T. Abekawa et al., Effect of low doses of L-NAME on methamphetamine-induced dopaminergic depletion in the rat striatum, J NEURAL TR, 108(11), 2001, pp. 1219-1230
The toxic dose of methamphetamine (METH) (5 mg/kg, s.c., x4, 2 hr intervals
) decreased contents of dopamine. dihydroxyphenylacetic acid (DOPAC), and h
omovanillic acid (HVA) in striatum, and decreased contents of serotonin (5-
HT) in both striatum and nucleus accumbens. Administration of low doses of
a non-selective endothelial and neuronal nitric oxide synthase (NOS) inhibi
tor, N omega -nitro-L-arginine methyl ester (L-NAME) (5 and 10 mg/kg, i.p.,
x 1) intensified the METH-induced decreases in contents of dopamine and it
s metabolites in striatum. NO substrate, L-arginine (500 mg/kg, i.p., x4) r
eversed these effects of L-NAME on the METH-neurotoxicity. L-NAME did not c
hange the METH-induced hyperthermia. These findings, which are contrary to
our previous study with a high dose of L-NAME, suggest that the inhibition
of endothelial or neuronal NOS-mediated NO production by low doses of L-NAM
E enhanced the METH-induced neurotoxicity. The finding that L-NAME can have
opposite effects on the METH-neurotoxicity according to the dosing is impo
rtant, however, additional experiments should be performed to clarify which
type of NOS is related to these effects.