The Influence Of Curcumin On The Oxidative Stress Of Acute Hyperlipidemia Model Rats And The Expression Of Nrf2 In Abdominal Aorta

Objective: As life style and dietary structure change, the incidence of hyperlipidemia increased year by year. Hyperlipidemia(HLP) can increase the activity of free radical release system within the arterial wall, damage the antioxidant function, cause vascular endothelial cells injury,lead to abnormal morphology and function abnormity, which promote the formation of atherosclerosis. Superoxide dismutase(SOD) and malondialdehyde(MDA) are the tyical indexes to test the level of tissue oxidative stress. Nuclear factor E-2-related 2(Nrf2) is the critical transcriptive factor to regulate the antioxidant defense systerm. Early prevention and treatment of hyperlipidemia, can delay the onset or even slow the progress of atherosclerotic diseases, and improve the life quality. The present study was performed to observe the changes of the morphology and function of endothelium and the changes of oxidative stress, investigate mechanisms of the effects of curcumin protect endothelial function and the regulation of oxidative stress.Method:Fourty healthy male Sprague Dawley(SD) rats were randomly divided into normal control group(NC group, n=8), hyperlipidemia model group(model group, n=8), low dose curcumin group(125mg/kg.d curcumin, LC group, n=8), high dose curcumin group(250 mg/kg.d curcumin, HC group, n=8) and 2.1mg/kg.d atorvastatin intervention group(tatin group, n=8).The rats in NC group and model group were taken intragastric administration with corn oil(2.5ml/kg),once a day for 10 days, at the same time,rats in LC group, HC group, and tatin group were taken intragastric administration with 125mg/kg.d curcumin, 250mg/kg.d curcumin,or 2.1 mg/kg*d atorvastatin(2.5ml/kg) respectively, once a day for 10 days.On the 10 th day, the rats in NC group were intraperitoneally injected with natual saline(25ml/kg), all rats in other groups were intraperitoneally injected with 75% yolk(25ml/kg). After 24 h of natual saline or 75% yolk intraperitoneally injection, the serum levels of total cholesterol(TC),triglyceride(TG), high-density lipoproteincholesterol(HDL-C), low-density lipoprotein- cholesterol(LDL-C), alanine transaminase(ALT), aspertate aminotransferase(AST), and glucose(GLU) were measured.THE activity of SOD, MDA and nitric oxideand(NO) were detect using the methods of xanthine oxidease, thiobarbituric acid and nitrate reductase respectively to evaluate the oxidative stress levels in abdominal aorta and endothelial function. Morphology of abdominal aorta were observed by light microscope. The expression and localization of Nrf2 were detected by Western blotting and immuno- histochemical method in rats’ abdominal aorta.All the data were dealed with statistical software packages SPSS13.0, thedata were expressed as the mean±standard deviation( x ±s), the data wereanalyzed using Oneway ANOVA of completely rabdom design, multiplecomparisons were analyzed using LSD test. Statistical significance was set atP<0.05.Results: 1 Generally observationAll rats were in good shape and gain steady growth.Their body weight were no significant difference among all the groups(P>0.05). 2 24 h after yolk injectin, TC、TG、LDL-C increase, HDL-C decreasd. Acutehyperlipidemia model is establish- mented successfully. 3 blood lipid level 3.1 compare with NC groupCompared with the NC group, the serum TC, TG, LDL-C in the rats of model group was increased(P<0.05); the serum HDL-C in the rats of model group was decreased(P<0.05). 3.2 compare with model groupCompared with the model group,serum TC in HC group and tatin group was decreased(P<0.05); serum TC in LC group has a downward trend(P>0.05). Compared with the model group,serum TG in HC group and tatin group was decreased(P<0.05); serum TG in LC group has a downward trend(P>0.05). Compared with the model group, serum LDL-C in LC group, HC group and tatin group has a downward trend(P>0.05). Compared with the model group, serum HDL-C in HC group has no significant change(P>0.05). The serum HDL-C in LC group and tatin group was lower than model group(P<0.05). 3.3 comparison among LC group, HC group, tatin groupThe TC level of HC group and tatin group was lower than LC group(P<0.05), the TC level of HC and tatin group has no significant difference(P>0.05).The HDL-C level of HC group was higher than LC and tatin group(P<0.05), the serum HDL-C level of LC and tatin group has no significant difference(P>0.05). 4 liver function, serum glucoseThe liver function and serum glucose in all groups have no significant change(P>0.05). 5 results of Abdominal aorta HE stainingAbdominal aorta intima of rats in NC group was integrated and smooth. Smooth muscle cell and elastic fibers were arranged regularly.There were no smooth muscle cell proliferation and no abnormalities inadventitia. Abdominal aorta intima of LC group rats was integrated,but was ridgy partly. Smooth muscle cell and elastic fibers were arranged unregularly. Abdominal aorta intima of HC group rats was integrated,and was not ridgy. Smooth muscle cell and elastic fibers were arranged unregularly slightly. Abdominal aorta intima of tatin group rats was integrated,and ridgy partly. Smooth muscle cell and elastic fibers were arranged unregularly. 6 IHC resultsNrf2 positive cells of abdominal aorta in model group were more than NC group(+44%,P<0.05). Nrf2 positive cells increased significantly in the LC(+69%,P<0.05), HC(+147%,P<0.05) and tatin(+51%,P<0.05) groups respectively,compared with the model group. Nrf2 positive cells of abdominal aorta in LC group were more than tatin group(+12%,P<0.05). Nrf2 positive cells of abdominal aorta in HC group were more than LC group(+46%,P<0.05). 7 SOD activity and MDA contentSerum SOD activity: The SOD activity of NC group was higher than model group(P<0.05); The SOD activity of LC group, HC group and tatin group was enchanced compared with model group(P<0.05). The SOD activity of HC group and tatin group was enchanced compared with LC group(P<0.05).MDA content of abdominal aorta: The MDA content of NC group was lower than model group(P<0.05). The MDA content of LC group, HC group and tatin group was decreased compared with model group(P<0.05). The MDA content of HC group was decreased compared with LC group(P<0.05). 8 NO contentSerum NO content: The serum NO content in NC group was higher than model group(P<0.05). The serum NO content of LC group, HC group and tatin group was increased compared with model group(P<0.05). The serum NO content of HC group was increased compared with LC and tatin group(P<0.05). 9 ox LDL contentThe serum ox LDL content of NC group was lower than model group(P<0.05). The serum ox LDL content of LC group, HC group and tatin group was decreased compared with model group(P<0.05). The serum ox LDL content of LC and model group has no significant difference(P>0.05). The serum ox LDL content of HC and tatin group was lower than LC group(P<0.05).Conclusion:1 Intraperitoneal injection of 75% yolk(25ml/kg) made an acute hyper- lipidemia rats model successfully. The acute hyperlipidemia model rats appeared abdominal aortic endothelial injury, including morphological changes(rough endothelium) and func- tional impairment(decreased NO content); The serum lipid peroxidation products of acute hyperlipidemia rats were increased, and their antioxidation ability was weakened.2 The preventive application of curcumin and atorvastatin can reduce blood lipids of acute hyperlipidemia model rats(HC group has better result compared with LC group), and may increase the expression of Nrf2 of abdominal aorta, enhance the antioxidant ability, and alleviate abdominal aortic structural abnormalities.