The mechanism of action of neuropeptide Y in rat colonic motility

Nah, Byung Kyu; Jeon, Won Joong; You, Il Young; Chae, Hee Bok; Park, Seon Mee; Youn, Sei Jin; Ko, Byung Sung

Abstract

BACKGROUND/AIMS: Neuropepetide Y (NPY) is involved in the regulation of several gut functions, but the neuronal action of NPY has not been fully investigated. This study was designed to investigate the effect and mechanism of action of NPY on motility in the proximal and distal rat colon.
METHODS
Rat colon with an intact superior mesenteric artery was isolated. After a basal period, NPY was administered at concentrations of 14 pM, 70 pM, 140 pM, and 280 pM. Intraluminal pressures were monitored in the proximal and distal colon. The contractile response was expressed as a percent change of motility indices over the basal level. After a pre-infusion of atropine (AT), tetrodotoxin (TTX), propranolol, hexamethonium, and phentolamine, NPY was infused at a concentration of 140 pM, and pressures were monitored.
RESULTS
NPY increased the colonic motility at concentrations of 14, 70, 140, and 280 pM in the proximal colon (28.5+/-28.2%, 48.4+/-34.3%, 122.9+/-97.3%, 68.2+/-28.1%, respectively) and in the distal colon (44.9+/-25.9%, 103.8+/-72.0%, 237.1+/-131.0%, 93.0+/-63.9%, respectively) in a dose-dependent manner. The enhancing effect of NPY (140 pM) on colonic motility was significantly suppressed by pretreatment with atropine, propranolol, and TTX. However, the effect of NPY was not inhibited by hexamethonium or phentolamine.
CONCLUSION
NPY increases colonic motility. The enhancing effect of NPY on colonic motility may require cholinergic input via muscarinic receptors or adrenergic input via beta-receptors.