[Effects of schizandrol A on monoamine neurotransmitters in the central nervous system].

Schizandrol A (2',3',4',1",2",3"-hexamethoxy-6, 7-dimethyl-1,2,3,4-dibenzo-1,3-cyclooctadien-6-ol) is one of the effective components in the dried fruit of Schizandra chinensis Bail. Previous studies have found that schizandrol A exerts inhibitory effects on the central nervous system (CNS). For the purpose of elucidating the mechanism of inhibition, the concentrations of monoamine neurotransmitters and their metabolites in rat brain and the effects of schizandrol A on some receptors were determined by the ion-pairing reversed-phase liquid chromatography with electrochemical detection method and competitive binding assay. In the neurotransmitter studies, significant elevations of dopamine and its metabolite DOPAC (in striatum) and DA (in hypothalamus) were observed after i.p. administration of 50 mg/kg or 100 mg/kg of schizandrol A. But the receptor binding experiments showed that schizandrol A had no affinity for dopamine D1 and D2 receptors. Serotonin receptors and alpha 1-,alpha 2-adrenergic receptors, and it did not affect the binding of dopamine to dopamine D1 or D2 receptors. These results indicate that the inhibition exerted by schizandrol A on the CNS may be related to the dopamine system, and the increase of dopamine turnover has nothing to do with dopamine receptors. The concentrations of the norepinephrine metabolite MHPG and the serotonin metabolite 5-HIAA showed changes in rat striatum and hypothalamus after schizandrol A treatment, but norepinephrine and serotonin levels were unaffected.