title: A novel technique for inducing local inner ear damage.
abstract: With significant development of mouse genomics and the availability of transgenic and knockout mice, the mouse will be the preferred animal model for inner ear research. However, few studies have used mice as experimental animals for examination of hair cell degeneration, because of their relative resistance to ototoxic agents and difficulties in surgical treatment. This study presents a model for induction of apoptotic cell death in sensory epithelia of the mouse inner ear using injection of neomycin into the posterior semicircular canal. Terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) assay revealed that local application of neomycin produced sufficient induction of apoptotic cell death in both auditory and vestibular epithelia over a definite time course. Supplementation of the general caspase-inhibitor significantly reduced induction of TUNEL-positive cells, indicating caspase-dependency of apoptotic cell death observed in the present model. In addition, the approach to the posterior semicircular canal was an easy technique, and sham-operation induced no significant induction of TUNEL-positive cells. This model, hence, enables the use of various genetic tools in studies for mechanisms of hair cell apoptosis.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Kyoto University, Graduate School of Medicine, 54 Kawahara-cho, Shogoin, Sakyo-ku, 606-8507 Kyoto, Japan. tnakagawa@ent.kuhp.kyoto-u.ac.jp
authors.forename: Takayuki
authors.initials: T
authors.lastname: Nakagawa
authors.forename: Tae Soo
authors.initials: TS
authors.lastname: Kim
authors.forename: Norihiko
authors.initials: N
authors.lastname: Murai
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Endo
authors.forename: Fukuichiro
authors.initials: F
authors.lastname: Iguchi
authors.forename: Ichiro
authors.initials: I
authors.lastname: Tateya
authors.forename: Norio
authors.initials: N
authors.lastname: Yamamoto
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Naito
authors.forename: Juichi
authors.initials: J
authors.lastname: Ito
mesh_terms: D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000818:Animals; D000900:Anti-Bacterial Agents / Q000008:administration & dosage*; D017209:Apoptosis; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism; D003051:Cochlea / Q000187:drug effects / Q000503:physiopathology; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D007758:Ear, Inner / Q000187:drug effects* / Q000503:physiopathology*; D004848:Epithelium / Q000187:drug effects / Q000503:physiopathology; D018072:Hair Cells, Auditory, Outer / Q000503:physiopathology; D020287:In Situ Nick-End Labeling; D007267:Injections; D051379:Mice; D008810:Mice, Inbred C57BL; D009355:Neomycin / Q000008:administration & dosage*; D012444:Saccule and Utricle / Q000187:drug effects / Q000503:physiopathology; D012665:Semicircular Canals / Q000187:drug effects* / Q000503:physiopathology*; D013997:Time Factors; D014722:Vestibule, Labyrinth / Q000187:drug effects / Q000503:physiopathology
chemical_list: D000590:Amino Acid Chloromethyl Ketones; D000900:Anti-Bacterial Agents; D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D020169:Caspases; D009355:Neomycin