Carbachol protects the intestinal barrier in severe acute pancreatitis by regulating Cdc42/F-actin cytoskeleton.

The present study aimed to investigate the effect of carbachol on the intestinal tight-junction barrier in a rat model of severe acute pancreatitis (SAP) without aggravating pancreatic injury, and to determine whether cell division cycle 42 (Cdc42)/F-actin could have a regulatory role. Rats were separated into a sham-operation (SO) group (n=10), SO + carbachol group (n=10), SAP group (n=60) and SAP + carbachol group (n=60). Sodium taurocholate (5%) was retrogradely injected into the biliopancreatic duct of rats to induce SAP. Subsequently, 16S rRNA sequencing was used to detect bacterial translocation (BT) in the gut of surviving animals. Hematoxylin and eosin staining was used to detect morphological changes in the pancreas and intestine. The expression of F-actin and tight junction proteins was analyzed by western blotting and immunofluorescence, and Cdc42 expression was analyzed by immunohistochemistry and western blotting. The results demonstrated that the intestinal injury in SO and SO + carbachol groups was lower than that in the SAP + carbachol group (P<0.05); however, the intestinal injury was similar in the SO and SO + carbachol groups (P>0.05), and was significantly more severe in the SAP group compared with the SAP + carbachol group (P<0.05). Similarly, pancreatic injury in the SAP and SAP + carbachol groups was significantly higher compared with the SO and SO + carbachol groups (P<0.05); however, pancreatic injury was similar in the SAP and SAP + carbachol groups (P>0.05), and in the SO and SO + carbachol groups (P>0.05). Furthermore, the mortality rate and BT in the SAP group were significantly higher compared with the SAP + carbachol group (mortality rate, 50% vs. 30%, P<0.05; BT, 60% vs. 33.3%, P<0.05). In addition, the expression of Cdc42, F-actin and claudin-2 was significantly higher in the SAP and SAP + carbachol groups compared with the SO and SO + carbachol groups (P<0.05), and the expression of occludin and zonula occludens-1 were significantly higher in the SO and SO + carbachol groups compared with the SAP and SAP + carbachol groups (P<0.05). In conclusion, these findings demonstrated that carbachol may protect the intestinal barrier in the SAP rat model without aggravating pancreatic injury via regulation of Cdc42/F-actin expression.