Papasozomenos S C, Binder L I, Bender P K, Payne M R
J Cell Biol. 1985 Jan;100(1):74-85. doi: 10.1083/jcb.100.1.74.
We have examined the distribution of microtubule-associated protein 2 (MAP2) in the lumbar segment of spinal cord, ventral and dorsal roots, and dorsal root ganglia of control and beta,beta'-iminodipropionitrile-treated rats. The peroxidase-antiperoxidase technique was used for light and electron microscopic immunohistochemical studies with two monoclonal antibodies directed against different epitopes of Chinese hamster brain MAP2, designated AP9 and AP13. MAP2 immunoreactivity was present in axons of spinal motor neurons, but was not detected in axons of white matter tracts of spinal cord and in the majority of axons of the dorsal root. A gradient of staining intensity among dendrites, cell bodies, and axons of spinal motor neurons was present, with dendrites staining most intensely and axons the least. While dendrites and cell bodies of all neurons in the spinal cord were intensely positive, neurons of the dorsal root ganglia were variably stained. The axons of labeled dorsal root ganglion cells were intensely labeled up to their bifurcation; beyond this point, while only occasional central processes in dorsal roots were weakly stained, the majority of peripheral processes in spinal nerves were positive. beta,beta'-Iminodipropionitrile produced segregation of microtubules and membranous organelles from neurofilaments in the peripheral nervous system portion and accumulation of neurofilaments in the central nervous system portion of spinal motor axons. While both anti-MAP2 hybridoma antibodies co-localized with microtubules in the central nervous system portion, only one co-localized with microtubules in the peripheral nervous system portion of spinal motor axons, while the other antibody co-localized with neurofilaments and did not stain the central region of the axon which contained microtubules. These findings suggest that (a) MAP2 is present in axons of spinal motor neurons, albeit in a lower concentration or in a different form than is present in dendrites, and (b) the MAP2 in axons interacts with both microtubules and neurofilaments.
我们研究了微管相关蛋白2（MAP2）在对照组和β，β'-亚氨基二丙腈处理大鼠的脊髓腰段、腹根和背根以及背根神经节中的分布。采用过氧化物酶-抗过氧化物酶技术，使用两种针对中国仓鼠脑MAP2不同表位的单克隆抗体（分别命名为AP9和AP13）进行光镜和电镜免疫组织化学研究。MAP2免疫反应性存在于脊髓运动神经元的轴突中，但在脊髓白质束的轴突和大多数背根轴突中未检测到。脊髓运动神经元的树突、细胞体和轴突之间存在染色强度梯度，树突染色最深，轴突染色最浅。虽然脊髓中所有神经元的树突和细胞体均呈强阳性，但背根神经节神经元的染色程度各不相同。标记的背根神经节细胞的轴突在其分支处之前均被强烈标记；在此点之后，虽然背根中只有偶尔的中枢突被弱染色，但脊神经中的大多数外周突呈阳性。β，β'-亚氨基二丙腈导致外周神经系统部分的微管和膜性细胞器与神经丝分离，以及脊髓运动轴突中枢神经系统部分的神经丝积累。虽然两种抗MAP2杂交瘤抗体在中枢神经系统部分均与微管共定位，但在脊髓运动轴突的外周神经系统部分只有一种与微管共定位，而另一种抗体与神经丝共定位，且未对含有微管的轴突中央区域进行染色。这些发现表明：（a）MAP2存在于脊髓运动神经元的轴突中，尽管其浓度低于或形式不同于树突中的；（b）轴突中的MAP2与微管和神经丝均相互作用。
