Hypericum Perforatum Decreased Hippocampus TNF-${\alpha}$ and Corticosterone Levels with No Effect on Kynurenine/Tryptophan Ratio in Bilateral Ovariectomized Rats

다국어 초록 (Multilingual Abstract)

The present study was designed to investigate the effect Hypericum Perforatum (HP), on behavioral changes, corticosterone, TNF-${\alpha}$ levels and tryptophan metabolism and disposition in bilateral ovariectomized rats compared to $17{\alpha}$-ethinylestradiol. Behavioral analysis by measuring immobility time in forced swimming test and open field test, serum and hippocampal corticosterone and TNF-${\alpha}$ along with hippocampal kynurenine/tryptophan ratio were determined in mature ovariectomized rats treated orally either by HP at three different doses 125, 250, and 500 mg/kg/day or by $17{\alpha}$-ethinylestradiol $30{\mu}g/kg/day$ for 30 days. Ovariectomized rats showed significant increase in immobility time in the forced swimming test. Along with elevation in serum and hippocampal TNF-${\alpha}$ and corticosterone levels associated with significant increase in hippocampal kynurenine/tryptophan ratio. Immobility time in the forced swimming test was decreased in rats treated by different doses of HP in a dose dependent manner and $17{\alpha}$-ethinylestradiol with no concomitant changes in the open field test. Only Rats treated with HP exhibited significant decrease in the elevated serum and hippocampal TNF-${\alpha}$ and corticosterone, which couldn't explain the associated insignificant effect on hippocampaus kynurenine/tryptophan ratio in comparison to ovariectomized untreated rats. It is concluded that increased tryptophan metabolism toward kynurenine secondary to elevated corticosterone and TNF-${\alpha}$ might be one of the pathohphysiological mechanisms that could explain depression like state observed in this rat model. Further, the observed attenuating effect of HP on TNF-${\alpha}$ and corticosterone could contribute in its antidepressant effect in this animal model by other ways than their effects on tryptophan-kynurenine metabolism pathway.