脑源性神经营养因子对高眼压后视网膜节细胞的保护作用

目的　观察大鼠眼高压所致视网膜损伤及脑源性神经营养因子 (BDNF)对节细胞的保护作用。方法　以生理盐水加压注入Wistar大鼠眼前房至动物视网膜电图 (ERG)b波消失的临界压并维持 90min ,制成大鼠急性高眼压模型。实验组加压前 2d玻璃体内注射BDNF(3μg/kg ,0 1μg/ μl) ,实验对照组注射等量小牛白蛋白 ,加压后存活 3d复查ERG后处死 ,美蓝染色后光镜下观察节细胞的形态改变并作细胞计数分析 ,测量视网膜内核层 (INL)及内网层外缘至内界膜 (IPL ILM)的厚度。ABC免疫组化法检测谷氨酸的表达变化。结果　视网膜高眼压后IPL -ILM厚度小于正常对照组 ;节细胞数目减少 ,部分节细胞呈现坏死特征。BDNF处理后视网膜病理改变有明显改善 ,与实验对照组比较节细胞存活数增加 ,IPL ILM厚度大于实验对照组。高眼压后视网膜内可见谷氨酸免疫反应阳性双极细胞 ,BDNF处理后其免疫反应性类似于正常对照组。 3d后视网膜电图b波在BDNF处理组为正常的 75 3% ,而实验对照组仅为正常的 11 4 % (P <0 0 5 )。结论　大鼠眼高压可导致视网膜节细胞死亡 ,BDNF对高压后节细胞具有明显的保护作用。兴奋性氨基酸对高眼压后节细胞的损害可被BDNF改善

Protection of the retinal ganglion cells from experimental glaucoma by brain derived neurotrophic factor

Objective A pressure induced ischaemia-reperfusion insult can lead to rat retinal ganglion cell death. In this study, an experimental glaucoma model was used to investigate the protection of RGCs from rat high intraocular pressure by BDNF.Methods Intraocular pressure in the rat was increased by injected the normal saline in pressure into the anterior chamber for 90 minutes. The BDNF or bovine serum albumin (BSA) for control were injected intravitreally 2 days before the operation. The post operation survival time was 3 days. Flash electroretinogram(FERG) was measured before the animals were perfused. Vertical semithin sections of the retinae were stained by methylene blue and the Glutamate immunohistochemistry was measured in the retinae sections. The thickness of inner nuclear layer (INL) and inner plexiform layer to internal limiting membrane (IPL ILM) were measured. The number of the RGCs was counted.Result: During operation, the b wave of FERG was disappeared. After 3 days, mean amplitudes of b wave from BDNF treated and control eyes were 75 3% and 11 4%, respectively(P<0 05). Control retinae thinned in the IPL-ILM and reduced cell numbers in the GCL. Some dying RGCs in the experimental retinae showed morphologic features of necrosis, including cytoplasmic vacuolization and karyolysis and cytolysis. But some of them exhibited morphologic features including chromatin condensation、margination and cytoplasmic condensation. BDNF ameliorated the degenerative changes of retina. The IPL ILM layer was far less damaged and more ganglion cells were present than in BSA injected eyes. The numbers of dead cells were much reduced than those in control eyes. The bipolar cells exhibited intensely Glutamate immunoreactivity after reperfusion. If pretreated the retina with BDNF, Glutamate immunostaining were similar to the normal condition.Conclusion This study lends support to the concept that the high intraocular pressure in the rat eyes induces the retinal ganglion cells death and BDNF may prevent the Glutamate insult and promotes the injured RGCs and functional recovery of high intraocular pressure retina.