Systemic localization of vascular inflammation biomarkers in rats with depression

This study aims at investigating the influence of depression on vascular inflammation in the vital organs of the body. Thirty male Sprague-Dawley rats were used as control and experimental groups. Forced swimming protocol was used for 21 days to initiate depression in the experimental rats. Depression was evaluated through automatically measuring the rats’ locomotor activity by the 6-minutes forced swimming test (FST) and by analyzing their serum corticosterone levels. Sera were collected from all rats before sacrifice and then tissue specimens of heart, lung, kidney, and liver were collected after sacrifice. The mean corticosterone level and the mean immobility duration were significantly increased in depression group. Through using the enzyme linked immunosorbent assay (ELISA), the serum levels of inflammatory biomarkers, tumor necrosis factor-alpha (TNF-α), vascular endothelial growth factor (VEGF), and inducible nitric oxide synthase (iNOS) were measured, and their tissue expression were examined. The area percentage of immune expression was measured using the Image J program. The mean serum levels of TNF-α and iNOS elevated significantly in the depression group compared to the control, whereas serum level of VEGF decreased significantly in depressed rats compared to control ones. Intense immuno-expression of inflammatory cytokines was detected in the endothelium of blood vessels of all examined tissues in depression group compared to control ones. Except for TNF-α expression in the lung tissues, the area percentage of immune expression of all the examined inflammatory cytokines were significantly increased in all the examined tissues. The study demonstrated that vasculitis can be a harmful outcome of stress and depression.