did not correspond to different activity levels. Though the mechanism of LHRH effect was not determined, this study may support that the sexual behavior of S. quadriocellata which occurs at the beginning of the injection despite regression of the gonads. This is the first report on the exogenous LHRH-A induced sexual behavior for this species. 

More results have been published in Asian Herpetological Research, which issued by Chengdu Institute of Biology of CAS.