The involvement of 5-HT1B receptors in the inhibitory effects of nitric oxide synthase inhibitor on 2-deoxy-D-glucose-induced hyperphagia in rats

The inhibitory effects of a potent nitric oxide (NO) synthase inhibitor, N(G)-nitro-L-arginine methyl ester (L-NAME), on 2-deoxy-D-glucose (2-DG)-induced hyperglycemia were investigated in rats. L-NAME significantly inhibited 2-DG-induced hyperglycemia, although N(G)-nitro-D-arginine methyl ester (D-NAME) did not affect it. A similar NO synthase inhibitor, N(G)-monomethyl-L-arginine (L-NMMA), also inhibited 2-DG-induced hyperglycemia. The antagonistic effects of L-NAME are unrelated to the cholinergic system, since the muscarinic receptor antagonist scopolamine did not affect 2-DG-induced hyperglycemia. The neuronal NO synthase inhibitor 7-nitroindazole (7-NI) did not reduce 2-DG-induced hyperglycemia, but rather enhanced it. Our results suggest that NO may be involved in glucose homeostasis and that the inhibitory effects of L-NAME on 2-DG-induced hyperglycemia are not related to muscarinic receptors or neuronal NO synthase.