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 (Ki) of l-CSL to D1 and D2 receptors were 5.7 nmol.L-1, while those of d-CSL for D1 and D2 receptors were 135 and 9150 nmol.L-1, respectively. The Ki of dl-CSL to D1 and D2 receptors were 8.9 and 9.6 nmol.L-1, respectively, which were slightly weaker than that of l-CSL. In the behavioral experiments, CSL enantiomers 5-60 mg.kg-1 antagonized the stereotypy induced by apomorphine 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 activity of normal or amphetamine-treated mice.

CONCLUSION

CSL enantiomers are antagonists to DA receptors: l-CSL > dl-CSL >> d-CSL.