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Smith KE, Murphy P, Jagger DJ. Divergent membrane properties of mouse cochlear glial cells around hearing onset. J Neurosci Res 2020; 99:679-698. [PMID: 33099767 DOI: 10.1002/jnr.24744] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 09/21/2020] [Accepted: 10/05/2020] [Indexed: 11/11/2022]
Abstract
Spiral ganglion neurons (SGNs) are the primary afferent neurons of the auditory system, and together with their attendant glia, form the auditory nerve. Within the cochlea, satellite glial cells (SGCs) encapsulate the cell body of SGNs, whereas Schwann cells (SCs) wrap their peripherally- and centrally-directed neurites. Despite their likely importance in auditory nerve function and homeostasis, the physiological properties of auditory glial cells have evaded description. Here, we characterized the voltage-activated membrane currents of glial cells from the mouse cochlea. We identified a prominent weak inwardly rectifying current in SGCs within cochlear slice preparations (postnatal day P5-P6), which was also present in presumptive SGCs within dissociated cultures prepared from the cochleae of hearing mice (P14-P15). Pharmacological block by Ba2+ and desipramine suggested that channels belonging to the Kir4 family mediated the weak inwardly rectifying current, and post hoc immunofluorescence implicated the involvement of Kir4.1 subunits. Additional electrophysiological profiles were identified for glial cells within dissociated cultures, suggesting that glial subtypes may have specific membrane properties to support distinct physiological roles. Immunofluorescence using fixed cochlear sections revealed that although Kir4.1 is restricted to SGCs after the onset of hearing, these channels are more widely distributed within the glial population earlier in postnatal development (i.e., within both SGCs and SCs). The decrease in Kir4.1 immunofluorescence during SC maturation was coincident with a reduction of Sox2 expression and advancing neurite myelination. The data suggest a diversification of glial properties occurs in preparation for sound-driven activity in the auditory nerve.
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Affiliation(s)
- Katie E Smith
- UCL Ear Institute, University College London, London, UK
| | - Phoebe Murphy
- UCL Ear Institute, University College London, London, UK
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Harasztosi C, Wolter S, Gutsche K, Durán-Alonso MB, López-Hernández I, Pascual A, López-Barneo J, Knipper M, Rüttiger L, Schimmang T. Differential deletion of GDNF in the auditory system leads to altered sound responsiveness. J Neurosci Res 2019; 98:1764-1779. [PMID: 31663646 DOI: 10.1002/jnr.24544] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Revised: 09/20/2019] [Accepted: 10/08/2019] [Indexed: 11/09/2022]
Abstract
Glial-derived neurotrophic factor (GDNF) has been proposed as a potent neurotrophic factor with the potential to cure neurodegenerative diseases. In the cochlea, GDNF has been detected in auditory neurons and sensory receptor cells and its expression is upregulated upon trauma. Moreover, the application of GDNF in different animal models of deafness has shown its capacity to prevent hearing loss and promoted its future use in therapeutic trials in humans. In the present study we have examined the endogenous requirement of GDNF during auditory development in mice. Using a lacZ knockin allele we have confirmed the expression of GDNF in the cochlea including its sensory regions during development. Global inactivation of GDNF throughout the hearing system using a Foxg1-Cre line causes perinatal lethality but reveals no apparent defects during formation of the cochlea. Using TrkC-Cre and Atoh1-Cre lines, we were able to generate viable mutants lacking GDNF in auditory neurons or both auditory neurons and sensory hair cells. These mutants show normal frequency-dependent auditory thresholds. However, mechanoelectrical response properties of outer hair cells (OHCs) in TrkC-Cre GDNF mutants are altered at low thresholds. Furthermore, auditory brainstem wave analysis shows an abnormal increase of wave I. On the other hand, Atoh1-Cre GDNF mutants show normal OHC function but their auditory brainstem wave pattern is reduced at the levels of wave I, III and IV. These results show that GDNF expression during the development is required to maintain functional hearing at different levels of the auditory system.
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Affiliation(s)
- Csaba Harasztosi
- Department of Otolaryngology, Hearing Research Centre Tübingen (THRC), Molecular Physiology of Hearing, ENT Clinic, University of Tübingen, Tübingen, Germany
| | - Steffen Wolter
- Department of Otolaryngology, Hearing Research Centre Tübingen (THRC), Molecular Physiology of Hearing, ENT Clinic, University of Tübingen, Tübingen, Germany
| | - Katja Gutsche
- Instituto de Biología y Genética Molecular, Universidad de Valladolid y Consejo Superior de Investigaciones Científicas, Valladolid, Spain
| | - María Beatriz Durán-Alonso
- Instituto de Biología y Genética Molecular, Universidad de Valladolid y Consejo Superior de Investigaciones Científicas, Valladolid, Spain
| | - Iris López-Hernández
- Instituto de Biología y Genética Molecular, Universidad de Valladolid y Consejo Superior de Investigaciones Científicas, Valladolid, Spain
| | - Alberto Pascual
- Instituto de Biomedicina de Sevilla, Hospital Universitario Virgen del Rocío/CSIC/, Universidad de Sevilla, Seville, Spain
| | - José López-Barneo
- Instituto de Biomedicina de Sevilla, Hospital Universitario Virgen del Rocío/CSIC/, Universidad de Sevilla, Seville, Spain
| | - Marlies Knipper
- Department of Otolaryngology, Hearing Research Centre Tübingen (THRC), Molecular Physiology of Hearing, ENT Clinic, University of Tübingen, Tübingen, Germany
| | - Lukas Rüttiger
- Department of Otolaryngology, Hearing Research Centre Tübingen (THRC), Molecular Physiology of Hearing, ENT Clinic, University of Tübingen, Tübingen, Germany
| | - Thomas Schimmang
- Instituto de Biología y Genética Molecular, Universidad de Valladolid y Consejo Superior de Investigaciones Científicas, Valladolid, Spain
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Ellis JK, Sorrells SF, Mikhailova S, Chavali M, Chang S, Sabeur K, Mcquillen P, Rowitch DH. Ferret brain possesses young interneuron collections equivalent to human postnatal migratory streams. J Comp Neurol 2019; 527:2843-2859. [PMID: 31050805 PMCID: PMC6773523 DOI: 10.1002/cne.24711] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2018] [Revised: 03/27/2019] [Accepted: 04/29/2019] [Indexed: 12/16/2022]
Abstract
The human early postnatal brain contains late migratory streams of immature interneurons that are directed to cortex and other focal brain regions. However, such migration is not observed in rodent brain, and whether other small animal models capture this aspect of human brain development is unclear. Here, we investigated whether the gyrencephalic ferret cortex possesses human‐equivalent postnatal streams of doublecortin positive (DCX+) young neurons. We mapped DCX+ cells in the brains of ferrets at P20 (analogous to human term gestation), P40, P65, and P90. In addition to the rostral migratory stream, we identified three populations of young neurons with migratory morphology at P20 oriented toward: (a) prefrontal cortex, (b) dorsal posterior sigmoid gyrus, and (c) occipital lobe. These three neuronal collections were all present at P20 and became extinguished by P90 (equivalent to human postnatal age 2 years). DCX+ cells in such collections all expressed GAD67, identifying them as interneurons, and they variously expressed the subtype markers SP8 and secretagogin (SCGN). SCGN+ interneurons appeared in thick sections to be oriented from white matter toward multiple cortical regions, and persistent SCGN‐expressing cells were observed in cortex. These findings indicate that ferret is a suitable animal model to study the human‐relevant process of late postnatal cortical interneuron integration into multiple regions of cortex.
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Affiliation(s)
- Justin K Ellis
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, California.,Department of Pediatrics and Neurological Surgery, University of California, San Francisco, San Francisco, California
| | - Shawn F Sorrells
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, California.,Department of Pediatrics and Neurological Surgery, University of California, San Francisco, San Francisco, California
| | - Sasha Mikhailova
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, California.,Department of Pediatrics and Neurological Surgery, University of California, San Francisco, San Francisco, California
| | - Manideep Chavali
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, California.,Department of Pediatrics and Neurological Surgery, University of California, San Francisco, San Francisco, California
| | - Sandra Chang
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, California.,Department of Pediatrics and Neurological Surgery, University of California, San Francisco, San Francisco, California
| | - Khalida Sabeur
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, California.,Department of Pediatrics and Neurological Surgery, University of California, San Francisco, San Francisco, California
| | - Patrick Mcquillen
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, California.,Department of Pediatrics and Neurological Surgery, University of California, San Francisco, San Francisco, California
| | - David H Rowitch
- Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, California.,Department of Pediatrics and Neurological Surgery, University of California, San Francisco, San Francisco, California.,Department of Paediatrics and Wellcome Trust-MRC Cambridge Stem Cell Institute, University of Cambridge, Cambridge, UK
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