Hidden hearing loss is associated with loss of ribbon synapses of cochlea inner hair cells
Biosci Rep. 2021 Mar 18:BSR20201637. doi: 10.1042/BSR20201637. Online ahead of print.
This study aimed to observe the changes in the cochlea ribbon synapses after repeated exposure to moderate-to-high intensity noise. Guinea pigs received 95 dB SPL white noise exposure 4 hours a day for consecutive 7 days (we regarded it a medium-term and moderate-intensity noise, or MTMI noise). Animals were divided into 4 groups: Control, 1DPN (1-day post noise), 1WPN (1-week post noise), and 1MPN (1-month post noise). Auditory function analysis by ABR and CAP recordings, as well as ribbon synapse morphological analyses by immunohistochemistry (Ctbp2 and PSD95 staining) were performed one day, one week, and one month after noise exposure. After MTMI noise exposure, the amplitudes of auditory brainstem response (ABR) I and III waves were suppressed. The compound action potential (CAP) threshold was elevated, and CAP amplitude was reduced in the 1DPN group. No apparent changes in hair cell shape, arrangement or number were observed, but the number of ribbon synapse was reduced. The 1WPN and 1MPN groups showed that part of ABR and CAP changes recovered, as well as the synapse number. The defects in cochlea auditory function and synapse changes were observed mainly in the high-frequency region. Together, repeated exposure in MTMI noise can cause hidden hearing loss, which is partially reversible after leaving the noise environment; and MTMI noise induced hidden hearing loss is associated with inner hair cell ribbon synapses.
PMID:33734328 | DOI:10.1042/BSR20201637
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Thu, 18 Mar 2021 06:00:00 -0400
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Hearing Loss Treatment Report, Urgent Research, 2021-03-18T23:41:43+00:00, https://www.hearinglosstreatmentreport.com.