ENDOGENOUS NITRIC-OXIDE MODULATES BEHAVIORAL-EFFECTS ELICITED BY SUBSTANCE-P IN RAT

Several studies have shown that the undecapeptide, substance P, alters behaviour following central or peripheral administration in the rat. Here we report that L-arginine administration increases substance P-in duced locomotion and changes in food intake in rats. N-G-Nitro-L-argin ine methyl ester, a specific inhibitor of nitric oxide synthase, reduc es substance P-induced effects. These results suggest that endogenous nitric oxide plays a role in the modulation of the catecholaminergic e ffect of substance P on motor behaviour. They also clarify the mechani sm underlying food intake induced by substance P.