title: Effect of manganese and manganese plus noise on auditory function and cochlear structures.
abstract: The degenerative actions of Mn caused by persistent exposure to high atmospheric levels not only provokes irreversible damage to the CNS with symptoms comparable to that of Parkinson's disease but also may have deleterious consequences to other organs including the auditory system. The putative deleterious consequences of prolonged Mn overexposure on hearing, however, is confounded by the fact that chronically-exposed individuals often work in high noise environments where noise by itself is known to cause hearing loss. Thus, the question as to whether Mn alone is actually ototoxic and whether exposure to Mn when combined with noise increases the risk of hearing loss and cochlear pathology has never been examined. To examine whether noise effects Mn ototoxicity, we exposed rats to a moderate dose of Mn (10mg MnCl2/liter water) alone, a high level of noise (octave band noise, 8-16kHz, presented at 90dB SPL for 8h/d) alone or the combination of Mn plus noise and measured the changes in auditory function and the cochlear histopathologies. Results of these studies, based on various measures of hearing including histological examination of cochlear tissue suggest that noise alone produced significant hearing deficits whereas semi-chronic exposure to moderate levels of Mn in drinking water for 90days either in the presence or absence of noise had, at best, only a minor effect on hearing.
authors.affiliation: Center for Hearing and Deafness, University at Buffalo, Buffalo, NY 14214, USA.
authors.forename: Vijaya Prakash Krishnan
authors.initials: VPK
authors.lastname: Muthaiah
authors.affiliation: Center for Hearing and Deafness, University at Buffalo, Buffalo, NY 14214, USA.
authors.forename: Guang-Di
authors.initials: GD
authors.lastname: Chen
authors.affiliation: Center for Hearing and Deafness, University at Buffalo, Buffalo, NY 14214, USA.
authors.forename: Dalian
authors.initials: D
authors.lastname: Ding
authors.affiliation: Center for Hearing and Deafness, University at Buffalo, Buffalo, NY 14214, USA.
authors.forename: Richard
authors.initials: R
authors.lastname: Salvi
authors.affiliation: Department of Pharmacology and Toxicology, Cary Hall, University at Buffalo, Buffalo, NY 14214, USA. Electronic address: jaroth@buffalo.edu.
authors.forename: Jerome A
authors.initials: JA
authors.lastname: Roth
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000704:Analysis of Variance; D000818:Animals; D001309:Auditory Threshold / Q000187:drug effects; D016923:Cell Death / Q000187:drug effects; D003051:Cochlea / Q000187:drug effects* / Q000503:physiopathology; D016057:Evoked Potentials, Auditory, Brain Stem / Q000187:drug effects; D006198:Hair Cells, Auditory / Q000187:drug effects / Q000473:pathology; D034381:Hearing Loss / Q000209:etiology / Q000473:pathology*; D008297:Male; D008345:Manganese / Q000378:metabolism / Q000633:toxicity*; D009622:Noise / Q000009:adverse effects*; D017084:Otoacoustic Emissions, Spontaneous / Q000187:drug effects / Q000502:physiology; D011571:Psychoacoustics; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D014131:Trace Elements / Q000633:toxicity*
chemical_list: D014131:Trace Elements; D008345:Manganese
keywords: Cochlea; Hearing; Manganese; Noise exposure; Ototoxicity; Rats