急性高眼压后大鼠视网膜突触囊泡素的表达变化

Expression of synaptophysin in rat retina following acute high intraocular pressure

目的研究急性高眼压后大鼠视网膜突触囊泡素(synaptophysin,SYN)的表达变化。方法SD大鼠左眼眼压升高至闪光视网膜电图b波消失并维持60min,右眼为正常对照,动物存活1、3、7、14、21d后处死,冰冻切片行SYN免疫组织化学及原位杂交检测。结果正常情况下SYN蛋白分布于视网膜内、外网层,外网层染色较深,急性高眼压后SYN阳性产物除外网层分布外,还出现于外核层的内侧部分,存活7d时,阳性产物在外网层及外核层的分布范围最宽,至14d时又恢复至与正常相似的分布模式。SYNmRNA阳性产物主要分布存在于内核层与节细胞层的神经元胞体,急性高眼压后1、3、7d时内核层SYNmRNA阳性细胞数逐渐增多,均高于正常水平,14d时又恢复至正常水平。结论急性高眼压后大鼠视网膜SYN的表达先增强后减弱,且出现空间分布的改变,提示急性高眼压损伤后视网膜内突触溃变前可能存在突触功能增强的时期。

Objective To investigate the expression of synaptophysin （SYN） in rat retina following acute high intraocular pressure （HIOP）. Methods The intraocular pressure of all left eyes was increased until b wave of flash electroretinogragh （fERG） disappeared and such pressure maintained for 60 min. All right eyes served as normal control. The animals, totally 60 SD rats, were sacrificed respectively on day 1,3, 7, 14 or 21 following operation, with 12 rats on each sacrifice day, half for immunohistochemistry and half for in situ hy-bridization to detect the expression of SYN. Results In normal condition, SYN was mainly located in the outer plexiform layer （OPL） and the inner plexiform layer （IPL）. SYN positive products were extended to the in- ner part of the outer nuclear layer （ONL） after HIOP. There was the widest distribution of SYN in the OPL and ONL on the 7th day after HIOP. On the 14th day, the distribution of SYN was similar to that of the normal control. By in situ hybridization, SYN positive neurons were mainly located in the inner nuclear layer （INL） and the ganglion cell layer （GCL）. The number of SYN mRNA positive cells in the INL was increased following HIOP and reached its peak on the 7^th day, then decreased to normal level at the 14^th day. Conclusion In rat retina, SYN expression was first up-regulated, then down-regulated, accompanied with spatial redistribution following HIOP, indicating that instead of synaptic degeneration,the synaptic function is first enhanced at the early stage following HIOP.