Premium
Quantitative analysis of neuronal nitric oxide synthase‐immunoreactive neurons in the mouse hippocampus with optical disector
Author(s) -
Jinno Shozo,
Aika Yusuke,
Fukuda Takaichi,
Kosaka Toshio
Publication year - 1999
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/(sici)1096-9861(19990802)410:3<398::aid-cne4>3.0.co;2-9
Subject(s) - colocalization , glutamate decarboxylase , biology , hippocampus , hippocampal formation , dentate gyrus , nitric oxide synthase , neuroscience , anatomy , endocrinology , nitric oxide , biochemistry , enzyme
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 × 10 3 /mm 3 ) to ventral (2.2 × 10 3 /mm 3 ) 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 γ‐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. J. Comp. Neurol. 410:398–412, 1999. © 1999 Wiley‐Liss, Inc.