The objective of this proposal is to study the molecular mechanisms by which neurotransmitters released by olivocochlear efferents influence outer hair cells (OHCs) of the cochlea. One theory about the contributions that cochlear efferents make to hearing is that they protect the cochlea from high frequency acoustic over-stimulation, whereas another theory is that they enhance sound recognition in the presence of background noise. The primary neurotransmitters of the efferents projecting on high frequency OHCs are acetylcholine (ACh) and calcitonin gene-related peptide (CGRP). The proposed experiments will test the hypothesis that CGRP exerts its effects by initiating a cascade of events resulting in desensitization of the cholinergic receptors present on OHCs. The first specific aim is to clone full-length cDNAs for ACh and CGRP receptor subtypes from the guinea pig cochlea using as probes partial cDNAs encoding the guinea pig a9 ACh and CGRP receptors. In situ hybridization techniques will be used to establish which cells in the guinea pig organ of Corti express these receptors. The second specific aim will use immunohistochemical and Western blotting techniques to verify the presence and distribution of proteins for the cochlear ACh a9 and CGRP efferent receptors. The third specific aim employs electrophysiological techniques to investigate whether the cloned CGRP and Ach receptors are able to interact functionally, such that CGRP preincubation causes second messenger effects, which leads to Ach receptor desensitization. Information gained from these studies may contribute to future drug therapies that target the cochlear efferents system, and thus, help decrease the occurrence of, and improve the treatment for patients with high-frequency hearing loss.

Agency
National Institute of Health (NIH)
Institute
National Institute on Deafness and Other Communication Disorders (NIDCD)
Type
First Independent Research Support & Transition (FIRST) Awards (R29)
Project #
5R29DC003086-02
Application #
2518096
Study Section
Hearing Research Study Section (HAR)
Project Start
1996-09-30
Project End
2001-08-31
Budget Start
1997-09-01
Budget End
1998-08-31
Support Year
2
Fiscal Year
1997
Total Cost
Indirect Cost
Name
University of Miami School of Medicine
Department
Physiology
Type
Schools of Medicine
DUNS #
City
Miami
State
FL
Country
United States
Zip Code
33146
Walton, Joseph P; Dziorny, Adam C; Vasilyeva, Olga N et al. (2018) Loss of the Cochlear Amplifier Prestin Reduces Temporal Processing Efficacy in the Central Auditory System. Front Cell Neurosci 12:291
Dickerson, Ian M; Bussey-Gaborski, Rhiannon; Holt, Joseph C et al. (2016) Maturation of suprathreshold auditory nerve activity involves cochlear CGRP-receptor complex formation. Physiol Rep 4:
Luebke, Anne E; Stagner, Barden B; Martin, Glen K et al. (2015) Influence of sound-conditioning on noise-induced susceptibility of distortion-product otoacoustic emissions. J Acoust Soc Am 138:58-64
Luebke, Anne E; Holt, Joseph C; Jordan, Paivi M et al. (2014) Loss of ?-calcitonin gene-related peptide (?CGRP) reduces the efficacy of the Vestibulo-ocular Reflex (VOR). J Neurosci 34:10453-8
Luebke, Anne E; Stagner, Barden B; Martin, Glen K et al. (2014) Adaptation of distortion product otoacoustic emissions predicts susceptibility to acoustic over-exposure in alert rabbits. J Acoust Soc Am 135:1941-9
Bogart, L J; Levy, A D; Gladstone, M et al. (2011) Loss of prestin does not alter the development of auditory cortical dendritic spines. Neural Plast 2011:305621
Luebke, Anne E; Rova, Cherokee; Von Doersten, Peter G et al. (2009) Adenoviral and AAV-mediated gene transfer to the inner ear: role of serotype, promoter, and viral load on in vivo and in vitro infection efficiencies. Adv Otorhinolaryngol 66:87-98