促红细胞生成素对大鼠脱离视网膜细胞信号转导途径的影响

Effect of erythropoietin on signal transduction pathway in rat model of retinal detachment

背景研究证明促红细胞生成素（EPO）通过抗凋亡作用对脱离视网膜光感受器细胞具有保护作用，然而其对细胞信号转导途径的影响尚不清楚。目的探讨EPO对大鼠脱离视网膜细胞信号转导途径的影响。方法24只SD大鼠采用随机数字表法分为正常对照组、视网膜脱离（RD）组、RD＋PBS组和RD＋EPO组。RD＋PBS组和RD＋EPO组在建立RD模型后立即分别向玻璃体体腔内注射5斗lPBS和400ngEPO。注射3d后剥取大鼠神经视网膜，采用Westernblot分别检测大鼠视网膜中Janus蛋白酪氨酸激酶2（JAK2）、p-JAK2、Akt、p-Akt、细胞外调节蛋白激酶1／2（ERK-1／2）、p-ERK-1／2、信号转导与转录活化因子5（STAT5）、p-STAT5、核因子-KB（NF-KB）和p-NF·KB。结果RD后3d，正常对照组、RD组、RD＋PBS组和RD＋EPO组JAK2在视网膜中的表达差异无统计学意义（F=0．298，P=0．826），但p-JAK2的磷酸化增强（F=24．435，P=0．000），RD组、RD＋PBS组及RD＋EPO组p-JAK2均高于正常对照组（P〈0．05），RD＋EPO组明显高于RD组和RD＋PBS组（P〈0．05）。Akt在4个组视网膜中的表达差异无统计学意义（F=0．681，P=0．588），但p-Akt表达的总体比较差异有统计学意义（F=48．163，P=0．000），RD＋EPO组明显高于RD组和RD＋PBS组（P〈0．05）。各组总ERK一1／2的表达差异均无统计学意义（F=0．978，P=0．450；F=1．115，P=0．399），但ERK-1／2的磷酸化程度增强（F=19．092、14．393，P=0．001），RD组、RD＋PBS组及RD＋EPO组p-ERK-1／2均高于正常对照组（P〈0．05），RD组和RD＋PBS组之间p-ERK-1／2的表达差异无统计学意义（P〉0．05），但RD＋EPO组P-ERK-1／2明显增强（P〈O．05）。STATS在各组大鼠视网膜中的表达差异无统计学意义（F=1．136，P=0．391），但RD后STAT5的磷酸化显著增强（F=14．189，P=0．001）；RD＋EPO组与RD组、RD＋PBS组之间差异无统计学意义（P〉0．05）。各组总NF-KB的表达无增强（F=0．696，P=0．580），但NF-KB的磷酸化显著增强（F=40．103，P=0．000）；RD＋EPO组与RD组、RD＋PBS组间差异无统计学意义（P〉0．05）。结论P13K／Akt途径和MAPK／ERK-1／2途径可能参与EPO对RD后光感受器细胞的保护作用。

Background Our previous study showed that erythropoietin （EPO） protects the photoreceptor from apoptosis in retinal detachment（RD） rat,but its signal transduction pathway remains unknown. Objective The present study was to investigate the effects of EPO on signal transduction pathway in RD. Methods Twenty four albino clean Sprague Dawley（SD） rats were randomly divided into 4 groups. 5 p,1 PBS was injected into vitreous cavity of rats in RD＋PBS group,and 400 ng EPO（5 p,1） was used at the same way in RD＋EPO group. Three days later,the rats were sacrificed and the retina was isolated in each group. The expression levels of Janus kinase 2 （JAK2） , p-JAK2, Akt, p-Akt, extraeellular regulated protein kinase-1/2 （ ERK-1/2 ） , p-ERK-1/2, signal transducer and activator of transcription 5 （ STAT5 ） , p-STAT5, nuclear factor-KB （ NF-KB ） and p-NF-KB were detected by Western blot assay. The administration of experimental animals followed the Standard of ARVO. Results Three days after RD,the expression levels of JAK2,Akt and ERK-1 ,ERK-2 in retinas among normal group, RD, RD＋PBS, RD＋EPO groups were statistically insignificant different （ F = 0. 298, P = 0. 826 ; F = 0. 681, P = 0. 588 ; F = 0. 978, P= 0. 450;F= 1. 115 ,P= 0. 399） , but the levels of p-JAK2, p-Akt, p-Erk-1 and p-Erk-2 among these 4 groups were significant difference （ F= 24. 435 , P = 0.000; F = 48. 163,P = 0.000; F = 19. 092, P = 0.001; F = 14. 393,P=0. 001）,and those in RD＋EPO group was significantly higher than that in RD and RD＋PBS groups（P〈0.05）. The expression levels of STAT5 and NF-~B among the 4 groups were no significantly differences （ F = 1. 136, P = 0.391 ; F = 0. 696, P = 0. 580） , but after the phosphorylation of STATS and NF-KB, the differences was significant （F= 14. 189,P = 0. 001 ;F=40. 103,P=0. 000）. Those in RD,RD＋PBS,RD＋EPO groups did not increase either （P〉0. 05 ）. Although the levels of p-STAT5 and p-NF-KB in RD, RD＋PBS, RD＋EPO groups were significantly higher than those in normal control group （P〈0.05） , the level of p-STAT5 in RD ＋EPO group was not significantly higher than that in RD and RD ＋ PBS groups （ P 〉 0. 05 ）. Conclusions PI3K/Akt and MAPK/ERK-I/2 signal transduction pathways might participate in the protecting process of EPO to photoreceptor in RD rats.