Effects of chronic restraint stress on esophageal epithelial dilated intercellular space and inflammation in mice

Abstract

Objective To investigate the effects of chronic restraint stress on the esophageal epithelial cells dilated intercellular space and the occurrence of inflammation. Methods Twenty male SPF Kunming mice aged 8 weeks were randomly divided into two groups, namely the chronic restraint stress group (n=10) and the control group (n=10). Stress mice were restrained in self-made restraint device for 2 hours every day, experiment lasted 14 days. The esophageal epithelium were observed by HE staining under optical microscope and the spaces between cells was measured. The expression of oxidative stress (Nox-4, 8-OHdG, MDA), antioxidant protein (Nrf-2, HO-1), tight junction protein (Claudin-1, Claudin-4, Occludin, ZO-1) and inflammatory factors (MCP-1, IL-1β, TNF-α) in esophageal tissues were detected by enzyme-linked immunosorbent assay (ELISA) and real-time quantitative RT-PCR. Results The mean intercellur space in stress mice was (1.16±0.02 μm), compare to control mice (0.64±0.04 μm), it was significantly wider than control group (t=20.63, P＜0.01). The results of ELISA showed that the blood concentrations of Nox-4 [(9.72±1.80) mg/ml vs (4.54±0.46) mg/ml], 8-OHdG [(4.94±0.58) mg/ml vs (1.44±0.16) mg/ml] and MDA [(3.56±0.41) mg/ml vs (1.02±0.12) mg/ml] in stress group were significantly higher than those in control group (t=25.54, 19.62, 13.67, P＜0.01). RT-PCR results of antioxidant proteins Nrf-2 and HO-1 in stress group were significantly lower than those in control group (t=-10.36, -9.28, P＜0.05). The transcription levels of tight junction proteins such as Claudin-1, Claudin-4, Occludin and ZO-1 in stress group were significantly lower than those in control group (t=-10.23, -9.65, -7.81, -8.75, P＜0.01). The transcription levels of inflammatory factors (MCP-1, IL-1β, TNF-α) in stress group were significantly higher than those in control group (t=31.42, 42.37, 46.83, P＜0.01). Conclusion Chronic restraint stress may directly disturb the balance of oxidation/antioxidant system in esophagus, which eventually lead to the esophageal epithelial dilated intercellular space and inflammation. Key words: Chronic stress; Tight junction proteins; Dilated intercellular space; Oxidative stress; Anti oxidants