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背景氧化应激与原发性高血压的发生密切相关。近年来研究表明氧化应激信号分子(ROS)可导致高血压动物血管功能紊乱,最近证明RhoA及其下游效应分子Rho激酶参与高血压发病,但参与机制还有许多不明之处。目的观察抗氧化剂N乙酰半胱氨酸(NAC)对Dahl盐敏感性(DSS)高血压大鼠主动脉Rho/Rho激酶(ROK)表达的影响,探讨盐敏感性高血压发病机制中ROS与Rho信号通路的关系。方法DSS高血压大鼠随机分为4组:正常饮食组;高盐饮食组(高盐组);高盐饮食辅以NAC治疗组(高盐+NAC组);正常饮食辅以NAC治疗组(正常饮食+NAC组),每组6只。每周测定鼠尾动脉血压,共4周;收集24 h尿,处死后取主动脉组织标本。DCF荧光法检测尿中氧化应激生物标志物过氧化氢(H2O2)水平;光泽精化学发光法检测主动脉超氧阴离子生成量;RT-PCR及Western Blot检测主动脉RhoA、ROK mRNA及蛋白表达。结果高盐饮食组与正常饮食组相比,血压明显升高[(219.7±5.3)比(152.8±3.8)mmHg,P<0.01],24 h尿中H2O2排出量显著增加[(663.8±67.7)比(18.9±4.5)nmol/d,P<0.01];高盐饮食大鼠主动脉超氧阴离子生成量较正常大鼠增多[(12.8±0.5)比(6.9±0.3)counts/(min.mg),P<0.01],主动脉ROK mRNA和蛋白表达亦明显增加(P<0.01)。NAC显著降低了高盐饮食大鼠血压[(161.8±2.9)mmHg,P<0.01]、尿H2O2排出量[(243.0±49.3)nmol/d,P<0.01]和主动脉超氧阴离子的生成[(7.7±0.6)counts/(min.mg),P<0.01],抑制了ROKmRNA和蛋白的过表达。但是,作为ROK上游的小G蛋白,RhoA表达在4组大鼠间并无差异(P>0.05)。结论DSS高血压大鼠主动脉ROK表达增加,表明Rho信号参与盐敏感性高血压的发生发展;RhoA可能不是此类高血压动物ROK激活的决定因素。NAC阻断后ROK表达显著下调,其机制可能与ROS的诱导作用降低有关,ROS可能作为上游信号直接参与DSS高血压大鼠ROK的激活。
Background Oxidative stress is closely related to the occurrence of essential hypertension. In recent years, studies have shown that oxidative stress signaling molecule (ROS) can lead to vascular dysfunction in hypertensive animals. RhoA and its downstream effector Rho kinase have recently been shown to be involved in the pathogenesis of hypertension. However, there are still many unknown mechanisms involved. Objective To investigate the effects of antioxidant N-acetylcysteine (NAC) on the expression of Rho / Rho kinase (ROK) in the aorta of Dahl salt-sensitive rats and to explore the role of ROS and Rho in the pathogenesis of salt-sensitive hypertension The relationship between signal pathways. Methods The DSS hypertensive rats were randomly divided into 4 groups: normal diet group, high salt diet group (high salt group), high salt diet supplemented with NAC group (high salt + NAC group), normal diet supplemented with NAC group Normal diet + NAC group), 6 in each group. Rat tail arterial blood pressure was measured weekly for 4 weeks; 24 h urine was collected and the aorta tissue samples were taken after sacrifice. DCF was used to detect the level of hydrogen peroxide (H2O2), a biomarker of urinary oxidative stress. The production of superoxide anion in aorta was detected by lucigenin chemiluminescence assay. The mRNA and protein expressions of RhoA and ROK in aorta were detected by RT-PCR and Western Blot . Results Compared with the normal diet group, the blood pressure of the high-salt diet group was significantly higher than that of the normal diet group [(219.7 ± 5.3) vs (152.8 ± 3.8) mmHg, P <0.01] (18.9 ± 4.5) nmol / d, P <0.01]. Compared with normal rats, the production of superoxide anion in the aorta of high-salt diet rats increased more than that of normal rats [(12.8 ± 0.5) vs ), P <0.01]. The aortic ROK mRNA and protein expression also increased significantly (P <0.01). NAC significantly reduced the blood pressure (161.8 ± 2.9) mmHg, P <0.01), and the urinary H2O2 excretion [(243.0 ± 49.3) nmol / d, P <0.01] and the generation of superoxide anion (7.7 ± 0.6) counts / (min.mg), P <0.01], inhibited the overexpression of ROK mRNA and protein. However, as a small G protein upstream of ROK, there was no difference in RhoA expression between the four groups (P> 0.05). Conclusion The expression of ROK in the aorta of DSS hypertensive rats is increased, indicating that Rho signaling is involved in the development of salt-sensitive hypertension. RhoA may not be the determining factor of ROK activation in such hypertensive rats. After NAC blockade, the expression of ROK is significantly downregulated, which may be related to the decrease of ROS induction. ROS may be directly involved in the activation of ROK in DSS hypertensive rats.