神经生长因子对激光致视网膜损伤后bFGF蛋白表达的影响

Effect of NGF on bFGF protein expression in laser-injured rat retina

目的观察神经生长因子(NGF)对激光致视网膜损伤后内源性碱性成纤维细胞生长因子(bFGF)蛋白表达的影响,以探讨激光致视网膜损伤的分子病理机制。方法Wistar二级大鼠,分为3组,即损伤对照组、生理盐水对照组、NGF组,分别于倍频Nd:YAG激光损伤后,玻璃体内注射NGF,用免疫组织化学、Western blot方法、苏木精-伊红染色及视觉电位仪测量视网膜电图(ERG)b波幅值,观察视网膜bFGF蛋白表达量的变化及对视网膜组织结构、视功能的影响。结果激光损伤视网膜后玻璃体内NGF组3dbFGF蛋白的表达明显低于损伤对照组(P<0.01);NGF组28d感光细胞结构的恢复较损伤对照组差,NGF组的b波幅值在各时间点与对照组比较差异均无统计学意义(P>0.05)。结论外源性NGF减少了激光视网膜损伤后bFGF产物,不利于感光细胞结构和功能的修复。

Objective It is known that apoptosis is a common pathway for the photoreceptor death in light-and laserinduced retinal degeneration. Some of neurotrophic factors have biological effects on photoreceptors. This study was to observed the effect of nerve growth factor （NGF） on the intrinsic basic fibroblast growth factor（bFGF） protein expression in rat retina after laser exposure and investigate the molecular pathological mechanism in laser-injured retina. Methods One eye of 24 Wistar rats was irradiated by frequency doubling Nd： YAG （ Neodymium： Yttrium, aluminum garnet A = 532 nm） laser. NGF 20 μl （0. 03 μg/μl） was injected into the vitreous using a microsyringe in 8 eyes of NGF group; equal amount of normal saline（NS） was injected intravitreouly in 8 eyes of NS control group, and laser exposure alone was performed in 8 eyes of laser group. The expression of intrinsic bFGF protein after laser exposure was observed by immunohistochemistry and Western blot analysis, and bFGF direct action on photoreceptor cells,retinal morphological and functional changes were studied using hematoxylin and eosin staining and visual electrophsiological technique. Results The bFGF protein was expressed in various layers of normal rat retina, showing a brown staining in cytoplasm. In NGF group, the expression of bFGF （2 013.81 ± 1 317.71 ） was downregulated in comparison with NS control group （23 598.24 ± 9 075.30） （ P 〈 0.01 ）. On day 28 after laser exposure, rod and cone layer was persistently existed in control group, and the structure of photoreceptor was disorder, and a few dead cells were found. However, in NGF group, a part of out nuclear layer was disappeared, and outer nuclear layer and inner nuclear layer showed confluent statue. The ERG b-waves amplitudes in NGF group were lower than other controls after laser exposure. Conclusion Extrinsic NGF can downregulate bFGF production and inhibit the structural and functional regeneration of photoreceptor cells.