Chaihu-Shugan-San and absorbed meranzin hydrate induce anti-atherosclerosis and behavioral improvements in high-fat diet ApoE-/- mice via anti-inflammatory and BDNF-TrkB pathway

The comorbidity of coronary heart disease (CHD) and depression in patients is extremely prevalent, with a rate from 20 to 50%, while depression-like behaviors exist in a larger percentage of patients. Therefore, the study of comorbidities is particularly urgent. Chaihu-Shugan-San (CSS), a classical traditional Chinese medicine formula, has been used to treat CHD with depression for hundreds of years. However, the mechanism of its action on comorbidities remains unclear. Here, we focused on the behavioral changes in apoE^-/- mice fed a high-fat diet (HFD) and elucidated the mechanism of CSS and its main absorbed component, meranzin hydrate (MH), as an anti-atherosclerosis and anti-depression agent. In the present study, mice were fed an HFD for 16 weeks and were intragastrically administered high and low doses of CSS and MH. Depressive-like behaviors were evaluated by the sucrose preference test, the open-field test, the light-dark test and the tail-suspension test, after which atherosclerotic plaques, plasma lipids, inflammatory cytokine levels and the expression of BDNF/TrkB were measured. We demonstrated that the atherosclerosis model group exhibited significant depressant behaviors. Moreover, CSS inhibited depressive-like behavioral changes, reduced atherosclerotic plaque areas, plasma total Cholesterol, triglycerides, LDL-cholesterol levels and inflammatory cytokines including TNF-α, IL-1β, and IL-6 in plasma and hippocampi, increased the protein and mRNA expression of BDNF and TrkB in the aorta and the hippocampus. Interestingly, MH, the main component in CSS that is absorbed in the plasma and hippocampus, exerted effects similar to those of CSS. In addition, MH increased the protein and mRNA expression of BDNF and TrkB in human umbilical vein endothelial cells (HUVECs) induced by LPS. Collectively, these results suggest that MH represents the CSS decoction, induces anti-atherosclerosis effects and improves depression-like behaviors in HFD-fed apoE^-/- mice. Moreover, the regulation of proinflammatory factors and BDNF-TrkB signaling are possibly involved in this process. Our findings indicate that MH is a potential phytochemical compound for the prevention of the comorbidity of atherosclerosis and depression.