The Study Of The Renal Protective Effects Of Ferulic Acid On Experimental Diabetic Rats And Its Mechanism

Objective:The present study was to investigate the effect of ferulic acid on expression of transforming growth factor-?₁?TGF-?₁?,matrix metallopeptidase 9?MMP9?,nephrin and podocin in renal tissue of experimental diabetic nephropathy rats,and to elucidate the underlying mechanisms.Methods:Diabetes mellitus?DM?was induced through a single injection of streptozotocin?STZ,50mg/kg?in male Sprague Dawley?SD?rats after starving overnight.72 hours after the first injection,only rats which with blood glucose?16.7mmol/L were selected as diabetic model in this study.The chosen diabetic rats were randomly divided into 4groups?n=10?:control group,diabetic model group,diabetic+Ferulic acid group?100mg/kg/d,i.g.?and diabetic+Valsartan group?12mg/kg/d,i.g.?.At the end of 5^th week,The agents were started to administer for5weeks and level of blood glucose for every week was recorded,other experiment were carry out at the end of 10^th week.Blood was collected via femoral artery,and before killing rats,their urine in 24 hours also be collected,all samples was centrifuged.The levels of urinary protein?UP?,blood urea nigtrogen?BUN?and serum creatinine?SCr?were examined.Both kidneys were weighted to calculate the kidney hypertrophy index?kidney weight/body weight,KW/BW?.The morphologic changes of renal tissues was observed under light microscope after Hematoxylin and eosin?HE?staining and fibrosis were also be evaluated through Masson staining.The expression of TGF-?₁,MMP-9,nephrin,podocin were detected through immunohistochemistry and western blot.Results:1.Characterrization of rats groups:The control group rats had good spirits and bright fur,the averge of weights were keeping increasing during the experiment.The rats of diabetic model group has low mental condition and fur smooth finish compared to control model group,and they already appeared the symptom of DM,such as the quantum of eating,drinking and urinating increased.These alterations were attenuated in Ferulic acid and Valsartan group.2.Alterrations of kidney hypertrophy index:Compare with control group,the value of kidney weight/body weight of diabetic model group was significantly increased?P<0.01?.And ferulic acid and valsartan treatment both can attenuated the kidney hypertrophy index compare to diabetic model group?P<0.05,P<0.05?.3.Level changes of blood glucose,UP,BUN and SCr:All the level of blood glucose,24h UP,BUN and SCr of diabetic model group significantly increased compare with these values of control group?P<0.01?;Intervention of ferulic acid could reduce level of blood glucose,UP,BUN and SCr in its group?P<0.05?.Valsartan groups could also attenuate,but didn't normalize?P<0.05?and valsartan could not improve blood glucose level?P>0.05?.4.Kidney histopathology observation:Hematoxylin-eosin staining:control group rats glomerular structure were clear and intact.The volume is normal and arrangement of tubular was normal and orderly.No mesangial hyperplasia,basement membrane thickening or renal tubular atrophy.Epithelial cell did not appear vacuolar degeneration.Compare with control group,glomerular of diabetic group rats appear hypertrophy,and thickening of the basement membrane and mesangial proliferation was obvious Epithelial cell appeared disorder,hypertrophy and vacuolar degeneration.These alterations were attenuated in Ferulic acid and Valsartan group.Massion staining:Glomerular basement membrane and Mesangial interstitial of control group rats was dyed blue slightly and fibrosis was at a low level.Diabetic group had a large number of blue collagen fibers and fibrosis was seriously.Blue collagen fibers in glomerular of ferulic acid group and valsartan group were significantly reduce.Fibrosis and pathological changes were significantly reduced.5.Immunohistochemistry:Control group had low expression of TGF-?₁ in renal tissue,brown granules could hardly be found in renal biopsy.Diabetic model group had numerous brown granules in renal biopsy,widely distributed and had a statistically significant difference compare to control group?P<0.01?.Ferulic acid and valsartan group both had same distribution area,but significantly reduced?P<0.01,P<0.05?.Expression MMP-9,nephrin and podocin were lower in diabetic group than which in control group and had a statistically significant difference compare to control group?P<0.01?.Ferulic acid group and valsartan group were all attenuated in expression of MMP-9,nephrin and podocin,but lower than control group?P<0.01,P<0.01?.6.Western blot analysis:Compare with control group,diabetic model group had high expression of TGF-?₁?P<0.01?.MMP-9,nephrin and podocin were prominent in control group significantly higher than diabetic group?P<0.01?.Meanwhile expression of TGF-?₁ in ferulic acid group and valsartan group was significantly reduced?P<0.01?,and expression of MMP-9,nephrin and podocin was also significantly increased at the same time?P<0.01,P<0.01,P<0.05?.Conculusion:Ferulic acid have protective effect on the renal of diabetic rats.The mechanism may be related to that ferulic acid can regulated the expression of TGF-?₁,MMP-9,nephrin and podocin,reduce renal fibrosis and Maintaining podocyte's structure.