Effects of psychological stress on xanthine oxidase expression, activity and related markers in adipose tissue of mice

Abstract

To investigate the effects of psychological stress on xanthine oxidase (XO) expression, activity and related markers in adipose tissue of mice. Twenty male Kunming mice were randomly divided into two groups (10 in each group), stress group and control group (10 in each group). Stress group were restrained in self-made restraint device for 2 hours per day for 14 days, then blood samples and white adipose tissues(WAT) were collected. The expression levels of XO and NADPH oxidase-4 (Nox-4) in WAT were detected by immunohistochemistry. The expression of XO, Nox-4, antioxidant proteins (manganese superoxide dismutase (Mn SOD), glutathione peroxidase (GSH-Px), and catalase (CAT)), adipocytokines (adiponectin (ADPN), monocyte chemotactic protein 1 (MCP-1), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α)) in WAT were further detected by quantitative PCR. Relative expressions of glucose metabolism (insulin receptor substrate-1(IRS-1) and glucose transporter type 4(GLUT-4)) and thrombin(tissue factor (TF) and plasminogen activator inhibitor 1 (PAI-1))were measured. XO activity and serum concentrations of (triglyceride (TG), total cholesterol (T-Cho), free fatty acid, (FFA), and uric acid (UA)) were detected by ELISA. XO expressed in stress mice inguinal WAT was deeper and more abundant than that of control group, mainly expressed in adipocytes. RT-PCR and ELISA results showed that the levels of XO mRNA, serum XO concentration and the activities of XO enzyme in WAT of stress group were significantly higher than those of control group(P ＜0.01). Compared with control group the concentrations of free fatty acid (FFA) and uric acid (UA) in stress group were increased significantly than in control group (P＜ 0.01). Nox-4 positive cells mainly expressed in adipocytes. The expression of Nox-4 in WAT of stress group was significantly higher(P ＜0.01); The levels of antioxidant proteins (Mn-SOD, GSH-Px, Catalase) in WAT of stress group were significantly lower (P＜ 0.01). WAT in stress group showed a large number of infiltration reactions and inflammatory changes of monocytes, neutrophils, eosinophils and plasma cells. Stress significantly decreased the expression of adiponectin in WAT, and significantly increased the expressions of MCP-1, IL-6 and TNF-α (P＜0.01). The levels of IRS-1 and GLUT-4 in WAT of stress mice were increased significantly (P＜ 0.01). The expressions of TF and PAI-1 in WAT of stress mice and blood concentrations were significantly higher (P＜0.01). Stress can induce excessive expressions of XO in adipose tissue, which eventaully can lead to adipose inflammation, glycometabolism and abnormal prothrombin.