百里醌对2型糖尿病大鼠脑内氧化应激及细胞因子表达的影响

Effects of thymoquinone on oxidative stress and cytokine expression in brain of type 2 diabetic rats

目的探讨植物单体百里醌(thymoquinone,TQ)对2型糖尿病大鼠脑组织内氧化应激相关蛋白及细胞因子表达的影响。方法 48只成年6周龄Wistar大鼠(140~160 g)随机分为正常对照组、模型组和百里醌组(n=16)。正常对照组给予清洁级普通饲料;模型组及百里醌组高糖高脂饲料喂养,6周后给予腹腔注射链脲佐菌素(streptozocin,STZ)35 mg/kg制备2型糖尿病模型,造模成功后继续高糖高脂饲料喂养6周。百里醌组造模成功后隔天给予腹腔注射TQ(5 mg/kg),模型组注射等剂量无水乙醇。治疗6周后同时处死3组大鼠,获取海马组织标本提取蛋白质。使用Western blot方法测定海马组织中的核因子E2相关因子2(nuclear factor erythroid 2-related factor 2,Nrf2)、血红素加氧酶-1(heme oxygenase-1,HO-1)及环加氧酶-2(cyclo-oxygenase2,COX-2)的蛋白质水平,使用超氧化物歧化酶(superoxide dismutase,SOD)试剂盒检测SOD的活性。使用血糖仪测量各组大鼠造模成功后及处死前的血糖。所有的计量资料采用x-±s表示,组间计量资料比较用单因素方差分析(One Way ANOVA)。结果与正常对照组相比,模型组海马组织中Nrf2和HO-1的蛋白质水平明显降低(P<0.05);与模型组相比,百里醌组海马组织中HO-1和Nrf2的蛋白质水平升高(P<0.05)。同时,与正常对照组相比,模型组海马组织中SOD的活性明显降低(P<0.05);与模型组相比,百里醌组SOD的活性明显升高(P<0.05)。此外,与正常对照组相比,模型组海马组织COX-2的蛋白质水平明显升高(P<0.05);与模型组相比,百里醌组海马组织的COX-2的蛋白质水平下降(P<0.05)。结论百里醌可以抑制2型糖尿病大鼠脑组织内的炎性反应并改善氧化应激。

Objective To investigate the effects of thymoquinone （TQ） on the levels of proteins involved in oxidative stress and cytokine in the brain of rats with type 2 diabetes mellitus. Methods Wistar rats （n=48） were randomly divided into 3 groups：normal control group, model group and TQ treatment group （n=16）. The normal control group was fed with clean grade ordinary feed. The model group and TQ treatment group rats were fed with high-glucose and high-fat diet. After 6 weeks’ feeding, model group and TQ treatment group rats were administered streptozocin （STZ） （35 mg/kg） to establish type 2 diabetic model by intraperitoneal injection. Then, the model group and TQ treatment group rats were fed with high-glucose and high-fat diet for another 6 weeks. After that, TQ treatment group rats were administered TQ （5 mg/kg） by intraperitoneal injection every other day. The model group rats were injected with an equal dose of ethanol. Six weeks later, all the rats were sacrificed to obtain the hippocampal tissue for the protein extract. The protein levels of nuclear factor erythroid 2-related factor 2 （Nrf2）, heme oxygenase-1 （HO-1） and cyclooxygenase 2 （COX-2） in the hippocampal tissue were measured by Western blot. Superoxide dismutase （SOD） activity was determined by SOD kit. Blood-glucose meter was used to assess the blood glucose before the rats were sacrificed and after the model was successfully established. All the measurement data was described by the x^-±s, measurement data were compared among groups using One Way ANOVA. Results The results by Western blots showed that the levels of the Nrf2 and HO-1 protein were significantly decreased in the model group compared with the normal control group, the levels of the Nrf2 and HO-1 proteins were increased in the TQ treatment group in comparison with the model group （P〈 0.05）.Meanwhile,compared with the normal control group, the SOD activity of the hippocampus in model group was significantly lower （P〈0.05）; by contrast with the model group, the SOD activity in the TQ treatment group was considerably increased （P〈0.05）. By contrast, the COX-2 level in the model group was substantially higher than that in the normal control （P〈0.05）, and the COX-2 level in the TQ treatment group was lower than that in the model group （P〈0.05）. Conclusions TQ might inhibit inflammation and improve oxidative stress of the brain tissue in the rats with type 2 diabetes mellitus.