Wan D C, Ng Y P, Choi R C, Cheung P W, Dong T T, Tsim K W
Department of Biochemistry, The Chinese University of Hong Kong, Shatin, China.
Neurosci Lett. 1997 Aug 29;232(2):83-6. doi: 10.1016/s0304-3940(97)00577-6.
In vertebrate neuromuscular junctions, acetylcholinesterase (AChE; EC 3.1.1.7) is highly concentrated at the synaptic basal lamina and the postsynaptic muscle fiber. The postsynaptic muscle cell is the primary source of AChE. However, several lines of evidence indicate that the presynaptic motor neuron is able to synthesize and secrete AChE at the neuromuscular junctions. By using anti-AChE monoclonal antibody in immunohistochemical staining, we found that the AChE-positive cells were labeled only at the motor neurons of the chick spinal cords. When the protein extract of chick spinal cords was analyzed by a Western blot analysis, a protein band of approximately 105 kDa was recognized. In denervated chicks, the expression of motor neuron AChE, as recognized on a Western blot, decreased by approximately 50% 4 days after denervation. The AChE expression in denervated chick spinal cords, however, was restored to control level 10 days after denervation. The decreased AChE expression was restricted to the ipsilateral side of the denervated chick spinal cord while the contralateral side was relatively unchanged. In comparison with the contralateral side, the level of AChE protein and enzymatic activity expressed in the ipsilateral spinal cord was approximately 50% lower. This is the first demonstration to show that the ipsilateral and contralateral sides of chick spinal cords respond differently after nerve denervation.
在脊椎动物的神经肌肉接头处，乙酰胆碱酯酶（AChE；EC 3.1.1.7）高度集中于突触基底膜和突触后肌纤维。突触后肌细胞是AChE的主要来源。然而，一些证据表明，突触前运动神经元能够在神经肌肉接头处合成并分泌AChE。通过在免疫组织化学染色中使用抗AChE单克隆抗体，我们发现AChE阳性细胞仅在鸡脊髓的运动神经元处被标记。当通过蛋白质免疫印迹分析对鸡脊髓的蛋白质提取物进行分析时，识别出一条约105 kDa的蛋白带。在去神经支配的雏鸡中，去神经支配4天后，蛋白质免疫印迹中识别出的运动神经元AChE表达下降了约50%。然而，去神经支配的鸡脊髓中的AChE表达在去神经支配10天后恢复到对照水平。AChE表达的下降仅限于去神经支配的鸡脊髓的同侧，而对侧相对未变。与对侧相比，同侧脊髓中表达的AChE蛋白水平和酶活性大约低50%。这是首次证明鸡脊髓的同侧和对侧在神经去神经支配后反应不同。
