Huard J, Fortier L P, Labrecque C, Dansereau G, Tremblay J P
Laboratoire de Neurobiologie, Université Laval, Québec, Canada.
Synapse. 1991 Feb;7(2):135-40. doi: 10.1002/syn.890070207.
Neuromuscular junctions (NMJs) were identified by revealing the presence of cholinergic receptors (AChR) with alpha-bungarotoxin coupled to the fluorescent dye cascade blue in 9- and 60-day-old normal and heterozygote mdx mice. Dystrophin was detected by an immunoperoxidase technique. All the muscle fibers of the normal animals observed in cross sections were immunoreactive for dystrophin and an accumulation of dystrophin was observed at all NMJs identified by alpha-bungarotoxin. In the 9-day-old mdx heterozygote animals, dystrophin positive, negative, and partially positive muscle cross sections were observed. Four different observations were made in these heterozygote animals on the coexistence of AChR and dystrophin. First, alpha-bungarotoxin sites (i.e., NMJs) were observed on dystrophin positive muscle fiber cross sections with an accumulation of dystrophin at these sites. Second, alpha-bungarotoxin sites were observed on dystrophin positive fibers without a dystrophin accumulation at NMJs. Third, there was a coexistence of alpha-bungarotoxin and dystrophin labelling at NMJs of muscle fibers with perimeters labelling negative for dystrophin. Fourth, NMJs, identified by alpha-bungarotoxin, were observed on muscle fibers negative for dystrophin even at the NMJ. These observations suggest that dystrophin is present not only in the muscle membrane but also in the presynaptic nerve terminals.
通过在9日龄和60日龄的正常和杂合mdx小鼠中，利用与荧光染料级联蓝偶联的α-银环蛇毒素揭示胆碱能受体（AChR）的存在来识别神经肌肉接头（NMJ）。采用免疫过氧化物酶技术检测肌营养不良蛋白。在正常动物的横截面中观察到的所有肌纤维对肌营养不良蛋白均呈免疫反应性，并且在通过α-银环蛇毒素识别的所有神经肌肉接头处均观察到肌营养不良蛋白的积累。在9日龄的mdx杂合子动物中，观察到肌营养不良蛋白阳性、阴性和部分阳性的肌肉横截面。在这些杂合子动物中，就AChR和肌营养不良蛋白的共存进行了四种不同的观察。首先，在肌营养不良蛋白阳性的肌纤维横截面上观察到α-银环蛇毒素位点（即神经肌肉接头），并且在这些位点有肌营养不良蛋白的积累。其次，在肌营养不良蛋白阳性的纤维上观察到α-银环蛇毒素位点，但在神经肌肉接头处没有肌营养不良蛋白的积累。第三，在肌纤维神经肌肉接头处，α-银环蛇毒素和肌营养不良蛋白标记共存，而肌纤维周边标记对肌营养不良蛋白呈阴性。第四，即使在神经肌肉接头处，在肌营养不良蛋白阴性的肌纤维上也观察到通过α-银环蛇毒素识别的神经肌肉接头。这些观察结果表明，肌营养不良蛋白不仅存在于肌膜中，还存在于突触前神经末梢中。
