Miettinen R, Gulyás A I, Baimbridge K G, Jacobowitz D M, Freund T F
Department of Functional Neuroanatomy, Hungarian Academy of Sciences, Budapest.
Neuroscience. 1992;48(1):29-43. doi: 10.1016/0306-4522(92)90335-y.
The possible co-existence of calretinin with other calcium binding proteins, parvalbumin and calbindin D28k, and with GABA, was studied in non-pyramidal cells of the rat dorsal hippocampal formation, using the mirror technique. The majority of the calretinin-containing neurons (83%) were found to be immunoreactive for GABA (79% in the dentate gyrus, 84% in the CA2-3, and 88% in the CA1 subfield). Most of the GABA-negative calretinin-immunoreactive neurons were located in the hilus of the dentate gyrus and in stratum lucidum of the CA3 subfield. Detailed analysis of the calretinin-immunoreactive cells of these subfields revealed that the two morphologically distinct types of calretinin neurons, i.e. the spiny and the spine-free cells, differ in their immunoreactivity for GABA. The overwhelming majority (92%) of the spine-free neurons were GABA-positive, whereas the immunoreactivity of spiny cells was ambiguous. At the sensitivity threshold of the immunocytochemical techniques used in the present study, most of the spiny cells (89%) had to be considered as GABA-negative, although the staining intensity in their cell bodies was somewhat above background level. Colchicine treatment resulted in a degeneration of calretinin-immunoreactive neurons; therefore, its effect on the GABA content of spiny neurons could not be evaluated. Nevertheless, the observations suggest that calretinin-containing neurons are heterogeneous both morphologically and neurochemically. Examination of the co-existence of calcium binding proteins revealed that none of the hippocampal cells contained both calretinin and parvalbumin in any regions of the hippocampal formation. Some overlap was detected between the calretinin- and the calbindin D28k-containing cell populations, 5.1% of the former and 6.2% of the latter were immunoreactive for both calcium binding proteins. This may be due to a small degree of cross-reactivity of the calbindin D28k antiserum with calretinin. Thus, our results demonstrate that the majority of calretinin-immunoreactive neurons are GABAergic and represent a subpopulation of non-pyramidal cells with no or only a negligible overlap with the subpopulations containing the other calcium binding proteins, parvalbumin and calbindin.
利用镜像技术，在大鼠背侧海马结构的非锥体细胞中研究了钙结合蛋白钙视网膜蛋白与其他钙结合蛋白（小白蛋白和钙结合蛋白D28k）以及与γ-氨基丁酸（GABA）可能的共存情况。发现大多数含钙视网膜蛋白的神经元（83%）对GABA呈免疫反应（齿状回中为79%，CA2 - 3中为84%，CA1亚区中为88%）。大多数GABA阴性的钙视网膜蛋白免疫反应性神经元位于齿状回的门区和CA3亚区的透明层。对这些亚区中钙视网膜蛋白免疫反应性细胞的详细分析表明，两种形态上不同类型的钙视网膜蛋白神经元，即有棘突和无棘突的细胞，在对GABA的免疫反应性上存在差异。绝大多数（92%）无棘突神经元是GABA阳性的，而有棘突细胞的免疫反应性不明确。在本研究使用的免疫细胞化学技术的敏感性阈值下，大多数有棘突细胞（89%）不得不被视为GABA阴性，尽管它们细胞体中的染色强度略高于背景水平。秋水仙碱处理导致钙视网膜蛋白免疫反应性神经元变性；因此，无法评估其对有棘突神经元GABA含量的影响。然而，这些观察结果表明，含钙视网膜蛋白的神经元在形态和神经化学上都是异质性的。对钙结合蛋白共存情况的检查发现，在海马结构的任何区域，海马细胞中都没有同时含有钙视网膜蛋白和小白蛋白的。在含钙视网膜蛋白和含钙结合蛋白D28k的细胞群体之间检测到一些重叠，前者的5.1%和后者的6.2%对两种钙结合蛋白都呈免疫反应。这可能是由于钙结合蛋白D28k抗血清与钙视网膜蛋白有一定程度的交叉反应。因此，我们的结果表明，大多数钙视网膜蛋白免疫反应性神经元是GABA能的，并且代表了非锥体细胞的一个亚群，与含有其他钙结合蛋白（小白蛋白和钙结合蛋白）的亚群没有或只有可忽略不计的重叠。
