Abstract: Objective: The objective of this study was to investigate the effect of Lactobacillus plantarum powder on intestinal mucosal barrier function in obese rats. Methods: Male Sprague-Dawley (SD) rats were randomly assigned into normal control group and high-fat diet (HFD) group, which were fed on a normal feed and a high-fat diet, respectively. After 5 weeks of feeding, the obese rats were randomly assigned into obese model, and high-, medium- and low-dose Lactobacillus plantarum powder intervention groups. The rats from the intervention groups were given Lactobacillus plantarum powder suspended in physiological saline, while those from the other groups were intragastrically administered with normal saline once a day. The body masses and body fat percentages of all rats were measured after 8 weeks of intervention. The contents of serum lipopolysaccharide (LPS) and D-lactic acid (D-LA) were assessed by enzyme-linked immunosorbent assay. The morphology of small intestine was observed by hematoxylin-eosin staining. Real-time quantitative polymerase chain reaction, immunohistochemistry and Western Blot were used to evaluate the mRNA and protein expression of zonula occludens protein-1 (ZO-1), Occludin and Claudin-1 in the small intestine of the rats from each group. Results: low-dose Lactobacillus plantarum powder could significantly reduce the HFD-induced increase in body mass and body fat percentage (P < 0.05). Besides, low-dose bacterial powder intervention could also reduce serum LPS and D-LA levels in HFD-fed rats (P < 0.05), and alleviate intestinal mucosal damage caused by the high-fat diet. Low-dose bacterial powder intervention increased the expression of tight junction proteins ZO-1 (P < 0.01), Occludin and Claudin-1 (P < 0.05) in the rat small intestine. Conclusion: Low-dose Lactobacillus plantarum powder intervention can protect the intestinal barrier function by up-regulating the expression levels of intestinal tight junction proteins ZO-1, Occludin and Claudin-1 in obese rats.

Key words: high-fat diet; Lactobacillus plantarum powder; intestinal barrier function; tight junction protein; quantitative real-time polymerase chain reaction; immunohistochecal technique