AIM: To investigate the influence of experimental obstructive jaundice and exogenous bombesin (BBS) and neurotensin (NT) administration on the expression of the tight junction (TJ)-protein claudin-4 in intestinal epithelium of rats. METHODS: Forty male Wistar rats were randomly divided into five groups:Ⅰ= controls,Ⅱ= sham operated,Ⅲ= bile duct ligation (BDL),Ⅳ= BDL+BBS (30μg/kg per d),Ⅴ= BDL+NT (300μg/kg per d). At the end of the experiment on d 10, endotoxin was measured in portal and aortic blood. Tissue sections of the terminal ileum were examined histologically and immunohistochemically for evaluation of claudin-4 expression in intestinal epithelium. RESULTS: Obstructive jaundice led to intestinal barrier failure demonstrated by significant portal and aortic endotoxemia. Claudin-4 expression was significantly increased in the upper third of the villi in jaundiced rats and an upregulation of its lateral distribution was noted. Administration of BBS or NT restored claudin-4 expression to the control state and significantly reduced portal and aortic endotoxemia. CONCLUSION: Experimental obstructive jaundice increases claudin-4 expression in intestinal epithelium, which may be a key factor contributing to the disruption of the mucosal barrier. Gut regulatory peptides BBS and NT can prevent this alteration and reduce portal and systemic endotoxemia. AIM: To investigate the influence of experimental obstructive jaundice and exogenous bombesin (BBS) and neurotensin (NT) administration on the expression of the tight junction (TJ) -protein claudin-4 in intestinal epithelium of rats. METHODS: Forty male Wistar rats were The rats were randomly divided into five groups: Ⅰ = controls, Ⅱ = sham operated, Ⅲ = bile duct ligation (BDL), Ⅳ = BDL + BBS (30μg / kg per day) and Ⅴ = BDL + NT (300μg / kg per day). At the end of the experiment on d 10, endotoxin was measured in portal and aortic blood. Tissue sections of the terminal ileum were examined histologically and immunohistochemically for evaluation of claudin-4 expression in intestinal epithelium. RESULTS: Obstructive jaundice led to intestinal barrier failure demonstrated by significant portal and aortic endotoxemia. Claudin-4 expression was significantly increased in the upper third of the villi in jaundiced rats and an upregulation of its lateral distribution was noted. Administration of BBS or NT restored claudin -4 expression to the control state and significantly reduced portal and aortic endotoxemia. CONCLUSION: Experimental obstructive jaundice increases claudin-4 expression in intestinal epithelium, which may be a key factor contributing to the disruption of the mucosal barrier. Gut regulatory peptides BBS and NT can prevent this alteration and reduce portal and systemic endotoxemia.