Aim: To assess potencies of tetrahydroprotoberberines (THPB) and hydrobenzyltetrahydroisoquinolines (HBTI) on DA receptors.
Methods: The receptor binding assay with calf striatum to D1 and D2 receptors, and the animal behavior tests were used.
Results: (+/-) 12-Chloroscoulerine (CSL) was the most potent one among the THPB and HBTI. The affinities of CSL to D1 and D2 receptors were 13 and 51 nmol.L-1, respectively. In rats, CSL showed an antagonistic effect on the stereotypy and induced catalepsy. In the 6-OHDA lesioned rats, however, CSL exerted the agonistic effect to DA receptors.
Conclusion: CSL had dual actions to DA receptors and its effects were similar to that of (-)stepholidine.