Nomura T, Fukuda T, Aika Y, Heizmann C W, Emson P C, Kobayashi T, Kosaka T
Department of Anatomy and Neurobiology, Faculty of Medicine, Kyushu University, Fukuoka, Japan.
Brain Res. 1997 Aug 1;764(1-2):197-204. doi: 10.1016/s0006-8993(97)00457-5.
In the present study we examined the laminar distributions of four types of chemically defined subpopulations of non-principal neurons, that is, those immunoreactive for parvalbumin (PV), calretinin (CR), nitric oxide synthase (NOS) and somatostatin (SS), in the rat hippocampus, by estimating their approximate numerical densities (NDs) and percentages in specific layers according to the 'disector' principle. CR-immunoreactive (CR-IR) neurons and NOS-IR neurons were scattered throughout layers, but among layers in each subdivision their NDs were largest in the principal cell layers, where 30-45% of CR-IR and NOS-IR somata in each subdivision were located. In addition, CR-IR and NOS-IR somata were also concentrated at the border between the stratum radiatum (SR) and stratum lacunosum moleculare (SLM) in the CA1 region, where the NDs of these neurons were far larger than those in the SR/SLM as a whole and close to those in the stratum pyramidale (SP) (CR-IR somata at the ventral level and NOS-IR somata at the dorsal level) or larger (NOS-IR neurons at the ventral level). The NDs of CR-IR somata were dorsoventrally different in all layers of the CA3 region, the SR/SLM in the CA1 region and the hilus and the granule cell layer (GCL) of the dentate gyrus (DG), whereas the NDs of NOS-IR somata were dorsoventrally different in all layers of the CA3 region and the SP in the CA1 region. In contrast, approx. 90% of somatostatin-like immunoreactive (SS-LIR) neurons were located in the stratum oriens/alveus (SO/SA) in the CA1 region and in the hilus of the DG, where they were the most predominant cell type among the four types of non-principal cells. In contrast, in the CA3 region, SS-LIR somata were scattered in various layers. The majority (50-70%) of PV-IR neurons were located in the principal cell layers, whereas one-fourth to one-third of them were located in the SO/SA and hilus. The NDs in the SP of the CA1 and CA3 regions showed a significant dorsoventral difference. Although PV-IR somata were most numerous among the four non-principal cell groups in the SP of the dorsal CA1 region, they were not necessarily predominant in the principal layers in other regions, that is, in the ventral CA1 region, CA3 region and DG, where the NDs of CR-IR and/or NOS-IR somata were nearly equal to or larger than that of PV-IR somata. The present study not only reveals the laminar distribution patterns of four types of non-principal neurons in each subdivision quantitatively, but also illustrates the prominent differences in the compositions of four types of non-principal cells in each layer of each subdivision.
在本研究中，我们通过根据“分割柱”原理估计大鼠海马体中四种化学定义的非主要神经元亚群（即对小白蛋白（PV）、钙视网膜蛋白（CR）、一氧化氮合酶（NOS）和生长抑素（SS）免疫反应的神经元）的近似数值密度（NDs）和在特定层中的百分比，来研究它们的分层分布。CR免疫反应性（CR-IR）神经元和NOS-IR神经元散布于各层，但在每个亚区的各层中，它们的NDs在主要细胞层中最大，每个亚区中30-45%的CR-IR和NOS-IR胞体位于该层。此外，CR-IR和NOS-IR胞体也集中在CA1区辐射层（SR）和分子层（SLM）之间的边界处，这些神经元在此处的NDs远大于SR/SLM整体的NDs，且接近锥体层（SP）的NDs（腹侧水平的CR-IR胞体和背侧水平的NOS-IR胞体）或更大（腹侧水平的NOS-IR神经元）。CR-IR胞体的NDs在CA3区的所有层、CA1区的SR/SLM以及齿状回（DG）的海马沟和颗粒细胞层（GCL）中存在背腹差异，而NOS-IR胞体的NDs在CA3区的所有层和CA1区的SP中存在背腹差异。相比之下，约90%的生长抑素样免疫反应性（SS-LIR）神经元位于CA1区的海马旁回/海马槽（SO/SA）和DG的海马沟中，它们是四种非主要细胞类型中最主要的细胞类型。相比之下，在CA3区，SS-LIR胞体散布于各层。大多数（50-70%）的PV-IR神经元位于主要细胞层，而其中四分之一到三分之一位于SO/SA和海马沟。CA1区和CA3区SP中的NDs存在显著的背腹差异。尽管在背侧CA1区的SP中，PV-IR胞体在四种非主要细胞组中数量最多，但在其他区域的主要层中它们不一定占主导地位，即在腹侧CA1区、CA3区和DG中，CR-IR和/或NOS-IR胞体的NDs几乎等于或大于PV-IR胞体的NDs。本研究不仅定量揭示了每个亚区中四种非主要神经元的分层分布模式，还阐明了每个亚区各层中四种非主要细胞组成的显著差异。
