Objective To explore the effect of mixed antibiotics on the intestinal flora of mice to affect the immune regulation of the body,explore the role of intestinal flora in the development of obesity,and provide new ideas and ways for the prevention and treatment of obesity.Methods Seventy-two 10-week-old male C57BL/6 mice were randomly divided into blank control(Ctrl)group,high-fat diet(HF)group,antibiotic(ABX)group,and combined(COMB)group(n=18).At the first 2 weeks(lavage intervention weeks),Ctrl and HF group were given normal saline gavage;ABX and COMB group were given mixed antibiotics gavage,and the gavage volume was 0.2 mL/animal/day.For the following 8 weeks(feeding weeks),Ctrl and ABX group were fed with ordinary diet,HF and COMB group were fed with high-fat diet.Body weight was measured weekly,and fasting blood glucose was measured before and after gavage,and at the 4th and 8th week of feeding.Oral glucose tolerance test was performed at the end of the experiment.The organ coefficient was measured and the cell morphology of white and brown adipose tissue was observed.Serum was collected for the determination of free fatty acid,high-density lipoprotein,low-density lipoprotein,triglyceride,and total cholesterol.Serum TNF-α,IL-10,IL-4,IL-13,IL-33 and MCP-1 was detected by ELISA.The stool of mice was collected for second generation sequencing.Results High-fat diet increased body weight,serum total cholesterol,low-density lipoprotein,IL-13,IL-33,TNF-α,MCP-1 content,and decreased glucose tolerance and organ coefficient in mice(P＜0.05).From the first feeding week to the end of the experiment,body weight in COMB group was significantly lower than that in HF group(P＜0.05).The level of glucose tolerance,serum total cholesterol,low density lipoprotein,IL-13,IL-33,TNF-α and MCP-1 in COMB group was lower than those in HF group(P＜0.05).The α diversity of intestinal flora in ABX group was lower than that in Ctrl group(P＜0.05).Congestion and bleeding in WAT were obvious in HF group,but not in COMB group.The microbial community composition of ABX and HF group was similar to that of Ctrl and COMB group,respectively.Conclusion High-fat diet induces obesity,disorder of glucose and lipid metabolism and inflammation in mice.Short-term mixed antibiotic use can regulate the intestinal flora of mice,mediate increased expression of related anti-inflammatory factors,up-regulate host immunity,and improve glucose and lipid metabolism in mice.

Objective To study the effects of antibiotics and high-fat diet on energy metabolism and the browning of white adipose tissue (WAT) and brown adipose tissue (BAT) in mice, so as to provide new ideas for the possible mechanism of adipose tissue in the prevention and treatment of obesity. Methods A total of 80 10-week-old C57BL/6 male mice were fed with normal diet in the early stage, and the antibiotic gavage group (AG) and antibiotic high-fat group (AFG) were given mixed antibiotics by gavage. The blank group (BG) and the high-fat diet group (FG) were given normal saline intragastric solution for 2 weeks, and after the gavage operation, the FG group and the AFG group were given high-fat diet for obesity modeling, and the BG group and AG group continued to be fed with normal diet for 8 weeks (N=20). After the experiment, each group was injected with β3-adrenergic receptor agonists for 5 days, and the high-fat/ordinary diet remained unchanged. At the end of the experiment, basal metabolic rate (BMR), fasting blood glucose (FBG) and rectal temperature were measured, and feces, blood, subcutaneous white fat, epididymis and brown adipose tissue in the scapular area of mice were collected. The automatic biochemical analyzer was used to determine the blood biochemical indexes; reverse transcription polymerase chain reaction (RT-qPCR) was used to measure the expression of genes related to browning of WAT and BAT adipose tissue, respectively. Real-time quantitative polymerase chain reaction (qPCR) was used to determine the expression of WAT mitochondrial DNA (mt DNA). Results From the 4th week to the end of the experiment, the weight of the AFG group was significantly higher than that of the AG group and significantly lower than that of the FG group (P<0.05). The body weight, organ coefficient, serum TC level, rectal temperature and WAT cell diameter in the AFG group were significantly higher than those in the AG group. The serum levels of FBG, TC and LDL in the AFG group were significantly lower than those in the FG group (P<0.05). The overall BMR(mlO2/h) FG group was significantly higher than that of BG group, and the AFG group was significantly higher than that of AG. BMR per unit body weight (mlO2/h/g) AFG was significantly higher than that of FG group (P<0.05). The expressions of RIP140, PPAR-γ and UCP-1 in BAT in the AFG group were significantly higher than those in the FG group, and the mt DNA copy number of WAT in the AFG group was significantly higher than that in the FG group (P<0.05). Conclusion Antibiotic intervention can up-regulate the expression of brown fat-related genes in high-fat diet mice, increase brown fat activity, increase the relative mitochondrial number of white fat, increase the level of browning of white fat, promote thermogenesis, increase the BMR per unit body weight of adult obese mice, and then improve the overall energy metabolism of the body, and slow down the weight gain induced by high-fat diet to a certain extent.