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Efferent synapses return to inner hair cells in the aging cochlea.

Publication ,  Journal Article
Lauer, AM; Fuchs, PA; Ryugo, DK; Francis, HW
Published in: Neurobiol Aging
December 2012

Efferent innervation of the cochlea undergoes extensive modification early in development, but it is unclear if efferent synapses are modified by age, hearing loss, or both. Structural alterations in the cochlea affecting information transfer from the auditory periphery to the brain may contribute to age-related hearing deficits. We investigated changes to efferent innervation in the vicinity of inner hair cells (IHCs) in young and old C57BL/6 mice using transmission electron microscopy to reveal increased efferent innervation of IHCs in older animals. Efferent contacts on IHCs contained focal presynaptic accumulations of small vesicles. Synaptic vesicle size and shape were heterogeneous. Postsynaptic cisterns were occasionally observed. Increased IHC efferent innervation was associated with a smaller number of afferent synapses per IHC, increased outer hair cell loss, and elevated auditory brainstem response thresholds. Efferent axons also formed synapses on afferent dendrites but with a reduced prevalence in older animals. Age-related reduction of afferent activity may engage signaling pathways that support the return to an immature state of efferent innervation of the cochlea.

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Published In

Neurobiol Aging

DOI

EISSN

1558-1497

Publication Date

December 2012

Volume

33

Issue

12

Start / End Page

2892 / 2902

Location

United States

Related Subject Headings

  • Synapses
  • Neurology & Neurosurgery
  • Models, Neurological
  • Microscopy, Electron, Transmission
  • Mice, Inbred C57BL
  • Mice
  • Hair Cells, Auditory, Inner
  • Female
  • Efferent Pathways
  • Cochlea
 

Citation

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Chicago
ICMJE
MLA
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Lauer, A. M., Fuchs, P. A., Ryugo, D. K., & Francis, H. W. (2012). Efferent synapses return to inner hair cells in the aging cochlea. Neurobiol Aging, 33(12), 2892–2902. https://doi.org/10.1016/j.neurobiolaging.2012.02.007
Lauer, Amanda M., Paul A. Fuchs, David K. Ryugo, and Howard W. Francis. “Efferent synapses return to inner hair cells in the aging cochlea.Neurobiol Aging 33, no. 12 (December 2012): 2892–2902. https://doi.org/10.1016/j.neurobiolaging.2012.02.007.
Lauer AM, Fuchs PA, Ryugo DK, Francis HW. Efferent synapses return to inner hair cells in the aging cochlea. Neurobiol Aging. 2012 Dec;33(12):2892–902.
Lauer, Amanda M., et al. “Efferent synapses return to inner hair cells in the aging cochlea.Neurobiol Aging, vol. 33, no. 12, Dec. 2012, pp. 2892–902. Pubmed, doi:10.1016/j.neurobiolaging.2012.02.007.
Lauer AM, Fuchs PA, Ryugo DK, Francis HW. Efferent synapses return to inner hair cells in the aging cochlea. Neurobiol Aging. 2012 Dec;33(12):2892–2902.
Journal cover image

Published In

Neurobiol Aging

DOI

EISSN

1558-1497

Publication Date

December 2012

Volume

33

Issue

12

Start / End Page

2892 / 2902

Location

United States

Related Subject Headings

  • Synapses
  • Neurology & Neurosurgery
  • Models, Neurological
  • Microscopy, Electron, Transmission
  • Mice, Inbred C57BL
  • Mice
  • Hair Cells, Auditory, Inner
  • Female
  • Efferent Pathways
  • Cochlea