Obstructive jaundice alters proliferating cell nuclear antigen expression in rat small intestine

Abstract

Translocation of bacteria and endotoxin has long been documented in obstructive jaundice, and altered intestinal barrier function is considered to be one of the important mechanisms for this phenomenon. Proliferating cell nuclear antigen (PCNA), also known as cyclin, is an auxiliary protein of DNA polymerase-delta, and the level of synthesis correlates directly with rates of cellular proliferation and DNA synthesis. This study was designed with the aim of evaluating the effect of obstructive jaundice on PCNA expression in small bowel epithelium. Male Sprague-Dawley rats were randomized to four groups. Group A (n = 10, control group) underwent a sham operation. Group B (n = 9, obstructive jaundice group for 1 week) underwent common bile duct ligation. Group C (n = 8, obstructive jaundice group for 2 weeks) underwent common bile duct ligation. Group D (n = 8, obstructive jaundice group for 2 weeks) underwent common bile duct ligation with oral glutamine intake. After periods of 7 days and 2 weeks, segments of small bowel were harvested from groups A & B and groups C & D, respectively. Nuclear immunohistochemical expression of PCNA in small bowel was evaluated. The PCNA-labeling index [(PCNA-positive cells/500 cells) x 100] was quantified. Comparisons among the four groups were performed. The PCNA-labeling index in small bowel of group B was significantly higher than that of group A (29.0% vs 21.2%, p = 0.001). After 2 weeks of common bile duct ligation, the PCNA-labeling index in small bowel of group C was significantly lower than that of group A (19.4% vs 21.2%, p = 0.045). With oral glutamine intake daily, the PCNA-labeling index in small bowel of Group D was restored and was significantly higher than that of group A (24.5% vs 21.2%, p = 0.002). Obstructive jaundice for 1 week upgraded PCNA expression in rat small intestine. PCNA expression in rat small intestine later became depressed after obstructive jaundice for 2 weeks. Oral glutamine intake daily could effectively restore the PCNA expression in small bowel of rats subjected to obstructive jaundice for 2 weeks.