4-苯基丁酸对糖尿病肾病大鼠的作用

目的 探讨化学分子伴侣4-苯基丁酸（4-PBA）对糖尿病肾病（DN）大鼠的治疗作用及其机制。 方法 54只大鼠随机分为正常对照组（NC）、糖尿病肾病组（DN）和4-PBA治疗组（4-PBA），每组各18只。在治疗第4、8及12周末分别检测各组大鼠肾质量指数（KI）、24 h尿蛋白排泄率（UAER）、血肌酐（Scr）、尿素氮(BUN)、尿丙二醛（MDA）含量和超氧化物岐化酶（SOD）活性；观察肾脏病理改变；实时荧光定量PCR法检测各组大鼠肾组织p47phox mRNA的表达变化；Western印迹检测p47phox和硝基酪氨酸（NT）的蛋白表达变化。 结果 与NC组大鼠比较，在4、8和12周时，DN大鼠的KI显著增高（P < 0.05），UAER（mg/24 h）也显著增高（4.92±0.70 比 0.26±0.07、 5.29±0.83 比0.28±0.08、5.54±0.81比0.29±0.04，均P < 0.05）。12周时病理显示DN大鼠肾小球系膜细胞增生，系膜基质积聚；而与DN组大鼠比较，4-PBA治疗组大鼠KI显著降低（P < 0.05），UAER（mg/24 h）亦显著降低（4、8和12周分别为3.71±0.37、3.47±0.36和3.28±0.40，P < 0.05），4-PBA能显著减轻肾脏的病理变化。在4、8和12周，与NC组大鼠比较，DN大鼠肾组织p47phox mRNA表达分别升高了154.72%、148.60%和91.95%（均P < 0.05）；p47phox蛋白表达分别升高了118.00%、140.10%和177.82%（均P < 0.05）；硝基酪氨酸蛋白表达分别升高了45.29%、59.13%和89.28%（均P < 0.05）；尿MDA含量分别增加了2.05倍、2.26倍和2.43倍；尿SOD活性分别下降了64.78%、71.29%和79.32%。与DN组比较，在8和12周时，4-PBA治疗组DN大鼠肾组织p47phox mRNA和蛋白表达均显著减少（均P < 0.05）；硝基酪氨酸蛋白表达显著减少（P < 0.05），且与NC组差异已无统计学意义。另外，在4~12周，4-PBA治疗可显著减少DN大鼠尿中MDA含量，增加尿SOD活性（均P < 0.05）。 结论 4-PBA能显著抑制糖尿病大鼠肾脏病理变化，其机制可能与抑制肾组织氧化应激有关。

Effect of 4-phenyibutyric acid on diabetic nephropathy rats

Objective To investigate the effect of 4-phenylbutyric acid(4-PBA)on the renal pathogenesis of rats with streptozotocin-induced diabetes and its mechanism. Methods Fifty-four male SD rats were randomly divided into three groups:normal control group(NC group,n=18),diabetic nephropathy group(DN group,n=18),diabetic nephropathy plus 4-PBA treatment group(4-PBA group,n=18).At the end of 4,8 and 12 weeks,index of kidney weight/body weight ratio(KI)were measured and calculated.Serum creatinine (Scr),blood urea nitrogen(BUN),urinary MDA levels,urinary SOD activity,and 24 hour urinary protein excretion ram(UAER)were detected by HITACHI automatically.Morphology of kidney wag examined by special staining of periodic acid-schitt (PAS).The p47phox and nitrotyrosine (NT) expression in kidney were determined by real-time fluorescence PCR and Western blotting. Results Compared with the NC group, the DN group rats showed a significant increase of KI(P＜0.05), UAER(mg/24 h) (4.92±0.70 vs 0.26±0.07, 5.29±0.83 vs 0.28±0.08, 5.54±0.81 vs 0.29±0.04,respectively, P＜0.05]for indicated time, mesangial cells proliferation and mesangial matrix expansion at 12 week. However,4-PBA treatment could significantly inhibit the increase of KI (P＜0.05), decrease UAER (mg/24 h) (3.71±0.37, 3.47±0.36, 3.28±0.40, respectively, P＜0.05]for indicated time, and prevent the glomeruler pathological alteration induced by diabetes. Moreover, the mRNA expression of p47phox in the kidney of DN group was 154.72%, 148.60% and 91.95% more than that of NC group (all P＜0.05) for indicated time. The protein expression of p47phox was 118.00%, 140.10% and 177.82% more than that of NC group (all P＜0.05), and the protein expression of NT was 45.29%,59.13% and 89.28% more than that of NC group (all P＜0.05). In addition, urinary MDA levels in DN group were 2.05-, 2.26- and 2.43- folds of NC group, and urinary SOD activities were decreased by 64.78%, 71.29% and 79.32% of NC group. Compared with the DN group, the mRNA and protein expression of p47phox, and protein expression of NT in 4-PBA group were decreased markedly (all P＜0.05) at the end of 8 and 12 weeks. The urinary MDA level was decreased, and the urinary SOD activity was increased significantly in rats with diabetes after 4-PBA treatment for indicated time (all P＜0.05). Conclusion 4-PBA treatment can significantly inhibit the renal pathogenesis of rats with diabetes through inhibition of oxidative stress.