ROLE OF NITRIC-OXIDE IN THE GASTRIC CYTOPROTECTION INDUCED BY CENTRALVAGAL-STIMULATION

The role of nitric oxide (NO) in the vagal cholinergic-mediated cytopr otective effect of intracisternal (i.c.) injection of the stable thyro tropin-releasing hormone (TRH) analog, RX 77368, was investigated in c onscious rats. RX 77368 (1.5 ng i.c.) reduced by 88% gastric hemorrhag ic lesions induced by oral administration of ethanol (60%). L-N(G)-Nit ro-arginine methyl ester (L-NAME, 3 mg/kg i.v.), an inhibitor of NO sy nthase, abolished the cytoprotection provided by i.c. RX 77368. The ef fect of L-NAME was reversed by L- but not D-arginine. These results su ggest that the L-arginine-nitric oxide pathway is involved in the cyto protective effect of i.c. TRH analog, probably through the modulation of gastric mucosal blood flow.