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

Abstract

To determine the effect of low and high doses of buspirone on motor activity and striatal monoamine metabolism in rats. Experimental study. The experiments were performed in the Department of Biochemistry, Karachi University from October to December 2003. 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. 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. 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.