与缺氧诱导因子-1α调控相关的缝隙连接43蛋白磷酸化参与脑缺血再灌注损伤的机制

Phosphorylation of Cx43 regulated by HIF-1α in cerebral ischemia-repufusion injury

目的观察缺氧诱导因子-1α(HIF-1α)所致的缝隙连接43蛋白(connexin43,Cx43)磷酸化对脑缺血再灌注(cerebral ischemia and reperfusion,I/R)损伤的相关机制。方法选取成年SD雄性大鼠100只,随机分为4部分5组,每组20只:(1)假手术组,仅暴露双侧颈总动脉而不予夹闭;(2)治疗组,I/R后立即腹腔注入HIF-1α特异抑制剂2甲氧基本雌二醇(2ME2) 15 mg/kg,实验时间设定为I/R后4 h及8 h;(3)溶媒组,以溶媒二甲基亚枫(DMSO)替代2ME2;(4) I/R损伤组,I/R形成后不给予处理,(3)和(4)实验时间均设定为I/R后8 h。每组取10只动物行脑组织含水量测定;另10只动物在预定时间取海马区域皮质标本,采用免疫印迹法(Western blot,WB)检测磷酸化Cx43(p-Cx43)、Bcl-2、Bax、Caspases-3的表达水平,并用酶联免疫法(ELISA)检测海马皮质组织中炎性因子的含量,用干蒸法测定脑水肿的程度。结果采用2ME2干预的治疗组大鼠各时间段的脑含水量及海马皮质组织的p-Cx43、炎性因子、Cx40、凋亡促进因子Bax、Caspases-3表达水平均明显降低(均P <0. 05),凋亡抑制因子Bcl-2表达水平明显升高(P <0. 05)。结论通过特异性抑制HIF-1α的形成,可降低神经细胞Cx43磷酸化的形成,明显降低炎性因子的分泌;并可对脑I/R所致的损伤产生缓解作用;对脑缺血疾病在超急性期的治疗有着重大的意义。

Objective To investigate the effect of inhibition of HIF-1α to alleviate the phosphorylation of Cx43 in the acute phase of cerebral ischemia-repufusion(I/R) injury.Methods One hundred Sprague-Dawley rats at 4 months age,weight at 300-500 g were randomly divided into 4 sections and 5 groups: sham operation,treament group(I/R4,8 hour+2ME2),vehicle(I/R 8 hour+ DMSO) and injury group(I/R 8 hour).Cerebral ischemia-repufusion injury model were established with clip bilateral ICA,and HIF-1αinhibitor 2ME2 was injected into peritoneal cavity.Half of rats were measured for cerebral water content by Hatashita wet-weight method.Another half rats were sacrificed for investigating the level of total-Cx43,phosphoylated Cx43,Bcl-2,Bax and Caspases-3 by western blot,TNF-α,IL-1β and IL-6 by Elisa kit.Result Unlike static total-Cx43,brain water content,phosphoylated Cx43,Bax,Caspases-3,and IL-1β,IL-6,TNF-α in each treatment group and sham group were significantly lower than in other groups.Bcl-2 by WB showed the opposite result to the above.Conclusion Inhibition of HIF-1αcan down-regulate the level of phosphoylation of Cx43 and apoptosis factors.Further more,the level of IL-1,IL-6 and TNF-α were reduced.Simultaneously,these alterations can protect the form and function of brain after cerebral ischemia-repufusion injury.