Neurokinin 3 receptor (NK3R) signaling has an integral role in the stimulated oxytocin (OT) and vasopressin (VP) release in response to hyperosmolarity and hypotension. Peripheral injections of cholecystokinin (CCK) receptor agonists for the CCK-A (sulfated CCK-8) and CCK-B (non-sulfated CCK-8) receptors elicit an OT release in rat. It is unknown if NK3R contributes to this endocrine response. Freely behaving male rats were administered an intraventricular pretreatment of 250 pmol or 500 pmol of SB-222200, a specific NK3R antagonist, or 0.15 M NaCl prior to an intraperitoneal or intravenous injection of CCK-8 (non-sulfated or sulfated) or 0.15 M NaCl. Blood samples were taken prior to intraventricular treatment and 15 minutes after intraperitoneal or intravenous injection, and plasma samples were assayed for OT and VP concentration. Intraperitoneal injection of both non-sulfated and sulfated CCK-8 significantly increased plasma OT levels and had no effect on plasma VP levels. Intravenous injection of sulfated CCK-8 stimulated an increase in plasma OT levels and did not alter plasma VP levels. However, intravenous injection of non-sulfated CCK-8 stimulated a significant increase in plasma levels of both OT and VP. No other studies have demonstrated CCK-8 stimulated release of VP in rat. NK3R antagonist did not alter baseline levels of either hormone. However, pretreatment of NK3R antagonist significantly blocked the CCK-stimulated release of OT in all CCK treatment groups and blocked VP release in response to intravenous injection of non-sulfated CCK-8. Therefore, central NK3R signaling is required for OT and VP release in response to CCK administration.