title: Excitotoxic effects of glutamate on cochlear organotypic cultures.
abstract: Glutamate (Glu) is the major afferent excitatory neurotransmitter in the auditory system, and excessive Glu may play an important role in cochlear dysfunction. It is unclear how excessive Glu plays roles in cochlear dysfunction in cochlear organotypic cultures. In this study neonatal rat cochlear organotypic cultures were prepared, and then the cochlear tissues were incubated with a new medium containing specific concentrations of Glu (0.1, 0.5, 1, 10 or 20 mmol/L) for 24 h, or incubated with the medium containing a concentration of 20 mmol/L Glu for 6, 12, 24 or 72 h, respectively. It was found that when the cochlear tissues were cultured for 24 h, the inner hair cells (IHCs) were damaged at the concentration of 0.5 mmol/L Glu, and with the increases of the concentrations, the injury was gradually aggravated, and 20 mmol/L Glu resulted in the significant loss of IHCs. In the 20 mmol/L Glu groups, the stereocilia bundles were missing or disarrayed on a few IHCs after culture for 6 h and the damage effect was time-dependent. The missing of IHCs was more significant in the basal turn of the cochlea than in the middle turn of the cochlea under the same concentration of Glu exposure. These results suggest that excessive exogenous Glu affects the morphology of IHCs, but not affects the outer hair cells (OHCs) in cochlear organotypic cultures, and the excitotoxic effects are different on IHCs of different parts of the cochlea under the same concentration of Glu exposure.
authors: Department of Otolaryngology-Head and Neck Surgery, Wuhan Central Hospital, Wuhan, 430014, China.
authors: Yao
authors: Y
authors: Hu
authors: Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China.
authors: Liu-Qing
authors: LQ
authors: Zhou
authors: Department of Otorhinolaryngology, Jingzhou Central Hospital, Jingzhou, 434020, China.
authors: Hai-Tao
authors: HT
authors: Lu
authors: Department of Otolaryngology-Head and Neck Surgery, Wuhan Central Hospital, Wuhan, 430014, China. entyuankun@163.com.
authors: Kun
authors: K
authors: Yuan
authors: Department of Otolaryngology-Head and Neck Surgery, Affiliated Beijing Tongren Hospital of Capital Medical University and Beijing Institute of Otolaryngology, Beijing, 100069, China. gongss@trhos.com.
authors: Shu-Sheng
authors: SS
authors: Gong
mesh_terms: D000818:Animals; D003051:Cochlea / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D018698:Glutamic Acid / Q000633:toxicity*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D018698:Glutamic Acid