Abstract
Hydroalcoholic hypericum extract inhibits the synaptosomal uptake of serotonin, norepinephrine, and dopamine with about similar affinities and leads to a significant down-regulation of cortical (3-adrenoceptors and β-HT2-receptors after sub-chronic treatment of rats. While neither hypericine nor kaempferol did show any reuptake inhibiting properties, hyperforin was identified as the unspecific reuptake inhibitor of hypericum extracts with half-maximal inhibitory concentrations for the three synaptosomal uptake systems mentioned above between 80 and 200nmol/l. Moreover, a hyperforin-enriched (38 %) CO2 extract also leads to a significant β-receptor down-regulation after subchronic treatment. The data suggest hyperforin as the active principle of hypericum extracts in biochemical models of antidepressant activity.
