Acoustic Trauma Increases Ribbon Number and Size in Outer Hair Cells of the Mouse Cochlea
- PDF / 2,903,859 Bytes
- 13 Pages / 595.276 x 790.866 pts Page_size
- 98 Downloads / 164 Views
JARO (2020) DOI: 10.1007/s10162-020-00777-w D 2020 The Author(s)
Research Article
Journal of the Association for Research in Otolaryngology
Acoustic Trauma Increases Ribbon Number and Size in Outer Hair Cells of the Mouse Cochlea MEGAN B WOOD,1 NATHANIEL NOWAK,1 KEIRA MULL,1 ADAM GOLDRING,1,2 MOHAMED LEHAR,1 AND PAUL ALBERT FUCHS1 Department of Otolaryngology – Head and Neck, Surgery, Johns Hopkins University School of Medicine, 820 Richard Starr Ross Research Building, 720 Rutland Ave, Baltimore, MD 21205, USA 1
2
Sutter Instrument, Co. 1 Digital Drive, Novato, CA 94949, USA
Received: 10 June 2020; Accepted: 19 October 2020
ABSTRACT Outer hair cells (OHCs) in the mouse cochlea are contacted by up to three type II afferent boutons. On average, only half of these are postsynaptic to presynaptic ribbons. Mice of both sexes were subjected to acoustic trauma that produced a threshold shift of 44.2 ± 9.1 dB 7 days after exposure. Ribbon synapses of OHCs were quantified in post-trauma and littermate controls using immunolabeling of CtBP2. Visualization with virtual reality was used to determine 3-D cytoplasmic localization of CtBP2 puncta to the synaptic pole of OHCs. Acoustic trauma was associated with a statistically significant increase in the number of synaptic ribbons per OHC. Serial section TEM was carried out on similarly treated mice. This also showed a significant increase in the number of ribbons in post-trauma OHCs, as well as a significant increase in ribbon volume compared to ribbons in control OHCs. An increase in OHC ribbon synapses after acoustic trauma is a novel observation that has implications for OHC:type II afferent signaling. A mathematical model showed that the observed increase in OHC ribbons considered alone could produce a significant Present address: Adam Goldring, Department of Otolaryngology – Head and Neck, Surgery, Johns Hopkins University School of Medicine, 820 Richard Starr Ross Research Building, 720 Rutland Ave, Baltimore, MD 21205, USA. Supplementary Information The online version contains supplementary material available at https://doi.org/10.1007/s10162-02000777-w. Correspondence to: Megan B Wood & Department of Otolaryngology – Head and Neck, Surgery & Johns Hopkins University School of Medicine & 820 Richard Starr Ross Research Building, 720 Rutland Ave, Baltimore, MD 21205, USA. email: [email protected]
increase in action potentials among type II afferent neurons during strong acoustic stimulation. Keywords: ribbon synapse, outer hair cell, acoustic trauma
INTRODUCTION Type II cochlear afferents are uncommon, smallcaliber, unmyelinated neurons that project to the brainstem cochlear nucleus (Brown et al. 1988). Their peripheral arbors extend hundreds of microns along the organ of Corti to contact numerous outer hair cells (OHCs) (Spoendlin 1969; Smith 1975; Kiang et al. 1982; Berglund and Ryugo 1987; Brown 1987; Simmons and Liberman 1988). Despite those many contacts, type II afferents respond poorly, if at all, to sound (Robertson 1984; Brown 1994; Robertson et al. 1999;
Data Loading...
