单眼斜视和剥夺猫视皮质17区N-甲基-D-天冬氨酸受体1亚单位的表达

Experimental studies on expression of N-methy-D-aspartate recepor-1-subunit in area 17 of the visual cortex in MS and MD kittens during the critical period

目的 :探讨敏感期内单眼斜视 (monocularstrabis mus,MS)和单眼剥夺 (monoculardeprivation ,MD)幼猫视觉系统中有可塑性变化的N 甲基 D 天门冬氨酸受体 1亚单位 (N methyl D aspartatereceptor 1 subunit,NMDAR 1)基因的表达规律 ,为临床防治斜视 (MS)和剥夺性弱视 (MD)提供参考依据。方法 :以 6导程图形视觉诱发电位仪 (6 channel patternvisualevokedpotential,6CPVEP)检测MS和MD弱视的形成 ,应用生物素过氧化物酶标记链酶卵白素复合物 (strept avidinbiotin peroxidaecomplex,SABC)技术处理NMDAR 1单克隆抗体标记的正常 (normal)组、MS组及MD组幼猫的同侧视皮质 17区组织连续切片 ,照相观察并行计算机图像分析和t test处理。结果 :视皮质 17区可见NMDAR 1免疫阳性神经元呈棕褐色 ,神经元胞浆及轴突、树突着色 ,但轴突更明显 ,核色淡或空染 ,具有明显的突触形态学特征。它主要分布在Ⅱ /Ⅲ、Ⅳ、Ⅴ和Ⅵ层。比较各组猫视皮质 17区Ⅳ层NMDAR 1免疫阳性细胞染色浓度和数密度 ,MS、MD与N组比较 ,差异均有显著性 (P <0 .0 5 ,P <0 .0 1) ,MS组和MD组幼猫视皮质 17区的NMDAR 1与正常组相比 ,其活性 (染色浓度 )减弱 ,数量明显减少。结论 :①敏感期内 ,单眼斜视和剥夺猫视皮质 17区神经元NMDAR 1表达表现?

Objective:To investigate plasticity changes in the regulation of the expression of N methyl D aspartate receptor 1 subunit(NMDAR1) in the visual system of N,MS and MD kittens during the critical period. To understand the mechanisms and find effective methods for preventing and treating strabismic and deprivation amblyopia during the development period. These studies offer a basis of reference in preventing and treating strabismic amblyopia and deprivation in children.Methods:Surgery was performed on kittens during the critical period(age 2 4 wks) and used as models for monocular strabismus(MS) and monocular deprivation(MD). The lateral rectus muscle of one eye was sectioned for esotropia and lid sutured for MD. Before surgery,the animals were randomly divided into 3 groups:normal(N),MS and MD. The animals were raised for sixteen weeks under the same visual environment conditions. N,MS and MD kittens were examined during the critical period with 6 channel pattern visual evoked potentials(6CPVEP). Monoclone antibodies were then used to study area 17 of the visual cortex of N,MS and MD animal models for NMDAR1subunit and the neurons in this area were identified by the immunocytochemical streptavidin biotin peroxidae complex(SABC) method. Results were obtained from slides examined under the microscope and by computer image analysis.Results:NMDAR1subunit protein and immnuopositive neurons in area 17 of the visual cortex presented as a drab brown color in the cellular cytoplasm and axodendritic synapses,but the nuclei of neurons were lightly stained or empty. The immunopositive neurons had synaptic morphology characteristics and were distributed over layers 2/3,4,5 and 6 of area 17 of the visual cortex. There was strong production of NMDAR1mRNA expressed in the pyramidal cells and astrocytes. A t test showed that there were significant differences between N/MS and N/MD(P<0.05,P<0.01) in integral optic density(IOD) and numerable density(P<0.05,P<0.01).Conclusion:NMDAR1 in layer 4 of area 17 of the visual cortex in MS1 and MD1 kittens was weaker in activity and lower in numbers than that of N. Immunopositive neurons of NMDAR1 are based on a typical synaptic morphology. Changes in the quantity and activity of NMDAR1 protein in the neurons in area 17 of the visual cortex in MS and MD kittens may follow the principle of elimination due to interocular competition. NMDAR1 is the most important transmission receptor in the visual pathway system.