Tóth K, Freund T F
Department of Functional Neuroanatomy, Hungarian Academy of Sciences, Budapest.
Neuroscience. 1992 Aug;49(4):793-805. doi: 10.1016/0306-4522(92)90357-8.
Calbindin D28k-containing non-pyramidal cells were found in all layers and subfields of the hippocampus, with the highest frequency in stratum radiatum of the CA1-CA3 subfields. A large number of these neurons had a vertically oriented dendritic tree, often restricted to to stratum radiatum. In stratum oriens and near to the border of strata radiatum and lacunosum moleculare cells with horizontally running dendrites were also found. Multipolar cells were most common in stratum radiatum of the CA3 region. The GABAergic nature of the calbindin D28k-containing non-pyramidal cells was studied using the "mirror" technique. Adjacent thick sections were immunostained for calbindin D28k and GABA, and halved neurons were identified on the common surfaces. The majority of calbindin D28k-containing non-pyramidal cells were shown to be GABAergic. The GABA-negative calbindin cells were found in relatively large numbers in stratum oriens of the CA1-CA3 region, and occasionally in strata radiatum and pyramidale of CA2, and in stratum radiatum of the CA3c region near to the border of the dentate hilus. However, even in these cells a weak immunostaining, only slightly but consistently above background level, was always observed. Earlier studies have demonstrated that the somata of GABAergic neurons with distant projections may contain a level of GABA that is below the detection threshold of immunocytochemistry. Here we provide direct evidence that the calbindin-containing non-pyramidal cells were among those projecting to the medial septum. Following horseradish peroxidase injections into the medial septum 80% of the retrogradely labelled non-pyramidal cells were found to be immunoreactive for calbindin D28k, and 20% contained neuropeptide Y. These results suggest that the calbindin D28k-containing and apparently GABA-immunonegative non-pyramidal cells in stratum oriens of the CA1-CA3 regions may also be GABAergic, but have a distant projection, that is, to the medial septum.
在海马体的所有层和亚区中均发现了含有钙结合蛋白D28k的非锥体细胞，在CA1-CA3亚区的辐射层中出现频率最高。大量此类神经元具有垂直排列的树突，通常局限于辐射层。在海马体的原层以及靠近辐射层和分子层边界的地方，也发现了具有水平延伸树突的细胞。多极细胞在CA3区的辐射层中最为常见。使用“镜像”技术研究了含有钙结合蛋白D28k的非锥体细胞的GABA能性质。相邻的厚切片用钙结合蛋白D28k和GABA进行免疫染色，并在共同表面识别出对半的神经元。大多数含有钙结合蛋白D28k的非锥体细胞显示为GABA能。在CA1-CA3区的原层中发现相对大量的GABA阴性钙结合蛋白细胞，偶尔在CA2的辐射层和锥体层，以及靠近齿状回门边界的CA3c区的辐射层中也有发现。然而，即使在这些细胞中，也总是观察到微弱的免疫染色，仅略高于背景水平但始终一致。早期研究表明，具有远距离投射的GABA能神经元的胞体可能含有低于免疫细胞化学检测阈值的GABA水平。在这里，我们提供直接证据表明，含有钙结合蛋白的非锥体细胞是投射到内侧隔区中的细胞之一。将辣根过氧化物酶注射到内侧隔区后，发现80%逆行标记的非锥体细胞对钙结合蛋白D28k具有免疫反应性，20%含有神经肽Y。这些结果表明，CA1-CA3区原层中含有钙结合蛋白D28k且显然GABA免疫阴性的非锥体细胞也可能是GABA能的，但具有远距离投射，即投射到内侧隔区。
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