内皮素-1介导循环间歇性低氧影响大鼠颈动脉体可塑性的机制

Mechanism of endothelin-1 mediated the cyclic intermittent hypoxia on carotid body plasticity in rats

目的探讨内皮素-1(ET-1)介导循环间歇性低氧(CIH)影响颈动脉体可塑性的潜在分子机制。方法 (1)动物实验:将32只雄性SD大鼠随机分为2组,常氧对照组(Con)和循环间歇性低氧模型组(CIH),每组16只。模型制作21 d后,将每组(Con和CIH)16只大鼠再分为2组,分别予尾静脉注射ET-1(1×10^(-6 )mol/kg体重)或按照上述剂量计算的等体积生理盐水。30 min后,收集颈动脉体,采用Western blotting检测相关信号通路分子蛋白水平的变化。(2)器官培养:离体培养颈动脉体组织,ET-1(1×10^(-4) mol/L)处理不同时间(0 min、10 min、60 min),通过Western blotting检测p38丝裂原活化蛋白激酶(p38 MAPK)磷酸化水平。结果 (1)CIH上调颈动脉体内皮素受体A(ET-A)和ET-B蛋白的表达;(2)与其他各组相比,ET-1可显著上调CIH大鼠颈动脉体磷酸化蛋白激酶A(p-PKA)、p-p38 MAPK、磷酸化的钙调蛋白激酶Ⅱ(p-CaMKⅡ)、磷酸化的环磷腺苷效应元件结合蛋白(p-CREB)磷酸化水平和RhoA蛋白表达水平;(3)ET-1上调离体器官培养的颈动脉体p-p38 MAPK磷酸化水平,10 min较60 min明显。结论 ET-1可能通过PKA/p38 MAPK/CaMKⅡ/CREB和RhoA信号通路调控CIH诱导的颈动脉体可塑性。

Objective To investigate the potential molecular mechanism of endothelin-1(ET-1) involved in cyclic intermittent hypoxia(CIH) induced carotid body chemoreceptor plasticity. Methods(1) Animal experiment: 32 male Sprague-Dawley(SD) rats were randomly divided into two groups: control group(Con) and CIH group(CIH), 16 rats per group. After 21 days of CIH exposure, each group(Con and CIH) was subdivided into 2 groups: tail vein injection of ET-1(1×10^-6 mol/kg body weight) or same volume of saline according to the above dose. After 30 minutes of injection, carotid bodies were collected and Western blotting was used to detect the change of tested proteins.(2) Carotid body organ culture: rat carotid bodies were isolated and cultured in the incubator, and treated with ET-1(1×10^-4 mol/L) for different times(0 minute, 10 minutes, 60 minutes). The effect of ET-1 on the phosphorylation of p38 mitogen-activated protein kinase(p38 MAPK) was detected by Western blotting. Results(1) CIH increased the protein level of endothelin receptor A(ET-A)and ET-B in the rat carotid body.(2) Compared with the ET-1 injected Con group, phosphorylated protein kinase A(p-PKA), p-p38 MAPK, phosphorylated Ca^2+/calmodulin-dependent protein kinase Ⅱ(p-CaMKⅡ) and phosphorylated cAMP response element-binding protein(p-CREB) and RhoA protein level were significantly up-regulated in ET-1 injected CIH rats.(3) Application of ET-1 to organ cultured carotid bodies resulted in the elevation of p-p38 MAPK in a time-dependent manner. Conclusion ET-1 may regulate CIH-induced carotid body chemoreflex plasticity through PKA/p38 MAPK/CaMKⅡ/CREB and RhoA signaling.