Sub-chronic Treatment Effects of an Extract of Hypericum perforatum (St. John’s Wort, Li 160) on Neuroendocrine Responses to the 5-T_2A Agonist, DOI in the Rat

Clinical studies have demonstrated the antidepressant efficacy of LI 160 extracts, which is comparable to antidepressants such as imipramine. The study was undertaken to assess the sub-chronic effects of LI 160 extract on plasma corticosterone and prolactin (PRL) responses to the post-synaptic 5-HT_2A receptor agonist, 2,5-dimethoxy-4-iodophenyl-2-aminopropane (DOI), in the male rat. Results show that sub-chronic treatment with the LI 160 extract reduced corticosterone and PRL responses to DOI. LI 160 may modify brain 5-HT function in the rat, possibly by reducing the sensitivity of central 5-HT_2A receptors. This may be a result of decreased receptor expression, signal transduction or intracellular messengers. These findings could be relevant to the therapeutic efficacy of St. John’s wort.

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