The esophageal expression of PAR-2 and its significance in a murine model of chronic restraint stress

Abstract

Objective To detect the expression level of proteinase-activated receptor-2(PAR-2) in mouse esophagus by establishing chronic restraint stress(CRS), and to discuss the role of PAR-2 in esophageal hypersensitivity and esophageal inflammation. Methods Total of 20 male Kunming mice were randomly divided into two groups: CRS and normal control (NC) group with 10 mice in each group.Mice in CRS group were subjected to 2 h per day of restraint stress using home-made device for a period of 14 d. Histopathological changes of esophageal tissue were observed using HE staining and histological damage scoring system.The expression levels of PAR-2 and related cytokines in esophageal tissues were detected by several methods such as immunohistochemistry, Western blotting and reverse transcription-PCR (RT-PCR). Result Compared to NC group, the body weight of CRS group were significantly decreased(t=4.28, P 0.05). Immunohistochemical results showed that PAR-2 positive staining cells were found in most specimens, but the positive staining in CRS group was deeper and more abundant than that in NC group.Western blotting showed that the expression level of PAR-2 protein in esophageal specimens of CRS group was significantly higher than that of NC group(t=-19.67, P<0.05). RT-PCR results showed that the expression level of PAR-2 in CRS group was higher than that in NC group(t=15.40, P<0.05). Compared with NC group, the levels of inflammatory related factors interleukin (IL) -1β, IL-8 and tumor necrosis factor (TNF)-α mRNA in CRS group were significantly higher than those in NC group (t values were-7.94, -17.82 and -25.54 respectively, both P<0.05). Pearson correlation analysis showed that the relative expression multiples of PAR-2 in esophagus of CRS mice were positively correlated with IL-1β, IL-8 and TNF-α(r values were 0.90, 0.95, and 0.98 respectively, both P<0.05). Conclusion Chronic stress may result in esophageal hypersensitivity through activation of PAR-2, and it may also cause esophageal inflammation. Key words: Proteinase-activated receptor-2; Chronic restraint stress; Esophageal hypersensitivity; Esophageal inflammation; Murine model