scholarly journals Susceptibility of Diabetic Mice to Noise Trauma

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Wook Kyoung Han ◽  
Eung Hyub Kim ◽  
Sun-Ae Shin ◽  
Dong-Sik Shin ◽  
Bong Jik Kim ◽  
...  
Keyword(s):  
Noise Exposure ◽  
Inflammatory Responses ◽  
Hearing Threshold ◽  
Cell Loss ◽  
Oxygen Species ◽  
Diabetic Mice ◽  
Hair Cell Loss ◽  
Wild Type ◽  
Noise Trauma ◽  
Species Production

Diabetes can lead to many end-organ complications. However, the association between diabetes and hearing loss is not well understood. Here, we investigated the effect of noise exposure on diabetic mice compared with wild-type mice. Hearing threshold shifts, histopathologic changes in the cochlea, and inflammatory responses were evaluated over time. After noise exposure, more severe hearing threshold shifts, auditory hair cell loss, and synaptopathies were notable in diabetic mice compared with wild-type mice. Moreover, increased inflammatory responses and reactive oxygen species production were observed in the ears of diabetic mice. The results demonstrated that diabetic mice are more susceptible to noise trauma.

scholarly journals Cochlin Deficiency Protects Against Noise-Induced Hearing Loss

2021 ◽  
Vol 14 ◽  
Author(s):  
Richard Seist ◽  
Lukas D. Landegger ◽  
Nahid G. Robertson ◽  
Sasa Vasilijic ◽  
Cynthia C. Morton ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Hair Cell ◽  
Noise Exposure ◽  
Conductive Hearing Loss ◽  
Cell Loss ◽  
Hair Cell Loss ◽  
Wild Type ◽  
Noise Trauma ◽  
Knock Out ◽  
Conductive Hearing

Cochlin is the most abundant protein in the inner ear. To study its function in response to noise trauma, we exposed adolescent wild-type (Coch+/+) and cochlin knock-out (Coch–/–) mice to noise (8–16 kHz, 103 dB SPL, 2 h) that causes a permanent threshold shift and hair cell loss. Two weeks after noise exposure, Coch–/– mice had substantially less elevation in noise-induced auditory thresholds and hair cell loss than Coch+/+ mice, consistent with cochlin deficiency providing protection from noise trauma. Comparison of pre-noise exposure thresholds of auditory brain stem responses (ABRs) and distortion product otoacoustic emissions (DPOAEs) in Coch–/– mice and Coch+/+ littermates revealed a small and significant elevation in thresholds of Coch–/– mice, overall consistent with a small conductive hearing loss in Coch–/– mice. We show quantitatively that the pro-inflammatory component of cochlin, LCCL, is upregulated after noise exposure in perilymph of wild-type mice compared to unexposed mice, as is the enzyme catalyzing LCCL release, aggrecanase1, encoded by Adamts4. We further show that upregulation of pro-inflammatory cytokines in perilymph and cochlear soft-tissue after noise exposure is lower in cochlin knock-out than wild-type mice. Taken together, our data demonstrate for the first time that cochlin deficiency results in conductive hearing loss that protects against physiologic and molecular effects of noise trauma.

scholarly journals Reduced Levels of Drp1 Protect against Development of Retinal Vascular Lesions in Diabetic Retinopathy

Cells ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 1379
Author(s):  
Dongjoon Kim ◽  
Hiromi Sesaki ◽  
Sayon Roy
Keyword(s):  
Diabetic Retinopathy ◽  
Cell Loss ◽  
Vascular Lesions ◽  
Protective Effects ◽  
Diabetic Mice ◽  
Wild Type ◽  
Apoptotic Genes ◽  
Retinal Vascular Lesions ◽  
Acellular Capillaries ◽  
Pericyte Loss

High glucose (HG)-induced Drp1 overexpression contributes to mitochondrial dysfunction and promotes apoptosis in retinal endothelial cells. However, it is unknown whether inhibiting Drp1 overexpression protects against the development of retinal vascular cell loss in diabetes. To investigate whether reduced Drp1 level is protective against diabetes-induced retinal vascular lesions, four groups of mice: wild type (WT) control mice, streptozotocin (STZ)-induced diabetic mice, Drp1+/− mice, and STZ-induced diabetic Drp1+/− mice were examined after 16 weeks of diabetes. Western Blot analysis indicated a significant increase in Drp1 expression in the diabetic retinas compared to those of WT mice; retinas of diabetic Drp1+/− mice showed reduced Drp1 level compared to those of diabetic mice. A significant increase in the number of acellular capillaries (AC) and pericyte loss (PL) was observed in the retinas of diabetic mice compared to those of the WT control mice. Importantly, a significant decrease in the number of AC and PL was observed in retinas of diabetic Drp1+/− mice compared to those of diabetic mice concomitant with increased expression of pro-apoptotic genes, Bax, cleaved PARP, and increased cleaved caspase-3 activity. Preventing diabetes-induced Drp1 overexpression may have protective effects against the development of vascular lesions, characteristic of diabetic retinopathy.

scholarly journals Treatment With Calcineurin Inhibitor FK506 Attenuates Noise-Induced Hearing Loss

2021 ◽  
Vol 9 ◽  
Author(s):  
Zu-Hong He ◽  
Song Pan ◽  
Hong-Wei Zheng ◽  
Qiao-Jun Fang ◽  
Kayla Hill ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Hair Cells ◽  
Calcineurin Inhibitor ◽  
Noise Exposure ◽  
Cell Loss ◽  
Outer Hair Cells ◽  
Oxygen Species ◽  
Noise Induced Hearing Loss ◽  
Activated T Cells ◽  
Interfering Rna

Attenuation of noise-induced hair cell loss and noise-induced hearing loss (NIHL) by treatment with FK506 (tacrolimus), a calcineurin (CaN/PP2B) inhibitor used clinically as an immunosuppressant, has been previously reported, but the downstream mechanisms of FK506-attenuated NIHL remain unknown. Here we showed that CaN immunolabeling in outer hair cells (OHCs) and nuclear factor of activated T-cells isoform c4 (NFATc4/NFAT3) in OHC nuclei are significantly increased after moderate noise exposure in adult CBA/J mice. Consequently, treatment with FK506 significantly reduces moderate-noise-induced loss of OHCs and NIHL. Furthermore, induction of reactive oxygen species (ROS) by moderate noise was significantly diminished by treatment with FK506. In agreement with our previous finding that autophagy marker microtubule-associated protein light chain 3B (LC3B) does not change in OHCs under conditions of moderate-noise-induced permanent threshold shifts, treatment with FK506 increases LC3B immunolabeling in OHCs after exposure to moderate noise. Additionally, prevention of NIHL by treatment with FK506 was partially abolished by pretreatment with LC3B small interfering RNA. Taken together, these results indicate that attenuation of moderate-noise-induced OHC loss and hearing loss by FK506 treatment occurs not only via inhibition of CaN activity but also through inhibition of ROS and activation of autophagy.

scholarly journals Osmotic stabilization prevents cochlear synaptopathy after blast trauma

2018 ◽  
Vol 115 (21) ◽  
pp. E4853-E4860 ◽  
Author(s):  
Jinkyung Kim ◽  
Anping Xia ◽  
Nicolas Grillet ◽  
Brian E. Applegate ◽  
John S. Oghalai
Keyword(s):  
Hearing Loss ◽  
Hair Cell ◽  
Hair Cells ◽  
Noise Exposure ◽  
Endolymphatic Hydrops ◽  
Surrogate Marker ◽  
Cell Loss ◽  
Hair Cell Loss ◽  
Blast Trauma

Traumatic noise causes hearing loss by damaging sensory hair cells and their auditory synapses. There are no treatments. Here, we investigated mice exposed to a blast wave approximating a roadside bomb. In vivo cochlear imaging revealed an increase in the volume of endolymph, the fluid within scala media, termed endolymphatic hydrops. Endolymphatic hydrops, hair cell loss, and cochlear synaptopathy were initiated by trauma to the mechanosensitive hair cell stereocilia and were K+-dependent. Increasing the osmolality of the adjacent perilymph treated endolymphatic hydrops and prevented synaptopathy, but did not prevent hair cell loss. Conversely, inducing endolymphatic hydrops in control mice by lowering perilymph osmolality caused cochlear synaptopathy that was glutamate-dependent, but did not cause hair cell loss. Thus, endolymphatic hydrops is a surrogate marker for synaptic bouton swelling after hair cells release excitotoxic levels of glutamate. Because osmotic stabilization prevents neural damage, it is a potential treatment to reduce hearing loss after noise exposure.

Second Place — Resident Basic Science Award 1995: Mitochondrial Role in Hair Cell Survival after Injury

1995 ◽  
Vol 113 (5) ◽  
pp. 530-540 ◽  
Author(s):  
Gregory E. Hyde ◽  
Edwin W. Rubel
Keyword(s):  
Hair Cell ◽  
Cell Survival ◽  
Mitochondrial Biogenesis ◽  
Noise Exposure ◽  
Mitochondrial Protein ◽  
Cell Loss ◽  
Control Group ◽  
Cell Integrity ◽  
Hair Cell Loss ◽  
Inferior Edge

The role of mitochondrial biogenesis in hair cell survival after injury was evaluated by inhibiting mitochondrial protein synthesis with chloramphenicol and then studying the effects on hair cell survival after exposure to two different types of ototoxins, gentamicin and acoustic trauma. Seven- to 10-day-old chicks were treated with either a single injection of gentamicin (250 mg/kg) or noise (1500 Hz at 120 dB sound pressure level for 14 hours). A subset of the gentamicin- and noise-treated animals also received chloramphenicol (1200 mg/kg during a 24-hour period) through a subcutaneous osmotic pump. A control group received chloramphenicol alone (1200 mg/kg during a 24-hour period). All animals were sacrificed after 5 days, and their basilar papillae (cochleas) were prepared for scanning electron microscopy. Hair cell loss was quantified with stereologic techniques. Animals treated with chloramphenicol alone did not have any evidence of hair cell loss. Gentamicin-treated animals had characteristic hair cell loss beginning at the basal tip and tapering out along the inferior edge more distally. The addition of chloramphenicol to gentamicin treatment significantly increased hair cell loss by 30%, extending the area of hair cell loss into the superior hair cell region at the distal boundary of the lesion. Pure-tone noise exposure characteristically produced hair cell loss along the inferior edge and occasionally included hair cells along the most superior edge. Addition of chloramphenicol to noise exposure significantly increased hair cell loss by 80%, with extension of the lesion across the full width of the sensory epithelium and basally. These results demonstrate that mitochondrial biogenesis is involved in cellular responses to injury. They suggest that mitochondrial function may regulate the probability of survival after metabolic challenges to hair cell integrity.

Hearing threshold elevation precedes hair-cell loss in prestin knockout mice

2004 ◽  
Vol 126 (1) ◽  
pp. 30-37 ◽  
Author(s):  
Xudong Wu ◽  
Jiangang Gao ◽  
Yunkai Guo ◽  
Jian Zuo
Keyword(s):  
Hair Cell ◽  
Knockout Mice ◽  
Hearing Threshold ◽  
Cell Loss ◽  
Hair Cell Loss ◽  
Threshold Elevation

scholarly journals Effects of cochlear synaptopathy on spontaneous and sound-evoked activity in the mouse inferior colliculus

2018 ◽  
Author(s):  
Luke A. Shaheen ◽  
M. Charles Liberman
Keyword(s):  
Inferior Colliculus ◽  
Noise Exposure ◽  
Acoustic Startle ◽  
Cell Loss ◽  
Exact Nature ◽  
Hair Cell Loss ◽  
Threshold Elevation ◽  
Compensatory Response ◽  
Auditory Responses ◽  
Evoked Activity

ABSTRACTTinnitus and hyperacusis are life-disrupting perceptual abnormalities that are often preceded by acoustic overexposure. Animal models of overexposure have suggested a link between these phenomena and neural hyperactivity, i.e. elevated spontaneous rates (SRs) and sound-evoked responses. Prior work has focused on changes in central auditory responses, with less attention paid to the exact nature of the associated peripheral damage. The demonstration that acoustic overexposure can cause cochlear nerve damage without permanent threshold elevation suggests this type of peripheral damage may be a key elicitor of tinnitus and hyperacusis in humans with normal audiograms. We addressed this idea by recording responses in the mouse inferior colliculus (IC) following a bilateral, neuropathic noise exposure. Two wks post-exposure, mean SRs were unchanged in mice recorded while awake, or under anesthesia. SRs were also unaffected by more intense, or unilateral exposures. These results suggest that neither neuropathy nor hair cell loss are sufficient to raise SRs in the IC, at least in mice. However, it’s not clear whether our mice had tinnitus. Tone-evoked rate-level functions at the CF were steeper following exposure, specifically in the region of maximal neuropathy. Furthermore, suppression driven by off-CF tones and by ipsilateral noise were also reduced. Both changes were especially pronounced in neurons of awake mice. These findings align with prior reports of elevated acoustic startle in neuropathic mice, and indicate that neuropathy may initiate a compensatory response in the central auditory system leading to the genesis of hyperacusis.

scholarly journals Influence of Mpv17 on hair-cell mitochondrial homeostasis, synapse integrity, and vulnerability to damage in the zebrafish lateral line

2021 ◽  
Author(s):  
Melanie Holmgren ◽  
Lavinia Sheets
Keyword(s):  
Hair Cell ◽  
Lateral Line ◽  
Hair Cells ◽  
Noise Exposure ◽  
Cell Loss ◽  
Water Current ◽  
Mitochondrial Activity ◽  
Wild Type ◽  
Mitochondrial Homeostasis ◽  
Inner Membrane Protein

AbstractNoise exposure is particularly stressful to hair-cell mitochondria, which must produce enough energy to meet high metabolic demands as well as regulate local intracellular Ca2+ concentrations. Mitochondrial Inner Membrane Protein 17 (Mpv17) functions as a non-selective channel and plays a role in maintaining mitochondrial homeostasis. In zebrafish, hair cells in mpv17a9/a9 mutants displayed elevated levels of reactive oxygen species (ROS), elevated mitochondrial calcium, hyperpolarized transmembrane potential, and greater vulnerability to neomycin, indicating impaired mitochondrial function. Using a strong water current to overstimulate hair cells in the zebrafish lateral line, we observed mpv17a9/a9 mutant hair cells were more vulnerable to morphological disruption and hair-cell loss than wild type siblings simultaneously exposed to the same stimulus. To determine the role of mitochondrial homeostasis on hair-cell synapse integrity, we surveyed synapse number in mpv17a9/a9 mutants and wild type siblings as well as the sizes of presynaptic dense bodies (ribbons) and postsynaptic densities immediately following stimulus exposure. We observed mechanically injured mpv17a9/a9 neuromasts, while they lost a greater number of hair cells, lost a similar number of synapses per hair cell relative to wild type. Additionally, we quantified the size of hair cell pre- and postsynaptic structures and observed significantly enlarged wild type postsynaptic densities, yet relatively little change in the size of mpv17a9/a9 postsynaptic densities following stimulation. These results suggest impaired hair-cell mitochondrial activity influences synaptic morphology and hair-cell survival but does not exacerbate synapse loss following mechanical injury.

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