Expression Of MK And TGF-β In Renal Tubules Of Diabetic Rats

Objectives: 1. To observe the expression of midkine and transforming growth factorβin the renal tubles of diabetic rats and to investigate their relationships,and to study the effect of midkine in the development of diabetic nephropathy. 2.To observe the therapeutic effect of insulin on the level of midkine and transforming growth factorβ, and on the pathologic changes of diabetic nephropathy.Methods: 70 male Sprague-Dawlry rats were randomly divided into two groups : normal control group(n=18) and model group(n=52). And model group was induced by streptozocin (STZ) in 60mg/kg. Diabetic rat was confirmed by fasting blood glucose≥16.7mmol/L after three days of STZ administration (4 cases failed to achieve the standard of diabetes were excluded). Diabetic rats were randomly divided into two groups: insulin treatment group and diabetes mellitus group. Each group was divided into the four week group, the eigh week group, the twelve week group. Long-acting insulin was injected subcutaneously to control blood glucose at dosage of 3u/(100g·d) in the insulin treamtment group, normal control group and diabetes mellitus group received 0.2ml 0.9% saline. At the end of fourth week, the eighth week, the twelfth week after diabetes mellitus model established, blood glucose and 24 hours urine protein were determined, and body weight were weighed, and then rats were killed to collect the serum and kidney. We calculated the ratio of kidney weigh to body weigh(KW/BW). The morphological changes of renal tissue were observed through light microscopy after hematoxylin-eosin(HE) staining. Immunohitochemistry stainin- g was used to detect the expression of MK, TGF-βprotein in the kidney.Results: 1.At the end of the fourth week, the eighth week, the twelfth week after diabetes mellitus model established, FBG, KW/BW and 24 hours urine protein were obviously decreased in the insulin treatment group and normal control group(P<0.01) compared with diabetes mellitus group. 2.At the end of the fourth week, the eighth week,the twelfth week after diabetes mellitus model established, immunohistochemis- try revealed a significant increase in the expression of MK and TGF-βin the kidney in diabetes mellitus group compared with insulin treatment group and normal control group(P<0.01). 3.With the development of diabetes, the expression of MK was obviously increased in the diabetes mellitus group (P<0.01). In diabetes mellitus group, there were positive correlations between MK and TGF-β(r=0.708, P<0.01).Conclusions:1. The expressions of MK and TGF-βwere gradually increased in the kidney of diabetic rat induced by STZ , and the expression of MK and TGF-βwere increased simultaneously, which possibly participated in pathogenesis of diabetic nephropathy. 2.Insulin therapy can reduce the expression of MK and TGF-βin the kidney of diabetic rat, relieves early pathological changes of diabetic nephropathy.