Differences in the effects of essential oil from Citrus junos and (+)-limonene on emotional behavior in mice

Citrus junos (Yuzu, CJ) is a traditional fruit in Japan and its essential oil (EO) has been used in food, cosmetics, and traditional medicine. The present study examined the influence of essential oil from Citrus junos (EOCJ) on emotional behavior in mice, and how its action differed in comparison to (+)-limonene (LI), its major component. The influence of inhaled administration (i.h.) of EOCJ for 90 minutes on mouse emotional behavior was examined using the light/dark box (LDB) test, open field (OF) test, and elevated plus-maze (EPM) test. In addition, gas chromatography (GC) was used in clarifying the amount of LI absorbed in the internal organs. Inhalation of EOCJ at 3.4 and 6.7 mg/L air indicated the tendency for an anxiolytic-like effect in LDB and EPM tests. In addition, an increase in locomotor activity was observed at 6.7 mg/L air EOCJ (i.h.) in the OF test. Inhalation of (+)-LI at 3.4 and 6.7 mg/L air indicated the same anxiolytic-like effect in EPM test as with EOCJ. In contrast, the anxiolytic-like effect of (+)-LI was smaller than that of EOCJ in the LDB test. Furthermore, an increase in locomotor activity was not observed at 6.7 mg/L air (+)-LI (i.h.).