Abstract:

Objective
To observe the effect of fluvastatin on the activity of extracellular signal-regulated kinase(ERK)1/2,expression of connective tissue growth factor(CTGF) in  glomerular mesangial cells stimulated by high glucose,and explore the pathogenic mechanism of diabetic nephropathy(DN) and its early prevention and treatment.Methods The study consisted of two parts,the first part was to repeat the existing experienment of stimulatory effect  of high glucose on mesangial cells,and validated that high glucose could up-regulated the expression of CTGF through stimulating  ERK,and the  change was unrelated with hypertonic conditions.There were five groups:①normal control group(NG);②high glucose group(HG);③mannitol group(MN);④NG+ERK inhibitor PD98059 group(NG+PD);⑤HG+ ERK inhibitor PD98059 group（HG+PD）.The second part was to observe the changes of the expressions of CTGF protein and mRNA in mesangial cells at high glucose concentration before and after fluvastatin intervention. There were also five groups:①normal control group(NG);②high glucose group(HG);③normal glucose and  fluvastatin group (NG+F);④high glucose + fluvastatin(HG+F);⑤high glucose + fluvastatin and  mevalonic acid group(HG+F+M).The activity of ERK1/2 and the expressions of CTGF  protein and mRNA in cultured glomerular mesangial cells stimulated by high glucose were detected   with Western blotting and RT-PCR.The amount of fibronectin (FN) in the supernatant of cells was analyzed by ELISA.Intracellular total protein level was measured by Coomassie brilliant blue method.Results The first part showed that the activity of ERK1/2 and the expression of CTGF protein in HG were more higher than those in NG（P<0.01）,which in HG+PD were more less than those in HG（P<0.01）,and all the indexes had no obvious difference between MN and NG+PD.The second part showed that the activity of ERK1/2 and the expressions of CTGF protein and mRNA in HG were  significantly  higher than those in NG(P<0.01),and the levels of intracellular total protein and FN were also increased significantly（P<0.01）.The activity of ERK1/2 and the expressions of CTGF protein and mRNA in HG+F were   significantly lower than those in HG,and the levels of intracellular total protein and FN were also significantly decreased（P<0.01）.The indexes mentioned above in HG+F+M had no obvious difference with those in HG+F.Conclusion Fluvastatin can decrease the expression of CTGF and FN level in the glomeruli and inhibit the activity of ERK1/2 to ameliorate the progression of glomerular hypertrophy and restrain and delay  DN progression.

Key words: mesangial cells;fluvastatin;connective tissue growth factor;ERK1/2