左旋多巴及胞二磷胆碱对单眼形觉剥夺大鼠视皮质α-氨基-3-羟基-5-甲基-4-异噁唑丙酸-GluR2表达的影响、

Influences of levodopa and cytidine diphosphate choline on the expression of alpha-amino-3-hydroxy-5- methyl-4-isoxazolepropionic acid GiuR2 in visual cortex of monocular deprivation rats

背景研究表明α-氨基-3-羟基-5-甲基±异嗯唑丙酸（AMPA）．GluR2与弱视的发生发展有关，左旋多巴及胞二磷胆碱对改善弱视患者的视功能有一定的疗效，但其作用机制尚不完全明了。目的检测敏感期单眼形觉剥夺（MD）大鼠分别应用左旋多巴及胞二磷胆碱后视皮质中AMPA—GluR2的表达情况，探讨左旋多巴及胞二磷胆碱改善视功能的作用机制。方法2周龄健康SD大鼠60只行单侧眼睑缝合31d制作MD动物模型，造模成功后与年龄匹配的正常大鼠15只在自然光条件下一起饲养。将大鼠用随机数字表法随机分为正常对照组、MD组、左旋多巴组、胞二磷胆碱组和生理盐水组，每组15只大鼠。造模后第32天左旋多巴组大鼠给予溶于1ml生理盐水中的左旋多巴40mg／kg灌胃，每日1次；胞二磷胆碱组大鼠给予胞二磷胆碱80mg／kg肌内注射，每日1次；生理盐水组给予1ml生理盐水灌胃，均连续给药28d。分别采用免疫组织化学法、Westernblot法、实时荧光定量PCR法检测各组大鼠视皮质中AMPA—GluR2的表达情况。结果MD组大鼠视皮质中AMPA—GluR2蛋白及mRNA表达均低于正常对照组，差异有统计学意义（0．32±O．02VS．0．64±0．05，t=13．287，P〈0．05；0．30±0．01VS．0．8±t-O．03，t=38．184，P〈0．05）；左旋多巴组视皮质中AMPA—GluR2蛋白及mRNA表达均高于生理盐水组（0．59±0．04VS．0．33±0．03，t=11．628，P〈0．05；0．71±0．06VS．0．33±0．02，t=13．435，P〈0．05）；胞二磷胆碱组大鼠视皮质中AMPA—GluR2蛋白及mRNA表达均高于生理盐水组，差异有统计学意义（0．52±0．04VS．0．33±0．03，t=8．497，P〈0．05；0．48±0．04VS．0．33±0．02，t=7．500，P〈0．05）。结论AMPA-GluR2与视觉发育的可塑性有关，左旋多巴、胞二磷胆碱能够在一定程度上逆转MD引起的AMPA．GluR2表达下降。这一机制可能与其能够改善视功能的作用有关，其作用部位可能在视皮质。

Background Research demonstrated that alpha-amino-3-hydroxy-5-methyl- sisoxazolepropionic acid GluR2 （AMPA-GluR2） is associated with amblyopia. It has been shown that levodopa and cytidine diphosphate choline can improve visual function of amblyopic children, but the mechanism is unclear. Objective This study was to explore the possible effects of levodopa and cytidine diphosphate choline on amblyopia. Methods Monocular deprivation （MD） animal models were created in 60 2-week-old SD rats by monolateral eyelid suturing and observed for 31 days and reared in natural light together with 15 other matched normal healthy SD rats. The models were randomly divided into the MD group, levodopa group, cytidine diphosphate choline group and normal saline control group,with 15 rats for each group. 40 mg/kg of levodopa, 80 mg/kg of cytidine diphosphate choline, 1 ml normal saline were given to the rats, respectively, for 28 consecutive days. Expressions of the AMPA-GluR2 protein and AMPA-GluR2 mRNA in the rat visual cortex were detected by immunohistoehemistry,Western blot and real-time fluorescence quantitative PCR. Use of the animals followed the Regulations for the Administration of Affairs Concerning Experimental Animals by State Science and Technology Commission. Results The expression values of the AMPA-GluR2 protein （AMPA-GluR2/β-actin） and AMPA-GluR2 mRNA （2-A） were significantly lower in the MD group than those of the normal control group （ protein ： 0.32 ＋ 0. 02 vs. 0.64 ＋ 0.05, t = 13. 287, P〈0.05 ; mRNA ：0.30＋0.01 vs. 0.84＋0. 03 ,t= 38. 184 ,P〈0.05 ）. Those in the levodopa group were significantly increased in comparison with the normal saline solution group （ protein ： 0. 59 ＋0.04 vs. 0.33＋0.03, t = 11. 628, P〈0.05 ; mRNA ： 0.71＋0.06 vs. 0.33 ＋0.02, t = 13. 435, P〈 0. 05 ）. The expression values of the AMPA-GluR2 protein and AMPA- GluR2 mRNA were significantly increased in the cytidine diphosphate choline group compared with the normal saline solution group （protein：0.52＋0.04 vs. 0.33＋0.03,t = 8. 497,P〈0.05;mRNA：0.48＋0.04 vs. 0.33＋0.02, t = 7. 500,P〈0. 05 ）. Conclusions AMPA-GluR2 is associated with the plasticity of visual development. Levodopa and cytidine diphosphate choline may improve visual function by down-regulating the expression of AMPA-GluR2 in the visual cortex.