左旋多巴对单眼形觉剥夺弱视大鼠视觉诱发电位及视皮质神经细胞的影响  

Effects of levodopa on visual evoked potential and visual cortex neuron in monocular deprivation rat

作　　者：吴小影[1] 罗瑜琳[1] 刘德林[1] 刘双珍[1] 

机构地区：[1]中南大学湘雅医院眼科,长沙410003

出　　处：《中华实验眼科杂志》2011年第3期220-225,共6页Chinese Journal Of Experimental Ophthalmology

基　　金：湖南省科技计划基金项目（1013-60）

摘　　要：背景对视皮质可塑性的研究目前已有40余年，但至今尚未发现能有效治疗弱视的药物。目的观察不同剂量左旋多巴对单眼形觉剥夺弱视大鼠视觉诱发电位（VEP）及视皮质神经细胞形态学的影响，探讨左旋多巴治疗弱视的可能机制。方法2周龄SD大鼠30只眼险缝合4周建立右眼单眼形觉剥夺性弱视模型后按随机数字表法分成3组，分别以生理盐水、20mg／kg左旋多巴溶液、80mg／kg左旋多巴溶液灌胃，每日1次。造模4周及给药4周后分别行闪光VEP（F—VEP）检测，给药4周后处死大鼠并取大脑视皮质行苏木精一伊红染色，TUNEL法观察各组大鼠视皮质神经细胞的凋亡情况。结果3个组大鼠形觉剥夺模型眼较未剥夺眼P．波隐含时明显延长（P〈0．05），20mg／kg和80mg／kg左旋多巴组剥夺眼给药后较给药前P．波隐含时明显缩短（P〈0．05）；3个组间剥夺眼给药前后P1波隐含时及差值比较差异均有统计学意义（P〈0．05）。苏木精-伊红染色显示未剥夺眼对侧视皮质V1区神经细胞数量及形态均正常，剥夺眼对侧视皮质神经细胞数量在生理盐水组明显减少，并出现类凋亡表现。20mg／kg左旋多巴组大鼠视皮质神经细胞数量及形态有轻度改变。TUNEL法示未剥夺眼对侧视皮质呈绿色荧光的阳性神经细胞数为（2．20±1．23）个，生理盐水组、20mg／kg左旋多巴组、80mg／kg左旋多巴组剥夺眼相应区域阳性神经细胞数量分别为（53．7±9．36）、（27．20±5．96）、（10．70±3．23）个，提示80mg／kg左旋多巴组剥夺眼阳性神经细胞数量减少（P〉0．05）。给药后各组大鼠剥夺眼对侧视皮质V1区阳性神经细胞数量与F—VEP的P1波隐含时差值呈负相关（r=－0．815，P=0．000）。结论左旋多巴可改善形觉剥夺弱视眼的视皮质神经细胞形态和视觉传导功能，其机制可能是通过抑制视皮质神经细胞的类凋�Background Nearly over 40 years have elapsed since the original findings of visual cortical plasticity,but none of drug has been found for curing amblyopia effectively. Objective The goal of this study was to investigate the effects of different dose of levodopa on flash visual evoked potential （F-VEP） and morphology of visual cortex cells in monocular deprivation rat and explore the possible mechanism of curing amblyopia. Methods Monocular deprivation model were established by suturing eyelids of 30 2-week-old Sprague Dawley （SD） rats for 4 weeks. The 30 SD rats were then divided into 3 groups randomly and 10 rats for each group. Normal saline,20 mg/kg levodopa,80 mg/kg levodopa were intragastrically administered once per day after modeling respectively for 4 weeks. F-VEP was recorded after establishment of model and administration of drug respectively. The rats were sacrificed and the visual cortex was obtained for histological examination, and TUNEL technique was used to assess the structural change of visual cortex. Results The latency of P1 wave was significantly longer in the deprived eye than the normal eyes （P〈0.05）. After administration of levodopa, the latent periods of P1 wave in the deprived eye were obviously shortened in comparison with before administration of levodopa in 20 mg/kg and 80 mg/kg levodopa group （ P〈0.05 ）. The difference values of latent period of P1 wave between before and after administration of drug showed statistically significant change in three groups （P 〈 0.05 ）. No evidently alterations were found in the amplitude differences of N1 P1 and P1 N2 waves among three groups （P〉0.05）. The number and structure of neurons in contralateral visual cortex of non-deprived eye were normal. However, the numbers of neurons in deprived eye were significantly less and presented the signs of para-apoptosis in normal saline group. In 20 mg/kg levodopa groups, the alterations of number and morphology in neurons of rat visual cortex were slight. TUNEL assay revealed

关 键 词：左旋多巴 弱视 视觉诱发电位 视皮质 类凋亡 

分 类 号：R777.44[医药卫生—眼科] R988.1[医药卫生—临床医学]