Intraventricular (i.c.v.) injection of d(CH2)5-Tyr(Me)-[Orn8]vasotocin, a potent oxytocin antagonist, antagonized in a dose-dependent manner (10-100 ng) penile erection and yawning induced by the systemic injection of apomorphine (80 μg/kg s.c.) or by the i.c.v. injection of oxytocin (30 ng). In contrast, the oxytocin antagonist, even at the dose of 10 μg, did not modify penile erection and yawning induced by the i.c.v. injection of ACTH-(1-24). These results suggest that apomorphine, but not ACTH-(1-24), induce penile erection and yawning by releasing oxytocin in some brain area. © 1987.
Argiolas, A., Melis, M. R., Vargiu, L., & Gessa, G. L. (1987). d(CH2)5Tyr(Me)-[Orn8]vasotocin, a potent oxytocin antagonist, antagonizes penile erection and yawning induced by oxytocin and apomorphine, but not by ACTH-(1-24). European Journal of Pharmacology, 134(2), 221–224. https://doi.org/10.1016/0014-2999(87)90168-3