Pharmacodynamic effects of St. John's Wort on rat intracerebral field potentials

Two extracts of St. John s Wort were compared with respect to their action on in vivo monitored field potentials from four brain areas of the freely moving rat. Quantitative assessment of the drug action revealed a late onset (3 to 4 hours after oral application) and main effects on the frontal cortex. Changes consisted in electrical power alterations reminiscent of the action of antidepressive and/or analgesic drugs. Particular frequency bands affected first line were alpha1 and alpha2, which in some way are related to serotonergic and dopaminergic transmission. From this it is concluded that St. Johns Wort could be used for the indication of depression with predictable success. The extract labeled "K" turned out to be superior especially after repetitive application and could thus far be used for further studies.