神经细胞黏附分子L1促进神经细胞突起和功能性突触的形成

摘要

BACKGROUND: Neural cell adhesion molecule L1 plays an important role on the origin, development of neural cells as well as the adhesion between nerves. However, the effect of L1 to the formation of neuritis and functional synapse is still uncertain.OBJECTIVE:To explore the effects of neural cell adhesion molecule L1 on forming neurites and functional synapses.DESIGN:Completely randomized controlled trial.SETTING and MATERIALS: Experiment was conducted in Neuroscience Research Institute of Guangxi College of Traditional Chinese Medicine.Materials include NG108-15 nerve cell strain, L1 cDNA, anti-L1 antibody:provided by Kanazawa University.METHODS: L1 cDNA was transfected into NG108-15 cells by lipid transfecting agent in vitro culture. Optical microscope was used to observe the cellular morphology. Electrophysiological technique was used to test the postsynaptic membrane potential of cell-muscular process.MAIN OUTCOME MEASURES: Cell process index; rate of synapse formation, frequency of miniatureplate potential.RESULTS: Four days after being processed by differentiation agent cAMP,the cells with protuberance and bifurcation in L1-transfection group accounted for(31 ±8)% of the total cells. This figure was much higher than that of non-transfection group ( 13 ± 2) % or Mock transfection group ( 15 ± 5 ) % ( P ＜ 0.01). The average length of cell process was(142.5 ± 12.3) μm, it was higher than that of non-transfection group(94.2 ± 12. 3) μ m or Mock transfection group(86. 8 ± 6.7) μm( P ＜ 0.05). The rate of synapse formation in L1 transfection group was(58.0±11.5)% , it was higher than that of non-transfection group ( 36.7 ± 0. 83 ) % or Mock-transfection group ( 39.2± 0. 84) % ( P ＜ 0.01 ) . However, there was no significant difference between the postsynaptic membrane potential of three groups ( P ＞ 0.05).CONCLUSION: The high expression of L1 in NG108 - 15 cells can enhance the formation of neural cell process and functional synapse induced by cAMP. The increase of rate of synapse formation is by increasing bifurcation of neural cell process as well as the length of protuberance. It is realized by increasing the amount of nerve-muscle connections not by increasing the release amount of transmitter.%背景:神经细胞黏附分子L1对神经细胞的发生、发育和神经-神经黏附发挥重要作用,然而L1对细胞突起和功能性突触形成的影响是不清楚的.目的:探讨神经细胞黏附分子L1在神经细胞突起生长和功能性突触形成中的作用.设计:完全随机对照实验研究.地点和材料:地点为广西中医学院神经科学研究所.材料为NG108-15神经细胞株、L1 eDNA、抗L1抗体:由日本金泽大学神经物性部门提供.方法:在体外细胞培养,用脂质转染剂将黏附分子L1cDNA表达到NG108-15细胞,用光学显微镜观察细胞形态和电生理学检查技术测定细胞-肌突触的突触后膜电位变化.主要观察指标:细胞突起指数、突触形成率、微小终板电位的频率.结果:以分化剂cAMP处理4 d后,L1-转染组有突起分叉的细胞占细胞总数的百分数为(31±8)%,明显高于非转染组的(13±2)%或Mock-转染组的(15±5)%(P＜0.001).L1-转染组的细胞突起平均长度为(142.5±12.3)μm,明显高于非转染组的(94.2±12.3)μm或Mock-转染组的(86.8±6.7)μm(P＜0.05).L1转染组功能性突触的形成率为(58.0±11.5)%,也高于非转染组的(36.7±0.83)%或Mock-转染组的(39.2±0.84)%(P＜0.001).但突触后膜电位的频率在3组之间差异无显著性意义(P＞0.05).结论:L1在NG108-15细胞的高度表达提高cAMP诱发的神经细胞突起和功能性突触的形成,功能性突触形成率的增加是通过增加神经细胞突起分叉和突起的长度,从而增加神经-肌连接数量来实现,而不是通过增加递质的释放量.