摘要
目的：研究和探讨敏感期内、末不同时限单眼斜视和剥夺动物模型视觉系统凋亡调节抑制基因Ｂｃｌ－２ 塑性变化的规律。方法：应用免疫细胞化学ＳＡＢＣ技术染色和计算机图像分析了Ｂｃｌ－ ２ 蛋白在Ｎ、ＭＳ１、ＭＤ１ 、ＭＳ２ 和ＭＤ２ 猫同侧视皮质１７ 区Ⅳ层及外侧膝状体相应层的表达。结果：在正常发育幼猫的视皮质和外侧膝状体主要是在神经元核浆，呈深棕黑色免疫阳性反应，胞浆淡染。在ＭＳ１ 和ＭＤ１ 眼输入的同侧视皮质１７区Ⅳ层及外侧膝状体相应层（Ａ１）表现为Ｂｃｌ－２ 蛋白表达的免疫阳性神经元数目减少，核浆染色淡，表明Ｂｃｌ－２ ｍＲＮＡ表达水平降低。在同侧视皮质１７ 区Ⅳ层表达浓度和数密度：Ｎ组与ＭＳ１ 和ＭＤ１ 组比较差异具有非常显著性（Ｐ＜０．００１）；Ｎ组与ＭＳ２ 和ＭＤ２ 组比较差异无显著性（ Ｐ＞ ０．０５）。结论：ＭＳ１ 和ＭＤ１ 组幼猫实验眼同侧视皮质１７ 区Ⅳ层及同侧外侧膝状体Ａｌ 层神经元在视觉发育敏感期内，由于长期的斜视及形觉剥夺效应以致功能低下，对Ｂｃｌ－２ 调节的敏感性降低，以及对ＮＴｓ 的营养保护及上调Ｂｃｌ－２ ｍＲＮＡ表达水平应答能力降低，在双眼竞争的神经元发育及突触连接中处于劣势，使对侧眼形成优势循环。
Objective:To investigate plasticity changes in the regulation of the expression of apoptosis inhibitory gene bcl-2 in the visual systems of normal (N),monocularly strabismic(MS) and monocularly deprived(MD) kittens during the critical period of development.The product (bcl-2 protein) of bcl-2 gene expression is an important bioactivator.It mediates neurtrophine and protective action by the NGF family.The studies provide a basis for understanding the mechanisms and for finding effective methods to prevent and treat amblyopia due to strabismus and deprivation in children.Methods:Surgery was performed on kittens during the critical period (age 2～4 wks) to induce esotropic MS by sectioning the lateral rectus muscle of one eye and MD by lid suture.Before surgery,the animals were randomly divided into 3 groups:N,MS and MD.After the animals were reared for sixteen weeks under the same environmental conditions,they were examined with 6-Channel Pattern Visual Evoked Potentials (6CPVEP).Then,visual cortex area 17 was investigated with polyclonal antibodies for bcl-2,which was used to label the neurons of visual cortex area 17 using the immunocytochemical Streptavidin Biotin Peroxidase Complex(SABC) method.Data were analyzed from photographs from optical microscopy and Computer Image Analysis.Results:Gene expression level of bcl-2mRNA (numeric density and concentration of bcl-2 immunopositive neurons) in layer Ⅲ of the ipsilateral visual cortex area 17 and the laminas receiving ipsilateral geniculate input from the strabismic and deprived eyes are significantly lower than the input from the untreated eyes.Conclusion:Results indicate that the functional status of neurons in layer Ⅲ of visual cortex area 17 and the laminas receiving lateral geniculate input from the treated eyes during the critical period of visual development are greatly weakened in the long term in response to convergence strabismus and form deprivation.That is,the treated eyes are hyposensitive to bcl-2 regulation.Their ability to respond to neurotrophine and the protective action of NTs (neurotrophic factors) is also reduced,with causes the synaptic connections of neurons in layer Ⅲ of visual cortex area 17 and layer Al of ipsilateral geniculate input from the treated eyes to be underdeveloped because the susceptibility of neurons to bcl-2 determines whether neurons in the visual pathways are affected by the NGF family to which they have been exposed.On the other hand,the fellow eye is dominant during binocular viewing so that critical synaptic links develop normally.
出处
《眼视光学杂志》
1999年第4期201-205,共5页
Chinese Journal of Optometry & Ophthalmology
基金
国家自然科学基金
