Immunoelectron microscopic analysis of neurotoxic effect of glutamate in the vestibular end organs during ischemia

• Published in: Acta oto-laryngologica Vol. 132; no. 7; pp. 686 - 692
• Main Authors: Sasaki, Akira, Matsubara, Atsushi, Tabuchi, Keiji, Hara, Akira, Namba, Atsushi, Yamamoto, Youhei, Shinkawa, Hideichi
• Format: Journal Article
• Language: English
• Published: Stockholm Informa Healthcare 01-07-2012; Taylor & Francis; Informa
• Subjects: Animals; Biological and medical sciences; Disease Models, Animal; electron microscope; Glutamatergic excitotoxicity; Glutamic Acid - metabolism; Guinea Pigs; Hair Cells, Auditory, Inner - metabolism; Hair Cells, Auditory, Inner - pathology; immunocytochemistry; Ischemia - etiology; Ischemia - metabolism; Ischemia - pathology; labyrinthine artery; Medical sciences; Microscopy, Immunoelectron; morphological change; Otorhinolaryngology. Stomatology; post-embedding immunogold labeling; Presynaptic Terminals - metabolism; Presynaptic Terminals - pathology; Risk Factors; Time Factors; vestibule; Vestibule, Labyrinth - blood supply; Vestibule, Labyrinth - metabolism; Vestibule, Labyrinth - pathology; Microscope; morphological change; post-embedding immunogold labeling; labyrinthine artery; Immunocytochemistry; Cardiovascular disease; ENT; Glutamate; Glutamatergic excitotoxicity; Vestibule; Artery; Anatomic pathology; Ischemia; electron microscope; Organ
• ISSN: 0001-6489; 1651-2251
• DOI: 10.3109/00016489.2012.656322

Abstract
Conclusion: The excessive glutamate released from the type I and type II hair cells and the supporting cells injure the bouton-type endings and the nerve chalices in 30 min ischemia, and neuronal damage of glutamate was slight in 10 min ischemia. Objective: In the present study, we investigated by means of post-embedding immunoelectron microscopic analysis whether neuronal damage in the vestibular end organs is associated with the change of cellular glutamate concentration during ischemia. Methods: Transient local anoxia (10 min, 30 min) of guinea pig inner ear was induced by pressing the left labyrinthine artery. The right sides were used as controls. The morphological changes of the vestibular end organs and the areal gold particle densities representing glutamate were compared in the ischemia side and the control side. Results: The areal gold particle densities of the type I and type II hair cells and the supporting cells in the ischemic side were lower than those of the control side. There were no remarkable morphological changes compared to the control side in 10 min ischemia. In 30 min ischemia, the bouton-type endings were swollen and intercellular spaces between the type I hair cells and the nerve chalices were enlarged.