金属硫蛋白对糖尿病大鼠肾脏氧化应激的影响

Influence of metallothionein on kidney oxidation of diabetic rats

目的:观察抗氧化剂金属硫蛋白(metallothionein,MT)对糖尿病大鼠肾脏氧化应激指标及NADPH氧化酶的影响,探讨MT对糖尿病大鼠肾脏保护作用的可能机制。方法:雄性SD大鼠随机分为正常对照组(NC,n=8)、糖尿病模型组(DM, n=7)以及糖尿病MT治疗组(DM+MT,n=8),糖尿病大鼠腹腔注射链脲佐菌素(60 mg／kg)制备糖尿病大鼠模型,DM+MT组大鼠给予10 g／kg体质量MT灌胃。4周后检测各组大鼠24 h尿蛋白(24 h UP)和肾质量／体质量(KW／BW)值,评价肾脏功能,比色法检测肾脏丙二醛(MDA)含量,real-time PCR法检测NADPH氧化酶亚基p47phox、p22phox,蛋白激酶C(PKC)-β和血管紧张素原(Ang)mRNA表达。结果:与NC组相比,DM组24 h UP、KW／BW以及肾皮质MDA水平明显升高(P< 0．05);肾皮质p47phox、p22phox、PKC-β和Ang mRNA表达显著升高(P<0．05或P<0．01)。与DM组相比,DM+MT组24 h UP、KW／BW以及肾皮质MDA水平降低(P<0．05),p47phox、PKC-β和Ang mRNA的表达水平降低(P<0．05),而p22phox无明显改变。结论:MT可能通过降低糖尿病大鼠肾脏氧化应激水平,抑制肾皮质PKC-β、Ang以及NADPH氧化酶亚基的表达,从而发挥肾脏保护作用。

Objective： To study the effect of metallothionein （MT）, a potent antioxidant, on the oxidative stress and NADPH oxidase in kidneys of diabetic rats. Methods： Male SD rats were assigned to the following 3 groups： normal control （NC,n=8）,diabetes mellitus control（DM,n= 7）, diabetes mellitus models treated with MT by lavage （10 g · kg^-1 · d^-1, DM＋MT, n= 8）. Diabetes in DM group and DM＋MT group was induced by intraperitoneal injection of streptozotacin（60 mg/ kg）. At 4 weeks after initiating treatment, 24 h urinary protein （24 h UP） and kidney weight/body weight （KW/BW） were determined in the 3 groups to assess the renal function of rats; malondialdehyde （MDA） was examined with visible spectrophotometry; NADPH oxidase subunits p47phox and p22phox, protein kinase C （PKC）-β, and Angiotensinogen（Ang） were examined by real-time PCR. Results： MDA,24 h UP and KW/BW in DM group were significantly higher than those in NC group（P〈0. 05）; expression of PKC-β, Ang, and NADPH oxidase subunits p22phox and p47phox mRNA were increased markedly in DM group compared with NC group（P〈0.05,P〈0.01）. 24 h UP,KW/BW and MDA were significantly lower in DM＋MT group compared with DM group（P〈0. 05）; expression of p47phox, PKC-β and Ang mRNA were significantly decreased in DM＋ MT group compared with DM group（P〈0.05）, but the expression of p22phox mRNA in DM and DM＋ MT groups had no significant changes. Conclusion： MT may lower the oxidase stress on kidney tissues, inhibit the expression of PKC-β and Ang in the kidney, and decrease NADPH oxidase activity, excerting protective effect on the kidney of rats with diabetes mellitus.