Behavioural, metabolic, and endothelial effects of the TNF-α suppressor thalidomide on rats subjected to chronic mild stress and fed an atherogenic diet

Abstract

There is accumulating evidence suggesting that depression is a risk factor for cardiovascular diseases. This study aimed to examine the hypothesis that the proinflammatory cytokine TNF-α would partially explain the link between depression and atherosclerotic endothelial changes. Rats were distributed among 6 groups: (i) control group; (ii) group subjected to chronic mild stress (CMS); (iii) group fed a cholesterol–cholic acid–thiouracil (CCT diet); and (iv) CMS group fed the CCT diet and treated with the vehicle for 8 weeks. The last 2 groups were subjected to CMS–CCT and received thalidomide (THAL) or imipramine (IMIP). Rats were assessed behaviorally (sucrose preference, open field, and forced-swimming tests). TNF-α protein was assessed from the serum, aorta, and liver. Aortic TNF-α gene expression (assessed using RT–PCR), serum lipid profile, and insulin levels were measured. Endothelial function was assessed in isolated aortic rings. The THAL and IMIP groups showed ameliorated CMS–CCT-related behavioral changes. CMS–CCT-induced metabolic and endothelial dysfunctions were improved in the THAL group but were worsened in the IMIP group. RT–PCR showed a significant reduction of aortic TNF-α mRNA expression in the THAL and IMIP treatment groups. These data paralleled the findings for aortic immunohistochemistry. The THAL group, but not the IMIP group, showed improved CMS–CCT-induced changes in the vascular reactivity of the aortic rings. Thus, TNF-α provides a target link between depression, metabolic syndrome, and endothelial dysfunction. This could open a new therapeutic approach to address the comorbidities of depression.