The negative regulatory effect of connexin 43 on myocardial injury in rats with common bile duct ligation and its mechanism

Abstract

Objective To investigate the role and molecular mechanism of connexin 43 (Cx43) in rats with myocardial injury induced by common bile duct ligation (CBDL). Methods A total of 18 Sprague-Dawley rats were randomly divided into sham-operation group, CBDL group, and Cx43 inhibitor group, with 6 rats in each group. The rats in the sham-operation group were given isolation of the common bile duct, those in the CBDL group were given isolation, ligation, and cutting of the common bile duct, and those in the Cx43 inhibitor group were given a single injection of 25 mg/kg Gap 26 via the caudal vein at 24 h before surgery, followed by the isolation, ligation, and cutting of the common bile duct. The rats in all three groups were reared to day 14 after surgery, and echocardiography was used to evaluate ejection fraction (EF), fractional shortening (FS), and heart rate (HR); the three groups were measured in terms of serum total bilirubin (TBil), alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH), creatine kinase-MB (CK-MB), superoxide dismutase (SOD), glutathione peroxidase (GSH-PX) activity, and malondialdehyde (MDA); HE staining and Masson staining were performed for heart tissues samples collected from the three groups; Western blotting was used to measure the levels of Cx43, Wnt 3α, and β-catenin in heart tissue. Results Echocardiography showed that the CBDL group and the Cx43 inhibitor group had significantly lower cardiac EF, FS, and HR than the sham-operation group (F=22.95-43.55,t=5.10-9.32,P<0.05). Measurement of blood biochemical parameters and oxidative stress indicators showed that compared with the sham-operation group, the CBDL group and the Cx43 inhibitor group had significant increases in serum TBil, AST, ALT, LDH, CK-MB, MDA, and GSH-PX and a significant reduction in SOD (F=19.29-100.60,t=3.67-13.72,P<0.05). HE staining and Masson staining showed myocardial injury and myocardial interstitial fibrosis in the CBDL group and the Cx43 inhibitor group. Western blotting showed that compared with the sham-operation group, the CBDL group and the Cx43 inhibitor group had a significant reduction in the level of Cx43 and significant increases in the levels of Wnt 3α and β-catenin in heart tissue (F=28.50-70.07,t=4.32-11.79,P<0.05); compared with the CBDL group, the Cx43 inhibitor group had a significant reduction in Cx43 and significant increases in Wnt 3α and β-catenin in heart tissue (t=4.95-5.20,P<0.05). Conclusion Downregulation of Cx43 in the heart tissue of rats with CBDL can negatively regulate activation of the Wnt 3α/β-catenin pathway, thereby leading to the aggravation of myocardial injury and the reduction in cardiac function.

Keywords

• heart injuries|biliary tract diseases|common bile duct|ligation|fibrosis|connexin 43|wnt signaling pathway|beta catenin