Nitric oxide synthase inhibition blocks amphetamine-induced locomotor activity in mice

FRANÇAIS :
L'activité locomotrice des souris est mesurée pendant 30 minutes après traitement par 1, 2 ou 4 mg/kg d'amphétamine. La L-NAME, inhibiteur non spécifique de la synthétase du monoxyde d'azote (NO) est injectée avant le traitement par l'amphétamine à un groupe de souris, avec ou sans association avec la L-arginine. L'amphétamine entraîne une augmentation dose-dépendante de l'activité locomotrice des souris, qui est bloquée par la L-NAME en fonction de la dose. La L-Arginine prévient les effets inhibiteurs de la L-NAME. Le NO interviendrait donc dans la modulation de la stimulation amphétaminique.
ENGLISH :
Effects of N(exponent)G-nitroarginine methyl ester (L-NAME), a nonspecific inhibitor of nitric oxide (NO) synthase, on amphetamine-induced locomotor activity were investigated in Swiss-Webster mice. Locomotor activity was measured for 30 min immediately following amphetamine (1, 2 and 4 mg/kg, i.p.) or saline treatments. L-NAME (15 and 30 mg/kg) and a combination of L-arginine (1000 mg/kg) and L-NAME (30 mg/kg) were injected 30 min before amphetamine (2 mg/kg) to other groups of the mice. L-Arginine was injected 30 min before L-NAME treatment when they were combined. L-NAME (30 mg/kg) and L-arginine (1000 mg/kg) were also tested for ability to depress or stimulate locomotor activity in the absence of amphetamine. Amphetamine caused a dose-dependent increase in locomotor activity of the mice. L-NAME blocked the amphetamine-induced locomotor stimulation dose dependently. L-Arginine pretreatment prevented the inhibitory effects of L-NAME on amphetamine-induced locomotor stimulation. L-NAME and L-arginine did not cause any significant change in locomotor activity in mice not treated with amphetamine. These results suggest that amphetamine-induced locomotor stimulation in mice is modulated by NO. (Author' s abstract)