Lateral cerebroventricular injection of neuropeptide Y stimulates feeding in sheep.

We compared the effects of neuropeptide Y (NPY) injected into the lateral ventricle (LV) and periphery (ip in rats; iv in sheep) on feed and water intake. In sated rats, a bolus injection of 1.18 or 2.35 nmol of NPY administered LV, but not ip, increased (P less than 0.05) feed intake on average of 809% within 30 min of injection. In sated sheep, an LV bolus injection of 2.35 nmol of NPY increased feed intake by 154% within 30 min. Similar doses of human pancreatic polypeptide and peptide YY were less orexigenic than NPY in sheep. After 24 h, cumulative feed intakes were similar among control and peptide treatments. Intravenous injection of 2.35 nmol NPY did not increase feed intake in sheep. Water intake was stimulated (P less than 0.05) by NPY (LV injection) in both the presence and absence of feed. We propose that NPY is involved in the central regulation of consummatory behavior in sheep.