Arginine vasotocin induces sexual behavior of newts by acting on cells in the brain.

To investigate whether arginine vasotocin (AVT) acts on target cells in the brain of Taricha granulosa (a urodele amphibian), the behavioral effects of intracerebroventricular (ICV) and intraperitoneal (IP) injections of AVT were compared. Male newts exhibited the greatest sexual activity (amplectic clasping) following an ICV injection of 0.1 microgram AVT. Another study showed that nanogram quantities of AVT, administered ICV, stimulated the behavior. An ICV injection of an antagonist to arginine vasopressin, d(CH2)5Tyr(Me)AVP, or an anti-AVT immune serum significantly inhibited the sexual behavior. Intracranial implants of 17 beta-estradiol (E2) or 5 alpha-dihydrotestosterone (DHT) in castrated males maintained the behavioral response to an injection of AVT. Another study found that an IP injection of DHT or E2 did not increase the incidence of newt sexual behavior during the 8 hours following the injection.