Cui Qi, Tang Louisa S, Hu Bing, So Kwok-Fai, Yip Henry K
Department of Anatomy, Faculty of Medicine, The University of Hong Kong, China.
Invest Ophthalmol Vis Sci. 2002 Jun;43(6):1954-64.
To investigate changes in percentage of tyrosine kinase (trk)A-, trkB-, and trkC-immunopositive ((+)) retinal ganglion cells (RGCs) at various times after optic nerve (ON) axotomy; the proportion of RGCs regenerating axons into peripheral nerve (PN) grafts that are trkA(+), trkB(+), and trkC(+); whether intravitreal PN-ON implants affect trk immunoreactivity; and the levels of trk mRNAs in ON-injured retinas.
The ON was transected intraorbitally. Proportions of trkA(+), trkB(+), and trkC(+) RGCs and levels of trk mRNAs were studied by using immunocytochemistry and Northern blot methods, respectively, in injured and RGC-regenerating retinas.
In normal retinas, only small numbers of trkB(+) and trkC(+), but not trkA(+), RGCs were seen. The optic fiber layer was intensively immunolabeled with trkB. After ON injury, the proportions of trkA(+), trkB(+), and trkC(+) RGCs rapidly increased and reached their peaks by 3 to 5 days. During the next 3 weeks, the proportion of trkA(+) or trkB(+) RGCs gradually decreased, but the proportion of trkC(+) RGCs remained high. Intravitreal implants of PN+ON segments transiently but significantly suppressed injury-induced increases in all these trk(+) RGC proportions for approximately 5 days. In contrast, 3 days after ON injury, quantitative retinal expression of trkA mRNA, and to a lesser extent trkC mRNA, was downregulated, whereas trkB mRNA expression remained unaffected. Higher proportions of trkA(+) and trkB(+) RGCs and higher levels of all trk mRNAs were seen in regenerating RGCs and retinas, respectively.
This study provides a kinetic analysis of expression of trk in RGCs and retinas after ON injury and during regeneration.
研究视神经（ON）切断术后不同时间酪氨酸激酶（trk）A、trkB和trkC免疫阳性（(+)）视网膜神经节细胞（RGCs）的百分比变化；再生轴突长入周围神经（PN）移植物的RGCs中trkA(+)、trkB(+)和trkC(+)的比例；玻璃体内PN-ON植入物是否影响trk免疫反应性；以及ON损伤视网膜中trk mRNA的水平。
在眶内切断ON。分别采用免疫细胞化学和Northern印迹法研究损伤和RGC再生视网膜中trkA(+)、trkB(+)和trkC(+) RGCs的比例以及trk mRNA的水平。
在正常视网膜中，仅可见少量trkB(+)和trkC(+) RGCs，未见trkA(+) RGCs。视神经纤维层被trkB强烈免疫标记。ON损伤后，trkA(+)、trkB(+)和trkC(+) RGCs的比例迅速增加，并在3至5天达到峰值。在接下来的3周内，trkA(+)或trkB(+) RGCs的比例逐渐下降，但trkC(+) RGCs的比例仍保持较高水平。玻璃体内植入PN+ON节段可在约5天内短暂但显著抑制损伤诱导的所有这些trk(+) RGC比例的增加。相反，ON损伤后3天，trkA mRNA的视网膜定量表达以及程度较轻的trkC mRNA表达下调，而trkB mRNA表达未受影响。在再生RGCs和视网膜中分别可见较高比例的trkA(+)和trkB(+) RGCs以及所有trk mRNA的较高水平。
本研究对视神经损伤后及再生过程中视网膜神经节细胞和视网膜中trk的表达进行了动力学分析。
