Pharmacological profile of hypericum extract. Effect on serotonin uptake by postsynaptic receptors.

In the present study is is reported that the methanolic Hypericum extract LI 160 (Jarsin 300) exerts no protective effect against N-methyl-D-aspartate (NMDA-) or gp120- (from the HIV virus) induced cytotoxicity. Moreover, it is established that Hypericum extract causes no activation of arachidonic acid release from neurons activated by gp120; hence it displays no sensitization effect on the NMDA receptor channel. The main outcome of this study is the finding that Hypericum extract causes a 50% inhibition (IC50 value) of serotonin uptake by rat synaptosomes at a concentration of 6.2 microglml. Therefore it is concluded that the antidepressant activity of Hypericum extract is due to an inhibition of serotonin uptake by postsynaptic receptors. Future studies might focus on the effect of Hypericum extract on serotonin binding to neurons, serotonin storage in granules, the rate of synthesis of serotonin, and on the activity of monoamine oxidase.