The Experimental Study Of Tubular Injury Induced By Xylitol In Diabetes Rats

Objective: As xylitol can ameliorate glucose metabolism, improveinsulin secretion and anti-ketoplasia, so it is widely used for diabeticpatients and parenteral nutrition who is unable to take food. It has beenused for sweeting agent for diabetic patients from 1990s in our cuntry.Compaird with other sweetening agents, xylitol is cheap, manufacturesimple, sugariness similar with cane sugar and so on. It is a good choiceto use xylitol for sweeting agent. Resently, some research demonstratesthat lots of xylitol enter into the body either in short time or in longtime could increase the level of serum uric acid and damage kidney, evencause acute renal failure ending in death. However, whether the use ofxylitol by mouth could cause the injury of kidney is still unreported.Accordingly, the aim of this study is to observe the effects of xylitolon diabetic rats of the level of serum uric aicd, allantoin and the tubularinjury. Providing some experiment data for the use of xylitol.Methods: 1. Developing a method for the simultaneous determination ofuric acid, allantoin and creatinine in serum and urine by reversed-phasehigh performance liquid chromatography: The serum was deproteinized with5% perchloric acid and the urine was diluted and filtrated beforedetermination. The reversed-phase column was a Fuji Silysia C₁₈ column. Themobile phase was phosphate buffer. The results were calculated by the peakarea. 2. The 100 male Wistar rats were randomly divided into followinggroups: normal control group (group NC, n=16). Diabetes was establishedin the other 84 rats. Then, 80 diabetic rats were selected and randomlydivided into four groups: diabetes control group( group DC, n=20),5%Xylitol-treated group (group 5%, n=20), 10%Xylitol-treated group (group 10%,n=20) and 20%Xylitol-treated group (group 20%,n=20). Diabetes wasestablished in rats by intravenous injection of STZ at dose of 50 mg·kg^-1.After 72 hours, measured blood glucose, and the one whose blood glucosewas above 16.7mmol/L was enlisted. Group NC and DC were feeded with animalfeeds. Others were gave 5%,10% and 20% Xylitol feeds for 4 or 8 weeksrespectively. After that, the expression of MCP-1 and COX-2 in kidneytissue of each group rats were tested.Results: 1. The concentration of uric acid, allantoin and creatinine wasdetected by RP-HPLC simultaneously. Good linearity was observed in therange of 5～1000μmol/L, r=0.999. The intra- and inter-assay coefficientsof variation were both below 7%. The average recovery rates of threesubstance is between 96.1% and 102.9%. 2. At the end of 4 and 8 weeks, thebody weight were lighter and the blood glucose were higher of all diabetesgroups than group NC (P＜0.05). Compared with the group DC, three groupsreceived dietary xylitol supplementation have higher body weight andlower blood glucose, but only the difference between the group 20% andthe group DC was significant (P＜0.05). 3. At the end of 4 and 8 weeks,the kidney weight index(kiney weight/body weight) of all diabetes groupswere higher than NC group (P＜0.05). Compared with the group DC, group20% bad lower kidney weight index (P＜0.05). 4. The concentration of serumuric acid and allantoin increased in the diabetes groups compared withthe group NC (P＜0.05). The level of urine uric acid and allantoin decreasedin the diabetes groups. Group 5% and group 10% had higher concentrationof serum uric acid, allantoin as well as lower urine uric acid andallantoin. Whereas, group 20% had lower concentration of serum uric acidand allantoin and higher urine uric acid and allantoin (P＜0.05). 5. Theconcentration of serum creatinine, the level of urine creatinine andclearance of creatinine had no significant variance among the five groups.6. The fractional excretion of uric acid(FEUA) of all diabetes groups were lower than group NC (P＜0.05). Compared with the group DC, FEUA of group5% and group 10% were lower and group 20% was higher (P＜0.05). 7. Theexpression of MCP-1 and COX-2 in kidney were up-regulated in all diabetesgroups at the end of 4 and 8 weeks (P＜0.05). Compared with the group DC,the expression of MCP-1 and COX-2 were significantly increased in group5% and group 10%, and decreased in group 20% (P＜0.05).Conclusion: 1. The RP-HPLC can detect the concentration of uric acid,creatinine and allantoin in quick,little sample, well accurate andsimple, can be used in study and clinical laboratory. 2. Xylitol coulddecrease the level of blood glucose, weight gain;Diabetic rats couldincrease the level of serum uric acid;Low and mediate dose of dietaryxylitol could aggravate the the tubular injury through increase the levelof serum uric acid and the expression of MCP-1 and COX-2 in renal tubuleup-regulated; High dose of xylitol could improve the blood glucose andrelieve symptom, as well as the expression of MCP-1 and COX-2 in renaltubule down-regulated. The tubular injury could be protected.