PERIPHERAL NEUROTENSIN PARTICIPATES RN THE MODULATION OF PREPRANDIAL AND POSTPRANDIAL INTESTINAL MOTILITY IN RATS

The present study was undertaken to determine whether neurotensin is i nvolved in the regulation of the intestinal postprandial motor respons e and, if so, whether the regulatory pathway depends upon peripheral o r central neurotensin secretion, Neurotensin, injected by the i.v. rou te (5 mu g/kg) during the fasting state, induced firstly an increased irregular spiking activity during 30-40 min. This effect was followed by an increase of frequency of the myoelectrical complexes during 60 m in, When injected by the i.c.v. route, neurotensin (0.5 mu g/kg) reinf orced the fasting motility pattern of the small intestine after a late ncy of 70 min. Neurotensin was ineffective on ?he colon, The neurotens in receptor antagonist SR 48692 (200 mu g/kg i.v.) reduced the duratio n of the postprandial motor response of the small intestine and blocke d the late postprandial phase on the proximal colon while it suppresse d the early postprandial phase on the distal colon. When administered i.c.v. (20 mu g/kg), SR 48692 had no effect. It is concluded that neur otensin modulates intestinal postprandial motility essentially by a pe ripheral regulatory pathway, Endogenous neurotensin is involved in the maintenance of the postprandial motility pattern on the small intesti ne and the proximal colon while it is involved in the initiation of th is response on the distal colon, This suggests that endogenous neurote nsin acts via both endocrine and nervous mechanisms.