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Guven SG, Ersoy O, Topuz RD, Bulut E, Kizilay G, Uzun C. Does Oral Monosodium Glutamate Have a Cochleotoxic Effect? An Experimental Study. Audiol Neurootol 2021; 27:109-121. [PMID: 34535584 DOI: 10.1159/000518616] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Accepted: 07/19/2021] [Indexed: 11/19/2022] Open
Abstract
INTRODUCTION The effect of orally consumed monosodium glutamate (MSG), which is a common additive in the food industry, on the cochlea has not been investigated. The present study aimed to investigate the possible cochleotoxic effects of oral MSG in guinea pigs using electrophysiological, biochemical, and histopathological methods. METHODS Thirty guinea pigs were equally divided into control and intervention groups (MSG 100 mg/kg/day; MSG 300 mg/kg/day). At 1 month, 5 guinea pigs from each group were sacrificed; the rest were observed for another month. Electrophysiological measurements (distortion product otoacoustic emission [DPOAE] and auditory brainstem response [ABR]), glutamate levels in the perilymph and blood samples, and histopathological examinations were evaluated at 1 and 2 months. RESULTS Change in signal-to-noise ratio at 2 months was significantly different in the MSG 300 group at 0.75 kHz and 2 kHz (p = 0.013 and p = 0.044, respectively). There was no statistically significant difference in ABR wave latencies of the guinea pigs given MSG compared to the control group after 1 and 2 months; an increase was noted in ABR thresholds, although the difference was not statistically significant. In the MSG groups, moderate-to-severe degeneration and cell loss in outer hair cells, support cells, and spiral ganglia, lateral surface junction irregularities, adhesions in stereocilia, and partial loss of outer hair cell stereocilia were noted. CONCLUSION MSG, administered in guinea pigs at a commonly utilized quantity and route of administration in humans, may be cochleotoxic.
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Affiliation(s)
- Selis Gulseven Guven
- Department of Otorhinolaryngology, Head and Neck Surgery, Trakya University Faculty of Medicine, Edirne, Turkey
| | - Onur Ersoy
- Department of Pathology Laboratory Techniques, Vocational School of Health Services, Trakya University, Edirne, Turkey
| | - Ruhan Deniz Topuz
- Department of Pharmacology, Trakya University Faculty of Medicine, Edirne, Turkey
| | - Erdoğan Bulut
- Department of Audiology, Trakya University Faculty of Health Sciences, Edirne, Turkey
| | - Gulnur Kizilay
- Department of Histology and Embryology, Trakya University Faculty of Medicine, Edirne, Turkey
| | - Cem Uzun
- Department of Otorhinolaryngology, Head and Neck Surgery, Trakya University Faculty of Medicine, Edirne, Turkey
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Altaher W, Alhelo H, Chosky D, Kulesza RJ. Neonatal exposure to monosodium glutamate results in impaired auditory brainstem structure and function. Hear Res 2021; 405:108243. [PMID: 33865019 DOI: 10.1016/j.heares.2021.108243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Revised: 03/14/2021] [Accepted: 03/31/2021] [Indexed: 10/21/2022]
Abstract
Excitotoxic injury during the neonatal period has been shown to result in neurodegenerative changes in several different brain regions. Exposure to monosodium glutamate (MSG) during the first two postnatal weeks results in glutamate neurotoxicity in the cochlea and has been shown to result in damage to cochlear hair cells and fewer neurons in the spiral ganglion. Further, we have shown that such exposure results in fewer neurons in the cochlear nucleus and superior olivary complex and abnormal expression of the calcium binding proteins calbindin and calretinin. Based on these findings, we hypothesized that neonatal MSG exposure would result in loss of neurons at more rostral levels in the auditory brainstem, and this exposure would result in abnormal brainstem auditory evoked potentials. We identified a significantly lower density of neurons in the spiral ganglion, heterogenous loss of neurons in the globular bushy cell-trapezoid body circuit, and fewer neurons in the nuclei of the lateral lemniscus and central nucleus of the inferior colliculus. The most severe loss of neurons was found in the inferior colliculus. Click-evoked auditory brainstem responses revealed significantly higher thresholds and longer latency responses, but these did not deteriorate with age. These results, together with our previous findings, indicate that neonatal exposure to MSG results in fewer neurons throughout the entire auditory brainstem and results in abnormal auditory brainstem responses.
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Affiliation(s)
- Weam Altaher
- Department of Anatomy, Lake Erie College of Osteopathic Medicine, 1858 West Grandview Blvd, Erie, PA 16504, United States
| | - Hasan Alhelo
- Department of Anatomy, Lake Erie College of Osteopathic Medicine, 1858 West Grandview Blvd, Erie, PA 16504, United States
| | - Devon Chosky
- Department of Anatomy, Lake Erie College of Osteopathic Medicine, 1858 West Grandview Blvd, Erie, PA 16504, United States
| | - Randy J Kulesza
- Department of Anatomy, Lake Erie College of Osteopathic Medicine, 1858 West Grandview Blvd, Erie, PA 16504, United States.
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Cao Z, Yang Q, Yin H, Qi Q, Li H, Sun G, Wang H, Liu W, Li J. Peroxynitrite induces apoptosis of mouse cochlear hair cells via a Caspase-independent pathway in vitro. Apoptosis 2017; 22:1419-1430. [PMID: 28900799 DOI: 10.1007/s10495-017-1417-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Peroxynitrite (ONOO-) is a potent and versatile oxidant implicated in a number of pathophysiological processes. The present study was designed to investigate the effect of ONOO- on the cultured cochlear hair cells (HCs) of C57BL/6 mice in vitro as well as the possible mechanism underlying the action of such an oxidative stress. The in vitro primary cultured cochlear HCs were subjected to different concentrations of ONOO-, then, the cell survival and morphological changes were examined by immunofluorescence and transmission electron microscopy (TEM), the apoptosis was determined by Terminal deoxynucleotidyl transferase dUNT nick end labeling (TUNEL) assay, the mRNA expressions of Caspase-3, Caspase-8, Caspase-9, Apaf1, Bcl-2, and Bax were analyzed by RT-PCR, and the protein expressions of Caspase-3 and AIF were assessed by immunofluorescence. This work demonstrated that direct exposure of primary cultured cochlear HCs to ONOO- could result in a base-to-apex gradient injury of HCs in a concentration-dependent manner. Furthermore, ONOO- led to much more losses of outer hair cells than inner hair cells mainly through the induction of apoptosis of HCs as evidenced by TEM and TUNEL assays. The mRNA expressions of Caspase-8, Caspase-9, Apaf1, and Bax were increased and, meanwhile, the mRNA expression of Bcl-2 was decreased in response to ONOO- treatment. Of interesting, the expression of Caspase-3 had no significant change, whereas, the expression alteration of AIF was observed. These results suggested that ONOO- can effectively damage the survival of cochlear HCs via triggering the apoptotic pathway. The findings from this work suggest that ONOO--induced apoptosis is mediated, at least in part, via a Caspase-independent pathway in cochlear HCs.
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Affiliation(s)
- Zhixin Cao
- Department of Pathology, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, 250021, People's Republic of China
- Department of Otolaryngology-Head and Neck Surgery, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, 250021, People's Republic of China
| | - Qianqian Yang
- Department of Otolaryngology-Head and Neck Surgery, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, 250021, People's Republic of China
- Shandong Provincial Key Laboratory of Otology, Jinan, 250021, People's Republic of China
| | - Haiyan Yin
- Department of Otolaryngology-Head and Neck Surgery, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, 250021, People's Republic of China
- Shandong Provincial Key Laboratory of Otology, Jinan, 250021, People's Republic of China
| | - Qi Qi
- Department of Otolaryngology-Head and Neck Surgery, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, 250021, People's Republic of China
- Shandong Provincial Key Laboratory of Otology, Jinan, 250021, People's Republic of China
| | - Hongrui Li
- Department of Otolaryngology-Head and Neck Surgery, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, 250021, People's Republic of China
- Shandong Provincial Key Laboratory of Otology, Jinan, 250021, People's Republic of China
| | - Gaoying Sun
- Department of Otolaryngology-Head and Neck Surgery, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, 250021, People's Republic of China
- Shandong Provincial Key Laboratory of Otology, Jinan, 250021, People's Republic of China
| | - Hongliang Wang
- Laboratory of Physical and Chemical Analysis, Shandong Academy of Occupational Health and Occupational Medicine, Shandong Academy of Medical Sciences, Jinan, 250062, People's Republic of China
| | - Wenwen Liu
- Department of Otolaryngology-Head and Neck Surgery, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, 250021, People's Republic of China.
- Shandong Provincial Key Laboratory of Otology, Jinan, 250021, People's Republic of China.
| | - Jianfeng Li
- Department of Otolaryngology-Head and Neck Surgery, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, 250021, People's Republic of China.
- Shandong Provincial Key Laboratory of Otology, Jinan, 250021, People's Republic of China.
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Foran L, Blackburn K, Kulesza RJ. Auditory hindbrain atrophy and anomalous calcium binding protein expression after neonatal exposure to monosodium glutamate. Neuroscience 2017; 344:406-417. [DOI: 10.1016/j.neuroscience.2017.01.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Revised: 12/31/2016] [Accepted: 01/03/2017] [Indexed: 01/29/2023]
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Calpain inhibitor PD150606 attenuates glutamate induced spiral ganglion neuron apoptosis through apoptosis inducing factor pathway in vitro. PLoS One 2015; 10:e0123130. [PMID: 25874633 PMCID: PMC4398365 DOI: 10.1371/journal.pone.0123130] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Accepted: 02/23/2015] [Indexed: 11/19/2022] Open
Abstract
Objective This research aimed to investigate whether glutamate induced spiral ganglion neurons (SGNs) apoptosis through apoptosis inducing factor (AIF) pathway. And verify whether PD150606, a calpain inhibitor could prevent apoptosis by inhibiting cleaving and releasing AIF in mitochondrion. Methods SGNs of postnatal days 0-3 were harvested and cultured in dishes. 20 mM Glu, the caspase inhibitor Z-VAD-FMK and calpain inhibitor PD150606 were added into cultured dishes separately. We used optical microscope and immunofluoresence staining to observe cell morphology and AIF distribution, RT-PCR and Westernblot to analyse AIF and calpain expression in SGNs. TUNEL assay was used to test cell apoptosis. Results Cell morphology and nuclear translocation of AIF were altered in SGNs by 20 mM Glu treated in vitro. The axon of SGN shortened, more apoptosis SGN were observed and the expression of AIF and calpain were up-regulated in Glu-treated group than the normal one (P<0.05). The same experiments were conducted in 20 mM+PD150606 treated group and 20 mM+Z-VAD-FMK group. Obviously AIF were located from cytoplasm to the nuclear and the expressions of AIF and calpain were down-regulated by PD150606 (P<0.05). Positive cells in TUNEL staining decreased after PD150606 treating. However, Z-VAD-FMK had no influence on AIF, calpain expression or cell apoptosis. Conclusion The AIF-related apoptosis pathway is involved in the process of Glu-induced SGN injury. Furthermore, the inhibition of calpain can prevent AIF from releasing the nuclear or inducing SGN apoptosis.
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Hu Y, Zhou LQ, Lu HT, Yuan K, Gong SS. Excitotoxic effects of glutamate on cochlear organotypic cultures. ACTA ACUST UNITED AC 2015; 35:117-121. [PMID: 25673204 DOI: 10.1007/s11596-015-1399-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Revised: 12/30/2014] [Indexed: 11/30/2022]
Abstract
Glutamate (Glu) is the major afferent excitatory neurotransmitter in the auditory system, and excessive Glu may play an important role in cochlear dysfunction. It is unclear how excessive Glu plays roles in cochlear dysfunction in cochlear organotypic cultures. In this study neonatal rat cochlear organotypic cultures were prepared, and then the cochlear tissues were incubated with a new medium containing specific concentrations of Glu (0.1, 0.5, 1, 10 or 20 mmol/L) for 24 h, or incubated with the medium containing a concentration of 20 mmol/L Glu for 6, 12, 24 or 72 h, respectively. It was found that when the cochlear tissues were cultured for 24 h, the inner hair cells (IHCs) were damaged at the concentration of 0.5 mmol/L Glu, and with the increases of the concentrations, the injury was gradually aggravated, and 20 mmol/L Glu resulted in the significant loss of IHCs. In the 20 mmol/L Glu groups, the stereocilia bundles were missing or disarrayed on a few IHCs after culture for 6 h and the damage effect was time-dependent. The missing of IHCs was more significant in the basal turn of the cochlea than in the middle turn of the cochlea under the same concentration of Glu exposure. These results suggest that excessive exogenous Glu affects the morphology of IHCs, but not affects the outer hair cells (OHCs) in cochlear organotypic cultures, and the excitotoxic effects are different on IHCs of different parts of the cochlea under the same concentration of Glu exposure.
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Affiliation(s)
- Yao Hu
- Department of Otolaryngology-Head and Neck Surgery, Wuhan Central Hospital, Wuhan, 430014, China
| | - Liu-Qing Zhou
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Hai-Tao Lu
- Department of Otorhinolaryngology, Jingzhou Central Hospital, Jingzhou, 434020, China
| | - Kun Yuan
- Department of Otolaryngology-Head and Neck Surgery, Wuhan Central Hospital, Wuhan, 430014, China.
| | - Shu-Sheng Gong
- Department of Otolaryngology-Head and Neck Surgery, Affiliated Beijing Tongren Hospital of Capital Medical University and Beijing Institute of Otolaryngology, Beijing, 100069, China.
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Lee Y, Kim HR, Ahn SC. Vesicular glutamate transporter 3 is strongly upregulated in cochlear inner hair cells and spiral ganglion cells of developing circling mice. Neurosci Lett 2015; 584:320-4. [DOI: 10.1016/j.neulet.2014.10.053] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Revised: 10/23/2014] [Accepted: 10/31/2014] [Indexed: 11/16/2022]
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Selective ablation of pillar and deiters' cells severely affects cochlear postnatal development and hearing in mice. J Neurosci 2013; 33:1564-76. [PMID: 23345230 DOI: 10.1523/jneurosci.3088-12.2013] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Mammalian auditory hair cells (HCs) are inserted into a well structured environment of supporting cells (SCs) and acellular matrices. It has been proposed that when HCs are irreversibly damaged by noise or ototoxic drugs, surrounding SCs seal the epithelial surface and likely extend the survival of auditory neurons. Because SCs are more resistant to damage than HCs, the effects of primary SC loss on HC survival and hearing have received little attention. We used the Cre/loxP system in mice to specifically ablate pillar cells (PCs) and Deiters' cells (DCs). In Prox1CreER(T2)+/-;Rosa26(DTA/+) (Prox1DTA) mice, Cre-estrogen receptor (CreER) expression is driven by the endogenous Prox1 promoter and, in presence of tamoxifen, removes a stop codon in the Rosa26(DTA/+) allele and induces diphtheria toxin fragment A (DTA) expression. DTA produces cell-autonomous apoptosis. Prox1DTA mice injected with tamoxifen at postnatal days 0 (P0) and P1 show significant DC and outer PC loss at P2-P4, that reaches ∼70% by 1 month. Outer HC loss follows at P14 and is almost complete at 1 month, while inner HCs remain intact. Neural innervation to the outer HCs is disrupted in Prox1DTA mice and auditory brainstem response thresholds in adults are 40-50 dB higher than in controls. The hearing deficit correlates with loss of cochlear amplification. Remarkably, in Prox1DTA mice, the auditory epithelium preserves the ability to seal the reticular lamina and spiral ganglion neuron counts are normal, a key requirement for cochlear implant success. In addition, our results show that cochlear SC pools should be appropriately replenished during HC regeneration strategies.
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