The antidepressant effect of Gastrodia elata Bl. on the forced-swimming test in rats

Depression is a common psychiatric disorder with a high morbidity and mortality rate. The pharmacotherapy used in clinic today is not suitable for all patients and causes certain side-effects. Thus, looking for alternative treatments with antidepressant effect and minimal side-effect is important. Gastrodia elata Bl. is a famous Chinese traditional medicine used for centuries. The aim of this study is to test the antidepressant effect of Gastrodia elata Bl. extract (GE) using forced-swimming test (FST). Sprague-Dawley rats were assigned to control, GE, and fluoxetine groups, treated with 10 ml/kg bw (body weight) water, 1 g/kg bw of GE, and 15 mg/kg bw of fluoxetine, respectively. Those samples were administered by gavage to rats 23.5, 4.5 and 1 hour prior to the test session of FST. After FST, the animals were sacrificed and their brains were collected for monoamines analysis. The results indicated that the duration of immobility was significantly decreased in GE group compared to the control (p < 0.05). The concentration of serotonin (5-HT), 5-hydroxyindoleacetic acid (5-HIAA), and the ratio of 5-HIAA/5-HT in frontal cortex, amygdala, and hippocampus were not significantly different between GE and the control groups. However, administration of GE significantly increased the dopamine (DA) concentration (p < 0.05) and decreased the concentration of 3,4-dihydroxyphenylacetic acid (DOPAC) (p < 0.01) and DA turnover (p < 0.05) in striatum compared to the control. The results of this study show that Gastrodia elata Bl. extract modulates the turnover of DA in rats, and thus probably possesses antidepressant effect in rats.