PI3K-AMPA受体GluR2通路在丙泊酚后处理减轻大鼠脑缺血再灌注损伤中的作用

Role of PDK-AMPA receptor subunit glutamate receptor 2 pathway in propofol postconditioning-induced reduction of cerebral ischemia-reperfusion injury in rats

目的评价磷脂酰肌醇3-激酶（P13K）-α-氨基-3-羟基-5-甲基-4-异恶唑丙酸（AMPA）受体GluR2通路在丙泊酚后处理减轻大鼠脑缺血再灌注损伤中的作用。方法雄性SD大鼠180只，体重260～280g，采用随机数字表法，将其分为5组（n=36）：假手术组（s组）、缺血再灌注组（IR组）、丙泊酚后处理组（P组）、内酯后处理组（I组）和P13K抑制剂wortmannin＋丙泊酚后处理组（W＋P组）。采用阻塞大脑中动脉的方法制备大鼠脑缺血再灌注损伤模型，P组于再灌注即刻经股静脉输注丙泊酚20mg·kg-1·h-1 2h；I组以相同速率给予10％脂肪乳；IR组和s组给予生理盐水；W＋P组于再灌注前30rain腹腔注射wortmannin0．6mg／kg。于术后12和24h时行改良神经行为学评分（mNSS），测定脑梗死体积，计算脑梗死体积比；术后4、6、12和24h时取缺血侧海马，采用免疫共沉淀及Westemblot法检测P13K．AMPA受体GluR2复合物的表达；采用ELISA法检测P13K活性。结果与s组比较，其余4组术后12和24h时mNSS评分、脑梗死体积比升高，术后4、6、12和24h时海马P13K活性降低，P13K．AMPA受体GluR2复合物表达下调（P〈0．05）；与IR组比较，P组术后12和24h时mNSS评分、脑梗死体积比降低，术后4、6、12和24h时海马P13K活性升高，P13K．AMPA受体GluR2复合物表达上调（P〈0．05）；与w＋P组比较，IR组和I组上述指标差异无统计学意义（P〉0．05），P组术后12和24h时mNSS评分、脑梗死体积比降低，术后4、6、12和24h时海马P13K活性升高，P13K．AMPA受体GJuR2复合物表达上调（P〈0．05）。结论P13K—AMPA受体GluR2通路参与了丙泊酚后处理减轻大鼠脑缺血再灌注损伤的过程。

Objective To evaluate the role of phosphatidyl-inositol 3 kinase （PI3K）-α-amino-3-hydroxy- 5-methylisoxazole-4-propionic acid （AMPA） receptor subunit glutamate receptor 2 （GluR2） pathway in propofol postconditioning-induced reduction of cerebral ischemia-reperfusion （I/R） injury in rats. Methods One hundred and eighty male Sprague-Dawley rats, weighing 250-280 g, were randomly divided into 5 groups with 36 rats in each group： sham operation group （group S）, I/R group, propofol postconditioning group （group P）, intralipid posteonditioning group （group I）, and PI3K inhibitor wortmannin ＋ propofol postconditioning group （group W ＋ P）. The rats were anesthetized with intraperitoneal 10% chloral hydrate 350 mg/kg. Cerebral I/R was produced by 60 min middle cerebral artery occlusion followed by reperfusion. Propofol and 10% intralipid were infused via the femoral vein at a rate of 20 mg. kg- 1. h -1 for 2 h starting from the onset of reperfusion in groups P and I, respec- tively, while the equal volume of normal saline was given instead in groups I/R and S. Wortmannin 0.6 mg/kg wasinjected intraperitoneally at 30 min before reperfusion in group W ＋ P. The modified Neurological Severity Score （mNSS） was assessed and the cerebral infarct volume was detected at 12 and 24 h after operation. The hippocampi on the ischemie side were obtained at 4, 6, 12 and 24 h after operation for determination of expression of PI3K- GluR2-containing AMPA receptor （by co-immunopreeipitation and Western blot） and activity of PI3K （by ELISA）. Results Compared with group S, the mNSSs and infarct volume were significantly increased at 12 and 24 h after operation, and the activity of PI3K was decreased, and the expression of PI3K-GluR2-eontaining AMPA re- ceptor was down-regulated at 4, 6, 12 and 24 h after operation in the other four groups （ P 〈 0.05）. Compared with group I/R, the mNSSs and infarct volume were significantly decreased at 12 and 24 h after operation, and the activity of PI3K was increased, and the expression of PI3K-GluR2-containing AMPA receptor was up-regulated at 4, 6, 12 and 24 h after operation in group P （ P 〈 0.05） . Compared with group W ＋ P, no significant change was found in the parameters mentioned above in groups I/R and I （P 〉 0.05）, and the mNSSs and infarct volume were significantly decreased at 12 and 24 h after operation, and the activity of PI3K was increased, and the expression of PI3K-GluR2-containing AMPA receptor was up-regulated at 4, 6, 12 and 24 h after operation in group P （ P 〈 0.05 ）. Conclusion PI3K-AMPA receptor subunit GluR2 pathway is involved in propofol posteonditioning-indueed reduction of cerebral I/R injury in rats.