Differential effects of arginine vasotocin and gonadotropin-releasing hormone on sexual behaviors in an anuran amphibian.

Both arginine vasotocin (AVT) and gonadotropin-releasing hormone (GnRH) are known to influence sexual behavior in many vertebrate taxa. We investigated the effects of both of these peptides on two different sexual behaviors, calling and amplexus, in the Great Plains toad (Bufo cognatus). AVT, at a dosage of 100 microg/100 g toad, significantly increased both the amount of calling behavior per individual and the probability that an individual would call. GnRH, however, had no effect on calling behavior. There was a reciprocal effect of these peptides on amplexus: AVT did not induce amplexus, while GnRH significantly induced this behavior. Furthermore, AVT-induced calling could be inhibited by Manning compound (an arginine vasopressin receptor antagonist). This is the first report of GnRH influencing sexual behavior in an anuran amphibian. These results suggest that specific sexual behaviors in B. cognatus may be under the regulation of independent peptide control. Copyright 1997 Academic Press.