Rhizomes of Gastrodia elata B_L possess antidepressant-like effect via monoamine modulation in subchronic animal model

Depression is one of the most common psychiatric disorders that affects over 10% of individuals. However there is no desirable therapeutic approach nowadays. Thus, looking for an alternative treatment is important. The objectives of this study are to investigate the antidepressant effects of the rhizomes of Gastradia elata B_L, a traditional Chinese medicine, in the animal model forced-swimming test (FST), and to analyze the monoamine content in the rats' brain regions in order to better understand the possible mechanisms of the water extract of the rhizomes of Gastrodia elata B_L (WGE). Subchronic administration of 0.5 or 1.0 mg/kg bw WGE by gavage for 21 consecutive days significantly reduced the immobility duration of rats in the test session of FST as compared to the control group (p < 0.05), with the equivalent effects as the antidepressant drug fluoxetine. The concentration of serotonin (5-HT) in the frontal cortex and dopamine (DA) in striatum were significantly increased after WGE administration (p < 0.05). The ratio of 5-HIAA/5-HT and (DOPAC + HVA)/DA, i.e. the turnover of 5-HT and DA respectively, were also significantly lowered in WGE groups (p < 0.05). In summary, the present study showed that the WGE possesses antidepressant-like effect on rats in the animal model FST, and the possible mechanism may be via regulating both the serotonergic and dopaminergic systems.