Medical Research Council Anatomical Neuropharmacology Unit, Department of Pharmacology, Oxford University Oxford, UK.
Front Neural Circuits. 2012 May 31;6:35. doi: 10.3389/fncir.2012.00035. eCollection 2012.
Neuronal nitric oxide synthase-expressing (nNOS+) GABAergic interneurons are common in hippocampal stratum (str.) radiatum. However, these cells are less well characterized than nNOS+ ivy cells in str. pyramidale or neurogliaform cells (NGC) in str. lacunosum-moleculare. Here we have studied the laminar distribution of the axons and dendrites, and the immunoreactivity of these neurons recorded in rat hippocampal slices. We have used spectral analysis of antibody- or streptavidin-conjugated fluorophores to improve recognition of genuine signals in reactions for molecules such as nNOS and neuropeptide-Y (NPY). We found that most nNOS+ cells with soma in the CA1 area str. radiatum exhibit characteristic properties of ivy cells, and were positive for NPY and negative for reelin. However, laminar distributions of their neurites differ from original characterization of ivy cells with the soma in or close to str. pyramidale. Both their dendrites and axon are mainly in str. radiatum and to a lesser extent in str. oriens, and in addition often extend to str. lacunosum-moleculare. We conclude that ivy cells in str. radiatum may predominantly be feedforward inhibitory interneurons in the CA1 area, and their axonal output delivering GABA, NPY, and NO can influence both the entorhinal cortex innervated and the CA3 innervated zones pre- and post-synaptically. Spectral analysis of fluorophores provides an objective algorithm to analyze signals in immunoreactions for neurochemical markers.
表达神经元型一氧化氮合酶（nNOS+）的 GABA 能中间神经元在海马放射层中很常见。然而，这些细胞的特征不如在海马锥体层中的 nNOS+常春藤细胞或在海马分子层中的神经胶质形态细胞（NGC）那样被充分描述。在这里，我们研究了这些神经元在大鼠海马切片中记录的轴突和树突的层分布以及它们的免疫反应。我们使用抗体或链霉亲和素缀合荧光团的光谱分析来提高对 nNOS 和神经肽 Y（NPY）等分子的真实信号的识别。我们发现，CA1 区放射层中具有胞体的大多数 nNOS+细胞表现出常春藤细胞的特征特性，并且对 NPY 呈阳性，对 reelin 呈阴性。然而，它们的神经突的层分布与原始的常春藤细胞的特征不同，原始的常春藤细胞的胞体位于或靠近锥体层。它们的树突和轴突主要位于放射层，程度较小的位于始层和扇形体层，并且还经常延伸到分子层。我们得出结论，放射层中的常春藤细胞可能主要是 CA1 区的前馈抑制性中间神经元，其 GABA、NPY 和 NO 的轴突输出可以影响受传入的内嗅皮层和受传入的 CA3 区的突触前和突触后。荧光团的光谱分析提供了一种客观的算法来分析神经化学标志物免疫反应中的信号。
