Bcl-2 genes regulate noise-induced hearing loss.
Proteins of the Bcl-2 family have been implicated in control of apoptotic pathways modulating neuronal cell death, including noise-induced hearing loss. In this study, we assessed the expressions of anti- and proapoptotic Bcl-2 genes, represented by Bcl-xL 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 4-kHz region. Additional animals were euthanized for immunohistochemical assessment. BcL-xL 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 Bcl-2 family proteins in regulating sensory cell survival or death following intense noise. Bcl-xL 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.
Objective(s): Noise-induced hearing loss (NIHL) is the major cause of acquired hearing loss. Celecoxib, a cyclooxygenase-2 (COX-2) inhibitor, is a non- steroidal anti- inflammatory drug (NSAID) with known antioxidant and antineoplastic activity. Therefore, we monitored the extent of temporary noise- induced threshold shifts (TTS) and cochlear damage caused by high level 4- kHz noise exposure t...متن کامل
Introduction: It has been shown that low levels of pigmentation increase susceptibility to noise-induced hearing loss in humans. For this reason, white populations develop more pronounced noise- induced hearing loss in comparison to black populations. Similarly, blue-eyed individuals exhibit greater temporary threshold shift than brown-eyed subjects; still, no strong correlation has been veri...متن کامل
Preconditioning by the inhalation of pure oxygen protects rat’s cochlear function against noise-induced hearing loss
Background: Occupational noise-induced hearing loss (ONIHL) is a hearing disorder that affects workers all over the world. Preconditioning with several mild or less potent stressors will effectively prevent the development of noise-induced hearing loss. This study investigated the possible preventive effects of normobaric hyperoxia preconditioning on preventing the noise-induced hearing impairm...متن کامل
Introduction: Nowadays, noise exposure is one of the most important industrial health problems. Noise exposure can cause hearing loss and many other health problems. So, paying attention to the noise exposure problem should be of main priority in industrial health programs. This study was conducted in an oil producing region, aimed to assess noise pollution and noise induced hearing loss. Met...متن کامل
Introduction: Exposure to hazardous noise induces one of the forms of acquired and preventable hearing loss that is noise-induced hearing loss (NIHL). Considering oxidative stress as the main mechanism of NIHL, it is possible that myricetin can protect NIHL by its antioxidant effect. Therefore, the present study aimed to investigate the preventive effect of myricetin on NIHL. <br /...متن کامل