Anesthetic concentrations of riluzole inhibit neuronal nitric oxide synthase activity, but not expression, in the rat hippocampus

We hypothesized that anesthetic dose of riluzole, an inhibitor of glutamate neurotransmission, may affect the activity and/or expression of neuronal N OS (nNOS). Riluzole. N-G-nitro-L-arginine-methyl ester (L-NAME) and 7-nitro indazole (7-NI) produced a concentration-related inhibition of nNOS activi ty in vitro. Riluzole competed with 7-NI for inhibition of nNOS activity, b ut had no effect on nNOS or endothelial NOS (eNOS) protein expression. Also , nNOS activity was significantly decreased in riluzole-anesthetized rats ( 40 mg kg(-1) i.p., -32+/-6% from controls, P<0.05). Therefore, blockade of nNOS activity may he involved in the anesthetic effects of riluzole in vivo . (C) 2000 Elsevier Science B.V. All rights reserved.