| Background and ObjectivesEpidemiological survey shows China has surpassed India to become the largest country in diabetic. Due to the upgrading of the level of medical technology, the extension of life expectancy and the increasing prevalence rate of type2diabetes mellitus, the prevalence of diabetic kidney disease (DKD) also increased year by year. Hyperperfusion, high pressure and hyperfiltration have been considered to play a pivotal role in the earlier development of diabetic nephropathy. Glomerular hypertrophy, thickening of the glomerular basement membrane, expansion of the mesangial area and increasing matrix are major histological changes of the disease. The exact pathogenesis of diabetic nephropathy has not been fully elucidated, possible mechanisms which include hemodynamic changes, oxidative stress, disorder of glucose metabolism, insulin resistance, the role of cytokines and genetic background are interacted with each other. With the development of molecular biology and immunology, an increasing number of studies have shown that cytokines play a vital role in the development and progression of DKD. Consequently, affecting cytokine expression in renal tissue becomes a hotspot research in the treatment of DKD.Previous studies have shown that the decreased activity of bone morphogenetic protein-7in the partial kidney tissue and the accumulation of transforming growth factor-betal play an important role in the development of DKD, there are much more attentions to the renal protection of the1,25(OH)2D3in recent years. The purpose of our study is to observe the BMP-7, TGF-β1expression changes in rat renal tissue of diabetic kidney disease and to explore the1,25(OH)2D3can produce what kind of impact on BMP-7and TGF-β1which were presented in nephridial tissue of diabetic rats.Objects and Methods1. According to the random number table, we made the normal Sprague-Dawley male rats into two groups:normal control rats (group NC) and model group rats which were given streptozotocin by intraperitoneal injection. After successful modeling, in accordance with the principle of randomization, the diabetic rats were divided into diabetic model group (group DM) and1,25-dihydroxyvitamin D3group equally treated as treatment group (group DT) which were treated with1,25-dihydroxyvitamin D3(0.03μg/kg-1·d-1). After12weeks of treatment, rats were monitored for renal function,24hours total urine protein, blood calcium and so on.2. PAS and Masson staining were used to get information about histological damage in the kidneys.Immunohistochemical and immunofluorescence were used to monitor the expression and distribution of BMP-7and TGF-β1on diabetic rats’ renal tissue. By using the technology of reverse transcription polymerase chain reaction (RT-PCR), which was used to be detected the contents of BMP-7and TGF-01mRNA in renal tissue.3. SPSS statistical version17.0was used for all statistical analysis. Measurement data were expressed as the x±S. Multiple sets of quantitative data were measured by one-way ANOVA, after ANOVA, we used Bonferroni test. Pearson test was performed to correlation analysis. P<0.05was considered as statistical significance.Results1. KW/BW reatio,24hours total urine protein, Scr, Cys-c were distinctly higher in the diabetic rats than those in the nomal control rats (all of P value=0.000), but the blood calcium decreased (P=0.002), and these biochemical indicators in the DT group were distinctly higher as well compared with the NC group (P=0.000, 0.001,0.000,0.000), in addition to calcium did not change significantly in the two groups of rats (P=0.454); KW/BW ratio,24hours total urine protein, Scr, Cys-c in the DT group were significantly lower than those in the DM group (P=0.005,0.000,0.000,0.003respectively), but the blood calcium increased (P=0.000).2. By hematoxylin-eosin staining, we found that the structure of glomerular and tubular in normal rats was clear, the thickness of glomerular basement membrane was uniform and capillary lumen was open, there was no inflammatory cell infiltrated as well as no proliferation of fibrotic tissue in renal interstitium. Through PAS staining and Masson staining, we can observe that diabetic rats have bigger glomerular volume, thicker basement membrane, more mesangial matrix than normal rats. We also can see part of renal tubule epitheliums were swelling, a large number of inflammatory cell infiltrated into the renal interstitial in kidney tissue of DM rats. After intervention of the1,25-dihydroxyvitamin D3, DT rats pathological damage were significantly improved compared with the DM rats.3. Immunohistochemistry noted that BMP-7was mainly expressed in the renal tubule epitheliums, TGF-β1was expressed in glomerular and tubular basement membrane, the same results showed by immunofluorescence. The expression of TGF-β1were increased in DM rats and DT rats compared with those in the normal control group (P=0.000,0.000), but it was decreased in DT rats compared with DM rats (P=0.000). In DM rats and DT rats the expression of BMP-7were both decreased compared with the nomal rats (P=0.000,0.005), but it was increased in DT rats compared with DM rats (P=0.030). RT-PCR results showed that the level of TGF-β1mRNA was higher in DM rats and DT rats than it in NC rats (P=0.000,0.000), but the expression levels of TGF-β1mRNA in the DT group were distinctly lower than those in DM group (P=0.000). The level of BMP-7mRNA was lower in DM rats and DT rats than it in NC rats (P=0.000,0.000), while the levels of BMP-7mRNA in the DT rats were distinctly higher than in DM rats (P=0.002).4. Correlation analysis revealed that there was clearly positive correlation between the24-hour proteinuria quantitation and the expression of TGF-β1mRNA (r=0.935,.P=0.000), but there was negative correlation between the24-hour proteinuria quantitation and the expression of BMP-7mRNA (r=-0.683, P=0.000). There was significantly negative correlation between the expression of TGF-β1mRNA and the expression of BMP-7mRNA (r=-0.670, P=0.000).Conclusions1. The expression of BMP-7was decreased but the expression of TGF-β1was on the contrary in STZ-diabetic rats, pointing out that BMP-7and TGF-β1participated in the occurrence and development of diabetic kidney disease.2. Diabetic rats which were treated by1,25-dihydroxyvitamin D3,24hours total urine protein, serum creatinine were decreased, suggesting that1,25-dihydroxyvitamin D3which may affect the expression of BMP-7and TGF-β1in the renal tissue plays renal protective effects in the kidney of diabetic rats. |
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