Effects Of Vitamin D On The Incidence Of Spontaneous Type 2 Diabetic Mellitus Mice Based On The Inflammatory Mechanism

ObjectiveTo observe the effects of vitamin D（Vit D）on incidence of spontaneous type 2diabetes mellitus（T2DM）mice,by establishing mice model of spontaneous T2DM and detecting glycolipid metabolic factors and insulin related indexes.In order to find the genes related to the possible changes in the NF-κB signaling pathway in the occurrence of T2DM mice by Vit D,through detecting of liver and adipose tissue in spontaneous T2DM mice by the NF-κB signal path PCR chip.The ultimate objectives of this research are to explore the effect of vitamin D on type 2 diabetes mellitus based on the NF-κB signaling pathway mechanism and provide the scientific evidence for the prevention of T2DM.MethodsFifty 3 week-old male KK-Ay mice were randomly divided into model control group（MC group）,Vit D deficiency group（VDD group）,low dose Vit D supplementation group（VDS-L group）,middle dose of Vit D supplementation group（VDS-M group）and high dose Vit D supplementation group（VDS-H group）,there were ten mice in each group.In addition,ten male C57 mice of the same age were used as the normal control group（NC group）.The VDD group was fed with Vit D deficiency diet based on AIN-93G standard,and the other groups were fed with AIN-93G standard feed.Vit D injection was dissolved in peanut oil and made into Vit D solution.Vit D supplementation groups were intragastric administration with Vit D solution at 1.5μg/kg BW·d,3μg/kg BW·d and 6μg/kg BW·d respectively,the other groups were filled with blank peanut oil according to their weight.During the experimental period,the body weight,food-intake and fasting blood glucose（FBG）of each group were measured,and the feeding status of the mice in each group was observed.After 9 weeks of intervention,the mice were extracted the eyeball blood and killed by the broken neck.Serum level of 25（OH）D₃ was detected by high performance liquid chromatography（HPLC）,serum triglyceride（TG）content was measured by end-point method,serum high-density lipoprotein cholesterol（HDL-C）and low-density lipoprotein cholesterol（LDL-C）were checked by Selective precipitation method,serum total cholesterol（TC）was detected by enzyme labelling method,serum fasting insulin（FINS）level was determined by enzyme-linked immunosorbent assay,and calculate homeostasis model assessment-insulin resistance（HOMA-IR）,the morphological changes of the pancreas were observed by HE staining,measure the genes expression by NF-κB signaling pathway PCR chip in liver and adipose tissue in T2DM mice.ResultsVit D supplementation had no significant influence on the weight and food-intake of all diabetic mice（P>0.05）.The results of HPLC detection show that Vit D supplementation could increase the content of 25（OH）D₃ in diabetic mice（P<0.05）.The results of glucose metabolism test showed that supplementation of medium and high doses of Vit D could reduce FBG level and reduce the incidence of T2DM in KK-Ay mice（P<0.05）.The test results of lipid metabolism index showed that Vit D supplementation could reduce serum TC and LDL-C levels in KK-Ay mice（P<0.05）,but had no significant effect on TG and HDL-C contents（P>0.05）,however the content of TG in mice was significantly different from baseline under the action of Vit D（P<0.05）.The results of insulin detection showed that the middle and high dose of Vit D supplementation could reduce the HOMA-IR level of KK-Ay mice（P<0.05）,but had no significant effect on FINS level（P>0.05）.The morphological observation of the pancreas showed that the islet of T2DM mice had significant compensatory hypertrophy,Vit D supplementation could improve the islet morphology of mice in different degrees,and the high dose Vit D supplementation group had the most obvious improvement.The detection results of NF-kappa B signaling pathway gene chip showed that,（1）Middle and high dose Vit D supplementation can make gene IL-10 and Tnfrsf10b downregulation,Cd40,Fasl,Tlr1 gene and Tnfaip3 upregulated in the mice liver of each group;（2）high dose Vit D supplementation coule make gene Hmox1、Icam1、Tlr6 and Tnf downregulation,the gene Agt upregulated in the epididymal fat of mice in each group.ConclusionIn conclusion,Vit D supplementation could increase the content of 25（OH）D₃ in serum of KK-Ay mice,improve the metabolism of glucose and lipid levels in mice,improve islet morphology and HOMA-IR mice,reduce the incidence rate of T2DM;Vitamin D could prevent the occurrence of T2DM by regulating the expression of some genes in the NF-κB signaling pathway and improving the level of inflammatory factors in KK-Ay mice.