Change of enterogenous lipopolysaccharide and its correlation analysis with weight change after sleeve gastrectomy in obese rats

Abstract

Objective This study aims to explore the correlation by detecting the metabolic changes and internal distribution of the LPS contained in rat during preoperative and postoperative period of sleeve gastrectomy. Methods (1) After successful obese rats modeling did, the weight, body length, glucose tolerance and insulin resistance level were measured and grouping them randomized. Rats in surgical group were performed sleeve gastrectomy. Then execute 5 rats per week. Rats in sham operation group were performed exploratory Laparotomy, whose grouping and execution coincides with surgical group. (2) Rats weight of surgical group and sham operation group were measured once for two days after operation. (3) Faeces of rats from two groups were selected both preoperatively and postoperatively, which were used to analysis the proportion of the gram-positive bacterium and gram-negative bacterium. (4) Rats' blood in two groups were collected regularly both before and post operation to measure serum levels of LPS. (5) In surgical group and sham operation group, tissues of liver, mesentery fat, perirenal fat and epididymal fat were picked and grinded for tissue homogenate when rats were executed to quantify the LPS contained in these tissues. 6) Glucose tolerance tests and insulin resistance level tests were performed in each group both preoperatively and postoperatively. Results (1) The weight of rats in sham operation group rebound gradually after decreased, even more heavier than preoperative. Oppositely, the weight of rats in surgical group decreased progressively and then stabilized. (2) the proportion of gram-positive bacteria of surgical group were increased compared with sham operation group. On the contrary, the proportion of gram-negative bacteria of surgical group were reduced. (3) The rats' serum level of LPS in operation group declined obviously after operation, however, the rats' serum level of LPS in sham operation group climbed up higher than preoperative levels. Also, serum levels of LPS in the two groups have significant linear correlation with contemporaneous body weight (P=0.0004). (4) The LPS of operation group in abdominal fat significantly decreased compared with sham operation group. (5) The glucose tolerance levels and HOMA IR of rats in surgical group significantly decreased after operation, while these index in sham operation group obviously elevated. Conclusions (1) There is a close relationship between their LPS and body weight after sleeve gastrectomy of obese rats; (2) After sleeve gastrectomy of obese rats, glucose tolerance and insulin sensitivity are improved. Key words: Sleeve gastrectomy; Enterogenous lipopolysaccharide; Models of obese rats