摘要目的 探讨血红素氧合酶1(HO-1)/一氧化碳(CO)系统对动脉粥样硬化斑块形成的影响及其机制.方法 新西兰大白兔32只,分为4组;对照组、胆固醇组、血红素组及卟啉锌组,每组8只.其中对照组喂饲普通饲料,胆固醇组喂饲含1.5%胆固醇饲料,血红素组及卟啉锌组在予以高胆固醇饮食的同时,分别经腹腔注射氯化血红素(HO激动剂,15 mg·kg-1·d-1)或锌原卟啉9(HO抑制剂,45 μmol·kg-1·d-1),共12周,12周末处死动物,取出胸、腹主动脉行病理形态学观察和HO-1、内皮素1(ET-1)免疫组织化学及Western blot分析.结果 主动脉大体油红O染色示对照组无斑块形成,胆固醇组斑块所占面积比为(54.0±4.2)%,与胆固醇组比较,卟啉锌组斑块所占面积比[(61.1±3.5)%]显著增大(P<0.01),而血红素组斑块所占面积比[(17.9±3.0)%]显著减小(P<0.01).透射电镜示胆固醇组内皮消失,代之以粥样物质,弹力层及平滑肌层结构紊乱,平滑肌细胞胞质内充满脂质空泡,胶原纤维增生;卟啉锌组上述改变加重,血红素组浅层平滑肌结构略微不整齐,余无明显异常.HE染色示胆固醇组内膜增厚[(74.6±39.0)μm],内皮细胞脱落,泡沫细胞增生明显,中膜萎缩、变薄、平滑肌结构和排列紊乱;卟啉锌组上述改变加重,内膜增厚更显著[(127.2±49.8)μm,P<0.01];血红素组内膜厚度[(48.5±42.3)μm]较胆固醇组显著减少(P<0.01),内皮细胞无脱落,少许泡沫细胞增生,平滑肌结构和排列正常.与对照组比较,胆固醇组主动脉cNOS活性、NO生成量明显降低,HO-1表达、CO生成量明显增高(均P<0.01);与胆固醇组比较,氯化血红素干预显著增高HO-1表达、CO生成量,而显著降低ET-1表达(均P<0.01),锌原卟啉9显著降低HO-1表达、CO生成量,而显著增高ET-1表达(均P<0.01).结论 HO-1/CO系统具有预防动脉粥样硬化斑块形成的作用,其机制可能与该系统代偿和调节NOS/NO系统以及下调ET-1表达从而改善血管内皮功能、抑制平滑肌细胞增殖有关.

abstractsObjective To investigate the effect of heme oxygenase/carbon monoxide (HO-1/CO) system on lipid deposition at aortic intima and the mechanism involved in hyperlipidemic rabbits.MethodsTotally 32 rabbits,were divided into four groups. One group as control. Three groups for the following treatments: 1.5% cholesterol ration (Ch group, n=8); 1.5% cholesterol ration plus HO-1 inducer hemin (Hm group, n=8); and instead of hemin, the HO-1 inhibitor, zinc protoporphyrin Ⅸ (Zn group, n=8) was given by injection into the abdominal cavity. Experiments were lasted for 12 weeks. Rabbit aortas were then isolated as the samples for histopathologic and ultrastructural examination. The protein expressions of HO-1 and endothelin-1(ET-1) were investigated by immunohistochemical staining and Western blot analysis. Results Comparing with the Ch group, rabbits of the Hm group showed a remarkably less extent of lipid deposition at the aortic intima[(17.9±3.0)% vs (54.0±4.2)%], and rabbits of the Zn group had a marked extent of lesion development [(61.1±3.5)%]. Lipid deposition, endothelial damage and neo-intimal formation were less severe in rabbits of the Hm group than those in the Zn or Ch group, respectively. Comparing with the control group, rabbits of the Ch group showed a significant decrease of aortic NO production and cNOS activity. However, there were an enhancement of CO production and HO-1 activity (P<0.01). Compared with Ch group, rabbits of the Hm group showed a remarkable elevation of aortic HO activity and CO production, whereas rabbits of the Zn group showed a marked decrease of both parameters. Compared with the Ch group, rabbits of the Hm group demonstrated a marked reduction of aorta ET-1 expression, whereas Zn group had a significantly higher ET-1 expression. Conclusions Modulation of HO-1/CO system may improve vascular endothelial function and inhibit smooth muscle cell proliferation in hypercholesterolemic rabbits, likely through a compensatory mechanism and a reduction of ET-1 expression, eventually leading to an inhibition of atherosclerotic plaque development.