PKC-β抑制剂LY333531对糖尿病肾脏NADPH氧化酶与SOD蛋白表达的影响

Effects of protein kinase C-β inhibitor LY333531 on the protein expression of nicotinamide dinucleotide phosphate oxidase and superoxide dismutase in diabetic kidney

目的研究蛋白激酶C（protein kinase,PKC）-β抑制剂LY333531对糖尿病肾脏尼克酰胺腺嘌呤二核苷酸磷酸（nicotinamide dinucleotide phosphate,NADPH）氧化酶与超氧化物歧化酶（superoxide dismutase,SOD）的影响。方法 24只SD雄性大鼠（240~260 g）,采用抽签法随机分为正常对照组（normal control,NC）、糖尿病组（diabetes mellitus,DM）及LY333531（LY）治疗组。LY组灌胃给予PKC-β抑制剂LY333531〔1 mg/（kg.d）〕治疗4周后测量血糖、肾质量/体质量、24 h尿蛋白、内生肌酐清除率（creatinine clearance rate,Ccr）、游离15-F2t-Isoprostane、总抗氧化浓度及SOD活性。Western blotting分析NADPH氧化酶亚基P22phox与P67phox,SOD亚型Cu/Zn-SOD与Mn-SOD蛋白改变。结果与NC组比较,DM组血糖、肾质量/体质量、24 h尿蛋白、Ccr、血浆与肾脏中15-F2t-Isoprostane、血浆总抗氧化浓度及P22phox与P67phox表达明显增加,而肾脏总抗氧化物浓度、血浆与肾脏SOD活性、Cu/Zn-SOD及Mn-SOD蛋白表达明显减少（P〈0.05）。LY333531除对血糖与Mn-SOD的表达无显著影响外,均能显著逆转上述变化。结论 LY333531通过抑制糖尿病肾脏NADPH氧化酶的活化与表达,及促进Cu/Zn-SOD的表达而恢复SOD活性,以减少早期糖尿病肾脏的氧化损伤,从而发挥其保护肾脏作用。

Objective To study the effects of protein kinase C（PKC）-β inhibitor LY333531 on nicotinamide dinucleotide phosphate（NADPH） oxidase and superoxide dismutase（SOD） in diabetic kidney.Methods Twenty-four male SD rats were randomly assigned to control group,diabetic group and diabetic with LY333531（1 mg/（kg·d）） treatment group.After the treatment with LY333531 for four weeks,the levels of blood glucose,kidney weight/body weight,24-hour urinary albumin,creatinine clearance rate（Ccr）,free 15-F2t-Isoprostane,total antioxidant concentration and SOD activity were measured.The subunits P22phox and P67phox of NADPH oxidase,Cu/Zn-SOD and Mn-SOD protein expression were analyzed by Western blotting.Results The levels of blood glucose,kidney weight/body weight,24-hour urinary albumin,creatinine clearance rate,15-F2t-Isoprostane in plasma and kidney,total antioxidant concentrations in plasma,the protein expression of P22phox and P67phox were all increased,but the levels of total antioxidant concentrations in kidney,SOD activity in plasma and kidney,Cu/Zn-SOD and Mn-SOD protein expression were significantly decreased in diabetic group as compared with control group（P0.05）.The treatment with LY333531 significantly prevented all these changes except for blood glucose and Mn-SOD protein expression.Conclusion The PKC-β inhibitor LY333531 may protect early diabetic kidney from oxidative injury by inhibiting NADPH oxidase activation and expression,and restoring SOD activity by improving the expression of Cu/Zn-SOD subunit.