Photobiomodulation using low‐level 808 nm diode laser rescues cochlear synaptopathy after acoustic overexposure in rat

Lee, Jae‐Hun; Lee, Min Young; Chung, Phil‐Sang; Jung, Jae Yun

doi:10.1002/jbio.201900145

Cited by 15 publications

(18 citation statements)

References 49 publications

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“…Functional changes in NICS can be characterized by ABR peak I amplitude decreases ( Kujawa and Liberman, 2009 ; Furman et al, 2013 ; Lee et al, 2019 ). To investigate changes in the ribbon synapses of hair cells, the peak I amplitude of ABR to tone burst stimuli was determined and compared at each test frequency.…”

Section: Resultsmentioning

confidence: 99%

Auditory Brainstem Response to Paired Click Stimulation as an Indicator of Peripheral Synaptic Health in Noise-Induced Cochlear Synaptopathy

Lee

Choi

et al. 2021

Front. Neurosci.

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IntroductionA defect in the cochlear afferent synapse between the inner hair cells and spiral ganglion neurons, after noise exposure, without changes in the hearing threshold has been reported. Animal studies on auditory evoked potentials demonstrated changes in the auditory brainstem response (ABR) measurements of peak I amplitude and the loss of synapses, which affect the temporal resolution of complex sounds. Human studies of auditory evoked potential have reported ambiguous results regarding the relationship between peak I amplitude and noise exposure. Paired click stimuli have been used to investigate the temporal processing abilities of humans and animals. In this study, we investigated the utility of measuring auditory evoked potentials in response to paired click stimuli to assess the temporal processing function of ribbon synapses in noise-induced cochlear synaptopathy.Materials and MethodsTwenty-two Sprague Dawley rats were used in this study, and synaptopathy was induced by narrow-band noise exposure (16 kHz with 1 kHz bandwidth, 105 dB sound pressure level for 2 h). ABRs to tone and paired click stimuli were measured before and 1, 3, 7, and 14 days after noise exposure. For histological analyses, hair cells and ribbon synapses were immunostained and the synapses quantified. The relationships among ABR peak I amplitude, number of synapses, and ABR to paired click stimuli were examined.ResultsOur results showed that ABR thresholds increase 1 day after noise exposure but fully recover to baseline levels after 14 days. Further, we demonstrated test frequency-dependent decreases in peak I amplitude and the number of synapses after noise exposure. These decreases were statistically significant at frequencies of 16 and 32 kHz. However, the ABR recovery threshold to paired click stimuli increased, which represent deterioration in the ability of temporal auditory processing. Our results indicate that the ABR recovery threshold is highly correlated with ABR peak I amplitude after noise exposure. We also established a direct correlation between the ABR recovery threshold and histological findings.ConclusionThe result from this study suggests that in animal studies, the ABR to paired click stimuli along with peak I amplitude has potential as an assessment tool for hidden hearing loss.

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Section: Resultsmentioning

confidence: 99%

Auditory Brainstem Response to Paired Click Stimulation as an Indicator of Peripheral Synaptic Health in Noise-Induced Cochlear Synaptopathy

Lee

Choi

et al. 2021

Front. Neurosci.

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“…Studies by Lee and colleagues observed NIR-related rescue of neural structures, including inner hair cell postsynaptic puncta, neurofilaments and spiral ganglion cells, when applied after ouabain treatment, a drug leading to auditory neuropathy by selectively damaging spiral ganglion cells (Lee et al, 2016b). In another study, the same group was also able to demonstrate a protection from inner hair cell synaptopathy through NIR treatment following moderate noise exposure (Lee et al, 2019;Chang et al, 2019).…”

Section: Introductionmentioning

confidence: 94%

“…It is possible that functional damage to hair cells occurred in the present experiments (e.g., stereocilia Wang, Hirose & Liberman, 2002), or that other cochlear structures are responsible for the hearing loss and the NIR-related preservation observed. Suitable candidates which are known to be influenced by NIR-light are spiral ganglion cells, pre-and postsynaptic structures at the inner hair cells (ribbon synapse), cochlear neurofilaments and Full-size DOI: 10.7717/peerj.9384/ fig-7 fibrocytes of the lateral wall (Tamura et al, 2016;Lee et al, 2016b;Lee et al, 2019;Chang et al, 2019). A first sign of such effects could be the relationship between the amplitude of a summating potential, which is generated within the auditory brainstem/midbrain (e.g., ABR wave IV), and the stimulus intensity.…”

Section: Effect On Cochlear Hair Cellsmentioning

confidence: 99%

Near-infrared-light pre-treatment attenuates noise-induced hearing loss in mice

Basta

Gröschel

Strübing

et al. 2020

PeerJ

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Noise induced hearing loss (NIHL) is accompanied by a reduction of cochlear hair cells and spiral ganglion neurons. Different approaches have been applied to prevent noise induced apoptosis / necrosis. Physical intervention is one technique currently under investigation. Specific wavelengths within the near-infrared light (NIR)-spectrum are known to influence cytochrome-c-oxidase activity, which leads in turn to a decrease in apoptotic mechanisms. It has been shown recently that NIR can significantly decrease the cochlear hair cell loss if applied daily for 12 days after a noise exposure. However, it is still unclear if a single NIR-treatment, just before a noise exposure, could induce similar protective effects. Therefore, the present study was conducted to investigate the effect of a single NIR-pre-treatment aimed at preventing or limiting NIHL. The cochleae of adult NMRI-mice were pre-treated with NIR-light (808 nm, 120 mW) for 5, 10, 20, 30 or 40 minutes via the external ear canal. All animals were noised exposed immediately after the pre-treatment by broad band noise (5–20 kHz) for 30 minutes at 115 dB SPL. Frequency specific ABR-recordings to determine auditory threshold shift were carried out before the pre-treatment and two weeks after the noise exposure. The amplitude increase for wave IV and cochlear hair cell loss were determined. A further group of similar mice was noise exposed only and served as a control for the NIR pre-exposed groups. Two weeks after noise exposure, the ABR threshold shifts of NIR-treated animals were significantly lower (p < 0.05) than those of the control animals. The significance was at three frequencies for the 5-minute pre-treatment group and across the entire frequency range for all other treatment groups. Due to NIR light, the amplitude of wave four deteriorates significantly less after noise exposure than in controls. The NIR pre-treatment had no effect on the loss of outer hair cells, which was just as high with or without NIR-light pre-exposure. Relative to the entire number of outer hair cells across the whole cochlea, outer hair cell loss was rather negligible. No inner hair cell loss whatever was detected. Our results suggest that a single NIR pre-treatment induces a very effective protection of cochlear structures from noise exposure. Pre-exposure of 10 min seems to emerge as the optimal dosage for our experimental setup. A saturated effect occurred with higher dosage-treatments. These results are relevant for protection of residual hearing in otoneurosurgery such as cochlear implantation.

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“…Ototoxic agents and acoustic overexposure may also trigger SNHL. Acoustic overexposure is sometimes preventable but may be inevitable [Lee et al, 2019a;Lee et al, 2019b]. Acoustic overexposure damages sensorineural structures in the cochlea, causing transient-to-permanent hearing loss.…”

Section: Introductionmentioning

confidence: 99%

“…Of the various affected neuronal structures, the synaptic ribbon running between the hair cells and the auditory nerve fibers is the most vulnerable part of the cochlea [Kujawa and Liberman, 2009]. Peripheral nerve damage caused by moderate noise compromises information transmission, triggering malfunctions in temporal processing [Shi et al, 2016;Lee et al, 2019a]. High blood glucose levels negatively affect neural function [Xu et al, 2013], perhaps exacerbating neural damage caused by acoustic overexposure.…”

Section: Introductionmentioning

confidence: 99%

High Blood Glucose Levels Affect Auditory Brainstem Responses after Acoustic Overexposure in Rats

Lee

Jung

et al. 2021

Audiol Neurotol

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Introduction: Diabetes mellitus (DM) is a systemic disease characterized by hyperglycemia and several pathological changes. DM-related hearing dysfunctions are associated with histological changes. Here, we explore hearing function and synaptic changes in the inner hair cells (IHCs) of rats with streptozotocin (STZ)-induced diabetes. Methods: STZ was injected to trigger diabetes. Rats with DM were exposed to narrow-band noise (105 dB SPL) for 2 h, and hearing function was analyzed 1, 3, 7, and 14 days later. Both the hearing threshold and the peak 1 amplitude of the tone auditory brainstem response were assessed. After the last functional test, animals were sacrificed for histological evaluation. Results: We found no changes in the baseline hearing threshold; however, the peak 1 amplitude at the low frequency (4 kHz) was significantly higher in both DM groups than in the control groups. The hearing threshold had not fully recovered at 14 days after diabetic rats were exposed to noise. The peak 1 amplitude at the higher frequencies (16 and 32 kHz) was significantly larger in both DM groups than in the control groups. The histological analysis revealed that the long-term DM group had significantly more synapses in the 16 kHz region than the other groups. Conclusions: We found that high blood glucose levels increased peak 1 amplitudes without changing the hearing threshold. Diabetic rats were less resilient in threshold changes and were less vulnerable to peak 1 amplitude and synaptic damage than control animals.

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Photobiomodulation using low‐level 808 nm diode laser rescues cochlear synaptopathy after acoustic overexposure in rat

Cited by 15 publications

References 49 publications

Auditory Brainstem Response to Paired Click Stimulation as an Indicator of Peripheral Synaptic Health in Noise-Induced Cochlear Synaptopathy

Auditory Brainstem Response to Paired Click Stimulation as an Indicator of Peripheral Synaptic Health in Noise-Induced Cochlear Synaptopathy

Near-infrared-light pre-treatment attenuates noise-induced hearing loss in mice

High Blood Glucose Levels Affect Auditory Brainstem Responses after Acoustic Overexposure in Rats

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