Centrally administered neuropeptide Y delays gastric emptying via Y2 receptors in rats

It has been shown that centrally administered neuropeptide Y (NPY) delays gastric emptying. To determine the receptor subtypes of NPY mediating the inhibitory effects on gastric emptying, effects of intracerebroventricular injection of NPY, [Leu(31),Pro(34)]NPY (a Y-1 agonist) and NPY-(3-36) (a Y-2 agonist) on solid gastric emptying and postprandial antropyloric motility were studied in conscious rats. Intracerebroventricular injection of NPY and NPY-(3-36), but not [Leu(31),Pro(34)] NPY, delayed solid gastric emptying in a dose-dependent manner (0.03-3 nmol). After the feeding (40 min), contractions with low frequency and high amplitude of the antrum were frequently observed, and the peak contraction of the antrum occurred most often 3-6 s before the peak contraction of the pylorus. Intracerebroventricular injection of NPY and NPY-(3-36) (3 nmol), but not [Leu(31),Pro(34)]NPY, significantly reduced antral contractions and the number of antropyloric coordination events. It is suggested that centrally administered NPY impairs postprandial antral contractions and antropyloric coordination via Y-2 receptors, resulting in delayed gastric emptying.