Oxytocin (OT) effect on ghrelin-stimulated neuropeptide Y (NPY) secretion was evaluated in 12 normal men.
Tests: ghrelin (1 microg/kg B.W. as an intravenous bolus); OT (2 mIU/min infusion); ghrelin plus OT; normal saline. Plasma NPY did not change during saline or OT infusions, whereas it showed a significant 29% increase vs baseline at 15 min after ghrelin injection. When OT was present, ghrelin-induced NPY increment was completely abolished. Results show that oxytocin modulates the NPY response to ghrelin, whereas it is unable to produce direct inhibitions of basal circulating NPY levels.