Anti-depressive effects of Kai-Xin-San on lipid metabolism in depressed patients and CUMS rats using metabolomic analysis

In this study, in order to explore potential depressive biomarkers and potential regulatory targets of KXS on depression, we assessed the effects of Kai-Xin-San (KXS) on lipid metabolism in depressed patients (DPs) and rats exposed to chronic and unpredictable mild stress (CUMS).Serum samples were collected from DPs, DPs with 8 weeks of KXS treatment (KXS) and healthy controls (HCs), and non-targeted lipidomics was used to analyze the effect of KXS on serum lipid metabolites in DPs. Based on UPLC-Q-TOF/MS technology, differential metabolites were validated in a large sample size. The potential regulatory network of KXS was analyzed by bioinformatic analysis, and the expressions of proteins in serum were verified using western boltting analysis. Moreover, effects of KXS on serum lipid and lipid metabolism-related hormone levels in CUMS rats were detected by enzyme-linked immunosorbent assay and enzymatic method.We validated that the levels of six serum lipid metabolites (N-Desmethylcitalopram (HMDB14021), PC(14:1(9Z)/24:0) (HMDB07926), PC(P-18:1(11Z)/20:0) (HMDB11281), PC(O-18:0/20:4(8Z,11Z,14Z,17Z)) (HMDB13420), PC(16:0/P-18:0) (HMDB07995) and PC(16:0/P-18:1(11Z)) (HMDB07996)) between HC/DP groups and between DP/KXS groups were significantly different. Among these six metabolites, HMDB07995, HMDB07996, HMDB13420 and HMDB11281 were highly sensitive and specific for depression and KXS treatment by receiver operating characteristic (ROC) curve analysis. matrix metalloproteinases (MMPs) including MMP2 and MMP9, apolipoproteins (Apo) including APOA1 and APOC1 were up-regulated and apolipoproteins (Apo) including APOB, APOD and APOE, phospholipid transfer protein (PLTP), Paraoxonase 1 (PON1) were down-regulated in DPs, and KXS treatment could reverse these changes. In CUMS rats, KXS could increase the open-field score, sucrose preference and body weight, and reduce immobility time. Furthermore, KXS increased the serum levels of the above-mentioned six metabolites, reduced serum total cholesterol (TCH), triglyceride (TG) and free fatty acid (FFA) levels and increased the serum high-density lipoprotein cholesterol (HDL-C) level in CUMS rats. In addition, leptin and ghrelin were down-regulated by KXS.The results suggested that KXS exerted antidepressant effects by regulating the signaling pathways involved in lipid metabolism disorders. The lipid metabolites might be potential biomarkers of depression and possible targets for KXS-based treatment of depression.