scholarly journals Chronic Lead Exposure Results in Auditory Deficits and Disruption of Hair Cells in Postweaning Rats

2019 ◽  
Vol 2019 ◽  
pp. 1-8 ◽  
Author(s):  
Shou-Sen Hu ◽  
Shi-Zhong Cai ◽  
Xiang-Zhen Kong
Keyword(s):  
Lead Exposure ◽  
Hair Cells ◽  
Molecular Mechanisms ◽  
Basilar Membrane ◽  
Morphological Changes ◽  
Spiral Ganglion ◽  
Antioxidant Enzyme Activities ◽  
Auditory Evoked Responses ◽  
Catalytic Function ◽  
Ganglion Neurons

Objective. The effects of lead exposure on cognitive function have been studied intensively over the past decade, but less attention has focused on its impact on auditory function. This study is aimed at investigating the effect of lead on the cochlea and the molecular mechanisms responsible for its actions. Methods. 0.2% lead acetate was administered to rats in drinking water for 30, 60, and 90 days. Brainstem auditory evoked responses (ABR) were recorded, and morphological changes in the hair cells were observed. We also measured glutathione (GSH) and malondialdehyde (MDA) concentrations and antioxidant enzyme activities such as catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and glutathione reductase (GR) activities in the cochlea. Results. Lead exposure increased the ABR threshold and slightly prolonged the latencies of wave II and wave IV in rats. Abnormally shaped hair cells and loss of hair cells were found in the cochlea basilar membrane, together with degenerative changes in spiral ganglion neurons following lead exposure. The activities of some antioxidant enzymes were also reduced in association with upregulation of MDA expression. These effects may be caused by impaired catalytic function of the enzymes as a result of lead interaction. Conclusion. The antioxidant system of the cochlea in the immature rat brain is highly vulnerable to developmental lead exposure. Oxidative stress may therefore represent a possible mechanism for lead-induced auditory deficits.

New insights into glutamate ototoxicity in cochlear hair cells and spiral ganglion neurons

2010 ◽  
Vol 130 (12) ◽  
pp. 1316-1323 ◽  
Author(s):  
Haitao Lu ◽  
Xiang Wang ◽  
Wenyan Sun ◽  
Yao Hu ◽  
Shusheng Gong
Keyword(s):  
Hair Cells ◽  
Spiral Ganglion ◽  
Spiral Ganglion Neurons ◽  
Cochlear Hair Cells ◽  
Ganglion Neurons

scholarly journals Exocyst Complex Member EXOC5 Is Required for Survival of Hair Cells and Spiral Ganglion Neurons and Maintenance of Hearing

2018 ◽  
Vol 55 (8) ◽  
pp. 6518-6532 ◽  
Author(s):  
Byeonghyeon Lee ◽  
Jeong-In Baek ◽  
Hyehyun Min ◽  
Seung-Hyun Bae ◽  
Kyeonghye Moon ◽  
...  
Keyword(s):  
Hair Cells ◽  
Spiral Ganglion ◽  
Spiral Ganglion Neurons ◽  
Exocyst Complex ◽  
Ganglion Neurons

scholarly journals Correction to: Exocyst Complex Member EXOC5 Is Required for Survival of Hair Cells and Spiral Ganglion Neurons and Maintenance of Hearing

2019 ◽  
Vol 56 (3) ◽  
pp. 2300-2300
Author(s):  
Byeonghyeon Lee ◽  
Jeong-In Baek ◽  
Hyehyun Min ◽  
Seung-Hyun Bae ◽  
Kyeonghye Moon ◽  
...  
Keyword(s):  
Hair Cells ◽  
Spiral Ganglion ◽  
Spiral Ganglion Neurons ◽  
Exocyst Complex ◽  
Ganglion Neurons

scholarly journals Pyroptosis Accelerates Spiral Ganglion Neuronal Degeneration Induced by Aminoglycosides in the Cochlea

2021 ◽  
Author(s):  
Yazhi Xing ◽  
Jia Fang ◽  
Zhuangzhuang Li ◽  
Mingxian Li ◽  
Chengqi Liu ◽  
...  
Keyword(s):  
Cell Death ◽  
Rna Sequencing ◽  
Hair Cells ◽  
Nlrp3 Inflammasome ◽  
Auditory Brainstem Response ◽  
Spiral Ganglion ◽  
Auditory Brainstem ◽  
Response Threshold ◽  
Brainstem Response ◽  
Ganglion Neurons

Abstract Background In aminoglycoside-induced hearing loss, damage to spiral ganglion neurons (SGNs) accelerates gradually after the acute outer hair cell death, accompanied by macrophage infiltration and cytokine release. Pyroptosis plays a critical role in neurodegenerative diseases. Here, we explored the potential role of pyroptosis in SGN degeneration. Methods C57BL/6J mice were randomly divided into a kanamycin plus furosemide group and saline control group. Auditory functions were evaluated by auditory brainstem response tests conducted before treatment and at 1, 5, 15, and 30 days after treatment. HCs and SGNs were assessed for morphological alterations. SGNs were subjected to RNA sequencing and mRNA and protein analyses of NLRP3 inflammasome-related molecules. Macrophage activation was evaluated based on morphological and mRNA alterations. The effect of NLRP3 inhibition on SGN survival after kanamycin treatment was evaluated in organ explant cultures treated with Mcc950, a specific inhibitor of the NLRP3 inflammasome. Results Kanamycin and furosemide administration led to irreversible deterioration of the auditory brainstem response threshold, accompanied by acute loss of outer hair cells and gradually progressive loss of inner hair cells. SGNs showed a progressive decrease in quantity, as well as swelling and membrane rupture, at 15 and 30 days. RNA sequencing of SGNs showed that inflammation and immune-related responses were significantly upregulated, as was the expression of the inflammasome-related gene NLRP3. During 30 days of kanamycin exposure, the canonical pyroptosis pathway was constantly activated in SGNs. Activation and infiltration of microglia-like cells/macrophages, and increased production of cytokines, hallmarks of neuroinflammation, were also observed. Mcc950 significantly ameliorated SGN degeneration by inhibiting NLRP3 expression and promoting release of interleukins 1β and 18. Conclusions Pyroptosis causes cell death during aminoglycoside-induced SGN degeneration. Activation of the NLRP3 inflammasome leads to a cascade of inflammatory events in SGNs. Inhibition of the NLRP3 inflammasome significantly alleviates SGN damage, suggesting that it could serve as a new molecular target for the treatment of aminoglycoside-induced SGN degeneration.

scholarly journals Spatiotemporal Developmental Upregulation of Prestin Correlates With the Severity and Location of Cyclodextrin-Induced Outer Hair Cell Loss and Hearing Loss

2021 ◽  
Vol 9 ◽  
Author(s):  
Dalian Ding ◽  
Haiyan Jiang ◽  
Senthilvelan Manohar ◽  
Xiaopeng Liu ◽  
Li Li ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Hair Cells ◽  
Auditory Nerve ◽  
High Frequency ◽  
Spiral Ganglion ◽  
Low Frequency ◽  
Nerve Fibers ◽  
Spiral Ganglion Neurons ◽  
Auditory Nerve Fibers ◽  
Ganglion Neurons

2-Hyroxypropyl-beta-cyclodextrin (HPβCD) is being used to treat Niemann-Pick C1, a fatal neurodegenerative disease caused by abnormal cholesterol metabolism. HPβCD slows disease progression, but unfortunately causes severe, rapid onset hearing loss by destroying the outer hair cells (OHC). HPβCD-induced damage is believed to be related to the expression of prestin in OHCs. Because prestin is postnatally upregulated from the cochlear base toward the apex, we hypothesized that HPβCD ototoxicity would spread from the high-frequency base toward the low-frequency apex of the cochlea. Consistent with this hypothesis, cochlear hearing impairments and OHC loss rapidly spread from the high-frequency base toward the low-frequency apex of the cochlea when HPβCD administration shifted from postnatal day 3 (P3) to P28. HPβCD-induced histopathologies were initially confined to the OHCs, but between 4- and 6-weeks post-treatment, there was an unexpected, rapid and massive expansion of the lesion to include most inner hair cells (IHC), pillar cells (PC), peripheral auditory nerve fibers, and spiral ganglion neurons at location where OHCs were missing. The magnitude and spatial extent of HPβCD-induced OHC death was tightly correlated with the postnatal day when HPβCD was administered which coincided with the spatiotemporal upregulation of prestin in OHCs. A second, massive wave of degeneration involving IHCs, PC, auditory nerve fibers and spiral ganglion neurons abruptly emerged 4–6 weeks post-HPβCD treatment. This secondary wave of degeneration combined with the initial OHC loss results in a profound, irreversible hearing loss.

scholarly journals Caffeine Induces Autophagy and Apoptosis in Auditory Hair Cells via the SGK1/HIF-1α Pathway

2021 ◽  
Vol 9 ◽  
Author(s):  
Xiaomin Tang ◽  
Yuxuan Sun ◽  
Chenyu Xu ◽  
Xiaotao Guo ◽  
Jiaqiang Sun ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Hair Cells ◽  
Stria Vascularis ◽  
Spiral Ganglion ◽  
Organ Of Corti ◽  
Spiral Ganglion Neurons ◽  
Auditory Hair Cells ◽  
Qrt Pcr ◽  
Ganglion Neurons

Caffeine is being increasingly used in daily life, such as in drinks, cosmetics, and medicine. Caffeine is known as a mild stimulant of the central nervous system, which is also closely related to neurologic disease. However, it is unknown whether caffeine causes hearing loss, and there is great interest in determining the effect of caffeine in cochlear hair cells. First, we explored the difference in auditory brainstem response (ABR), organ of Corti, stria vascularis, and spiral ganglion neurons between the control and caffeine-treated groups of C57BL/6 mice. RNA sequencing was conducted to profile mRNA expression differences in the cochlea of control and caffeine-treated mice. A CCK-8 assay was used to evaluate the approximate concentration of caffeine. Flow cytometry, TUNEL assay, immunocytochemistry, qRT-PCR, and Western blotting were performed to detect the effects of SGK1 in HEI-OC1 cells and basilar membranes. In vivo research showed that 120 mg/ kg caffeine injection caused hearing loss by damaging the organ of Corti, stria vascularis, and spiral ganglion neurons. RNA-seq results suggested that SGK1 might play a vital role in ototoxicity. To confirm our observations in vitro, we used the HEI-OC1 cell line, a cochlear hair cell-like cell line, to investigate the role of caffeine in hearing loss. The results of flow cytometry, TUNEL assay, immunocytochemistry, qRT-PCR, and Western blotting showed that caffeine caused autophagy and apoptosis via SGK1 pathway. We verified the interaction between SGK1 and HIF-1α by co-IP. To confirm the role of SGK1 and HIF-1α, GSK650394 was used as an inhibitor of SGK1 and CoCl2 was used as an inducer of HIF-1α. Western blot analysis suggested that GSK650394 and CoCl2 relieved the caffeine-induced apoptosis and autophagy. Together, these results indicated that caffeine induces autophagy and apoptosis in auditory hair cells via the SGK1/HIF-1α pathway, suggesting that caffeine may cause hearing loss. Additionally, our findings provided new insights into ototoxic drugs, demonstrating that SGK1 and its downstream pathways may be potential therapeutic targets for hearing research at the molecular level.

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