Effects of thymoquinone on oxidative stress and cytokine expression in brain of type 2 diabetic rats / 复旦学报（医学版）

ABSTRACT

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 groupsnormal 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.