Effects Of High Salt Diet On Glucose And Lipid Metabolism In Mice And Expression Of SGLT1 In Intestines And SGLT1/2 In Kidneys

Objective: 1.To investigate the effects of high salt diet on glucose and lipid metabolism in mice.2.To investigate the expression of SGLT1 in the upper small intestine and the lower small intestine in mice after high salt diet.3.To investigate the expression of SGLT1 and SGLT2 in mice kidney after high salt diet.Methods: Eight week male C57 mice were randomly divided into three groups,which were fed with standard diet(NC group,n=10)and 3% high salt diet(HS-1group,n=10)and 8% high salt diet(HS-2 group,n=10)separately.Total feeding time is 4 weeks.At the end of the fourth week,intraperitoneal injection of glucose tolerance test(IPGTT)and intestinal glucose absorption were measured.After the experiment,the indexes of weight,fasting blood glucose(FBG),plasma sodium concentration,plasma lipids and creatinine levels were measured in all three mice groups.The expression of SGLT1 was examined with immunohistochemistry,the expression of SGLT1 protein was examined with Western blot,and the expression of SGLT1 m RNA in the intestines was detected by real-time fluorescence quantitative PCR expression.The expression of SGLT1 and SGLT2 protein levels in the kidneys were detected by Western blot.Results: 1.Compared with NC group,IPGTT results showed that the areas under curve of HS-1 group and HS-2 group were higher(p<0.05),and blood glucose in HS-2 group increased at 30 min and 60min(p<0.05),blood glucose in HS-1 group increased at 60min(p<0.05);Compared with NC group,the results of intestinal glucose absorption showed that the areas under curve of HS-1 group and HS-2 group increased(p<0.05),the blood glucose increased obviously at the 10 min and20min(P<0.01),and the blood glucose increased at 30 min,60min and 120min(p<0.05).2.Compared with NC group,the total consumption of HS-1 group and HS-2 group decreased(p<0.05),and the amount of urine and drinking water increased in 24 hours(p<0.05);Compared with NC group,HDL-C decreased(p<0.05),TC,blood creatinine and GSP increased(p<0.05)in both HS-1 group and HS-2 group,and plasma creatinine of HS-2 group was higher than HS-1 group(p<0.05),LDL-C and TG of HS-2 group increased(p<0.05);The HS-1 group and the HS-2 group had higher FBG than the NC group,but the difference was not statistically significant(p>0.05);Compared with the NC group,the plasma sodium concentration in HS-1 and HS-2 group were slightly higher,remains in the normal range(p>0.05).3.Compared with NC group,the expression of SGLT1 protein and SGLT1 m RNA in the upper and lower small intestinal tissues of HS-2 group mice increased(p<0.05),the expression of SGLT1 protein and SGLT1 m RNA in the upper small intestine of HS-1group mice increased(p<0.05);The results of SGLT1 immunohistochemistry show that the small intestine tissue SGLT1 is located on the membrane of small intestine villus epithelial cells,compared with NC group,the expression of SGLT1 in the upper and the lower small intestine increased in the HS-2 group,and the expression of SGLT1 in the upper small intestine increased in the HS-1 group;Compared with NC group,the expression of renal SGLT2 protein in HS-1 group increased(p<0.05),the expression of SGLT1 protein in renal tissue of HS-2 group decreased and the expression of SGLT2 protein increased(p<0.05).Conclusion: High salt diet can cause glucose and lipid metabolism disorders in mice,and with the increase of salt intake,metabolic disorders exacerbated.Increased expression of SGLT1 in intestinal tissue and SGLT2 in kidney tissue may be an important cause of glucose metabolism disorders in mice after high salt diet.