内源性降钙素基因相关肽在应激性视网膜细胞凋亡中的作用

Role of endogenous calcitonin gene related peptide in stress-induced retinal cell apoptosis

背景急性应激反应可以诱发视网膜细胞凋亡，同时引起视网膜内源性降钙素基因相关肽（CGRP）表达量的增加，CGRP在应激反应诱发的视网膜凋亡过程中的作用尚不清楚。目的探讨内源性感觉神经递质CGRP对急性心肌缺血诱发应激反应引起的大鼠视网膜细胞凋亡的影响。方法取健康成年雄性sD大鼠12只24只眼，采用结扎大鼠冠状动脉左前降支3h法制备大鼠急性心肌缺血应激反应模型。按随机数字表法将实验动物分为CGRP8-37干预组和对照组，每组各6只12只眼。CGRP8-37干预组大鼠于造模前经尾静脉注射10μmol／LCGRP受体拮抗剂CGRP8-37,对照组注射等容量的生理盐水。采用TUNEL法和caspase-3活性检测法分别检测各组大鼠视网膜细胞凋亡情况。结果光学显微镜下结扎大鼠冠状动脉3h后，CGRP8-37干预组视网膜内外核层细胞排列较紊乱、神经节细胞层空泡变性较对照组明显，CGRP8-37干预组视网膜细胞的总凋亡指数为42．8％±2．8％，明显高于对照组的37．5％±2．9％，差异有统计学意义（t=-3．244，P〈0．01）。CGRP8-37干预组大鼠视网膜中caspase-3活性的吸光度值为11．3±3．1，明显高于对照组的4．9±1．2，差异有统计学意义（t=-4．603，P〈0．01）。结论CGRP8-37干预后视网膜应激性损伤加重，提示内源性CGRP对应激反应引起的视网膜细胞凋亡有保护作用。

Background Acute stress can provoke the apoptosis of retina ceils and induce increasing expression of calcitonin gene related peptide （CGRP） in retina. However,the role of CGRP in pathology of the stressinduced apoptosis of the retina cells is still elusive. Objective The aim of this study was to investigate the effects of endogenous CGRP on retinal cell apoptosis induced by stress of acute myocardial ischemia after coronary artery occlusion in rats. Methods The acute myocardial ischemia model was established by ligating the left anterior descending branch of coronary artery in 12 male Sprague-Dawley rats. The rats were randomized into CGRPs 37 injection group and normal saline injection group,6 rats 12 eyes for every group. CGRP8-37 （10^-7 tool/L） , a specific antagonist of CGRP receptor,was intravenously injected in CGRP8-37 group by caudal vine at 15 minutes prior to the coronary artery ocelusion,and the equivalent amount of normal saline was used at the same fashion in normal saline group. The retinal samples of the rats were collected at 3 hours after coronary artery occlusion for TUNEL staining and caspase-3 activity detection respectively. Results The cellular displacement was observed in inner and outer nuclear layer,and vacuolar degeneration of retinal ganglion cells was found in the coronary artery occlusion animals. The total apoptosis index of retinal cells in CGRP8-37 group was significantly higher than that in normal saline group （ 42.8 % ± 2.8 % vs 37.5 % ±2.9 % , t = -3. 244, P〈0.01 ）. The retinal capase-3 activity was significantly enhanced in the CGRP8-37 group compared with saline group（ 11. 3±3. 1 fold vs 4.9±1.2 fold,t= -4. 603 ,P〈0. 01 ） at 3 hours of coronary artery occlusion. Conclusion The results suggest that the endogenous CGRP may play an anti-apoptotic role in the stress-induced retinal cell injury.