查看文章

The effect of the intracerebroventricular (ICV) injection of the oxytocin antagonist d(CH₂)₅Tyr(Me)-Orn⁸-vasotocin on the stimulation of copulatory behavior induced by the dopamine (DA) agonist apomorphine was studied in male rats. Apomorphine (80 μg/kg SC) given 5 min before mating tests decreased intromission frequency and ejaculation latency in experienced male rats. Such effects were abolished and reversed by pretreatment with 50 and 1000 ng of the oxytocin antagonist given ICV 5 min before apomorphine. The peptide per se markedly increased intromission and ejaculation latency and abolished ejaculation in control rats. The results suggest that brain oxytocin is implicated in the expression of sexual behavior, and apomorphine might improve male copulatory behavior by releasing oxytocin in brain.