Pollard H, Bouthenet M L, Moreau J, Souil E, Verroust P, Ronco P, Schwartz J C
Unité de Neurobiologie et Pharmacologie (U109) de l'INSERM, Centre Paul Broca, Paris, France.
Neuroscience. 1989;30(2):339-76. doi: 10.1016/0306-4522(89)90258-3.
The metallopeptidase enkephalinase known to participate in the inactivation of endogenous enkephalins and, possibly, other neuropeptides such as tachykinins, was visualized by autoradiography using a [125I]iodinated monoclonal antibody. A detailed mapping of the enzyme in rat brain and spinal cord was established on 10-micron serial sections prepared in a frontal plane as well as a few sections in a sagittal plane. On adjacent sections, and for the purpose of comparison, substance P-like and enkephalin-like immunoreactivities were also visualized by autoradiography using a 125I-monoclonal antibody and a polyclonal antibody detected by a secondary 125I-anti-rabbit antibody respectively. Histological structures were identified on adjacent Nissl-stained sections. Using the highly sensitive 125I-probe, enkephalinase immunoreactivity was found to be distributed in a markedly heterogeneous manner in all areas of the central nervous system. Immunoreactivity was undetectable in white matter areas, for example the corpus callosum or fornix, and had a laminar pattern in, for example, the cerebral cortex or hippocampal formation. Hence, although immunodetection was not performed at the cellular level, a major neuronal localization of the peptidase is suggested. The latter is consistent with the detection of a strong immunoreactivity in a pathway linking the striatum to the globus pallidum, the entopeduncular nucleus and the substantia nigra, as well as with a series of biochemical and lesion data. The strong immunoreactivity also present in choroid plexuses and ependymal cells as well as in the intermediate lobe and in scattered cells of the anterior lobe of the pituitary suggests that populations of glial and endocrine cells also express the peptidase. The highest density of enkephalinase immunoreactivity was observed in basal ganglia and limbic areas (caudate putamen, globus pallidus, nucleus accumbens, olfactory tubercles) as well as in areas involved in pain control mechanisms (superficial layers of the spinal nucleus of the trigeminal nerve or of the dorsal horn of the spinal cord) which also display the highest immunoreactivities for both enkephalins and substance P (except in globus pallidus for the latter). These localizations account for the opioid-like analgesic and motor effects of enkephalinase inhibitors inasmuch as a selective or predominant participation of the peptidase in enkephalin inactivation is assumed. A number of other areas appear richly endowed in both enkephalinase and enkephalins whereas substance P is hardly detectable. This is particularly the case for the olfactory bulb, bed nucleus of the accessory olfactory tract, the cerebellum (where enkephalinase mainly occurs in the molecular layer) and the hippocampal formation (namely in the molecular layer of the dentate gyrus).(ABSTRACT TRUNCATED AT 400 WORDS)
金属肽酶脑啡肽酶已知参与内源性脑啡肽以及可能的其他神经肽（如速激肽）的失活过程，通过使用[125I]碘化单克隆抗体的放射自显影法对其进行了可视化研究。在冠状面制备的10微米连续切片以及矢状面的少数切片上，建立了该酶在大鼠脑和脊髓中的详细分布图。在相邻切片上，为了进行比较，还分别使用125I单克隆抗体和由二级125I抗兔抗体检测的多克隆抗体，通过放射自显影法对P物质样和脑啡肽样免疫反应性进行了可视化。在相邻的尼氏染色切片上识别组织学结构。使用高灵敏度的125I探针，发现脑啡肽酶免疫反应性在中枢神经系统的所有区域分布明显不均一。在白质区域（如胼胝体或穹窿）未检测到免疫反应性，而在例如大脑皮层或海马结构中呈层状分布。因此，尽管未在细胞水平进行免疫检测，但提示该肽酶主要定位于神经元。这与在连接纹状体与苍白球、内苍白球核和黑质的通路中检测到的强免疫反应性一致，也与一系列生化和损伤数据相符。脉络丛和室管膜细胞以及垂体中间叶和前叶的散在细胞中也存在的强免疫反应性表明，神经胶质细胞和内分泌细胞群体也表达该肽酶。在基底神经节和边缘区域（尾状壳核、苍白球、伏隔核、嗅结节）以及参与疼痛控制机制的区域（三叉神经脊髓核或脊髓背角的浅层）观察到脑啡肽酶免疫反应性密度最高，这些区域对脑啡肽和P物质也显示出最高的免疫反应性（后者在苍白球中除外）。鉴于假定该肽酶选择性或主要参与脑啡肽的失活，这些定位解释了脑啡肽酶抑制剂的阿片样镇痛和运动效应。许多其他区域似乎脑啡肽酶和脑啡肽都很丰富，而P物质几乎检测不到。嗅球、副嗅束的终纹床核、小脑（脑啡肽酶主要存在于分子层）和海马结构（即齿状回的分子层）尤其如此。（摘要截短于400字）
