THE DIFFERENTIAL-EFFECTS OF 2 ENANTIOMERS OF TETRAHYDROPALMATINE ON THE RELEASE AND METABOLISM OF MONOAMINE TRANSMITTERS

Semi-differential voltammetry combined with carbon fiber electrodes an d high performance liquid chromatography with electrochemical detectio n (HPLC-ECD) was used to study the effects of two enantiomers of tetra hydropalmatine (THP) isolated from Chinese herbs: (-)-THP and (+)-THP on the release and metabolism of monoamine. Voltammetric results showe d that the two enantiomers (2 mg kg-1, i.v.) increased markedly the ex tracellular dihydroxyphenylacetic acid (DOPAC) level and elevated sigh tly 5-hydroxyindoleacetic acid (5-HIAA) level in rat striatum, but the time course of effects differed. Biochemical detection results showed that the two enantiomers (2 mg kg-1, i.v.) raised DOPAC, 5-HIAA, and homovanillic acid (HVA) contents in rat striatum and limbic area. (+)- THP produced a significant fall of DA content, while (-)-THP hardly re duced the DA content in the striatum and limbic area. Our study sugges ted that the two enantiomers of THP possess different effects on the r elease and metabolism of monoamine transmitters at low dose.