Therapeutic efficacy of topical application of dexamethasone to the round window niche after acoustic trauma caused by intensive impulse noise in guinea pigs

AbstractObjective:To assess the therapeutic efficacy of dexamethasone administered topically to the round window niche, following acoustic trauma induced by intensive impulse noise, in guinea pigs.Methods:Adult, male, albino guinea pigs with a normal Preyer's reflex were exposed to 80 impulse noises (peak value 167 dB, duration 0.5 ms, interval 2 s). Dexamethasone (40 mg/ml) or saline was then topically applied to the round window niche. Each animal's auditory brainstem response was measured before and one day after exposure, and three weeks after topical treatment. Cochlear morphology was examined to assess hair cell loss and spiral ganglion cell damage. To assess oxidative activity, cochlear malondialdehyde and superoxide dismutase concentrations were determined three weeks post-treatment. Following topical application, the pharmacokinetic characteristics of dexamethasone in cochlear perilymph were analysed using high-performance liquid chromatography.Results:Animals receiving dexamethasone showed reduced noise-induced outer hair cell loss (three weeks post-treatment), and significant attenuation of noise-induced auditory brainstem response threshold shifts (one day post-exposure and three weeks post-treatment), compared with controls. There was no difference in spiral ganglion morphology. Animals receiving dexamethasone also showed a significantly lower malondialdehyde concentration and a higher superoxide dismutase concentration, post-exposure. Following topical application, the perilymph dexamethasone level peaked at 5330.522 µg/ml (15 minutes post-treatment), and was 299.797 µg/ml 360 minutes later.Conclusion:Topical application of dexamethasone to the round window niche has protective effects against intensive impulse noise induced trauma in the guinea pig cochlea. This drug can diffuse into the inner ear through the round window membrane and persist in the perilymph for a relatively long period. The mechanism of protection may involve an anti-oxidant effect.

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PromBERA: A preoperative eABR: An update

Current Directions in Biomedical Engineering ◽

10.1515/cdbme-2018-0135 ◽

2018 ◽

Vol 4 (1) ◽

pp. 563-565 ◽

Cited By ~ 2

Author(s):

Daniel Polterauer ◽

Maike Neuling ◽

Joachim Müller ◽

John-Martin Hempel ◽

Giacomo Mandruzzato ◽

...

Keyword(s):

Cochlear Implantation ◽

Auditory Nerve ◽

Round Window ◽

Electrode Array ◽

Auditory Brainstem ◽

Auditory Brainstem Responses ◽

Speech Comprehension ◽

Testing Procedures ◽

Brainstem Response ◽

Round Window Niche

AbstractPrior to cochlear implantation, audiological tests are performed to determine candidacy in subjects with a hearing loss. This is usually done by measuring the acoustic auditory brainstem response (ABR). Unfortunately, for some subjects, a reproducible ABR recording cannot be obtained, even at high acoustic levels. Having a healthy stimulating auditory nerve is required for cochlear implantation in order to benefit from the electrical pulses that are generated by the implant and to improve speech comprehension. In some subjects, this prerequisite cannot be measured using routine audiological tests. In this study, the feasibility of recording electrically evoked auditory brainstem responses (eABR) using a stimulating transtympanic electrode, placed on the round window niche, together with MED-EL clinical system is investigated. The results show that it is possible to record reproducible eABR measurements using PromBERA. The response was also confirmed with intraoperative eABR measurements that were stimulated using the implanted CI electrode array. Similarities between the intraoperative measurements and the preoperative recorded waveforms were observed. In summary, the integrity and excitability of the auditory nerve can be objectively measured using the PromBERA in subjects where standard clinical testing procedures are unable to provide the information required.

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The design of a lumped parameter model considering the stimulus path of round window

Technology and Health Care ◽

10.3233/thc-218005 ◽

2021 ◽

Vol 29 ◽

pp. 49-56

Author(s):

Jong Hoon Kim ◽

Min Gyu Park ◽

Qun Wei ◽

Ki Woong Seong ◽

Jyung Hyun Lee

Keyword(s):

Guinea Pigs ◽

Round Window ◽

Animal Experiments ◽

Hearing Threshold ◽

Auditory Brainstem ◽

Oval Window ◽

Lumped Parameter Model ◽

Piezo Actuator ◽

Lumped Parameter ◽

Brainstem Response

BACKGROUND: Sound normally enters the ear canal, passes through the middle ear, and stimulates the cochlea through the oval window. Alternatively, the cochlea can be stimulated in a reverse manner, namely round window stimulation. The reverse stimulation is not well understood, partly because in classic lumped-parameter models the path of reverse drive during the round window stimulation is usually not considered. OBJECTIVE: The study goal is to gain a better understanding of the hearing mechanism during round window stimulation. METHODS: A piezo actuator was coupled to the oval and round window of the guinea pigs. The auditory brainstem response produced by the forward and reverse stimulation at four frequencies was recorded. RESULTS: The results show that the input voltage of the actuator required at the hearing threshold in the round window drive was higher than that in the oval window drive. In order to understand the data, we designed a lumped-parameter cochlear model that can simulate both forward and reverse drive. The model-predicted results were consistent with the experimental results. CONCLUSIONS: The response of the auditory system to stimulus of oval window and round window was quantified through animal experimentation, and guinea pigs were used as experimental animals. When the same stimulus was applied to the oval window and round window of the cochlea, the ABR signals were compared. A lumped parameter model was designed to incorporate the sound transmission paths in both oval and round window stimulation. The simulated results are consistent with those of animal experiments. This model will be useful in understanding the inner-ear response in round window.

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Contralateral Suppression of DPOAEs in Mice after Ouabain Treatment

Neural Plasticity ◽

10.1155/2018/6890613 ◽

2018 ◽

Vol 2018 ◽

pp. 1-8 ◽

Cited By ~ 3

Author(s):

Jieying Li ◽

Yan Chen ◽

Shan Zeng ◽

Chuijin Lai ◽

Yanping Zhang ◽

...

Keyword(s):

Otoacoustic Emissions ◽

Round Window ◽

Spiral Ganglion ◽

Auditory Brainstem ◽

Spiral Ganglion Neurons ◽

Type I ◽

Type Ii ◽

Contralateral Suppression ◽

Brainstem Response ◽

Ganglion Neurons

Medial olivocochlear (MOC) efferent feedback is suggested to protect the ear from acoustic injury and to increase its ability to discriminate sounds against a noisy background. We investigated whether type II spiral ganglion neurons participate in the contralateral suppression of the MOC reflex. The application of ouabain to the round window of the mouse cochlea selectively induced the apoptosis of the type I spiral ganglion neurons, left the peripherin-immunopositive type II spiral ganglion neurons intact, and did not affect outer hairs, as evidenced by the maintenance of the distorted product otoacoustic emissions (DPOAEs). With the ouabain treatment, the threshold of the auditory brainstem response increased significantly and the amplitude of wave I decreased significantly in the ouabain-treated ears, consistent with the loss of type I neurons. Contralateral suppression was measured as reduction in the amplitude of the 2f1−f2 DPOAEs when noise was presented to the opposite ear. Despite the loss of all the type I spiral ganglion neurons, virtually, the amplitude of the contralateral suppression was not significantly different from the control when the suppressor noise was delivered to the treated cochlea. These results are consistent with the type II spiral ganglion neurons providing the sensory input driving contralateral suppression of the MOC reflex.

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Age-Related Hearing Loss in Mn-SOD Heterozygous Knockout Mice

Oxidative Medicine and Cellular Longevity ◽

10.1155/2013/325702 ◽

2013 ◽

Vol 2013 ◽

pp. 1-12 ◽

Cited By ~ 22

Author(s):

Makoto Kinoshita ◽

Takashi Sakamoto ◽

Akinori Kashio ◽

Takahiko Shimizu ◽

Tatsuya Yamasoba

Keyword(s):

Hearing Loss ◽

Manganese Superoxide Dismutase ◽

Stria Vascularis ◽

Spiral Ganglion ◽

Cell Loss ◽

Auditory Brainstem ◽

Spiral Ganglion Cell ◽

Age Related ◽

Brainstem Response ◽

Age Related Hearing Loss

Age-related hearing loss (AHL) reduces the quality of life for many elderly individuals. Manganese superoxide dismutase (Mn-SOD), one of the antioxidant enzymes acting within the mitochondria, plays a crucial role in scavenging reactive oxygen species (ROS). To determine whether reduction in Mn-SOD accelerates AHL, we evaluated auditory function in Mn-SOD heterozygous knockout (HET) mice and their littermate wild-type (WT) C57BL/6 mice by means of auditory brainstem response (ABR). Mean ABR thresholds were significantly increased at 16 months when compared to those at 4 months in both WT and HET mice, but they did not significantly differ between them at either age. The extent of hair cell loss, spiral ganglion cell density, and thickness of the stria vascularis also did not differ between WT and HET mice at either age. At 16 months, immunoreactivity of 8-hydroxydeoxyguanosine was significantly greater in the SGC and SV in HET mice compared to WT mice, but that of 4-hydroxynonenal did not differ between them. These findings suggest that, although decrease of Mn-SOD by half may increase oxidative stress in the cochlea to some extent, it may not be sufficient to accelerate age-related cochlear damage under physiological aging process.

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Antioxidant Enzyme Levels Inversely Covary with Hearing Loss After Amikacin Treatment

Journal of the American Academy of Audiology ◽

10.1055/s-0040-1715718 ◽

2003 ◽

Vol 14 (03) ◽

pp. 134-143 ◽

Cited By ~ 6

Author(s):

James J. Klemens ◽

Robert P. Meech ◽

Larry F. Hughes ◽

Satu Somani ◽

Kathleen C.M. Campbell

Keyword(s):

Hearing Loss ◽

Enzyme Activity ◽

Antioxidant Enzyme ◽

Guinea Pigs ◽

Auditory Brainstem ◽

Antioxidant Enzyme Activity ◽

Control Group ◽

Glutathione S Transferase ◽

Brainstem Response ◽

The Difference

This study's purpose was to determine if a correlation exists between cochlear antioxidant activity changes and auditory function after induction of aminoglycoside (AG) ototoxicity. Two groups of five 250-350 g albino guinea pigs served as subjects. For 28 days, albino guinea pigs were administered either 200 mg/kg/day amikacin, or saline subcutaneously. Auditory brainstem response testing was performed prior to the first injection and again before sacrifice, 28 days later. Cochleae were harvested and superoxide dismutase, catalase, glutathione peroxidase, glutathione-S-transferase, glutathione reductase activities and malondialdehyde levels were measured. All antioxidant enzymes had significantly lower activity in the amikacin group (p ≤ 0.05) than in the control group. The difference in cochlear antioxidant enzyme activity between groups inversely correlated significantly with the change in ABR thresholds. The greatest correlation was for the high frequencies, which are most affected by aminoglycosides. This study demonstrates that antioxidant enzyme activity and amikacin-induced hearing loss significantly covary.

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