Possible involvement of nitric oxide in locomotor behaviour in rats

Spontaneous motor activity (SMA) which is a motivated behaviour of rats was measured using photoactometer 5 and 30 m after injecting graded doses (1000 and 2000 mg/kg) of Nitric Oxide (NO) precursor, L - arginine. In order to test a forced task, motor coordination was determined in similarly treated rats using a rota-rod instrument. The data were correlated with the changes produced by the same doses of L-arginine on NO concentration in the whole brain. NO concentration was increased in a dose dependent manner 5 as well as 30 m after L-arginine treatment. However no difference was found between 5 and 30 m data SMA was suppressed significantly in both 5 and 30 m treated animals. Motor coordination was not affected by either dose of L-arginine. Thus, brain NO concentration data coincided well with L-arginine-induced suppression of SMA. These results suggest that motivation to perform a task and not a forced task is suppressed if NO activity is increased in the brain. It is concluded that locomotor behaviour may be impaired if No concentration is increased significantly in the brain.