Effects of a nitric oxide synthase inhibitor on 5-HT1A receptor agonist 8-OH-DPAT-induced hyperphagia in rats

We investigated nitric oxide (NO) involvement in the hyperphagia induced by the 5-HT1A receptor agonist 8-hydroxy-2-di-n-(propylamino)tetralin (8-OH-DPAT). A NO synthase inhibitor, NG-nitro-L-arginine methyl ester (L-NAME), dose dependently inhibited 8-OH-DPAT-induced eating in freely feeding rats. However, the inactive isomer D-NAME was without effect. The inhibitory effects of L-NAME on 8-OH-DPAT-induced hyperphagia were reversed by simultaneous administration of L-arginine. These results suggest that NO participates in the 8-OH-DPAT-induced hyperphagia which is elicited by activation of the 5-HT1A receptor.