Westlund K N, Krakower T J, Kwan S W, Abell C W
Department of Anatomy, University of Texas Medical Branch, Galveston 77550.
Brain Res. 1993 May 28;612(1-2):221-30. doi: 10.1016/0006-8993(93)91664-e.
Monoamine oxidase A and B (MAO A and B; EC 1.4.3.4) are integral proteins of the outer mitochondrial membrane that degrade monoamines including the neurotransmitters norepinephrine, dopamine, and serotonin. In this study, monoclonal antibodies that recognize rat or monkey MAO A were used in immunocytochemical studies to visualize the subcellular localization of this enzyme within neurons in the central nervous system of these species. The regions examined included the locus coeruleus, substantia nigra, spinal cord, and pallidostriatum, which are known to contain MAO A-positive structures. Ultrastructural studies revealed that most MAO A staining was associated with the outer membrane of mitochondria, within the cell bodies, dendrites, axons and terminals. However, some immunoreactive staining for MAO A was also observed in the rough endoplasmic reticulum in the cell bodies. Staining for mitochondrial MAO A in dendrites was observed in terminal fields of the monoamine system, including the spinal cord and the pallidostriatum. The intensity of staining also increased in the subsynaptic density. MAO A was also found associated with mitochondria in ependymal cells lining the fourth ventricle adjacent to the locus coeruleus and in the endothelial cells lining the blood vessels. Localization of MAO A in noradrenergic neurons, ependymal cells, and subsynaptic regions of dendrites in monoamine terminal fields supports the concept that this neurotransmitter-degrading enzyme may play a protective role in the central nervous system.
单胺氧化酶A和B（MAO A和B；EC 1.4.3.4）是线粒体外膜的整合蛋白，可降解包括神经递质去甲肾上腺素、多巴胺和5-羟色胺在内的单胺。在本研究中，识别大鼠或猴MAO A的单克隆抗体被用于免疫细胞化学研究，以观察该酶在这些物种中枢神经系统神经元内的亚细胞定位。所检查的区域包括蓝斑、黑质、脊髓和苍白球纹状体，这些区域已知含有MAO A阳性结构。超微结构研究显示，大多数MAO A染色与线粒体的外膜相关，位于细胞体、树突、轴突和终末内。然而，在细胞体的粗面内质网中也观察到了一些MAO A的免疫反应性染色。在单胺系统的终末区域，包括脊髓和苍白球纹状体，在树突中观察到了线粒体MAO A的染色。突触下致密区的染色强度也增加。在与蓝斑相邻的第四脑室室管膜细胞以及血管内皮细胞的线粒体中也发现了MAO A。MAO A在去甲肾上腺素能神经元、室管膜细胞和单胺终末区域树突的突触下区域的定位支持了这样一种观点，即这种神经递质降解酶可能在中枢神经系统中发挥保护作用。
