目的:探讨弱氧化修饰低密度脂蛋白(mmLDL)是否通过激活p38 MAPK炎症通路上调小鼠肠系膜动脉内皮素(ET)A型(ETA)和B型(ETB)受体.方法:将昆明小鼠分为正常对照组(尾静脉注射生理盐水)、mmLDL组(尾静脉注射mmLDL)、LDL组(尾静脉注射LDL)、mmLDL+SB 203580组(尾静脉注射mmLDL及腹腔注射p38 MAPK抑制剂SB 203580)和mmLDL+DMSO组(尾静脉注射mmLDL及腹腔注射DMSO).微血管张力描记仪记录ETB受体激动剂角蝰毒素6c和ET-1引起肠系膜动脉收缩的量效曲线;RT-qPCR检测ETB受体、ETA受体和白细胞介素(IL-6)的mRNA表达;ELISA检测血清IL-6的水平;Western blot检测ETB受体、ETA受体、IL-6、p38 MAPK、p-p38 MAPK、NF-κB和p-NF-κB的蛋白水平.结果:mmLDL引起ETB受体和ETA受体介导的血管收缩反应显著增强(P＜0. 01),ETB受体、ETA受体和IL-6的mRNA和蛋白表达显著增加(P＜0. 01),p-p38 MAPK和p-NF-κB蛋白水平显著升高(P＜0. 01),血清中IL-6水平显著升高(P＜0. 01);腹腔注射SB 203580抑制了mmLDL的作用.mmLDL引起的IL-6血清浓度升高分别与ETB受体和ETA受体介导的最大收缩率呈正相关.结论:mmLDL通过激活p38 MAPK通路及下游NF-κB转录因子,提高炎症因子IL-6血清水平,增加小鼠肠系膜动脉IL-6、ETA受体和ETB受体表达,增强ETA受体和ETB受体介导的血管收缩功能.

目的 本研究从整体动物水平探讨弱氧化低密度脂蛋白(mmLDL)对小鼠肠系膜动脉内皮素B(ETB)受体的作用.方法 将40只KM小鼠随机分成5组:mmLDL组(尾静脉注射mmLDL),mmLDL+ U0126组(尾静脉注射mmLDL同时腹腔注射U0126),mmLDL+ DMSO组(尾静脉注射mmLDL同时腹腔注射DMSO),LDL组(尾静脉注射LDL),生理盐水(NS)组(尾静脉注射NS).采用微血管肌张力描记仪观察ETB受体激动剂蛇毒类似物(S6c)引起的血管收缩量效曲线变化.RT-PCR和Western blot检测p-ERK1/2、ETB受体表达.结果 研究发现mmLDL引起S6c介导的收缩效应明显增强,Emax值由NS组的(0.15±0.08)％上升到mmLDL组的(71.08±7.56)％(P＜0.001),引起ETB受体mRNA水平由NS组(0.16±0.03)上升到mmLDL组的(0.99±0.01)(P＜0.001),蛋白水平由NS组的(0.31±0.02)上升到mmLDL组的(0.83±0.03)(P＜0.001).此作用被腹腔注射ERK1/2抑制剂U0126抑制,同时,U0126还抑制mmLDL诱导p-ERK1/2 mRNA水平增高的作用.结论 mmLDL激活ERK1/2通路引起血管平滑肌ETB受体表达增加,介导血管收缩功能增强.

Objective To investigate the effect of ERK1/2 pathway in the up-regulation of mesenteric artery α1 receptor by minimally modified low density lipoprotein (mmLDL) in mice. Methods Seventy-two mice were randomly divided into 3 groups:the normal control group(injection of normal saline via caudal vein in mice),mmLDL group(injection of mmLDL via caudal vein in mice),U0126 intervention group(injection of mmLDL via caudal vein and intraperitoneal injection of ERK1/2 pathway specific inhibitor U0126 in mice)(n=24 each). Microvascular myograph was employed to examine the changes of noradrenaline(NA)induced contraction curve of mesenteric artery in mice. The expressions of α1 receptor, TNF-α,IL-1βand p ERK1/2 were determined by RT-PCR and Western Blotting,respectively. The Elisa kits were used to measure the serum concentrations of TNF-α and IL-1β. Results Compared with the normal control group, the Emax and pEC50 values in the mmLDL group significantly increased;the vascular contraction mediated by the α1 receptor was enhanced;the mRNA and protein expression of the α1 receptor, the phosphorylation level of pERK1/2 protein,and the mRNA and serum concentrations of TNF-α and IL-1β increased significantly (all P<0.05). U0126 could dose-dependently inhibit the increase of α1-receptor mediated contraction induced by mmLDL. The indexes in the U0126 group were lower than those in the mmLDL group,with statistically significant differences (all P<0.05). The serum TNF-α and IL-1β concentrations were positively correlated with the α1 receptor-mediated maximum contraction percentage Emax (r=0.94,r=0.96,P<0.05). Conclusion The activation of ERK1/2 signal transduction pathway by mmLDL can increase the levels of TNF-α and IL-1β and the expression of α1 receptor in vascular smooth muscle,and enhance α1 receptor-mediated vasoconstriction.