Pharmacological and endocrine effects of Hypericum perforatum and hypericin after repeated treatment

Clinical studies have demonstrated the antidepressant efficacy of Hypericum (St. John's wort) extracts comparable to tricyclic antidepressants such as imipramine. We examined the effects of Hypericum extract and hypericin, on e active constituent, in the forced swimming test (FST) after treatment rep eated for 14 days. it has recently been shown that hypericin was inactive i n the FST after acute treatment, but remarkably active when solubilized by subfraction IIIc(1) containing mainly procyanidin B2. Therefore, we investi gated the cooperative effects of hypericin and procyanidin B2 after repeate d treatment. Imipramine (15 mg/kg), Hypericum extract (500 mg/kg) and hyper icin (0.1 mg/kg) given daily for 2 weeks significantly reduced immobility t ime in the FST. No differences were observed between animals receiving pure hypericin and those receiving hypericin in combination with procyanidin B2 . As several antidepressants act on the neuroendocrine axis resulting in al tered hormone concentrations, selected endocrine parameters were investigat ed after repeated treatment. Daily treatment with either imipramine, Hyperi cum extract or hypericin alone or in combination with procyanidin B2 for 14 days significantly decreased plasma ACTH and corticosterone levels. None o f the substances had pronounced effects on plasma prolactin or LH levels. F rom our present data, we propose that cooperative effects of hypericin and procyanidin B2 are of important relevance for the acute, but not for the ch ronic effects of this polycylic quinone.