Effects of Hypericum perforatum extract on ethanol intake, and on behavioral despair: A search for the neurochemical systems involved

The present study investigated the-possible involvement of a receptors and of serotonergic mechanisms in the effects of Hypericum perforatum extract ( HPE) on immobility time in the forced swimming test (FST) and on ethanol in take in Marchigian Sardinian alcohol-preferring rats. The HPE employed was a dry extract containing 0.3% hypericin and 3.8% hyperforin. Intraperitonea l pretreatment with 20 mg/kg of the sigma receptor antagonist rimcazole (RI M), 30 min prior to HPE, completely suppressed the antiimmobility effect of HPE (3 intragastric injections of 250 mg/kg). Intracerebroventricular pret reatment with 5,7-dihydroxytryptamine (5,7-DHT), which produced a marked de pletion of brain serotonin, reduced the antiimmobility effect, although thi s reduction was not as pronounced as that of RIM. On the other hand, the in hibitory effect of HPE on 10% ethanol intake was modified neither by 5,7-DH T nor by RIM pretreatment. These results suggest that the antidepressant-li ke effect of HPE in the FST may be mediated by interaction with a receptors and to some extent by increased serotonergic neurotransmission. On the oth er hand, these mechanisms appear to be unimportant for the effect of HPE on ethanol intake. (C) 2000 Elsevier Science Inc.