| [Background and Objective] Diabetic nephropathy(DN) is one of the common reasons which induce chronic renal failure.The previous studies about DN had been always focused on glomerules.Recent years, in the research on tubular interstitial lesion in progress of renal disease, people found that renal tubular epithelial cells had very important function in the development of DN.Rosiglitazone(RGZ) ,a member of thiazolidinediones(TZDs), is the ligand of peroxisome proliferator-activated receptorγ(PPARγ) and novel insulin sensitizing agent. Now it is being taken to cure type 2 diabetes as an oral antidiabetic compound. A series of studies indicated, besides ameliorating insulin resistance, TZDs had many other functions, such as antiinflammation, inhibiting visceras fibrosis,affecting cell proliferation and transdifferentiation, et al. These functions were highly connect with kidney and kidney disease. However, there are no reports about direct effects of TZDs on renal tubular epithelial cells in the diabetic condition.This research was designed to investigate the protective effects and mechanism of rosiglitazone on rat renal tubular epithelial cells stimulused by high glucose, provide theoretical basis for the treatment on diabetic nephropathy with TZDs inclinically.[Methods] In the first place, rat renal tubular epithelial cells were cultured with high glucose for 24,48,72 hours respectively. The mRNA expressions of PPARγ, transforming growth factor - β1 (TGF-β1) and plasminogen activator inhibitor-1 (PAI-1) were detected with reverse transcription-polymerase chain reaction(RT-PCR) .The results help choosing suitable time for next research. To determine experimental dose of rosiglitazone , cells were cultured with different concentration of rosiglitazone for 48 hours and the cell proliferation was examined by MTT colorimetry. Cells were randomly divided into five groups: normal glucose group(NG, 1000 mg/L D-glucose), high glucose group(HG, 4500 mg/L D-glucose), HG+RGZ (5μmol/L) , HG+RGZ(l0μmol/L) and HG+RGZ (15μmol/L) ,all of them were cultured for 48 hours. The mRNA expressions of PPARy, TGF- β1 and PAI-1 were measured with RT-PCR. The protein levels of PPARγ, TGF- β 1 and α -smooth muscle actin( α -SMA ) were detected by Western blotting. The differences of date among groups were compared by One-Way ANOVA Test.[Results](1) Compared with NG group, the expressions of PPARγ mRNA and protein markedly increased in HG group(5 and 2.3 times respectively, gray scale:0.140±0.036 vs 0.694±0.052, 0.497±0.023 vs 0.212±0.034). These overexpressions were downregulated by rosiglitazone in dose-dependent manner.(2) Compared with NG group, the expressions of TGF- 0 lmRNA and protein significantly increased in HG group(both 2 times, gray scale: 0.589±0.057vs 0.314±0.041,0.617±0.027vs0.296±0.038,P<0.01) .Rosiglitazone markedly inhibited the expression of TGF- β 1 in dose-dependent manner. The protein level of TGF- β 1 in HG+R15μmol/L group was similar to the one in NG group.(3) Compared with NG group ,the mRNA expression of PAI-1 group enhanced significantly in HG group(2.5times).However, the mRNA level in HG+R10 μmol/L and HG+R15 μmol/L group were notablely lower than that in HG group (P<0.01) .(4) The NRK52E cells expressed minimal α -SMA protein in NG group.The proteinlevel of a -SMA increased significantly in HG group(4times, P<0.01) compared with that in NG group. Rosiglitazone markedly inhibited the expression of a -SMA in dose-dependent manner. [Conclusion]1. High glouse induces the mRNA and protein expression of PPARy in NRK52E cells;2. Rosiglitazone suppresses the high expression of TGF- 3 1 and PAI-1 in NRK52E cells induced by high glucose by activating PPARy, then inhibits synthesis of extracellular matrix and promotes degradation of extracellular matrix;3. Rosiglitazone inhibits the protein expression of a -SMA in NRK52E cells induced by high glucose, blocks the cellular transdifferentiation. |
PDF Full Text Request