Anxiolytic effect of Gardeniae Fructus-extract containing active ingredient from Kamishoyosan (KSS), a Japanese traditional Kampo medicine

Kamishoyosan (KSS), a Kampo formula used to treat menopausal psychotic syndromes in women, consists of ten crude herbal drugs. The anxiolytic effect of KSS was investigated by the social interaction (SI) test using mice, and whether the effect of KSS was due to the stimulating and/or sedating effects was examined by the open field locomotion test. Furthermore, the present study examined the effect of individual crude drugs in KSS by the SI test to clarify its active components. Oral administration of KSS increased the total SI time in a dose-dependent manner (50–200 mg/kg), but this effect was not observed over a dose of 300 mg/kg. On the other hand, there were no significant changes observed for the open field locomotion test. These results suggest that the appearance of KSS-induced SI behavior is due to an anxiolytic effect. The unaltered results of the open field test indicated that KSS was neither a stimulant nor sedative. To identify the essential herbs in KSS, the effects of “the component herbs in KSS” and “KSS minus one component herb” using the SI test were examined. An increase in the SI time was observed for hot water extracts of Menthae herba and Gardeniae Fructus, the same as for the KSS treatment. On the other hand the effect of KSS on the SI time was reduced to the control level for KSS minus Gardeniae Fructus, KSS minus Paeoniae Radix, KSS minus Glycyrrhizae Radix and KSS minus Hoelen. Oral administration of Gardeniae Fructus-extract or its common constituent, geniposide increased the SI time in a dose-dependent manner. These results indicate that Gardeniae Fructus and geniposide play a role in the anxiolytic effect of KSS.