Comparison of 12-chloroscoulerine enantiomers on animal behavior to dopamine receptors

AIM: To compare the pharmacological characteristics of 12-chloroscoulerine (CSL) enantiomers to dopamine (DA) receptors. METHODS: Radioligand receptor binding assay with calf striatum and behavioral tests of mice or rats were used. RESULTS: In the competitive binding assay, the affinities (K-i) of l -CSL to D-1 and D-2 receptors were 5.1 nmol.L-1, while those of d-CSL for D -1 and D-2 receptors were 135 and 9150 nmol.L-1, respectively. The K-i of d l-CSL to D-1 and D-2 receptors were 8.9 and 9.6 nmol.L-1, respectively, whi ch were slightly weaker than that of l-CSL. In the behavioral experiments, CSL enantiomers 5 - 60 mg.kg(-1) antagonized the stereotypy induced by apom orphine in rats, and 5 - 150 mg.kg(-1) produced catalepsy. The enantiomers 10 - 60 mg.kg(-1) reduced the mice jumping behavior induced by amphetamine + levodopa. l-CSL 10 - 80 mg.kg(-1) antagonized the spontaneous locomotor a ctivity of normal or amphetamine-treated mice. CONCLUSION: CSL enantiomers are antagonists to DA receptors: l-CSL > dl-CSL > > d-CSL.