Tetrodotoxin-sensitive, voltage-dependent sodium currents in hair cells from the alligator cochlea

Evans, Michael G.; Fuchs, P. A.

doi:10.1016/s0006-3495(87)83256-3

Cited by 44 publications

(29 citation statements)

References 21 publications

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“…I Na is downregulated during the first postnatal week, decreasing the sodium-based excitability in mature hair cells. This developmental excitability, also observed in the mouse utricle (Geleoc et al, 2004), has also been reported in other sensory organs of the higher vertebrates, such as the cochlea (Evans and Fuchs, 1987;Kros et al, 1998) and the retina (Pan and Hu, 2000;Kawai et al, 2001). Although, in most cases, the physiological relevance of the I Na remains unknown, we first reported that I Na was involved in the activity-dependent secretion of brain-derived neurotrophic factor (BDNF) in the neonate rat utricle (Chabbert et al, 2003).…”

Section: Introductionsupporting

confidence: 60%

Control of Hair Cell Excitability by Vestibular Primary Sensory Neurons

et al. 2007

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In the rat utricle, synaptic contacts between hair cells and the nerve fibers arising from the vestibular primary neurons form during the first week after birth. During that period, the sodium-based excitability that characterizes neonate utricle sensory cells is switched off. To investigate whether the establishment of synaptic contacts was responsible for the modulation of the hair cell excitability, we used an organotypic culture of rat utricle in which the setting of synapses was prevented. Under this condition, the voltage-gated sodium current and the underlying action potentials persisted in a large proportion of nonafferented hair cells. We then studied whether impairment of nerve terminals in the utricle of adult rats may also affect hair cell excitability. We induced selective and transient damages of afferent terminals using glutamate excitotoxicity in vivo. The efficiency of the excitotoxic injury was attested by selective swellings of the terminals and underlying altered vestibular behavior. Under this condition, the sodium-based excitability transiently recovered in hair cells. These results indicate that the modulation of hair cell excitability depends on the state of the afferent terminals. In adult utricle hair cells, this property may be essential to set the conditions required for restoration of the sensory network after damage. This is achieved via re-expression of a biological process that occurs during synaptogenesis.

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Section: Introductionsupporting

confidence: 60%

Control of Hair Cell Excitability by Vestibular Primary Sensory Neurons

et al. 2007

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“…Similarly, there were increased amounts of the sodium channel transcript SCN3B in the LF end and of SCNN1A in the HF end. While sodium channels have not been observed in the chicken, hair cells from the LF end of alligator BP were found to contain TTX-sensitive currents (Evans and Fuchs 1987). Actin was detected by our array but found not to be tonotopically expressed (data not shown), a finding that is intuitive given that the total amount of actin per hair cell does not vary tonotopically in chickens (Tilney and Tilney 1988).…”

Section: Discussionmentioning

confidence: 60%

Gene Expression Gradients along the Tonotopic Axis of the Chicken Auditory Epithelium

Frucht

Uduman

Kleinstein

et al. 2011

JARO

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There are known differences in the properties of hair cells along the tonotopic axis of the avian auditory epithelium, the basilar papilla (BP). To determine the genetic basis of these differences, we compared gene expression between the high-(HF), middle-, and lowfrequency (LF) thirds of 0-day-old chick auditory epithelia. RNA amplified from each sample was hybridized to whole-genome chicken arrays and GeneSpring software was used to identify differentially expressed genes. Two thousand six hundred sixty-three genes were found to be differentially expressed between the HF and LF segments, using a fold-change cutoff of 2 and a p value of 0.05. Many ion channel genes were differentially expressed between the HF and LF regions of the BP, an expression pattern that was previously established for some but not all of these genes. Quantitative PCR was used to verify tonotopic expression of 15 genes, including KCNMA1 (Slo) and its alternatively spliced STREX exon. Gene set enrichment analyses (GSEA) were performed on the microarray data and revealed many microRNA gene sets significantly enriched in the HF relative to the LF end, suggesting a tonotopic activity gradient. GSEA also suggested differential activity of the kinases protein kinase C and protein kinase A at the HF and LF ends, an interesting corollary to the observation that there is tonotopic expression of the STREX exon that confers on Slo sensitivity to the activity of kinases. Taken together, these results suggest mechanisms of induction and maintenance of tonotopicity and enhance our understanding of the complex nature of proximal-distal gene expression gradients in the chicken BP.

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“…A third Na ϩ current type, TTX-sensitive (like I Na,2 ) but negatively inactivating (like I Na,1 ), is reported from hair cells of diverse juvenile and mature hair cell organs (Evans and Fuchs 1987;Masetto et al 2003;Sugihara and Furukawa 1989;Witt et al 1994). The channel composition may change with maturation or, because most of these are nonmammals, differ between vertebrate classes.…”

Section: Two Na ϩ Currents In Hair Cellsmentioning

confidence: 99%

“…Information on voltagegated sodium (Na ϩ ) channels is more fragmentary. By the classic properties of voltage range of inactivation and sensitivity to tetrodotoxin (TTX), voltage-gated Na ϩ currents in hair cells fall into three classes: TTX-sensitive currents that inactivate at very negative potentials (Evans and Fuchs 1987;Masetto et al 2003;Sugihara and Furukawa 1989;Witt et al 1994); TTX-sensitive currents that inactivate at less negative potentials (Chabbert et al 2003;Marcotti et al 2003); and TTX-insensitive currents that inactivate at very negative potentials (Géléoc et al 2004;Oliver et al 1997;Rüsch and Eatock 1997).…”

Section: Introductionmentioning

confidence: 99%

Developmental Changes in Two Voltage-Dependent Sodium Currents in Utricular Hair Cells

Wooltorton¹,

Gaboyard²,

Hurley³

et al. 2007

Journal of Neurophysiology

112

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. Two kinds of sodium current (I Na ) have been separately reported in hair cells of the immature rodent utricle, a vestibular organ. We show that rat utricular hair cells express one or the other current depending on age (between postnatal days 0 and 22, P0 -P22), hair cell type (I, II, or immature), and epithelial zone (striola vs. extrastriola). The properties of these two currents, or a mix, can account for descriptions of I Na in hair cells from other reports. The patterns of Na channel expression during development suggest a role in establishing the distinct synapses of vestibular hair cells of different type and epithelial zone. All type I hair cells expressed I Na,1 , a TTX-insensitive current with a very negative voltage range of inactivation (midpoint: Ϫ94 mV). I Na,2 was TTX sensitive and had less negative voltage ranges of activation and inactivation (inactivation midpoint: Ϫ72 mV). I Na,1 dominated in the striola at all ages, but current density fell by two-thirds after the first postnatal week. I Na,2 was expressed by 60% of hair cells in the extrastriola in the first week, then disappeared. In the third week, all type I cells and about half of type II cells had I Na,1 ; the remaining cells lacked sodium current. I Na,1 is probably carried by Na V 1.5 subunits based on biophysical and pharmacological properties, mRNA expression, and immunoreactivity. Na V 1.5 was also localized to calyx endings on type I hair cells. Several TTX-sensitive subunits are candidates for I Na,2 .

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Tetrodotoxin-sensitive, voltage-dependent sodium currents in hair cells from the alligator cochlea

Cited by 44 publications

References 21 publications

Control of Hair Cell Excitability by Vestibular Primary Sensory Neurons

Control of Hair Cell Excitability by Vestibular Primary Sensory Neurons

Gene Expression Gradients along the Tonotopic Axis of the Chicken Auditory Epithelium

Developmental Changes in Two Voltage-Dependent Sodium Currents in Utricular Hair Cells

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