Anxiolytic effect of essential oils of Salvia miltiorrhiza in rats

This study aims to investigate the anxiolytic effects of essential oil from S. miltiorrhiza in rats. The elevated plus maze test and the social interaction test were performed to evaluate the anxiolytic effects of essential oil. The levels of noradrenaline (NE), dopamine (DA) and serotonin (5-HT) in cerebral cortex of rats as well as the plasma corticosterone (CORT) level were examined in the rats with the treatment of essential oil. The rota-rod test was carried out to exclude any false positive results in experimental procedures related to anxiety disorders. The catalepsy test was carried out to investigate whether essential oil induces the catalepsy. Our results showed that oral administration of essential oil increased the percentage of time spent in the open arms and increased the number of entries to the open arms in the elevated plus maze test. Oral administration of essential oil also increased the time for social interaction in rats. No apparent extrapyramidal symptom (EPS) was observed in the animals with essential oil treatment. The effect of essential oil in the intracellular chloride (Cl(-)) concentration in the cultured human neuroblastoma cells was assessed. Treatment with essential oil (50-100 mg/kg) increased intracellular Cl(-) concentration in the cell culture in a dose-dependent manner, suggesting the involvement of GABAA receptor-Cl(-) ion channel. Together, our data indicate an anxiolytic effect induced by the essential oil from S. miltiorrhiza.