Effect of Allium macrostemon on a rat model of depression studied by using plasma lipid and acylcarnitine profiles from liquid chromatography/mass spectrometry.

The present study aimed to investigate the anti-depressive effect of the traditional Chinese medicine Allium macrostemon in a rat model of depression induced by exposure to chronic immobilization stress. Lipid and acylcarnitine metabolism were set into the focus of this study due to their key role in the pathogenesis of depression. Plasma lipid profiling was performed by ultra fast liquid chromatography/ion trap-time of flight mass spectrometry. Ultra-high performance liquid chromatography/triple quadrupole mass spectrometry was used to characterize the plasma acylcarnitine profile. Principal component analysis (PCA) revealed distinct differences in plasma lipid and acylcarnitine profiles of depressed rats from those in the control rats, which were also validated by univariate analysis. Several lysophosphatidylcholines (LPC (18:1→:2), LPC (20:1), LPC (O-16:2), and LPC (O-18:3)) as well as most medium- and long-chain acylcarnitines were elevated, while some phosphatidylcholines (PC (32:1), PC (36:4→:5), PC (37:4), PC (38:4→:6), PC (40:6), PC (O-36:4), and PC (O-38:5)) and triglycerides (TG (58:12), TG (60:12), and TG (62:13→:14)) were decreased in the plasma of depressed rats. These changes indicate that depressed rats were associated with inflammatory conditions and an incomplete β-oxidation of fatty acids. Most of these dysregulated metabolites were returned to their normal levels after treatment with A. macrostemon according to PCA and univariate analysis, highlighting the anti-depressive effect of this traditional Chinese medicine. These results show that liquid chromatography/mass spectrometry-based quantitative metabolic profiling method is a useful tool to investigate the metabolic changes in depression and the anti-depressive effect of traditional Chinese medicine.