The Effect Of Bariatric Surgery On The Metabonomics Of Rats With Hyperuricemia

BackgroudHyperuricemia(HUA)is a metabolic disease caused by abnormal purine metabolism.The end product of purine metabolism in human body is uric acid.HUA can be diagnosed when the level of uric acid in fasting blood is more than 7 mg/dl twice in the same day when normal purine is taken.In recent years,with the improvement of people's living standards and the change of dietary structure,the prevalence of HUA has increased.HUA has become the second largest metabolic disease after diabetes.A large number of studies have shown that HUA is not only the biochemical basis of gout,but also closely related to obesity,cardiovascular disease,kidney disease,hypertension,diabetes,metabolic syndrome and other diseases.Metabonomics is a science that studies metabolic pathways of biological systems by investigating the changes of metabolites or their changes over time after stimulation or disturbance of biological systems.It has been widely used in the diagnosis and treatment of diseases,elucidation of pathogenesis and screening of early markers of diseases.At present,the treatment of hyperuricemia,mainly including lifestyle improvement and drug treatment,has not achieved ideal results.In clinical practice,many adverse reactions of drug treatment for hyperuricemia prompt people to find better ways to reduce blood uric acid level.In recent years,with the development of bariatric surgery,clinical studies have found that bariatric surgery can not only maintain long-term weight loss and improve the quality of life of morbidly obese patients,but also improve a variety of obesity-related metabolic diseases,such as type 2 diabetes,hypertension and hyperuricemia,significantly reducing the level of serum uric acid in patients.However,the specific mechanism of weight-loss surgery in improving uric acid levels and other related metabolic disorders remains unclear.In this study,we first used the method of metabonomics to study the hyperuricemia rat model induced by potassium oxalate combined with adenine.Then,by observing the effects of two different methods of bariatric surgery(Roux-en-Y gastric bypass RYGB and sleeve gastrectomy SG)on the serum metabolic profiles of hyperuricemia rats,the metabolic changes of hyperuricemia rats after two different methods of weight-loss surgery were explored from the perspective of metabolomics,and the partial mechanism of reducing serum uric acid level by bariatric surgery was discussed.Our research provides some evidence about the treatment of hyperuricemia or gout by bariatric surgery.In this paper,two parts of the research are briefly introduced: Part One Study on Serum Metabolomics in Hyperuricemia Rats by High Performance Liquid Chromatography-Mass SpectrometryObjective: To study the changes of metabolic profiles in rats with hyperuricemia and screen potential biomarkers related to hyperuricemia by liquid chromatography-tandem mass spectrometry(LC-MS).Methods: Twenty eight-week-old Wistar rats were randomly divided into hyperuricemia model group(HUA,n=10)and blank control group(CON,n=10).The rats in HUA group were fed with adenine 0.1 g/kg and potassium oxalate 1.5 g/kg daily for 3 weeks and fed with yeast extract containing 10% for free to establish hyperuricemia model.Serum samples were collected after three weeks and stored at-80 ?.The general biochemical indexes of rat serum were detected,and the metabolic profiles of rat serum in two groups were described based on Ultra High Performance Liquid Chromatography-tandem Mass Spectrometry(UPLC-MS/MS).The differences of serum metabolic profiles between HUA group and CON group were analyzed by Principal Component Analysis(PCA)and Partial Least Square Discriminant Analysis(PLS-DA).Results: Compared with the control group,the levels of serum uric acid,creatinine,urea nitrogen,fasting blood glucose,fasting insulin,insulin resistance index,triglyceride,total cholesterol and low density lipoprotein cholesterol in HUA group increased significantly(P < 0.01),while the levels of high density lipoprotein cholesterol decreased(P < 0.01).Metabonomic analysis revealed and identified 14 potential biomarkers in hyperuricemia model rats,namely uric acid,hypoxanthine,allantoin,creatinine,hippuric acid,canine uric acid,tryptophan,indolephenol sulfate,p-cresol sulfate,taurine,palmitic acid,stearic acid,LPC(17:0)and LPC(18:0).It is suggested that hyperuricemia may induce disorders of glucose and lipid metabolism in rats by affecting purine metabolism,amino acid metabolism,bile acid metabolism,fatty acid metabolism and bacterial flora metabolism.Conclusion: Compared with the control group,the serum metabolic profiles of hyperuricemia rats are significantly different.The screening of 14 biomarkers is helpful to explain the changes of glucose and lipid metabolism caused by hyperuricemia,and may provide help for the molecular mechanism,early screening and diagnosis of hyperuricemia.Part Two Metabonomics Study on the Effect of Bariatric Surgery on Hyperuricemia RatsObjective: To investigate the effects of two main methods of bariatric surgery,Roux-en-Y gastric bypass(RYGB)and sleeve gastrectomy(SG),on serum uric acid level and serum metabolic profiles in rats with hyperuricemia(HUA),and to screen potential biomarkers related to bariatric surgery and explore their possible mechanisms.Methods: Forty eight-week-old male Wistar rats were randomly divided into hyperuricemia model group(HUA,n=30)and control group(CON,n=10).The HUA group was fed a high purine diet containing 10% yeast extract and administered with adenine and potassium oxalate suspension daily for three weeks to establish a rat model of hyperuricemia.The blank control group was given a normal diet and intragastric administration of saline at the same time.Then,the HUA group was randomly divided into sham operation group(SH,n = 10),Roux-en-Y gastric bypass operation group(RYGB,n = 10)and sleeve gastrectomy group(SG,n = 10),and the corresponding surgical treatment was carried out.Blood samples were taken from the medial canthal vein of rats before and 2,4,6 and 8 weeks after operation,and their body mass were recorded.The changes of serum uric acid,creatinine,urea nitrogen,fasting blood glucose,triglyceride and total cholesterol were detected.The serum metabolic profiles of rats in each group at 8 weeks after operation were described based on the metabolomic method of ultra-high performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS).The differences of serum metabolic profiles among the groups were analyzed by principal component analysis(PCA)and partial least squares discriminant analysis(PLS-DA).Results: Before operation,there was no significant difference in body weight among the four groups(P> 0.05).At 2,4,6 and 8 weeks after operation,there was no significant difference in body weight between SH group and CON group,but the body weight of RYGB group and SG group was significantly lower than that of SH group at each time point(P < 0.01).Before operation,the serum uric acid level in HUA group was significantly higher than CON group(P < 0.001).Compared with SH group,serum uric acid,creatinine,urea nitrogen,triglyceride,fasting blood glucose,fasting insulin,insulin resistance index,total cholesterol and low density lipoprotein cholesterol levels were significantly lower in SG group and RYGB group 2,4,6 and 8 weeks after operation(P < 0.01),high density lipoprotein cholesterol level was increased(P < 0.01),xanthine oxidase activity and serum inflammatory index IL-6 and TNF-? were significantly lower(P < 0.01).Twenty potential biomarkers were identified by metabonomic analysis,including uric acid,hypoxanthine,allantoin,creatinine,hippuric acid,tryptophan,indole sulfate,p-cresol sulfate,dimethyl sulfone,isoleucine,glutamic acid,tyrosine,cholic acid,deoxycholic acid,taurine,taurine,palmitic acid,stearic acid,LPC(17:0)and LPC(18:0),respectively.These results suggest that bariatric surgery affects purine metabolism,amino acid metabolism,bile acid metabolism,fatty acid metabolism,intestinal microbial metabolism and glycerol phospholipid metabolism in HUA rats.Conclusion: RYGB and SG can reduce the uric acid level of hyperuricemia rats,alleviate insulin resistance and improve the disorder of blood glucose and lipid metabolism in hyperuricemia rats.The 20 differential metabolites screened in this study may contribute to a better understanding of the mechanism of reducing uric acid levels in bariatric surgery from the perspective of metabonomics,and provide some research evidence for the application of bariatric surgery in the treatment of hyperuricemia.