Effect of vitamin D on the expression of growth factor growth factor beta 1,recombinant human collagen-1 and connective tissue growth factor in kidney of rats with type 2 diabetic nephropathy

Objective To explore the effect of vitamin D on the expression of transforming growth factor-β1(TGF-β1),connective tissue growth factor(CTGF) and restructuring of collagen-1(collagen-1) in diabetic nephropathy rat,discuss their interaction in diabetic nephropathy,and the protective effect of vitamin D for the kidney of diabetic nephropathy rat.Methods 54 male SD rats were randomly divided into three groups:normal control group(n=18),model group(n=18),treatment group(n=18).The model group and treatment group rats were established diabetic nephropathy model,and fed with high fat diet for 6 weeks,then intraperitoneal injection of small dose streptozotocin after fasting for 12hours.1 week after injection,3 times of blood glucose(GLU) on a different date were measured,if 3 times of GLU all≥16.7 mmol/L indicated that rats had type 2 diabetes mellitus.6 and 7 weeks after type 2 diabetes mellitus model establishment,trace protein urine dipstick was used for detection of the morning urine of rats for at least 3 times,if the results were positive,indicated that rats had type 2 diabetic nephropathy.The treatment group was given 0.03μg/(kg·d) calcitriol dissolved in 0.05 mL peanut oil by intragastric administration for 37 d.The model group was given peanut oil by intragastric administration for 37 d.After treatment all rats were killed,and the kidneys were removed.HE,electron microscopy were used for morphological changes observation of renal tissue,real-time fluorescence quantitative PCR(RT-PCR) was used for evaluation of expression changes of renal TGF-β1,collagen-1 and CTGF genes.Results ①The expression of TGF-β1,collagen-1 and CTGF genes in the model group were significantly higher than those in the normal control group(P 0.05),which in the treatment group were significantly lower than those in the model group(P 0.05).②The results of HE,electron microscopy showed that in the treatment group the pathological tissue morphology,especially organizational structure integrity was better than that of model group significantly.Conclusion Vitamin D can down regulate the expression of TGF- β1,collagen-1 and CTGF genes,has protective effect on diabetic nephropathy for the diabetic nephropathy rats.