Effect of psychological stress on oxidative stress in rats and the role of TLR4.

Objective To investigate the role of psychological stress in the formation of atherosclerosis by studying the effects of psychological stress on oxidative stress and the inflammatory response in rats. Methods Forty male Wistar rats were equally divided into 4 groups: the normal control group (NC group), no-stress group (NS group), physical stress group (PS group) and psychological stress group (ES group). The rat models with psychological stress were established. The blood samples were immediately obtained after the last stress for assay of serum SOD activity, MDA content and the level of TNF-α by radioimmunoassay kit. HE staining was used to detect the change of rat aorta, and immunohistochemistry was used to detect the change of expression of TLR4 in rat aorta. Results The ES group showed significantly more evident oxidative stress (decreased SOD activity and increased MDA, P0.05) and inflammation (elevated TNF-α, P0.05) than the remaining three groups. HE staining showed that the ES group had early atherosclerotic changes. The expression of TLR4 was at a higher level in ES group than other groups (P0.05). Conclusion Oxidative stress might promote vessel wall inflammation by the release of TNF-α and other proinflammatory cytokins TLR4 induced in the early stage of the formation of atherosclerosis.