Morphological basis of nitric oxide production and its correlation with the polysialylated precursor cells in the dentate gyrus of the adult guinea pig hippocampus

• Published in: Anatomical Science International 2003-06, Vol.78 (2), p.98-103
• Main Authors: Islam, A. T. M. Shariful, Kuraoka, Akio, Kawabuchi, Masaru
• Format: Article
• Language: English
• Subjects: adult hippocampus; Animals; Cell adhesion molecules; Cell Differentiation - physiology; Cell Size - physiology; Dendrites - metabolism; Dendrites - ultrastructure; Dendritic spines; Dentate gyrus; Dentate Gyrus - cytology; Dentate Gyrus - growth & development; Dentate Gyrus - metabolism; Female; guinea pig; Guinea Pigs; highly polysialylated neural cell adhesion molecule; Hippocampus; immunocytochemistry; Immunohistochemistry; Immunoreactivity; Localization; Male; Microscopy, Confocal; Neural cell adhesion molecule; Neural Cell Adhesion Molecule L1 - metabolism; Neural stem cells; Neurogenesis; Neurons - cytology; Neurons - metabolism; Nitrergic Neurons - metabolism; Nitrergic Neurons - ultrastructure; Nitric oxide; Nitric Oxide - biosynthesis; Nitric Oxide Synthase - metabolism; Nitric-oxide synthase; Sialic Acids - metabolism; Stem Cells - cytology; Stem Cells - metabolism
• ISSN: 1447-6959; 0022-7722; 1447-073X
• DOI: 10.1046/j.0022-7722.2003.00045.x

Neurogenesis in the hippocampus persist throughout life and precursors of neurons reside in the granule cell layer of the dentate gyrus. Until now, the role of nitric oxide (NO) in the phenomenon has been unclear. By using specific antibodies and a confocal laser scanning microscope, the localization of NO synthase (NOS) was examined in the dentate gyrus of the adult guinea pig in relation with the neuronal precursor marker highly polysialylated neural cell adhesion molecule (PSA‐N‐CAM). Observation of single immunolabeled sections has revealed that both the PSA‐N‐CAM‐ and most NOS‐positive cells were localized in the granule cell layer of the dentate gyrus. The former were small in size and showed a punctate, clustered immunoreaction with an irregular cellular margin, whereas the latter showed somewhat diverse cellular profiles. Some NOS‐positive neurons had elliptical‐like morphology with elongated dendrites, whereas others were small, irregularly shaped and mostly lacking dendritic spines. Double immunolabeling has revealed that NOS‐immunoreactivity intermingled, as well as colocalized, with that of PSA‐N‐CAM, particulary in the granule cell layer. The doubly stained cells were morphologically indistinguishable from PSA‐N‐CAM single positive cells. These results not only suggest the role of NO production in adult hippocampal neurogenesis, but also indicate that some PSA‐N‐CAM‐expressing neuronal precursors produce NO.