Efficacy of an Hypericum perforatum (St. John's Wort) extract in preventing and reverting a condition of escape deficit in rats

The treatment of unselected depressed patients with an hydro-alcoholic extr act of Hypericum perforatum has been reported to have an efficacy similar t o that of classical antidepressants. In the present report, the effects of H. perforatum were studied on three animal models of depression: (i) an acu te form of escape deficit (ED) induced by an unavoidable stress; (ii) a chr onic model of ED, which can be maintained by the administration of mild str essors on alternate days; (iii) a model of anhedonia based on the finding t hat repeated stressors prevent the development of an appetitive behavior in duced by vanilla sugar in satiated rats fed ad libitum. H. perforatum acute ly protected animals from the sequelae of unavoidable stress; such an effec t was partially prevented by the administration of SCH 23390 or (-)-pindolo t. Moreover, H. perforatum reverted the ED maintained by repeated stressors and preserved the animal's capacity to learn to operate for earning a posi tive reinforcer. It was concluded that H. perforatum contains some active p rinciple(s) endowed with antidepressant activity. (C) 1999 American College of Neuropsychopharmacology. Published by Elsevier Science Inc.