Age changes in cellular interactions among the endplate components (axon, Schwann cells, acetylcholine receptor, synaptic matrix) during reinnervation to the motor endplate

我们已经发现再生NMJs中存在一些与年龄相关的变化，例如坐骨神经挤压损伤后终末雪旺细胞和乙酰胆碱受体（acetylcholine receptors, AChRs）区域的持续损伤。本研究旨在解决这些变化与信号机制之间的关系。取比目鱼肌冰冻切片，首先标记NMJ上的组成元件（轴突、雪旺细胞、AChR区）后，免疫组化双标记信号相关物质（神经调节蛋白（NRG）、NRG受体（erB2、erB3）和胶质细胞系源性神经营养因子（GDNF））的表达。接下来，由于已知NRG/erbB信号与AChR聚集有关，我们检测了由α -bungarotoxin标记的AChR区域中肌营养不良蛋白（dystrophin， DYS，突触后细胞骨架蛋白）的表达。观察时间为NMJ再生进行的时间（术后4-12周）。在更多的幼龄动物中，NRG分布在再生轴突的整个长度上，直至生长锥或末端。NRG受体的ErB2和erB3分布在突触褶皱和末端雪旺细胞上。NRG/erB2（或erB3）的表达在术后4周出现短暂性升高。GDNF定位于NMJ的雪旺细胞链、突触折叠和末端雪旺细胞。GDNF的表达随着再生的进展而增强，许多NMJs在术后8周表现出强烈的阳性。在老年肌肉中，任何信号相关物质（NRG、erB2、erB3、GDNF）均表现出一些异常（表达延迟、染色弱、畸形）。2. 在老年动物中，受体区域分布的紊乱往往伴随着DYS表达的异常（弱染色和部分缺失）。结论:1。突触前和突触后区域之间的相互作用对于NMJ的再生或结构特化，即生理功能的恢复是重要的。据认为，本文报道的信号分子分布中与年龄相关的异常与NMJs的再生不足有关。2. 老年模型对于研究NMJs信号机制的干扰是有用的。少

We have already shown some age-related changes in regenerating NMJs, such as persistent damage in the terminal Schwann cell and the acetylcholine receptor (acetylcholine receptors, AChRs) region after sciatic nerve crushing injury. This research aimed at solving the relation of these changes and the signal mechanism. Cryostat sections of the soleus muscle were made, and first, after the composition element (axon, Schwann cell, AChR region) on NMJ was labeled, the expression of signal-related-substances (neuregulin (NRG), NRG receptors (erB2 and erB3) and glial cell line-derived neurotrophic factor (GDNF)) was double labeled by immunohistochemistry. Next, since NRG/erbB signaling is known to be concerned with the aggregation of AChRs, we examined the expression of dystrophin (DYS, postsynaptic cytoskeleton protein) in the AChR region as labeled by alpha-bungarotoxin. Observation was performed at the time when regeneration of NMJ was in progress (4-12 postoperative weeks).Results. In the … More young animals NRG was distributed over the full length of regenerating axons, up to a growth cone or a terminal. ErB2 and erB3 of a NRG receptor were distributed over the synaptic folds and the terminal Schwann cells. Expression of NRG/erB2 (or erB3) became transiently increased at four postoperative week. GDNF was localized in the Schwann cell strands, and synaptic folds and terminal Schwann cells in the NMJ. Expression of GDNF was reinforced as regeneration progressed, and numerous NMJs showed the strong positivity at eight postoperative week. In the aged muscles any signal-related-substance (NRG, erB2, erB3, and GDNF) showed some abnormalities (delayed expression, weak staining, malformation). 2. Derangement in the distribution of a receptor region in aged animals frequently accompanied abnormalities in the expression of DYS (weak staining and partial lack). Conclusion. 1. The interaction between the presynaptic and postsynaptic region is important for regeneration or structural specialization of the NMJ, i.e., for recovery of a physiological function. It is thought that age-related abnormalities in the distribution of signal molecules reported here relate to the insufficiency of regeneration at the NMJs. 2. The old-age-model is useful in order to study the disturbance of the signal mechanism at NMJs. Less