Zimmermann H, Vogel M, Laube U
Zoologisches Institut der J. W. Goethe-Universität, Frankfurt am Main, F.R.G.
Neuroscience. 1993 Jul;55(1):105-12. doi: 10.1016/0306-4522(93)90458-r.
The distribution of binding sites for an antibody against ecto-5'-nucleotidase was investigated in the mouse hippocampus by light microscopical immunocytochemistry. The antibody selectively labels a band corresponding to the innervation area of mossy fibre terminals within area CA3. Area CA1 as well as the dendate gyrus are negative. In area CA3 only the proximal but not the distal parts of the apical dendrites of pyramidal cells are labelled. Labelling is in the form of large dots around dendrites of pyramidal cells suggesting that mossy fibre terminals are immunopositive. In contrast, an antibody against the ubiquitous synaptic vesicle protein SV2 labels the large mossy fibre terminals as well as fine and punctate structures in the dendritic and somatic regions throughout the hippocampus. Labelled astrocytes can be found in the entire hippocampus and are frequent in the stratum radiatum and stratum oriens of the CA1 region. Immunopositive astrocytic processes can be found in association with capillary walls. Our results suggest that ecto-5'-nucleotidase may play a crucial role in the hydrolysis of AMP to adenosine at the mossy fibre synapses. Thus, at these synapses, 5'-nucleotidases could function both in completing the extracellular hydrolysis of synaptically released ATP as well as in the extracellular formation of adenosine.
通过光学显微镜免疫细胞化学方法，研究了抗胞外5'-核苷酸酶抗体结合位点在小鼠海马体中的分布。该抗体选择性标记了一条与CA3区内苔藓纤维终末神经支配区域相对应的带。CA1区以及齿状回呈阴性。在CA3区，仅锥体细胞顶树突的近端而非远端被标记。标记呈围绕锥体细胞树突的大圆点形式，表明苔藓纤维终末免疫阳性。相比之下，抗普遍存在的突触囊泡蛋白SV2的抗体标记了整个海马体中大型苔藓纤维终末以及树突和体细胞区域的精细点状结构。在整个海马体中均可发现标记的星形胶质细胞，在CA1区的辐射层和原层中较为常见。免疫阳性的星形胶质细胞突起可与毛细血管壁相关联。我们的结果表明，胞外5'-核苷酸酶可能在苔藓纤维突触处将AMP水解为腺苷的过程中起关键作用。因此，在这些突触处，5'-核苷酸酶可能既参与完成突触释放的ATP的胞外水解，也参与腺苷的胞外形成。
