| Objective: This study was to investigate the effects of cold and warm water swimming on the browning of white adipose tissue in type 2 diabetic rats and normal rats and the role of FNDC5/Irisin,providing experimental basis for type 2 diabetes improve blood glucose and insulin regulation through white fat browning pathways in cold environments.Method: Six-week-old male Sprague-Dawley rats were randomly divided into normal diet(NF,n = 22)and high-fat diet(HF,N = 43).The latter finally obtained 31 type 2 diabetic model rats(modeling success rate is about 72.1%)through 9 weeks of HFD / STZ.Then the normal diet group was randomly divided into 3 groups: control group(NA,n = 6).Cold water swimming group(NCS,N = 8)and warm water swimming group(NWS,n = 8);Rats with successful T2 DM modeling(HFD,N = 26)were randomly divided into 3 groups: diabetic control group(DA,N = 6),Diabetes cold water training group(DCS,n = 10)and Diabetes warm water swimming group(DWS,N = 10)swimming training program: 8W,5D / watt,30 minutes / d,weight 2% weight The temperature of cold and warm water is 22°C±1°C and 33°C±1°C,respectively.After feeding,T2 DM was successfully modeled.After 8 weeks of swimming training,rats' tail vein whole blood was used to measure fasting blood glucose(FBG),enzyme-linked immunosorbent assay was used to detect fasting serum insulin(FINS),and insulin resistance index was calculated(HOMA-IR and insulin sensitivity index(ISI),glucose tolerance test(IPGTT),and serum triglyceride(TG),total cholesterol(CHO),high-density lipoprotein(HDL-C),and low-density lipoprotein(LDL-C)After the completion of the 0.8-week swim training,serum was collected,iBAT,eWAT and soleus were prepared;eWAT paraffin sections were prepared and observed by HE WAT morphology;Western Blot was used to detect the expression of UCP1 and PGC-1? protein in eWAT and rWAT,FNDC5 protein in PGC-1? in Solesus,and ELISA was used to detect serum Irisin level.Results:(1)After 9 weeks of HFD / STZ,body weight,FINS and ISI of T2 DM rats were significantly decreased(P <0.01).FBG,HOMA-IR and AUCBG were significantly increased(P <0.01).(2)After 8 weeks of swimming exercise,the body weights of NCS group,NWS group and DA group,and the difference between NCS group and DA group were statistically significant(P <0.01);8 weeks(3)8 After exercise,DA group(P <0.01),and the food intake of DCS group and DWS group was significantly higher than that of DA group(P <0.01),and HOMA-IR was still higher than that of NA group(P <0.01).),FINS was still significantly lower than NA group(P <0.01),HOMA-IR was significantly improved in DCS group and DWS group(P <0.05).(4)The results of HE staining showed that the cross-sectional area and lipid droplet area of eWAT cells in DA group were decreased,and the cell membrane integrity was relatively unclear,and some cells had a tendency of fusion at the junction.In the exercise group,except that after 5 weeks of 8 weeks of exercise,compared with the control group,the NCS group showed a smaller cell cross-sectional area,a smaller intracellular lipid droplet,and a deeper cytoplasmic staining,similar to the NWS group.Brown adipose-like cells or beige fat cells.The expression of PGC-1? and UCP1 protein in rat eWAT was significantly higher than that in NA group(P<0.01 and P<0.05),and it was significantly higher in NCS group than that in NWS group(P <0.05).Lower than NA group(P<0.05);In addition DCS group was significantly higher than DA group(P<0.05),UCP1 of DWS group was significantly higher than DA group(P<0.05)(7)After 8 weeks of exercise,NCS group Compared with NWS group,the expression of PGC-1? and FNDC5 protein in Soleus was significantly higher(P<0.05)than that in NA group(P <0.01 and P <0.05),and NCS group PGC-1? was significantly higher than that in NWS group(P<0.05);FNDC5 was only significantly lower in DA group than in NA group(P<0.05);(8)After 8 weeks of exercise,serum Irisin in NCS group was significantly higher than that in NA group(P<0.01);DA in this group was significantly higher than that in NA group(P<0.01).Conclusions:(1)8-week swimming in cold water promoted browning of epididymal white adipose tissue in normal rats by up-regulating FNDC5/Irisin pathway.The effect of retroperitoneal white fat was no obvious change.(2)8-week cold-water swimming improved the glucose metabolism by promoting the browning of epididymal white adipose tissue in T2 DM rats,but the FNDC5/Irisin pathway may be inhibited by hyperglycemia and high insulin levels and low insulin sensitivity. |
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