SUGGESTIVE EVIDENCE FOR A DA D-3 RECEPTOR-MEDIATED INCREASE IN THE RELEASE OF OXYTOCIN IN THE MALE-RAT

THE dopamine (DA) D-2/3 receptor agonists quinpirole (0.5-8.0 mg kg(-1 ), s.c.) and 7-OH-DPAT (0.2-3.2 mg kg(-1), s.c.), but not the preferen tial DA D, receptor agonist bromocriptine (2.0-32.0 mg kg(-1), s.c.), produced increased plasma oxytocin levels in the rat. In keeping with their affinity for the DA D-2 receptor, all three compounds produced a marked suppression of plasma prolactin levels in their respective dos e range. It is suggested that DA D-3 receptors are involved in mechani sms regulating oxytocin secretion in the rat.