Immediate and Delayed Cochlear Neuropathy after Noise Exposure in Pubescent Mice
Moderate acoustic overexposure in adult rodents is known to cause acute loss of synapses on sensory inner hair cells (IHCs) and delayed degeneration of the auditory nerve, despite the completely reversible temporary threshold shift (TTS) and morphologically intact hair cells. Our objective was to de...
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| Format: | Article |
| Language: | en_US |
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Public Library of Science
2016
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| Online Access: | http://hdl.handle.net/1721.1/101675 https://orcid.org/0000-0003-0233-279X |
| _version_ | 1811070138081869824 |
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| author | Jensen, Jane Bjerg Lysaght, Andrew C. Liberman, M. Charles Qvortrup, Klaus Stankovic, Konstantina M. |
| author2 | Harvard University--MIT Division of Health Sciences and Technology |
| author_facet | Harvard University--MIT Division of Health Sciences and Technology Jensen, Jane Bjerg Lysaght, Andrew C. Liberman, M. Charles Qvortrup, Klaus Stankovic, Konstantina M. |
| author_sort | Jensen, Jane Bjerg |
| collection | MIT |
| description | Moderate acoustic overexposure in adult rodents is known to cause acute loss of synapses on sensory inner hair cells (IHCs) and delayed degeneration of the auditory nerve, despite the completely reversible temporary threshold shift (TTS) and morphologically intact hair cells. Our objective was to determine whether a cochlear synaptopathy followed by neuropathy occurs after noise exposure in pubescence, and to define neuropathic versus non-neuropathic noise levels for pubescent mice. While exposing 6 week old CBA/CaJ mice to 8-16 kHz bandpass noise for 2 hrs, we defined 97 dB sound pressure level (SPL) as the threshold for this particular type of neuropathic exposure associated with TTS, and 94 dB SPL as the highest non-neuropathic noise level associated with TTS. Exposure to 100 dB SPL caused permanent threshold shift although exposure of 16 week old mice to the same noise is reported to cause only TTS. Amplitude of wave I of the auditory brainstem response, which reflects the summed activity of the cochlear nerve, was complemented by synaptic ribbon counts in IHCs using confocal microscopy, and by stereological counts of peripheral axons and cell bodies of the cochlear nerve from 24 hours to 16 months post exposure. Mice exposed to neuropathic noise demonstrated immediate cochlear synaptopathy by 24 hours post exposure, and delayed neurodegeneration characterized by axonal retraction at 8 months, and spiral ganglion cell loss at 8-16 months post exposure. Although the damage was initially limited to the cochlear base, it progressed to also involve the cochlear apex by 8 months post exposure. Our data demonstrate a fine line between neuropathic and non-neuropathic noise levels associated with TTS in the pubescent cochlea. |
| first_indexed | 2024-09-23T08:27:15Z |
| format | Article |
| id | mit-1721.1/101675 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T08:27:15Z |
| publishDate | 2016 |
| publisher | Public Library of Science |
| record_format | dspace |
| spelling | mit-1721.1/1016752022-09-23T12:42:04Z Immediate and Delayed Cochlear Neuropathy after Noise Exposure in Pubescent Mice Jensen, Jane Bjerg Lysaght, Andrew C. Liberman, M. Charles Qvortrup, Klaus Stankovic, Konstantina M. Harvard University--MIT Division of Health Sciences and Technology Lysaght, Andrew C. Liberman, M. Charles Stankovic, Konstantina M. Moderate acoustic overexposure in adult rodents is known to cause acute loss of synapses on sensory inner hair cells (IHCs) and delayed degeneration of the auditory nerve, despite the completely reversible temporary threshold shift (TTS) and morphologically intact hair cells. Our objective was to determine whether a cochlear synaptopathy followed by neuropathy occurs after noise exposure in pubescence, and to define neuropathic versus non-neuropathic noise levels for pubescent mice. While exposing 6 week old CBA/CaJ mice to 8-16 kHz bandpass noise for 2 hrs, we defined 97 dB sound pressure level (SPL) as the threshold for this particular type of neuropathic exposure associated with TTS, and 94 dB SPL as the highest non-neuropathic noise level associated with TTS. Exposure to 100 dB SPL caused permanent threshold shift although exposure of 16 week old mice to the same noise is reported to cause only TTS. Amplitude of wave I of the auditory brainstem response, which reflects the summed activity of the cochlear nerve, was complemented by synaptic ribbon counts in IHCs using confocal microscopy, and by stereological counts of peripheral axons and cell bodies of the cochlear nerve from 24 hours to 16 months post exposure. Mice exposed to neuropathic noise demonstrated immediate cochlear synaptopathy by 24 hours post exposure, and delayed neurodegeneration characterized by axonal retraction at 8 months, and spiral ganglion cell loss at 8-16 months post exposure. Although the damage was initially limited to the cochlear base, it progressed to also involve the cochlear apex by 8 months post exposure. Our data demonstrate a fine line between neuropathic and non-neuropathic noise levels associated with TTS in the pubescent cochlea. National Institute on Deafness and Other Communication Disorders (U.S.) (Grant K08DC010419) National Institute on Deafness and Other Communication Disorders (U.S.) (Grant R01 DC00188) National Institute on Deafness and Other Communication Disorders (U.S.) (Grant P30 05209) National Institute on Deafness and Other Communication Disorders (U.S.) (Grant T32 DC00038) Bertarelli Foundation 2016-03-11T03:45:49Z 2016-03-11T03:45:49Z 2015-05 2014-11 Article http://purl.org/eprint/type/JournalArticle 1932-6203 http://hdl.handle.net/1721.1/101675 Jensen, Jane Bjerg, Andrew C. Lysaght, M. Charles Liberman, Klaus Qvortrup, and Konstantina M. Stankovic. “Immediate and Delayed Cochlear Neuropathy after Noise Exposure in Pubescent Mice.” Edited by Fan-Gang Zeng. PLoS ONE 10, no. 5 (May 8, 2015): e0125160. https://orcid.org/0000-0003-0233-279X en_US http://dx.doi.org/10.1371/journal.pone.0125160 PLOS ONE Creative Commons Attribution http://creativecommons.org/licenses/by/4.0/ application/pdf Public Library of Science Public Library of Science |
| spellingShingle | Jensen, Jane Bjerg Lysaght, Andrew C. Liberman, M. Charles Qvortrup, Klaus Stankovic, Konstantina M. Immediate and Delayed Cochlear Neuropathy after Noise Exposure in Pubescent Mice |
| title | Immediate and Delayed Cochlear Neuropathy after Noise Exposure in Pubescent Mice |
| title_full | Immediate and Delayed Cochlear Neuropathy after Noise Exposure in Pubescent Mice |
| title_fullStr | Immediate and Delayed Cochlear Neuropathy after Noise Exposure in Pubescent Mice |
| title_full_unstemmed | Immediate and Delayed Cochlear Neuropathy after Noise Exposure in Pubescent Mice |
| title_short | Immediate and Delayed Cochlear Neuropathy after Noise Exposure in Pubescent Mice |
| title_sort | immediate and delayed cochlear neuropathy after noise exposure in pubescent mice |
| url | http://hdl.handle.net/1721.1/101675 https://orcid.org/0000-0003-0233-279X |
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