左旋多巴对形觉剥夺性弱视鼠VEP及视网膜内多巴胺含量的影响

目的观察不同剂量左旋多巴对形觉剥夺性弱视大鼠视觉诱发电位（VEP）及视网膜内多巴胺质量分数的影响，探讨其治疗弱视的可能机制。方法30只14日龄SD大鼠建立单眼形觉剥夺性弱视鼠模型，按随机数字表法随机分为弱视对照组、小剂量给药组、大剂量给药组，每组10只，分别给予8％淀粉溶液及20mg／kg、80mg／kg左旋多巴灌胃，于给药前（45日龄）和给药后（75日龄）测量闪光视觉诱发电位（F-VEP），并于75日龄时检测各组大鼠视网膜内多巴胺的质量分数。结果给药前剥夺眼P1波潜伏期较未剥夺眼明显延长，差异有统计学意义（P〈0．05）；给药后左旋多巴组剥夺眼P1波潜伏期较给药前以及对照组剥夺眼均明显缩短（P〈0．05），且大剂量给药组较小剂量给药组P1波潜伏期更短（P〈0．05），未剥夺眼P1波潜伏期各组比较差异无统计学意义（P〉0．05）；剥夺眼视网膜内多巴胺的质量分数较未剥夺眼低（P〈0．05），给药后剥夺眼视网膜内多巴胺的质量分数较未剥夺眼及对照组剥夺眼明显增高，且随药物剂量的增加多巴胺质量分数提高，二者比较差异有统计学意义（P〈0．05）；未剥夺眼给药前后视网膜多巴胺质量分数差异无统计学意义（P〉0．05）。结论左旋多巴能显著提高形觉剥夺性弱视鼠弱视模型眼的视网膜内多巴胺质量分数，改善弱视眼视觉传导功能，并由此影响视觉系统发育可塑性敏感期。

Influences of levodopa on retinal dopamine level and VEP of rat

Objective Many studies have demonstrated the effectiveness of levodopa in improving the visual function and sensitivity of retina of maeular area for childhood with amblyopia, but the treating mechanism is undefined. Present study was to study the effects of levodopa on visual evoked potential（VEP） and retinal dopamine level in form-deprived amblyopic rat and explore the possible mechanism. Methods The animal models of form-deprived amblyopia were established by suturing the eyelids for 4 weeks in 30 14-day-old SD rats. Rats were randomly divided into 3 groups,including amblyopia control group（ Ⅰ ） , 20 mg/kg levodopa administration group （ Ⅱ ） and 80 mg/kg levodopa group （Ⅲ）. Flash-VEP （F-VEP） was recorded before administration（45 day age） and after administration （at 75 day age） of levodopa. Then the retinal dopamine levels were analyzed. Results The P1 wave latency period was obviously shorter in 20 mg/kg levodopa administration group （ Ⅱ ） and 80 mg/kg levodopa group（ Ⅲ） compared with amblyopic control group（ P 〈 0. 05）, and that in 80 mg/kg levodopa group was significantly shorter than 20 mg/kg levodopa group（ P 〈 0. 05 ）. No significant alteration was found in amplitudes of N1P1 and P1N2 wave among the three groups （P 〉 0. 05）. The content of retinal dopamine in form-deprived eyes was reduced in comparison with undeprived eyes after administration of levodopa（P 〈 0.05 ） , showing a significant increase in 20 mg/kg levodopa administration group and 80 mg/kg levodopa group after form-deprived but was unchanged in undeprived eyes. Conclusion Levodopa can influence visual function and plasticity of visual system in visual sensitive period by regulating dopamine content in retina.