TY - JOUR T1 - Caspase Activation in Hair Cells of the Mouse Utricle Exposed to Neomycin JF - The Journal of Neuroscience JO - J. Neurosci. SP - 8532 LP - 8540 DO - 10.1523/JNEUROSCI.22-19-08532.2002 VL - 22 IS - 19 AU - Lisa L. Cunningham AU - Alan G. Cheng AU - Edwin W Rubel Y1 - 2002/10/01 UR - http://www.jneurosci.org/content/22/19/8532.abstract N2 - Aminoglycoside exposure results in the apoptotic destruction of auditory and vestibular hair cells. This ototoxic hair cell death is prevented by broad-spectrum caspase inhibition. We have used in situ substrate detection, immunohistochemistry, and specific caspase inhibitors to determine which caspases are activated in the hair cells of the adult mouse utricle in response to neomycin exposurein vitro. In addition, we have examined the hierarchy of caspase activation. Our data indicate that both upstream caspase-8 and upstream caspase-9, as well as downstream caspase-3 are activated in hair cells exposed to neomycin. The inhibition of caspase-9-like activity provided significant protection of hair cells exposed to neomycin, whereas the inhibition of caspase-8-like activity was not effective in preventing neomycin-induced hair cell death. In addition, caspase-9 inhibition prevented the activation of downstream caspase-3, whereas the inhibition of caspase-8 did not. These data indicate that caspase-9 is the primary upstream caspase mediating neomycin-induced hair cell death in this preparation. ER -