| 摘 要
近视眼是目前全球发生率最高的屈光不正，其发病年龄不断提前，发生率不断增加，且发生后呈进展趋势，已经成为严重的公共卫生问题。世界卫生组织(WHO)己将近视眼的防治列为全球防盲计划之一。
自从1977年Wiesel和Raviola首次建立形觉剥夺动物模型以来，人们对近视的发生机制有了一定的认识，即形觉剥夺主要通过局部视网膜机制来调控邻近巩膜的生长，视网膜含有多种神经递质，形觉剥夺可以导致神经递质水平发生改变，参与调控FDM的形成。形觉剥夺性实验动物模型的建立是近视眼的研究中一次重大突破，通过这种研究方法，我们已对实验性近视眼有了初步的认识，为近视眼的理论探讨提供了极有价值的信息和思路。病理性近视眼是常见的致盲眼病，在其发展过程中视网膜感光细胞不断减少，凋亡可能是其感光细胞死亡的机制之一，细胞凋亡是指为维持内环境稳定，由基因控制的细胞自主的有序的死亡。细胞凋亡与细胞坏死不同，细胞凋亡不是一件被动的过程，而是主动过程，它涉及一系列基因的激活、表达以及调控等的作用，它并不是病理条件下，自体损伤的一种现象，而是为更好地适应生存环境而主动争取的一种死亡过程。
研究认为细胞凋亡是细胞在各种死亡信号刺激后发生的一系列瀑布式激活的主动性细胞死亡过程，
神经生长因子是一种蛋白质，广泛存在于动物体内，不仅能够维持感觉神经元存活和神经纤维生长，还有在个体发育期间增加分枝及保护分化后神经元的特殊功能,能够增加感觉神经肽基因的表达，鉴于此，我们设计了利用形觉剥夺性近视动物模型，运用玻璃体腔注射神经生长因子的方法干预近视形成程，从而了解神经生长因子对形觉剥夺性近视的作用，为近视的防治提供新的思路。
目的
通过运用半透明眼罩遮盖豚鼠眼睛以形成形觉剥夺性近视，并在形成形觉剥夺性近视形成过程中形觉剥夺眼玻璃体内注射神经生长因子进行干预，观察其对形觉剥夺性近视的影响，从而探讨神经生长因子对形觉剥夺性近视的作用，为近视的防治提供新的试验依据。
方法
50只一周龄豚鼠随机分为三组，第一组10只，第二组和第三组各20只，每只豚鼠均用半透明眼罩遮盖右眼，各组豚鼠室内分笼饲养，自由饮食，室内日光灯照明，每日照明与黑暗时间均为12小时，第一组实验动物不进行其它干预，饲养两周后麻醉下微量注射器分别向第二和第三组遮盖眼玻璃体内注射神经生长因子5μg(1μg/μl )和生理盐水5μl，隔日一次，共三次,每组豚鼠在形觉剥夺12周后由一验光经验丰富的医师在暗室内带状检影验光，散光按等效球镜计算，验光前一小时用脱品酰氨点眼散瞳4次。表面麻醉后做A型超声测量眼球前后径（自角膜顶点到玻璃体与视网膜交界处后极点距离，每眼测量5次，取平均值），麻醉致死后立即取出眼球，除去筋摸，固定，包埋，切片后做免疫组化检测视网膜中Caspase-3的表达，运用TUNEL技术检测视网膜凋亡细胞: 操作步骤均严格按说明书进行。
结果
三组试验动物形觉剥夺眼与自身对照眼相比均形成相对性近视；形觉剥夺眼眼轴均有所延长，第一组形觉剥夺眼眼轴最长，为12.02±0.16mm，第二组形觉剥夺眼眼轴最短，为11.84±0.17mm，第三组形觉剥夺眼眼轴长度为11.86±0.11mm。
三组试验动物形觉剥夺眼与自身对照眼相比眼轴长度差异有显著性；第二组试验动物的形觉剥夺眼眼轴长度为11.84±0.17mm与第三组试验动物的形觉剥夺眼眼轴长度为11.86±0.11mm两组形觉剥夺眼眼轴长度相比没有显著差异；
第二组试验动物的形觉剥夺眼屈光度为﹣9.25±0.5D，第三组试验动物的形觉剥夺眼屈光度为﹣9.4±0.68D，两组形觉剥夺眼屈光度相比没有显著差异；第二组试验动物的形觉剥夺眼视网膜细胞凋亡率为1.4±0.11（单位%），第三组试验动物的形觉剥夺眼视网膜细胞凋亡率为 2.9±0.13（单位%），两者相比差异有显著性；另外，我们发现遮盖眼bad的表达（吸光光度值测定显示）与细胞凋亡有相关性，凋亡率高，bad的表达增高．
结论
形觉剥夺能够造成豚鼠剥夺眼近视的形成；bad的表达与视网膜细胞凋亡有相关性；神经生长因子能够减少视网膜细胞凋亡的发生。
关键词
神经生长因子 豚鼠 形觉剥夺 近视
Abstract
Myopia is one ametropia and the morbidity is the highest in the world. The morbidity of myopia increases constantly and the age of onset is younger than before and it will have progress when it occurs.So it becomes a very serious public progrem in our global.The prevention and cure of myopia has been included one of the plan which to prevent the blindness by the world health organization(WHO)
Since the eraction of the model of the form deprivation myopia by Wiesel and Raviola in 1977 years. We have got a some congnition in myopia by this method.That,s the regulation of the sclera,s growth mainly by the partly retinal technique in the form deprivation and there are many neurotransmitters in the retina.The neurotransmitters could be changed by form deprivation and it is one factor to form the form deprivation myopia. The eraction of the model of the form deprivation myopia is a great progress in the studying of myopia. We have got a juiner congnition in myopia by this method. It provides a valuable information and thought for the theory studying of myopia.Pathological myopia is a common growing blind disease.The retinal photosensory cells become fewer when it occurs.Apoptosis may one reason to this changes.Cell apoptosis is a procedure cell death controled by genes to maintain the stabilization of the internal environment.Cell apoptosis and cell death is different.Cell apoptosis is not a passive course but an active course.It includes a serious of gene,s activation,expression and regulation. It is not a damage in the pathologcal condition,but an active death to adapt the change of the environment.
Nerve growth factor (NGF)is a kind of protin extensive occurrence in many kinds of animal.It could not only maintain the survival of the sensory neuron and the growth of the neurofibr, but have a special function of increasing the arborization of the neurone and conservation the differentiated neurone in the individual development and raise the expression of the sensory neuron. So we have a thought that we could inject NGF into the form deprivation eyes, vitreous body during the time that the course of forming deprivation myopia in the guinea pigs to find the function of NGF on the course of forming deprivation myopia in the guinea pigs.Thereby to provid a new method on the prevention and cure myopia.
Methods
50 neonatal genipa pigs of one week old were divided randamly into group A ,B and C and were monocularly deprived(MD)of pattern visual by transpartant eye shield of right eye .Each group genipa pigs were raised in different cages and the bait and water were no confined to them.The lighting came from the daylight lamp and the lighting and the darkness were both 12 hours.In group A(n=10)no drug was used ,while guinea pigs in group B(n=20)and C(n=20)were received a series of introvitreal injection of NGF5μg(1μg/μl ) and salin vehicle5μl with MD after two weeks when they were anesthetized. Once two days and total three times. The guinea pigs diopter were measured by a practised optometrist after full mydriasis by semitransparent eye-lids when the guinea pigs were raising after 12 weeks,meanwhile the axle length(the length from the topic of the cornea to posteria pole of the boundary of the viyreous and the retina.The mean of 5 measurements was the result) wer measured byA ultrasonic when the guinea pigs were received a surface anesthesia.The eye ball were extracted and immobilizated and embeded and sliced and undertake immunhistochemistry strickly by the instruction to examine the expression of bad and we used the TUNEL technique to find the cell apoptosis in the retina.
Results
A reletivity myopia was received on the form deprivative eyes contrast with the other eyes in each group.The axle length of the form deprivative eyes was extended in each group. The axle length in group A was the longest ,the mean was 12.02±0.16㎜;On the contrary, the axle length in group B was the shortest, the mean was 11.84±0.17㎜. The axle length showed a significient difference on the form deprivatived eyes and the other eyes in each group.The mean axle length in group C was 11.86±0.11㎜.there was no significient difference on the form deprivatived eyes in group B and group C. The form deprivative eyes, diopter in group B is ﹣9.25±0.5D and in group C is ﹣9.4±0.68D and there was no significient difference in group B and group C while the apoptosis rate of the retina in group B was 6.4±0.11（单位%）and in group C was 9.9±0.13（单位%）and the apoptosis rate showed a significient difference in group B and group C.
Conclusion
The guinea pigs eyes can became myopia by monocularly deprived(MD);The expression of bad is related to the apoptosis of the retinal cells; The retional cell apoptosis could be find in the form deprivation myopia eyes and NGF can partly block these changes.
The key words
Nerve growth factor guinea pig myopia form deprivation
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