Anti-depressant effects of Xiaoyaosan on rat model of chronic unpredictable mild stress: a plasma metabonomics study based on NMR spectroscopy

Objectives To investigate the antidepressant effects of Xiaoyaosan (XYS) in a chronic unpredictable mild stress (CUMS) depression model. Methods The changes in behaviour and plasma metabolic profiles were investigated after four-week CUMS exposure and treatment. Drugs were administered during the four-week period of CUMS, with the healthy group serving as negative controls, and the fluoxetine and venlafaxine groups serving as positive controls. Plasma samples were collected at 28th day, and the plasma metabolic profiling was measured using NMR, followed bymultivariate analysis. Key findings Exposure to CUMS for four weeks caused depression-like behaviour in rats, as indicated by significant decreases in weight gain, sucrose consumption and locomotor activity. Eleven potential biomarkers, including seven in the Carr-Purcell-Meiboom-Gill spectra, five in the diffusion-edited spectra, and one in both were identified. It was found that trimethylamine-N-oxide, alanine, b-hydroxybutyrate, valine, leucine/isoleucine, low-density lipoprotein/very lowdensity lipoprotein and lipids were lower and phosphatidylcholine, high-density lipoprotein, choline and N-acetyl glycoproteins were higher in CUMS-treated rats, as compared with controls. XYS significantly suppressed behavioural changes and attenuated plasma metabolite changes. Conclusions XYS produced an obvious antidepressant effect, and the metabonomic approach benefits estimation of the pharmacodynamic action of traditional Chinese medicine prescriptions.