The Distribution Of Methanobrevibacter Smithii In Intestine Of Diet-induced Obesity C57BL/6Mice And The Relationship Between M. Smithii And Obesity

Objective:To study the distribution of Methanobrevibacter smithii in intestine of diet-induced obesity C57BL/6mice, and to explore the relationship between M. smithii and obesity.Methods:Twenty4-week-old male C57BL/6mice were averagely and randomly divided into two groups:a controled group and a diet-induced obesity (DIO) model group. Mice in the controled group were fed with control diets, while mice in the DIO model group were maintained on high-fat diets. All of them were raised in Special Pathogen Free (SPF) laboratory animal room and their body weights were weekly collected. After12weeks, the DIO model had been established successfully, then three mice were randomly selected in each group. Laparotomy was performed and sections of the duodenum, the superior, mid and inferior of the small intestine, cecum and distal colon were resected from each mice. DNA was extracted from each segment, and real-time quantitative PCR with M.smithii-special primers was performed to determine the level of M. smithii in each segment respectively. Results:(1) The average body weight of mice in the DIO model group are39.46±1.53g, and mice in the controled group are30.63±1.39g. Compared with the controled mice, the DIO mice showed significant increase in body weight and had reached the standard of obesity after maintained on high-fat diets for12weeks. The DIO model had been establised successfully.(2) All mice demonstrated the presence of M.smithii both in small intestine and colon. Through statistical analysis, the levels of M.smithii in each bowel segment of the controled mice had no significant differences (P>0.05). However, in the DIO Mice, higher M.smithii levels were identified in all small intestinal segments than in colon(P<0.05), and the mid segment of the small intestine had the highest level.(3) Compared to the controled mice, higher M.smithii levels were identified in all small intestine segments of DIO mice. However, only the mid and inferior of the small intestine reached statistical significance(P<0.05). In contrast, the controled mice had the higher levels of M.smithii in cecum and distal colon than the DIO mice, but there were no significant differences.Conclusions:(1) DIO model of C57BL/6mice could be established by rodent diet with60%fat in a relatively short period of time. (2) C57BL/6mice demonstrated the presence of M.smithii both in small intestine and colon.(3) The levels of M.smithii in the mid and inferior segment of the small intestine were higher significantly in DIO mice than in controled mice. This finding suggests that the increase levels of M.smithii in the mid and inferior of the small intestine may have a positive relationship with obesity.