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Sahley TL, Anderson DJ, Hammonds MD, Chandu K, Musiek FE. Evidence for a dynorphin-mediated inner ear immune/inflammatory response and glutamate-induced neural excitotoxicity: an updated analysis. J Neurophysiol 2019; 122:1421-1460. [DOI: 10.1152/jn.00595.2018] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Acoustic overstimulation (AOS) is defined as the stressful overexposure to high-intensity sounds. AOS is a precipitating factor that leads to a glutamate (GLU)-induced Type I auditory neural excitotoxicity and an activation of an immune/inflammatory/oxidative stress response within the inner ear, often resulting in cochlear hearing loss. The dendrites of the Type I auditory neural neurons that innervate the inner hair cells (IHCs), and respond to the IHC release of the excitatory neurotransmitter GLU, are themselves directly innervated by the dynorphin (DYN)-bearing axon terminals of the descending brain stem lateral olivocochlear (LOC) system. DYNs are known to increase GLU availability, potentiate GLU excitotoxicity, and induce superoxide production. DYNs also increase the production of proinflammatory cytokines by modulating immune/inflammatory signal transduction pathways. Evidence is provided supporting the possibility that the GLU-mediated Type I auditory neural dendritic swelling, inflammation, excitotoxicity, and cochlear hearing loss that follow AOS may be part of a brain stem-activated, DYN-mediated cascade of inflammatory events subsequent to a LOC release of DYNs into the cochlea. In support of a DYN-mediated cascade of events are established investigations linking DYNs to the immune/inflammatory/excitotoxic response in other neural systems.
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Affiliation(s)
- Tony L. Sahley
- Department of Biological, Geological, and Environmental Sciences, Cleveland State University, Cleveland, Ohio
- School of Health Sciences, Cleveland State University, Cleveland, Ohio
| | - David J. Anderson
- Department of Chemistry, Cleveland State University, Cleveland, Ohio
| | | | - Karthik Chandu
- Department of Chemistry, Cleveland State University, Cleveland, Ohio
| | - Frank E. Musiek
- Department of Speech, Language, and Hearing Sciences, University of Arizona, Tucson, Arizona
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Smit AL, Lambermont VA, Stokroos RJ, Anteunis LJC, Chenault MN, Schaefer SM, Schoenmakers LWG, Kremer B, Kramer BW. Intrauterine Lipopolysaccharide-Induced Chorioamnionitis in a Sheep: Does It Affect the Auditory System? Reprod Sci 2015; 23:257-63. [PMID: 26702124 DOI: 10.1177/1933719115602759] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Fetal exposure to in utero inflammation such as chorioamnionitis is related to central nervous system injury. We hypothesized that chorioamnionitis can provoke inflammatory changes in the perilymph and alter hearing outcome. METHODS Pregnant ewes were randomized into 2 groups: intrauterine injection with lipopolysaccharide (LPS; n = 19) or saline (n = 21). In the first experiment, fetal perilymph samples were taken for cytokine analysis. In the second experiment, consecutive bone-conducted auditory brain stem responses were obtained from 1 to 7 months after birth. RESULTS Perilymph samples showed a significant elevation in interleukin 8 in the LPS group. Auditory brain stem response analysis demonstrated higher response thresholds and a prolongation of absolute peak V and interpeak intervals I to V and III to V in the LPS group compared to sham treatment. CONCLUSION Our study confirms the hypothesis that an intrauterine inflammation by LPS can result in a fetal perilymphatic inflammatory response and functional impaired hearing outcomes after birth in a sheep model.
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Affiliation(s)
- Adriana L Smit
- Department of Otorhinolaryngology, Head and Neck Surgery, Maastricht University Medical Centre, Maastricht, the Netherlands School for Mental Health and Neuroscience, Maastricht University, Maastricht, the Netherlands
| | - Verena A Lambermont
- Department of Pediatrics, Maastricht University Medical Centre, Maastricht, the Netherlands
| | - Robert J Stokroos
- Department of Otorhinolaryngology, Head and Neck Surgery, Maastricht University Medical Centre, Maastricht, the Netherlands School for Mental Health and Neuroscience, Maastricht University, Maastricht, the Netherlands
| | - Lucien J C Anteunis
- Department of Otorhinolaryngology, Head and Neck Surgery, Maastricht University Medical Centre, Maastricht, the Netherlands School for Mental Health and Neuroscience, Maastricht University, Maastricht, the Netherlands
| | - Michelene N Chenault
- Department of Otorhinolaryngology, Head and Neck Surgery, Maastricht University Medical Centre, Maastricht, the Netherlands School for Mental Health and Neuroscience, Maastricht University, Maastricht, the Netherlands Department of Methodology and Statistics, Maastricht University, Maastricht, the Netherlands
| | - Simone M Schaefer
- Department of Otorhinolaryngology, Head and Neck Surgery, Maastricht University Medical Centre, Maastricht, the Netherlands
| | - Luke W G Schoenmakers
- Department of Otorhinolaryngology, Head and Neck Surgery, Maastricht University Medical Centre, Maastricht, the Netherlands
| | - Bernd Kremer
- Department of Otorhinolaryngology, Head and Neck Surgery, Maastricht University Medical Centre, Maastricht, the Netherlands School of Oncology and Developmental Biology, Maastricht University, Maastricht, the Netherlands
| | - Boris W Kramer
- School for Mental Health and Neuroscience, Maastricht University, Maastricht, the Netherlands Department of Pediatrics, Maastricht University Medical Centre, Maastricht, the Netherlands School of Oncology and Developmental Biology, Maastricht University, Maastricht, the Netherlands
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