โ Scribed by Daisuke Yamashita; Shujiro B. Minami; Sho Kanzaki; Kaoru Ogawa; Josef M. Miller
No coin nor oath required. For personal study only.
Proteins of the Bclโ2 family have been implicated in control of apoptotic pathways modulating neuronal cell death, including noiseโinduced hearing loss. In this study, we assessed the expressions of antiโ and proapoptotic Bclโ2 genes, represented by BclโxL and Bak following noise exposures, which yielded temporary threshold shift (TTS) or permanent threshold shift (PTS). Auditory brainstem responses (ABRs) were assessed at 4, 8, and 16 kHz before exposure and on days 1, 3, 7, and 10 following exposure to 100 dB SPL, 4 kHz OBN, 1 hr (TTS) or 120 dB SPL, 4 kHz OBN, 5 hr (PTS). On day 10, subjects were euthanized. ABR thresholds increased following both exposures, fully recovered following the TTS exposure, and showed a 22.6 dB (4 kHz), 42.5 dB (8 kHz), and 44.9 dB (16 kHz) mean shift on day 10 following the PTS exposure. PTS was accompanied by outer hair cell loss progressing epically and basally from the 4โkHz region. Additional animals were euthanized for immunohistochemical assessment. BcLโxL was robustly expressed in outer hair cells following TTS exposure, whereas Bak was expressed following PTS exposure. These results indicate an important role of the Bclโ2 family proteins in regulating sensory cell survival or death following intense noise. BclโxL plays an essential role in prevention of sensory cell death following TTS levels of noise, and PTS exposure provokes the expression of Bak and, with that, cell death. ยฉ 2007 WileyโLiss, Inc.
๐ SIMILAR VOLUMES
## Abstract Acoustic overstimulation increases Ca^2+^ concentration in auditory hair cells. Because calcineurin is known to activate cell death pathways and is controlled by Ca^2+^ and calmodulin, this study assessed the role of calcineurin in auditory hair cell death in guinea pigs after intense n
## Abstract ## Objectives/Hypothesis: The purpose of this study is to investigate whether diabetes impairs the recovery from noisedโinduced temporary hearing loss. ## Methods: Twentyโeight male Wistar rats were divided into three groups: control, diabetes with insulin control (DI), and diabetes