Hamel E, Beaudet A
Nature. 1984;312(5990):155-7. doi: 10.1038/312155a0.
The regional distribution of opioid receptors in the mammalian central nervous system has been extensively studied by light microscopic autoradiography. Little is known, however, about the fine structural localization of these receptor sites apart from the fact that they are present in both synaptosomal and smooth microsomal subcellular fractions of whole brain homogenates. Previously, using the Met-enkephalin analogue FK 33-824 (Sandoz), we determined that brain opioid binding sites could be visualized by electron microscopic autoradiography. We now report on the ultrastructural distribution of these sites in the caudate-putamen of the rat. The vast majority of specifically labelled opioid binding sites were found to be associated with axo-dendritic (53%), axoaxonic (18%) or axo-somatic (3%) neuronal membrane interfaces. Only 7%, however, were associated with synaptic junctions. These results suggest that opioids act primarily at non-junctional interfaces on the dendrites, axons and soma of neurones in the neostriatum.
通过光学显微镜放射自显影术，对阿片受体在哺乳动物中枢神经系统中的区域分布进行了广泛研究。然而，除了这些受体位点存在于全脑匀浆的突触体和光滑微粒体亚细胞组分中这一事实外，关于这些受体位点的精细结构定位所知甚少。此前，我们使用甲硫氨酸脑啡肽类似物FK 33 - 824（山德士公司），确定脑阿片结合位点可通过电子显微镜放射自显影术观察到。我们现在报告这些位点在大鼠尾状核 - 壳核中的超微结构分布。发现绝大多数特异性标记的阿片结合位点与轴突 - 树突（53%）、轴突 - 轴突（18%）或轴突 - 胞体（3%）神经元膜界面相关。然而，只有7%与突触连接相关。这些结果表明，阿片类药物主要作用于新纹状体神经元树突、轴突和胞体的非连接界面。
