晚期糖基化终产物通过氧化应激加速动脉粥样硬化斑块形成

Advanced glycation end products accelerate atherosclerosis via enhancement of oxidative stress

目的 探讨晚期糖基化终产物 (AGE)对动脉粥样斑块形成的影响及机制。方法 5 0只新西兰白兔随机分为 5组 ,A组 :喂饲高胆固醇饲料加注射AGE修饰的兔血清白蛋白 (AGE RSA ,5mg/kg ,1次 /隔天 ) ;B组 :喂饲高胆固醇饲料加注射未加修饰的兔血清白蛋白 (RSA ,5mg/kg ,1次 /隔天 ) ;C组 :单纯喂饲高胆固醇饲料 ;D组 :喂饲普通饲料 ;E组 :喂饲普通饲料加注射AGE RSA(5mg/kg ,1次 /隔天 )。 10周后取主动脉全段 ,苏丹Ⅳ染色 ,PHOTOSHOP系统测定粥样斑块面积占内膜面积的百分比 ,免疫组化法观察主动脉AGE、氧化修饰低密度脂蛋白 (ox LDL)、丙二醛修饰低密度脂蛋白 (MDA LDL)的沉积及AGE受体 (RAGE)的表达。同时检测循环AGE、血脂、血清硒谷胱甘肽过氧化物酶 (SeGSHPx)活性、丙二醛 (MDA)及氧化修饰低密度脂蛋白 (ox LDL)水平。结果 (1)喂饲高胆固醇饲料各组动物主动脉均见粥样硬化斑块形成 ,但A组动脉粥样斑块面积 /内膜面积百分比 (5 0 %± 8% )明显高于B组 (2 1%± 7% )和C组 (2 9%± 6 % ) (P均 <0 0 5 ) ,A组粥样斑块病变部位MDA LDL、ox LDL、AGE的沉积面积较B、C组明显增大 ,内皮细胞RAGE表达上调 ;而D组和E组主动脉未见粥样斑块病变。 (2 )喂饲高胆固醇饲料各组动物的血清甘油三酯及胆固醇水平明显?

Objective To investigate the effect of advanced glycation end products (AGE) on atheromatous plaque formation and its possible mechanisms. Methods Fifty rabbits were randomly divided into five groups of 10 rabbits: group A, fed with hypercholesterolemic diet and injected intravenously with AGE modified rabbit serum albumin (AGE-RSA); group B, fed with hypercholesterolemic diet and injected with unmodified RSA; group C, fed with hypercholesterolemic diet; group D, fed with normal diet alone: and group E, fed with normal diet and injected with AGE-RSA. Ten weeks after the rabbits were killed. Their aortas were taken out and stained with Sudan red IV. The extent of atheromatous plaques in the aortas en face was evaluated by computer-assisted morphometry and by histologic examination. Photoshop system was used to measure the percentage of atheromatous plaques in the area of tunica intima. The depositions of AGE, malondialdehyde modified low-density lipoprotein (MDA-LDL), oxidized low-density lipoprotein (ox-LDL) and expression of receptor of AGE (RAGE) in aortic tissue were detected by using immunohistological staining.The circulating AGE, blood lipids, serum selenium glutathione peroxydase (SeGSHPx) activity, malonyldialdehyde (MDA), and oxidized LDL (ox-LDL)were detected before the experiment and after the rabbits were killed. Results (1) The relative plaque area was significantly increased in group A (50%±8%)compared with in group B (21%±7%)and group C(29%±6%). No plaque could be found in animals fed with normal diet (group D)even in those receiving repeated injections of AGE-RSA(group E). Depositions of ox-LDL, MDA -LDL and AGE in atherosclerotic lesions increased and RAGE expression were upregulated in the rabbits fed with hypercholesterolemic diet and injected with AGE-RSA (group A) compared with the other four groups. (2) All hypercholesterolemic rabbits showed comparable serum levels of triglyceride and cholesterol. However, the serum levels of AGE, ox-LDL and MDA were significantly higher and the serum level of SeGSHPx was relatively lower in group A compared with those in the other four groups. (3) The serum level of AGE was directly correlated with the serum ox-LDL (r=0.459,P<0.01) or serum MDA concentration (r=0.423,P<0.05), and inversely correlated with the serum level of SeGSHPx (r=-0.448, P<0.01). A close correlation was found between the serum level of AGE and endothelium RAGE expression (r=0.384,P<0.05) and deposition area of AGE (r=0.468,P<0.05) in aorta. Conclusion AGE accelerates the atheromatous plaque formation through induction of oxidative stress and upregulation of RAGE.