COX-2通过PI3K/Akt通路调节氧诱导视网膜病变模型中视网膜新生血管的形成

目的 探讨环氧化酶-2(COX-2)调节氧诱导视网膜病变(OIR)模型中视网膜新生血管形成的信号转导机制.方法 将乳鼠随机分为正常对照组、OIR模型组以及COX-2选择性抑制剂NS-398组(每组18只乳鼠).正常对照组小鼠生长于正常空气氧浓度(21%),OIR模型组和NS-398组小鼠于出生后第7天放置于高浓度氧环境(75%)生长,第12天调整氧浓度为正常.NS-398组小鼠于出生后第12～17天每日腹腔注射10 mg/kg NS-398.于第17天,获取3组视网膜标本,采用常规病理学检查在光镜下观察视网膜新生血管的变化;应用免疫组织化学法、Real-time PCR以及West-ern blot技术检测视网膜组织中COX-2、VEGF和PI3K/Akt的表达.结果 正常对照组病理切片未见视网膜新生血管形成,OIR模型组和NS-398组均出现与内界膜相连的新生血管,以OIR模型组为甚.COX-2、VEGF和PI3K/Akt在正常对照组均存在一定表达,在OIR模型组呈强表达,在NS-398组的表达明显低于OIR组,但仍高于正常对照组.3组间COX-2、VEGF的吸光度值、mRNA和蛋白相对量及PI3K/Akt的蛋白相对量两两比较,差异均有显著性意义(均P<0.05).结论 COX-2表达受到抑制后通过下调VEGF的表达减少OIR模型中的视网膜新生血管形成,在此过程中涉及到PI3K/Akt信号通路的作用.

Involvement of PI3K/Akt Signaling Pathway in COX-2-Mediated Retinal Neovascularization in Oxygen-induced Retinopathy Mouse Models

Objective To investigate the signal transduction mechanism of cyclooxygenase-2(COX-2)-mediated VEGF expression and retinal neovascularization in mouse models of oxygen-induced retinopathy(OIR). Methods The mother mice were randomly divided into three groups, including normal control group, OIR model group and NS-398 group with each group having 18 new-born mice. The new-born mice in the normal group had been growing up in the atmosphere with normal oxygen con-centration(21 % )since their birth. The new-born mice in the OIR model group and NS-398 group were housed in the high-oxygen environment(75 % )from 7th day after birth to the 11th day. The oxygen concentration was adjusted to the normal on the 12th day. The new-born mice in the NS-398 group were introperitoneally injected with NS-398 at the concentration of 10 tng/ kg. On the 17th day, the samples of retinal tissues were obtained from the new-born mice of the three groups. The retinal neovessels were observed under a light microscope by using routine pathological examination. The expression of COX-2, VEGF and PI3K/Akt was detected by immunohistochemistry, real-time PCR and Western blot, respectively. Results No retinal neovessels were found on the pathological sections of the normal control group. The retinal neovessels connected with the inner limiting membrane were observed in both the OIR model group and the NS-398 group,and the former group had more neovessels. The normal control group had the positive expression of COX-2, VEGF and PI3K/Akt which were found to be the strongest in the OIR model group. Compared with the OIR model group, the NS-398 group had decreased expression of COX-2, VEGF and PI3K/Akt despite the intensity of the expression higher than that in the normal control group. There were significant differences in the absorbance values and the relative values of mRNA and protein of COX-2, VEGF and the relative values of PI3K/Akt protein among the three groups(all P<0. 05). Conclusion COX-2 inhibition can down-regulate the VEGF expression and thus ameliorate neovascularization in OIR mouse models, and the PI3K/Akt signaling pathway was involved in the process.