Intracisternal injection of peptide YY inhibits gastric emptying in rats.

Peptide YY (PYY) has been shown to effectively regulate gastrointestinal function when administered intravenously. In the present study, the effect of intracisternal (i.c.) injection of rat PYY on the rate of gastric emptying was investigated in conscious animals. Vehicle, bombesin or different doses of PYY was given i.c. after animals had been given an oral liquid meal. A dose-dependent inhibition of gastric emptying was observed following the injection of PYY (400 fmol, 40 fmol and 40 amol; in 10 microliters) into the cisterna magna. The 400 fmol dose of PYY produced an inhibition of similar magnitude as that caused by bombesin (600 fmol in 10 microliters). Furthermore, subdiaphragmatic vagotomy resulted in an elimination of the inhibitory PYY effect on gastric emptying, suggesting that PYY action to inhibit gastric function depends on intact vagal pathways.