Disease relevance of Hair Cells, Outer

• Cisplatin-induced hyperactivity in the dorsal cochlear nucleus and its relation to outer hair cell loss: relevance to tinnitus [1].
• The outer hair cells were most sensitive to cisplatin toxicity [2].
• In the present review, selected examples of several forms of sensorineural hearing loss demonstrate that DPOAEs have the ability to act as objective indicators of the frequency/level configuration of the conventional audiogram in cases in which hearing impairment results primarily from damage to the outer hair cells [3].
• In this animal an AChE-positive reaction was found not only in efferent fibers and terminals but also in type II ganglion cells, their peripheral and central processes and in outer hair cell terminals [4].
• In long-term hydrops, degenerated outer hair cells were replaced by the swelling of the phalangeal process of the Deiters' cells which became highly immunoreactive to taurine [5].

Psychiatry related information on Hair Cells, Outer

• On membrane motor activity and chloride flux in the outer hair cell: lessons learned from the environmental toxin tributyltin [6].
• These findings suggest that the individual variations in the outer hair cell damage induced by kanamycin are more closely correlated to the individual differences in the transferability of kanamycin into inner ear than to those in the vulnerability of the outer hair cells or kidneys [7].

High impact information on Hair Cells, Outer

• KCNQ4, a novel potassium channel expressed in sensory outer hair cells, is mutated in dominant deafness [8].
• Prestin is required for electromotility of the outer hair cell and for the cochlear amplifier [9].
• Mice lacking either brain-derived neurotrophic factor (BDNF) or its associated receptor, TrkB, lose all innervation to the semicircular canals and have reduced innervation of the outer hair cells in the apical and middle turns of the cochlea [10].
• However, TR-betaGS/GS mutant mice maintained normal hearing at certain frequencies and did not display significant outer hair cell loss, in contrast to TR-beta-/- mice [11].
• Auditory outer hair cells present a unique inhibitory synapse that uses a Ca2+-permeable excitatory acetylcholine receptor to activate a hyperpolarizing potassium current mediated by small conductance calcium-activated potassium (SK) channels [12].

Chemical compound and disease context of Hair Cells, Outer

• The outer hair cell is also a target of diseases involving tinnitus and sensorineural hearing loss, including salicylate intoxication [13].
• This developmental pattern of carbachol-elicited IPs accumulation reveals a striking time coincidence with both the efferent synaptogenesis at the outer hair cells (OHCs) level and the period of increased sensitivity of OHCs to aminoglycoside toxicity [14].
• The results demonstrate that fosfomycin ameliorates the acute renal tubular necrosis and interstitial nephritis and markedly inhibits the elevation of ABR thresholds and simultaneous outer hair cell loss that can result from cisplatinum administration [15].
• The percentage of damaged outer hair cells was significantly higher when streptomycin had been treated with sera or a serum protein fraction from patients with hearing loss (58+/-10% and 68+/-9%, respectively) than with sera or a serum protein fraction from a control group (10+/-5% and 17+/-4%, respectively) [16].
• Differential vulnerability of inner and outer hair cell systems to chronic mild hypoxia and glutamate ototoxicity: insights into the cause of auditory neuropathy [17].

Biological context of Hair Cells, Outer

• As prestin mediates changes in outer hair cell length in response to membrane potential variations, it might be responsible for sound amplification in the mammalian hearing organ [18].
• A synthetic peptide designed from the predicted protein was used to produce specific polyclonal antibodies, and strong immunoreactivity was observed on hair bundles of both inner and outer hair cells in cochleae of newborn +/+ controls and +/hscy heterozygotes but was absent in hscy/hscy mutants [19].
• Fluorescence imaging of extracellular adenosine-5'-triphosphate (ATP) binding sites on inner and outer hair cells isolated from the guinea pig organ of Corti was achieved using the fluorescent analog of ATP, 2'-(or-3')-O-(trinitrophenyl)adenosine-5'- triphosphate (TNP-ATP; 30-75 microM) [20].
• The results indicate that the main action of capsaicin is on outer hair cells and suggest that VRs in the cochlea play a role in cochlear homeostasis [21].
• Concomitant injections of antioxidants, however, such as 2,3-dihydroxybenzoic acid or salicylate (which prevent cell death induced by kanamycin), promoted the translocation of NF-kappaB into the nuclei of outer hair cells [22].

Anatomical context of Hair Cells, Outer

• K(+) probably exits outer hair cells by KCNQ4 K(+) channels(), and is then transported by means of a gap junction system connecting supporting Deiters' cells and fibrocytes() back to the stria vascularis [23].
• In the cochlea, BDNF mutants lost type 2 spiral neurons, causing an absence of outer hair cell innervation [24].
• Htu/+ mutants also demonstrate a significant reduction in the numbers of outer hair cells in the organ of Corti [25].
• Cldn14-null mice have a normal endocochlear potential but are deaf due to rapid degeneration of cochlear outer hair cells, followed by slower degeneration of the inner hair cells, during the first 3 weeks of life [26].
• These proteins co-localize with whirlin at the synaptic regions of both photoreceptor cells and outer hair cells in the cochlea [27].

Associations of Hair Cells, Outer with chemical compounds

• As salicylate blocks electromotility in cochlear outer hair cells at the same concentration, the role of prestin as a motor protein may need to be reassessed [28].
• We show here that outer hair cells selectively take up fructose, at rates high enough to suggest that a sugar transporter may be part of the motor complex [29].
• This response was observed in outer hair cells from basal and apical turns of the cochlea and was reversed when the cells were rinsed with calcium-free medium supplemented with 2 mM EGTA [30].
• Exogenous retinoic acid significantly increased the number of cells that developed as hair cells and resulted in large regions of supernumerary hair cells and supporting cells containing two rows of inner hair cells and up to 11 rows of outer hair cells [31].
• Approximately 50% of cochlear outer hair cells are lost at a dose of 35 microM neomycin, and most surviving cells show disorganized stereocilia [32].

Gene context of Hair Cells, Outer

• Prestin, a membrane protein that is highly and almost exclusively expressed in the outer hair cells (OHCs) of the cochlea, is a motor protein which senses membrane potential and drives rapid length changes in OHCs [33].
• The loss of Gfi1 results in outer hair cell degeneration, which appears comparable to that observed in Pou4f3 mutants [34].
• In the absence of Jag1, by contrast, the total number of these cells is strongly reduced, with complete loss of cochlear outer hair cells and some groups of vestibular hair cells, indicating that Jag1 is required for the prosensory inductive function of Notch [35].
• In the cochlea, Hes1 is selectively expressed in the greater epithelial ridge and lesser epithelial ridge regions which are adjacent to inner and outer hair cells [36].
• In mice homozygous for targeted mutations of both Jag2 and Lfng, the generation of supernumerary hair cells in the inner hair cell row is suppressed, while supernumerary hair cells in the outer hair cell rows are unaffected [37].

Analytical, diagnostic and therapeutic context of Hair Cells, Outer

• In situ hybridization demonstrated that the CGRP receptor component protein is expressed in outer hair cells of the organ of Corti and is colocalized with CGRP-containing efferent nerve terminals [38].
• Here we report that extracellular dihydrostreptomycin not only blocks the mechano-electrical transducer channels of mouse outer hair cells at negative membrane potentials, as previously shown, but also enters the cells through these channels, which are located in the cells' mechanosensory hair bundles [39].
• By using whole-cell recordings from isolated outer hair cells, we show that acetylcholine activates a large rapidly desensitizing outward potassium current [40].
• By using immunohistochemistry against cyclic guanosine monophosphate, cochlear sGC activity was localized to pericytes in the spiral ligament as well as nerve fibers innervating outer hair cells [41].
• Analysis of a cDNA library of rat outer hair cells by the polymerase chain reaction, using isoform specific primers, showed expression only of FGF receptor 3, splice variant IIIc [42].

References