title: Leupeptin protects cochlear and vestibular hair cells from gentamicin ototoxicity.
abstract: Calpains, a family of calcium-activated proteases that breakdown proteins, kinases, phosphatases and transcription factors, can promote cell death. Since leupeptin, a calpain inhibitor, protected against hair cell loss from acoustic overstimulation, we hypothesized that it might protect cochlear and vestibular hair cells against gentamicin (GM) ototoxicity. To test this hypothesis, mouse organotypic cultures from the cochlea, maculae of the utricle and the crista of the semicircular canal (P1-P3) were treated with different doses of GM (0.1-3 mM) alone or in the presence of leupeptin (0.1-3 mM). The percentage of outer hair cells (OHCs) and inner hair cells (IHCs) decreased with increasing doses of GM between 0.1 and 3 mM. The addition of 1 mM of leupeptin significantly reduced GM-induced damage to IHCs and OHCs; this protective effect was dose-dependent. GM also significantly reduced hair cell density in the crista and utricle in a dose-dependent manner between 0.1 and 3 mM. The addition of 1 mM of leupeptin significantly reduced hair cell loss in the crista and utricle for GM concentrations between 0.1 and 3 mM. These results suggest that one of the early steps in GM ototoxicity may involve calcium-activated proteases that lead to the demise of cochlear and vestibular hair cells.
authors.affiliation: Hearing Research Lab, 215 Parker Hall, SUNY University at Buffalo, NY 14214, USA.
authors.forename: Dalian
authors.initials: D
authors.lastname: Ding
authors.forename: Alfred
authors.initials: A
authors.lastname: Stracher
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Salvi
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000037:antagonists & inhibitors* / Q000633:toxicity*; D002154:Calpain / Q000378:metabolism; D003051:Cochlea / Q000187:drug effects / Q000293:injuries / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005839:Gentamicins / Q000008:administration & dosage / Q000037:antagonists & inhibitors* / Q000633:toxicity*; D006198:Hair Cells, Auditory / Q000187:drug effects* / Q000293:injuries* / Q000378:metabolism; D006199:Hair Cells, Auditory, Inner / Q000187:drug effects / Q000293:injuries / Q000378:metabolism; D018072:Hair Cells, Auditory, Outer / Q000187:drug effects / Q000293:injuries / Q000378:metabolism; D007976:Leupeptins / Q000008:administration & dosage / Q000494:pharmacology*; D051379:Mice; D008854:Microscopy, Electron; D009924:Organ Culture Techniques; D012444:Saccule and Utricle / Q000187:drug effects / Q000293:injuries / Q000378:metabolism; D012665:Semicircular Canals / Q000187:drug effects / Q000293:injuries / Q000378:metabolism; D014722:Vestibule, Labyrinth / Q000187:drug effects / Q000293:injuries / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D005839:Gentamicins; D007976:Leupeptins; D002154:Calpain; C032854:leupeptin