Effects of N-acetylcysteine on expression of transforming growth factor-β1 in diabetic nephropathy rats

Objective To investigate the effects of N-acetylcysteine (NAC) on the expression of transforming growth factor-β1 (TGF-β1) in renal cortex of diabetic nephropathy rats.Methods A rat model of DN was established.The rats were randomly divided into control group,DN group and NAC group.After 8 weeks treatment,urinary albumin excretion rate (UAER) was determined.The expression of TGF-β1 in renal cortex was detected by immunohistochemistry and RT-PCR analysis.Pathomorphological changes of renal cortex were observed.Results (1)The levels of UA ER were significantly higher in DN group and NAC group [(1268.3±297.5) μg/24 h and (315.9-±86.8) μg/24 h] than in control group [(31.2±8.9) μg/24 h,q-29.85,16.76,both P＜0.01].The groups of DN and NAC versus group of control showed the increased levels of activity of TGF-β1 in renal cortex [immune-histochemistry index of glomerular mesangial area:7.35±1.17 and 3.87 ± 0.71 vs.1.95±0.34,q= 10.75,5.82,both P＜0.01];immune-histochemistry index of renal tubulointerstitium [21.21± 3.78 and 10.67±1.86 vs.3.62±0.79,q=15.20,11.36,both P＜0.01];the expression of mRNA in renal cortex[0.72±0.06 and 0.45±0.05 vs.0.23±0.04,q=9.13,7.45,both P＜0.01].The pathomorphological changes were significant in DN group and NAC group.(2)The NAC group versus DN group showed a decreased levels of UAER (q=8.17,P＜0.01),activity of TGF-β1 in renal cortex [immune-histochemistry index of glomerular mesangial area:q= 4.97,P＜0.01]immune-histochemistry index of renal tubulointerstitium (q = 6.86,P ＜ 0.01 );the expression of mRNA in renal cortex (q= 3.69,P＜0.05) and showed improvement of pathomorphology in renal cortex.(3) There was a significantly positive correlation between expression quantity of TGF-β1 mRNA in renal cortex and UAER level in NAC group(r= 0.749,P＜0.05).Conclusions The protective effects of NAC on the kidney of DN rats may be partly related with inhibition on the expression of TGF-β1.