Motor effects of buspirone: Relationship with dopamine and serotonin in the striatum.

Objective: To determine the effect of low and high doses of buspirone on motor activity and striatal monoamine metabolism in rats.

Design: Experimental study.

Place And Duration Of Study: The experiments were performed in the Department of Biochemistry, Karachi University from October to December 2003.

Subjects And Method: Behavioral and neurochemical effects of agents were monitored acutely. Motor activity was scored in open field. Neurochemical estimations in the striatum were carried out by high performance liquid chromatography.

Results: Administration of buspirone at low (1 mg/kg) and high (10 mg/kg) doses increased latency to move in open field and decreased number of squares crossed. The agent injected at a dose of 1 mg/kg decreased dopamine concentration and increased the concentration of homovanillic acid. Increases of homovanillic acid were smaller at a dose of 1 mg/kg than 10 mg/kg. Changes in the levels of dihydroxyphenyl acetic acid were not significant. Administration of buspirone decreased 5-hydroxytryptamine metabolism at a dose of 1 mg/kg but not at a dose of 10 mg/kg.

Conclusion: The present results provide neurochemical evidence that low but not high dose of buspirone preferentially stimulates somatodendritic 5-hydroxytryptamine-1A receptors resulting in a decrease in striatal serotonin metabolism. Low dose of buspirone could release dopaminergic neurons from inhibitory influence of serotonin and may be useful in reducing parkinsonian-like effects of traditional antipsychotics.