title: Cisplatin-induced apoptotic cell death in Mongolian gerbil cochlea.
abstract: Cisplatin is well known to cause cochleotoxicity. In order to determine the underlying mechanisms of cisplatin-induced cell death in the cochlea, we investigated the apoptotic changes and the expression of bcl-2 family proteins controlling apoptosis. Mongolian gerbils were administered 4 mg/kg/day cisplatin consecutively for 5 days. The cisplatin-treated animals showed a significant deterioration in the responses of both distortion product otoacoustic emissions and the endocochlear potential as compared with those of the age-matched controls, suggesting outer hair cell and stria vascularis dysfunction. The presence of DNA fragmentation revealed by a terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labelling method was recognized in the organ of Corti, the spiral ganglion, and the stria vascularis in the cisplatin-treated animals whereas almost negative results were obtained in the control animals. The nuclear morphology obtained by Hoechst 33342 staining revealed pyknotic and condensed nuclei, confirming the presence of the characteristic features of apoptosis. A significant increase and reduction in the number of bax- and bcl-2-positive cells, respectively, following cisplatin treatment was observed in the cells of the organ of Corti, the spiral ganglion, and the lateral wall. These findings suggest a critical role for bcl-2 family proteins in the regulation of apoptotic cell death induced by cisplatin. The underlying mechanisms of the cisplatin-induced cell death are discussed.
authors.affiliation: Department of Otorhinolaryngology, Head and Neck Surgery, Tohoku University School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai, Japan.
authors.forename: S A
authors.initials: SA
authors.lastname: Alam
authors.forename: K
authors.initials: K
authors.lastname: Ikeda
authors.forename: T
authors.initials: T
authors.lastname: Oshima
authors.forename: M
authors.initials: M
authors.lastname: Suzuki
authors.forename: T
authors.initials: T
authors.lastname: Kawase
authors.forename: T
authors.initials: T
authors.lastname: Kikuchi
authors.forename: T
authors.initials: T
authors.lastname: Takasaka
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000633:toxicity*; D017209:Apoptosis / Q000187:drug effects*; D002467:Cell Nucleus / Q000187:drug effects / Q000473:pathology; D002945:Cisplatin / Q000633:toxicity*; D003051:Cochlea / Q000187:drug effects* / Q000473:pathology* / Q000503:physiopathology; D053938:DNA Fragmentation / Q000187:drug effects; D004594:Electrophysiology; D005260:Female; D005849:Gerbillinae; D006319:Hearing Loss, Sensorineural / Q000139:chemically induced / Q000473:pathology / Q000503:physiopathology; D007150:Immunohistochemistry; D008297:Male; D009925:Organ of Corti / Q000187:drug effects / Q000473:pathology / Q000503:physiopathology; D017084:Otoacoustic Emissions, Spontaneous / Q000187:drug effects; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D013136:Spiral Ganglion / Q000187:drug effects / Q000473:pathology / Q000503:physiopathology; D013316:Stria Vascularis / Q000187:drug effects / Q000473:pathology / Q000502:physiology; D014018:Tissue Distribution; D051028:bcl-2-Associated X Protein
chemical_list: D000970:Antineoplastic Agents; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; D002945:Cisplatin