Development of mammalian endocochlear potential: normal ontogeny and effects of anoxia

1986 ◽  
Vol 250 (3) ◽  
pp. R493-R498 ◽  
Author(s):  
N. K. Woolf ◽  
A. F. Ryan ◽  
J. P. Harris
Keyword(s):  
Glucose Metabolism ◽  
Mongolian Gerbil ◽  
Hair Cells ◽  
Stria Vascularis ◽  
Organ Of Corti ◽  
Endocochlear Potential ◽  
Cochlear Microphonic ◽  
Cochlear Hair Cells ◽  
Apical Membranes ◽  
Cochlear Microphonic Potential

The development of the positive endocochlear potential (EP), the negative anoxic EP, and the organ of Corti potential were measured at various postnatal ages in the Mongolian gerbil, beginning at 8 days after birth (DAB). The organ of Corti potential (OCP) was present at 8 DAB but averaged 21% less than the adult value. OCP increased regularly with age, reaching adult values of -90 mV by 14 DAB. The positive EP was first observed at 10 DAB, at which age it averaged only 2-3 mV. This potential increased monotonically between 10 and 20 DAB, by which time it had reached the adult value of 75 mV. Anoxia did not result in a negative EP until 12 DAB, at which age this potential averaged -7 mV. The negative anoxic EP matured more rapidly than the positive EP, achieving the adult value of 40 mV by 18 DAB. During development the positive EP appeared to closely parallel the maturation of glucose metabolism in the stria vascularis. The negative anoxic EP was more closely related temporally to the development of cochlear microphonic potential (CM) thresholds. It is hypothesized that changes which occur between 10 and 16 DAB in the apical membranes of the cochlear hair cells contribute to the maturation of both CM and the negative anoxic EP.

scholarly journals Preferential Cochleotoxicity of Cisplatin

2021 ◽  
Vol 15 ◽  
Author(s):  
Pattarawadee Prayuenyong ◽  
David M. Baguley ◽  
Corné J. Kros ◽  
Peter S. Steyger
Keyword(s):  
Inner Ear ◽  
Hair Cells ◽  
Driving Force ◽  
Stria Vascularis ◽  
Endocochlear Potential ◽  
Current Evidence ◽  
Cochlear Hair Cells ◽  
Anatomy And Physiology ◽  
Mechanoelectrical Transduction ◽  
Direct Exposure

Cisplatin-induced ototoxicity in humans is more predominant in the cochlea than in the vestibule. Neither definite nor substantial vestibular dysfunction after cisplatin treatment has been consistently reported in the current literature. Inner ear hair cells seem to have intrinsic characteristics that make them susceptible to direct exposure to cisplatin. The existing literature suggests, however, that cisplatin might have different patterns of drug trafficking across the blood-labyrinth-barrier, or different degrees of cisplatin uptake to the hair cells in the cochlear and vestibular compartments. This review proposes an explanation for the preferential cochleotoxicity of cisplatin based on current evidence as well as the anatomy and physiology of the inner ear. The endocochlear potential, generated by the stria vascularis, acting as the driving force for hair cell mechanoelectrical transduction might also augment cisplatin entry into cochlear hair cells. Better understanding of the stria vascularis might shed new light on cochleotoxic mechanisms and inform the development of otoprotective interventions to moderate cisplatin associated ototoxicity.

The morphological and functional development of the stria vascularis in miniature pigs

2017 ◽  
Vol 29 (3) ◽  
pp. 585 ◽  
Author(s):  
Weiwei Guo ◽  
Haijin Yi ◽  
Zhang Yan ◽  
Lili Ren ◽  
Lei Chen ◽  
...  
Keyword(s):  
Animal Studies ◽  
Stria Vascularis ◽  
Organ Of Corti ◽  
Lateral Wall ◽  
Cell Types ◽  
Endocochlear Potential ◽  
Miniature Pigs ◽  
Functional Development ◽  
Transmission Electron ◽  
Different Types

The purpose of this study was to examine the morphological and functional development of the lateral wall of the scala media of the cochlea in miniature pigs; light and transmission electron microscopy and electrophysiology were used for this purpose. We showed that the lateral wall of the scala media of the cochlea appears at embryonic Day 21 (E21) when the cochlear duct begins to form. From E28 to E49, the lateral wall can be distinguished according to its position along the cochlea. At E56, cells in the lateral wall begin to differentiate into three different types. At E70, three cell types, marginal, intermediate and basal, can be clearly distinguished. At E91, the stria vascularis is adult-like and the organ of Corti is also morphologically mature. The average endocochlear potential measured from the second turn of the cochlea (at E98, postnatal Day 1 (P1), P13 and P30) was 71.4 ± 2.5 (n = 7), 78.8 ± 1.5 (n = 10), 77.3 ± 2.3 (n = 10) and 78.0 ± 2.1 mV (n = 10), respectively. Our results suggest that in miniature pigs the stria vascularis develops during the embryonic period, concurrent with maturation of the organ of Corti. The magnitude of the endocochlear potential reached its mature level when the stria vascularis was morphologically adult-like at E98. These findings provide a morphological and functional basis for future animal studies using the miniature pig model concerning the pathogenesis of various inner-ear diseases.

scholarly journals Otic Pathology of Caprine β-Mannosidosis

1988 ◽  
Vol 25 (6) ◽  
pp. 437-442 ◽  
Author(s):  
J. A. Render ◽  
K. L. Lovell ◽  
M. Z. Jones
Keyword(s):  
Storage Disease ◽  
Stria Vascularis ◽  
Genetic Disorder ◽  
Spiral Ganglion ◽  
Clinical Signs ◽  
Organ Of Corti ◽  
Scala Tympani ◽  
Electron Microscopic ◽  
Middle Ear Mucosa ◽  
Cochlear Hair Cells

Caprine β-mannosidosis is an autosomal recessive defect of glycoprotein catabolism with a deficiency of tissue and plasma β-mannosidase activity and tissue accumulation of oligosaccharides within lysosomes. This rapidly fatal genetic disorder of Nubian goats is expressed at birth by a variety of clinical signs including deafness. Affected goats had folded pinnas, and the tympanic cavity was decreased due to multiple, polypoid projections of bone covered by middle ear mucosa which obstructed the view of the cochlear promontory. Numerous cells of the cochlear duct including mesothelial and epithelial cells of Reissner's membrane, mesothelial cells lining the scala tympani, cells of the stria vascularis, numerous supportive cells of the organ of Corti, cochlear hair cells, endothelial cells, perithelial cells, fibroblasts, macrophages, and neurons of the spiral ganglion contained numerous nonstaining intracytoplasmic vacuoles which resulted in distention of affected cells and caused thickening of involved structures. Ultrastructurally, the vacuoles were membrane-bound and consistent with lysosomes. Vacuolated cells were desquamated into the scala vestibuli and scala tympani. This is one of few reports describing light and electron microscopic otic alterations of a storage disease. Goats with β-mannosidosis appear to be good models of hearing loss in patients with storage disease.

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.

scholarly journals Amplification lags nonlinearity in the recovery from reduced endocochlear potential

2020 ◽  
Author(s):  
C. Elliott Strimbu ◽  
Yi Wang ◽  
Elizabeth S. Olson
Keyword(s):  
Hair Cells ◽  
Otoacoustic Emissions ◽  
Basilar Membrane ◽  
Frequency Tuning ◽  
Organ Of Corti ◽  
Endocochlear Potential ◽  
Outer Hair Cells ◽  
Frequency Resolution ◽  
Operating Condition ◽  
Distortion Product

ABSTRACTThe mammalian hearing organ, the cochlea, contains an active amplifier to boost the vibrational response to low level sounds. Hallmarks of this active process are sharp location-dependent frequency tuning and compressive nonlinearity over a wide stimulus range. The amplifier relies on outer hair cell (OHC) generated forces driven in part by the endocochlear potential (EP), the ~ +80 mV potential maintained in scala media, generated by the stria vascularis. We transiently eliminated the EP in vivo by an intravenous injection of furosemide and measured the vibrations of different layers in the cochlea’s organ of Corti using optical coherence tomography. Distortion product otoacoustic emissions (DPOAE) were monitored at the same times. Following the injection, the vibrations of the basilar membrane lost the best frequency (BF) peak and showed broad tuning similar to a passive cochlea. The intra-organ of Corti vibrations measured in the region of the OHCs lost their BF peak and showed low-pass responses, but retained nonlinearity, indicating that OHC electromotility was still operational. Thus, while electromotility is presumably necessary for amplification, its presence is not sufficient for amplification. The BF peak recovered nearly fully within 2 hours, along with a non-monotonic DPOAE recovery that suggests that physical shifts in operating condition are a final step in the recovery process.SIGNIFICANCEThe endocochlear potential, the +80 mV potential difference across the fluid filled compartments of the cochlea, is essential for normal mechanoelectrical transduction, which leads to receptor potentials in the sensory hair cells when they vibrate in response to sound. Intracochlear vibrations are boosted tremendously by an active nonlinear feedback process that endows the cochlea with its healthy sensitivity and frequency resolution. When the endocochlear potential was reduced by an injection of furosemide, the basilar membrane vibrations resembled those of a passive cochlea, with broad tuning and linear scaling. The vibrations in the region of the outer hair cells also lost the tuned peak, but retained nonlinearity at frequencies below the peak, and these sub-BF responses recovered fairly rapidly. Vibration responses at the peak recovered nearly fully over 2 hours. The staged vibration recovery and a similarly staged DPOAE recovery suggests that physical shifts in operating condition are a final step in the process of cochlear recovery.

scholarly journals Inhibition of ferroptosis protects House Ear Institute‐Organ of Corti 1 cells and cochlear hair cells from cisplatin‐induced ototoxicity

2020 ◽  
Vol 24 (20) ◽  
pp. 12065-12081
Author(s):  
Honglin Mei ◽  
Liping Zhao ◽  
Wen Li ◽  
Zhiwei Zheng ◽  
Dongmei Tang ◽  
...  
Keyword(s):  
Hair Cells ◽  
Organ Of Corti ◽  
Cochlear Hair Cells

scholarly journals Elmod3 knockout leads to progressive hearing loss and abnormalities in cochlear hair cell stereocilia

2019 ◽  
Vol 28 (24) ◽  
pp. 4103-4112 ◽  
Author(s):  
Wu Li ◽  
Yong Feng ◽  
Anhai Chen ◽  
Taoxi Li ◽  
Sida Huang ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Actin Cytoskeleton ◽  
Hearing Impairment ◽  
Hair Cells ◽  
Organ Of Corti ◽  
Vestibular Function ◽  
Outer Hair Cells ◽  
Auditory Function ◽  
Cochlear Hair Cells

Abstract ELMOD3, an ARL2 GTPase-activating protein, is implicated in causing hearing impairment in humans. However, the specific role of ELMOD3 in auditory function is still far from being elucidated. In the present study, we used the CRISPR/Cas9 technology to establish an Elmod3 knockout mice line in the C57BL/6 background (hereinafter referred to as Elmod3−/− mice) and investigated the role of Elmod3 in the cochlea and auditory function. Elmod3−/− mice started to exhibit hearing loss from 2 months of age, and the deafness progressed with aging, while the vestibular function of Elmod3−/− mice was normal. We also observed that Elmod3−/− mice showed thinning and receding hair cells in the organ of Corti and much lower expression of F-actin cytoskeleton in the cochlea compared with wild-type mice. The deafness associated with the mutation may be caused by cochlear hair cells dysfunction, which manifests with shortening and fusion of inner hair cells stereocilia and progressive degeneration of outer hair cells stereocilia. Our finding associates Elmod3 deficiencies with stereocilia dysmorphologies and reveals that they might play roles in the actin cytoskeleton dynamics in cochlear hair cells, and thus relate to hearing impairment.

Cochlear and Brain Stem Responses in Hearing Loss following Neonatal Hyperbilirubinemia

1979 ◽  
Vol 88 (3) ◽  
pp. 352-357 ◽  
Author(s):  
R. Chisin ◽  
M. Perlman ◽  
H. Sohmer
Keyword(s):  
Hearing Loss ◽  
Brain Stem ◽  
Hair Cells ◽  
Auditory Nerve ◽  
Auditory Pathway ◽  
Neonatal Hyperbilirubinemia ◽  
Cochlear Hair Cells ◽  
History Of ◽  
Histopathological Studies ◽  
Cochlear Microphonic Potential

The site of lesion in hearing loss following neonatal hyperbilirubinemia is unclear. Histopathological studies have implicated the brain stem auditory nuclei while other investigations have hinted at a lesion in the cochlea. In order to clarify this issue, attempts were made to record responses from the auditory pathway in 13 patients with hearing loss following neonatal hyperbilirubinemia. The neural response from the auditory nerve was absent in 11 of the 13 patients and present only in response to high intensity stimuli in 2 patients. However, the response of the cochlear hair cells (cochlear microphonic potential) was present in 9 of the 13 patients. In most other cases of sensorineural hearing loss, with no history of hyperbilirubinemia, the hair cell response was absent. This is functional evidence for auditory nerve damage in cases of hearing loss following neonatal hyperbilirubinemia while the hair cells are spared.

Pathophysiology of the Ototoxicity of Cis-Diamminedichloroplatinum

1981 ◽  
Vol 89 (2) ◽  
pp. 275-282 ◽  
Author(s):  
Shizuo Komune ◽  
Shinichiro Asakuma ◽  
James B. Snow
Keyword(s):  
Hair Cells ◽  
Stria Vascularis ◽  
Organ Of Corti ◽  
Outer Hair Cells ◽  
Cochlear Microphonics ◽  
Normal Range ◽  
Basal Turn ◽  
Summating Potential ◽  
Dc Potential ◽  
Histopathologic Changes

The electrophysiologic and histopathologic changes in the inner ear caused by the administration of cis-diamminedichloroplatinum (CP) were studied in guinea pigs. The endocochlear dc potential (EP) gradually decreased after the intravenous injection of CP and reached approximately 0 mV on the fourth day, but the EP did not become negative. The cochlear microphonics also diminished and could not be recorded on the fourth day. The negative potential of the organ of Corti remained in the normal range during the experiment. A large negative summating potential (SP) was observed one day after injection, but the amplitude of the negative SP became small on the second day. Light microscopic examination demonstrated that the outer hair cells are destroyed in the basal turn of the cochlea and are preserved in the upper turns, while the inner hair cells are almost completely preserved in all turns. The stria vascularis was found to be slightly atrophic. Severe collapse of Reissner's membrane was observed in the basal turn.

scholarly journals Morphometry of the chinchilla organ of Corti and stria vascularis.

1979 ◽  
Vol 27 (11) ◽  
pp. 1539-1542 ◽  
Author(s):  
P A Santi ◽  
D C Muchow
Keyword(s):  
Morphometric Analysis ◽  
Hair Cells ◽  
Basilar Membrane ◽  
Stria Vascularis ◽  
Organ Of Corti ◽  
Outer Hair Cells

This research describes a procedure for a morphometric analysis of the organ of Corti and stria vascularis in the chinchilla. In nine normal cochleae the length of the basilar membrane and the stria vascularis measured 18.47 and 25.22 mm, respectively. An average of 1910 inner and 7501 outer hair cells were present while an average of 15 inner and 90 outer hair cells were absent. In all cochleae examined there were always some missing hair cells in varying numbers even though the animals had no known ototoxic exposure. Stria area, width and thickness increased from the cochlear apex toward the base. Consistency of changes in stria dimensions among animals was enhanced by expressing position in terms of percentage stria length rather than distance as such. Total stria volume was estimated at 0.15 microliter.

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