title: Time course of tinnitus development following noise exposure in mice.
abstract: Gap-induced prepulse inhibition of acoustic startle (GPIAS) has been used in rats and mice to study the problem of tinnitus. The current study demonstrates that similar methods can be used to study the temporal development of tinnitus over time in middle-aged mice. Six-month-old mice on a mixed C57Bl6 × 129 background were anesthetized with isoflurane and exposed to unilateral noise (n = 15), or sham exposure for controls (n = 8), for 1 hr (16-kHz octave band signal, 116-dB SPL). Tinnitus was tested in eight different sound frequency bands before and at postexposure time points of 1, 3-4, 7, 14, 21, and 30 days and monthly thereafter until 7 months postexposure. Noise-exposed mice displayed a number of changes in GPIAS consistent with the presence of hyperacusis and tinnitus. Noise exposure was associated with acute tinnitus measured 1 day later at several frequencies at and above the exposure frequency center. Consistent, chronic tinnitus then emerged in the 24-kHz range. Several time points following noise exposure suggested evidence of hyperacusis, often followed temporally by the development of deficits in GPIAS (reflecting tinnitus). Temporal development of these changes following noise exposure are discussed in the context of the interactions among aging, noise exposure, and the associated neurochemical changes that occur at early stages of auditory processing.
authors.affiliation: Department of Surgery/Otolaryngology, Southern Illinois University School of Medicine, Springfield, IL 62794, USA. jturner@siumed.edu
authors.forename: Jeremy
authors.initials: J
authors.lastname: Turner
authors.forename: Deb
authors.initials: D
authors.lastname: Larsen
authors.forename: Larry
authors.initials: L
authors.lastname: Hughes
authors.forename: Diederik
authors.initials: D
authors.lastname: Moechars
authors.forename: Susan
authors.initials: S
authors.lastname: Shore
mesh_terms: D000208:Acute Disease; D000818:Animals; D001522:Behavior, Animal / Q000502:physiology; D002908:Chronic Disease; D003051:Cochlea / Q000473:pathology / Q000503:physiopathology; D018450:Disease Progression; D005260:Female; D008297:Male; D051379:Mice; D057507:Mice, 129 Strain; D008810:Mice, Inbred C57BL; D009622:Noise / Q000009:adverse effects*; D013216:Reflex, Startle / Q000502:physiology; D013136:Spiral Ganglion / Q000473:pathology* / Q000503:physiopathology*; D013997:Time Factors; D014012:Tinnitus / Q000473:pathology* / Q000503:physiopathology*