MG132 enhances the renal anti-oxidative ability in diabetic nephropathy rats / 中华肾脏病杂志

ABSTRACT

Objective To investigate the effects of MG132 on diabetic nephropathy (DN) rats induced with streptozocin. Methods Seventy-two male SD rats were randomly divided into three groups normal control group (NC, n=24), DN group (n=24) and DN treated with MG132 group (DN+MG132, n=24). At the end of 4, 8 and 12 weeks, 24 hour urinary protein excretion rate (UPER) was detected. Morphology of kidney was examined by special staining of periodic acid-schiff (PAS). Renal 26S proteasome activity was determined by quantifying the hydrolysis of S-LLVY-AMC in a fluorescence reader. Urinary malondialdehyde (MDA) level and renal SOD and GSH-PX activity were detected by commercial kits. Renal SOD, GSH-PX and p47phox mRNA expressions were determined by real-time fluorescence PCR. Renal p47phox protein expression wasdetermined by Western blotting. Results Compared with NC group, the DN group showed a significant increased of UPER at week 4, 8, 12 (all P<0.05), of mesangium proliferation and mesangial matrix expansion at week 12. In DN+MG132 group, UPER was significantly decreased compared with DN group at the end of 4, 8 and 12 weeks (P<0.05, respectively), and the glomeruler pathological alteration induced by diabetes was attenuated. Increased renal 26S proteasome activity in DN rats was significantly inhibited after MC132 administration (P<0.05). Moreover, renal p47phox mRNA expression in DN group was 155%, 149% and 120% more than those in NC group at 3 time points (all P<0.05), and so was the renal p47phox protein expression, 139%, 152% and 186% more (all P<0.05). Urinary MDA levels in DN group were 1.95-, 2.04-and 2.62-folds more than those in NC group (all P<0.05). In addition, compared with NC group at 3 time points, in DN group, renal SOD activity was decreased by 23.09%, 33.59% and 53.31% (all P<0.05); renal GSH-PX activity was decreased by 28.57%, 33.06% and 48.76% (all P< 0.05); renal SOD mRNA was decreased by 38.09%, 61.44% and 76.53% (all P<0.05); renal GSH-PX mRNA group was decreased by 29.16%, 37.26% and 62.40% (all P<0.05). Compared with DN group, renal p47phox mRNA and protein expression, and urinary MDA levels were significantly lower in DN+MG132 group (all P<0.05); renal SOD and GSH-PX activity as well as mRNA expression were significantly increased in DN+MG132 group (all P<0.05). Conclusions MG132 treatment can provide renoprotection for DN rats effectively maybe through enhancing renal anti-oxidative ability.