Jinno S, Aika Y, Fukuda T, Kosaka T
Department of Anatomy and Neurobiology, Faculty of Medicine, Kyushu University, Fukuoka, Japan.
J Comp Neurol. 1999 Aug 2;410(3):398-412.
A detailed quantitative analysis of immunocytochemically identified nonprincipal neurons containing neuronal nitric oxide synthase (nNOS) was performed on the mouse hippocampus, with particular reference to the dorsoventral gradient. The present study applied two variations of a stereologic technique, the optical disector--one that used confocal laser-scanning microscope optical sections to examine colocalization of nNOS and glutamic acid decarboxylase 67 (GAD67), and the other that used conventional thick sections to examine numerical densities (NDs) and cell sizes of nNOS-immunoreactive (IR) neurons. Colocalization analysis indicated that practically all nNOS-IR neurons (97.6%) were GAD67-IR, whereas a part of the GAD67-IR neurons (about 30%) were nNOS-IR in the whole hippocampus at both dorsal and ventral levels. The percentages of GAD67-IR neurons containing nNOS were higher in the dentate gyrus (DG, about 50%), and lower in the Ammon's horn (about 20%). Laminar analysis revealed that the majority of GAD67-IR neurons contained nNOS in the stratum lacunosum-moleculare of the CA3 region (about 60%) and in the molecular layer of the DG (about 80%). The NDs of nNOS-IR neurons in the whole hippocampus showed a dorsoventral gradient, which increased from dorsal (1.6 x 10(3)/mm3) to ventral (2.2 x 10(3)/mm3) levels. The NDs were relatively higher in the principal cell layers, where about 40% of nNOS-IR neurons were situated both in the Ammon's horn and DG. The mean cell sizes of nNOS-IR neurons showed no remarkable laminar differences or dorsoventral gradient in the Ammon's horn, but they were extensively larger in the hilus of the DG than in other layers. These results indicate that nNOS-IR neurons in the mouse hippocampus represent a subpopulation of gamma-aminobutyric acid (GABA)ergic neurons and suggest that the laminar distributions of nNOS-IR neurons related to possible functional heterogeneity of GABAergic neurons in each hippocampal layer.
对小鼠海马体中通过免疫细胞化学鉴定出的含有神经元型一氧化氮合酶（nNOS）的非主要神经元进行了详细的定量分析，特别关注背腹梯度。本研究应用了两种立体学技术变体，即光学分割器——一种使用共聚焦激光扫描显微镜光学切片来检测nNOS与谷氨酸脱羧酶67（GAD67）的共定位，另一种使用传统厚切片来检测nNOS免疫反应性（IR）神经元的数量密度（NDs）和细胞大小。共定位分析表明，实际上所有nNOS-IR神经元（97.6%）都是GAD67-IR，而在整个海马体的背侧和腹侧水平，一部分GAD67-IR神经元（约30%）是nNOS-IR。在齿状回（DG，约50%）中含有nNOS的GAD67-IR神经元百分比更高，而在海马角（约20%）中更低。分层分析显示，大多数GAD67-IR神经元在CA3区的腔隙分子层（约60%）和DG的分子层（约80%）中含有nNOS。整个海马体中nNOS-IR神经元的NDs呈现背腹梯度，从背侧（1.6×10³/mm³）到腹侧（2.2×10³/mm³）水平增加。在主要细胞层中NDs相对较高，在海马角和DG中约40%的nNOS-IR神经元位于此处。nNOS-IR神经元的平均细胞大小在海马角中没有明显的分层差异或背腹梯度，但在DG的hilus中比其他层大得多。这些结果表明，小鼠海马体中的nNOS-IR神经元代表γ-氨基丁酸（GABA）能神经元的一个亚群，并表明nNOS-IR神经元的分层分布与每个海马层中GABA能神经元可能的功能异质性有关。
