Effects Of Vitamin D Combined With Aerobic Exercise On Antioxidant Enzymes And NF-κB Inflammatory Pathway In Db/db Mice Liver

Objective: Diabetes mellitus is a metabolic disease with chronic increase of blood glucose levels.Existing studies have suggested that inflammation and oxidative stress are related to the pathogenesis of type 2 diabetes mellitus.Inflammation and oxidative stress are closely linked and promote each other,mediating the occurrence of a variety of chronic diseases in the body,which is an important reason for inducing insulin resistance and leading to the relative deficiency of insulin.In recent years,the study found that vitamin D and aerobic exercise to improve the body’s inflammatory response,removal of oxygen free radicals,etc all have certain effect,vitamin D and aerobic exercise on the role of inflammation and oxidative stress,not only helps to parse the causes of diabetes,also will provide theoretical basis for the prevention and control of diabetes.In this study,by establishing an intervention model of vitamin D combined with aerobic exercise in DB/DB mice with diabetes,the mechanism of vitamin D combined with aerobic exercise was explored from the perspectives of inflammatory signaling pathway,oxidative stress and insulin resistance,so as to provide a new idea and experimental basis for the prevention and control of diabetes.Methods:(1)In this study,32 7-week-old male db/db mice were fed adaptively for one week and their tails were cut off to collect blood.The qualified standard was that fasting blood glucose(FBG)was higher than 16.1mmol/L.Then they were randomly divided into 4 groups according to their body weight,namely,blank control group(Blank control group,CG group),aerobic exercise group(Aerobic exercise group,EG group),vitamin D intervention group(Vitamin D intervention group,VG group),vitamin D combined with aerobic exercise group(Vitamin D combined with aerobic exercise group,EVG group),with 8 rats in each group.(2)Vitamin D injection was made by dissolving VD in injection grade soybean oil.VG group and VEG group were given intraperitoneal injection according to 7ug/kg dose,CG group and VEG group were given the same amount of peanut oil injection,3 times a week;EG group and VEG group were treated with aerobic exercise 5 times a week for 8 weeks.(3)Oral glucose tolerance test(Oral glucose tolerance test,OGTT)was performed before and after the experiment,and the changes of blood glucose,body weight,diet and drinking water were monitored every week.At the end of the 8-week experiment,the mice were killed under anesthesia after fasting for 12 hours.The expression of TNF-α,IL-6 and CRP in liver was measured by ELISA kit.The expression of NF-κ B in liver was detected by immunohistochemistry and Western Blot methods.The levels of superoxide dismutase(SOD),glutathione peroxidase(GSH-Px)and malondialdehyde(MDA)in liver were detected by kit.Results :(1)During the intervention experiment,compared with CG group,the food intake of mice in VG group,EG group and VEG group decreased significantly at the 8th week(P<0.01),but only in VG group and VEG group decreased significantly at the 8th week(P<0.01);and the growth trend of body weight was inhibited at the 6th week of intervention,and significantly decreased compared with CG group at the 8th week(P<0.01).The change of fasting blood glucose in CG group was relatively stable.From the 4th week,the blood glucose of the intervention group began to decrease,which was significantly lower than that of the VEG group in the CG group(P<0.01);and at the end of the 8th week,there were significant differences among the other three groups compared with the CG group(P<0.01,P<0.01,P<0.01).There was a significant decrease in the VEG group.(2)The results of HE staining showed that there were vacuoles of different sizes in the cytoplasm of hepatocytes in db/db mice.Compared with CG group,EG,VG and VEG fat vacuoles were significantly reduced,and the cell density was relatively high and arranged neatly.(3)The blood glucose and its area under the curve in ITT test were significantly different from those in CG group,EG group,VG group and VEG group(P<0.01,P<0.05,P<0.01).The blood glucose and its area under the curve in OGTT test were higher in CG group than those before intervention,while those in EG group,VG group and VEG group were significantly decreased(P<0.01).(4)Immunohistochemical staining of NF-κ B in the liver showed that the positive staining was located in the cytoplasm and was brown.Compared with the CG group,the staining degree of each group was decreased,and the difference was significant(P<0.05,P<0.05,P<0.01).The results of Western blot showed that the expression of NF-κ B P65 decreased in all intervention groups.Compared with CG group,the expression of NF-κ B P65 in EG group,VG group and VEG group decreased significantly(P<0.01,P<0.01,P<0.01).Compared with VG group,the expression in VEG group also decreased(P<0.05).(5)Compared with CG group,the level of CRP in EG,VG and VEG group decreased significantly(P<0.01,P<0.01,P<0.01).The level of IL-6 in VG and VEG group also decreased,and the level of IL-6 decreased significantly compared with CG group(P<0.01,P<0.05,P<0.01).Compared with VG group,the level of IL-6 in VEG group also decreased significantly(P<0.05).The trend of TNF-α was similar to that of IL-6,and the level of TNF-α in the other three groups was significantly lower than that in CG(P<0.05,P<0.05,P<0.01).(6)Compared with CG group,the level of SOD activity in EG,VG and VEG groups increased significantly(P<0.05,P<0.05,P<0.01),and the level of SOD in EVG group also increased compared with VG group(P<0.05).Compared with CG group,the level of GSH-Px activity in EG,VG and VEG groups increased significantly(P<0.05,P<0.05,P<0.05),while the level of MDA in EG,VG and VEG groups decreased significantly(P<0.01,P<0.05,P<0.01).Conclusions:(1)Aerobic exercise intervention and vitamin D supplementation can prevent excessive weight gain,reduce polydipsia and polyphagia,and improve insulin resistance in DB/DB mice.(2)Exercise and vitamin D can reduce the degree of chronic inflammation in mice,increase the content of antioxidant enzymes,improve insulin sensitivity,and protect islet β cells to a certain extent.(3)Vitamin D and aerobic exercise is one of the important strategies for the prevention and treatment of diabetes.Compared with simple exercise,the effect of vitamin D supplementation is obvious.