Antidepressant-like effect of essential oil isolated from Toona ciliata Roem. var. yunnanensis.

Depressive order is one of the most common psychiatric diseases, and Toona ciliata Roem. var. yunnanensis has shown many bioactivities in folk medicine. This study was designed to investigate the antidepressant-like effect of essential oil isolated from T. ciliata Roem. var. yunnanensis. Gas chromatography and mass spectrometry (GC-MS) was used to analyze the compositions of essential oil. The immobility time in the forced swimming test (FST), tail suspending test (TST), and open field test (OFT) were used to evaluate the antidepressive effects of essential oil. Furthermore, chronic mild stress (CMS) rats were established, and contents of dopamine (DA), norepinephrine (NE), and 5-hydroxytryptamine (5-HT) in the brain were determined by high-performance liquid chromatography-electron capture detector (HPLC-ECD). Western blotting was performed to investigate the effects of essential oil on the expressions of brain-derived neurotrophic factor (BDNF) protein in rats' brain. The GC-MS analysis showed that the main components of essential oil were estragole (6.16 %), β-elemene (24.91 %), β-cubebene (14.29 %), and γ-elemene (8.05 %). The results from the FST and TST demonstrated that the immobility time could be significantly reduced by essential oil (10, 20, 40, and 80 mg/kg), without accompanying changes in ambulation when assessed in the OFT. Additionally, the contents of DA, NE, 5-HT, and BDNF in the hippocampus of CMS rats could be increased by treatment with essential oil at doses of 20, 40, and 80 mg/kg. All these results suggested that essential oil could be considered as a new candidate for curing depressive disorders.