Effects of food and gastrointestinal secretions on intestinal integrity in an experimental rat model

Introduction: Paracelluler intestinal permeability is mediated by mainly tight junction proteins. Deteriotion of tight junction (TJ) proteins and morphological structure of intestinal epithelium may permit translocation of bacterial end-products (lipopolysaccharides) into the serum. Impaired gut barrier fuction is related to several disease states. Intestinal epithelium and tight juntion proteins are regulated by many factors. Aim: The aim of this study was to investigate effect of biliopancreatic secretions and foods on intestinal morphology and microbial flora of rat jejunum Methods: Thirty sprague-dawley male rats were randomly divided into three groups. (10 per groups): Control, biliopancreatic (BP) and jejunal by-pass (JP) group. By these operations biliopancreatic juice deficient (bile(-)), food deficient (food(-)) and both of them deficient (bile(-)/food(-)) jejunal segments and corresponding control segments were obtained. Animals were sacrified at the end of week 3. We obtained blod from portal vein for lipopolysaccharides(LPS) and citrulline levels. Each jejunal segment samples were cultured quantitatively (log10(cfu/mg)). We observed the changes in the intestinal morphology (villus/crypt ratio, intraepithelial lymphocytes) and expression and distribition of tight junction proteins (occludin, claudin-1, Zonula Occludens-3) by using immunohistochemistry Results: Villus height to crypt depth ratio was lower in the bile and food deficient segment than others(p:0.007). Intaepithelial lymphocytes were significantly highest in the bile and food deficient segment(p:<0.001). Immunohistchemical staining pattern of claudin-1 was weaker when there was no food(p:0.035). Occludin expression increased if the segment contained food(0.016). Jejunal aeorobic bacterial count decreased in bile and food deficient segment(log10(CFU/mg):-1.32±0.61) and increased in bile deficient segment(log10(CFU/mg):0.1±1.08) when compared with control segment(log10(CFU/mg):-0.3±0.6)(p:0.043). There were no statistically significant difference in plasma lipopolisaccharides and citrulline levels between the groups. Conclusions: There are significant effects of foods and gastrointestinal secretions on intestinal morphology and integrity markers. In our study; the presence or absence of bile and pancreatic secretions altered the expression pattern of jejunum morphology, the number of intraepithelial lymphocytes, and the expression of some TJ proteins (occludin, claudin-1). These effects were more prominent in the presence or absence of food. The microbiological environment also affected by these changes. Our results implicate the importance of oral food on the structure and integrity of the gastrointestinal tract which may play role on some diseases. Key Words: Tight junction, claudin, occludin, zonula occludens, intestinal integrity, rat, immunohistochemistry, lipopolysaccharides, citrullin