title: Reduction of noise-induced hearing loss using L-NAC and salicylate in the chinchilla.
abstract: The effects of a combination of two antioxidant compounds were studied in a chinchilla model of noise-induced hearing loss. After obtaining baseline hearing thresholds using inferior colliculus evoked potentials, chinchillas were exposed for 6 h to octave band noise centered at 4 kHz (105 dB SPL). Post-noise thresholds were obtained 1 h after the noise exposure, and then animals received either saline or salicylate and N-L-acetylcysteine combination. Another group received antioxidant treatment 1 h prior to noise. Hearing was tested at 1, 2 and 3 weeks post-noise. Subsequently, the cochleae were harvested, and cytocochleograms were prepared. There was a 20-40 dB SPL threshold shift at 3 weeks for tested controls. Permanent threshold shifts (PTS) were significantly reduced (P<0.05) to approximately 10 dB for the pre-treatment group at week 3. The PTS for the post-treatment group at week 3 was similar to the pre-treatment group at 1 and 2 kHz (0-10 dB) but was intermediate between the control and pre-treatment groups at 4 and 8 kHz (23 dB). Animals pre-treated with antioxidant had a significant reduction in hair cell loss but those post-treated with antioxidant had no protection from hair cell loss. These findings demonstrate the feasibility of reduction of noise-induced hearing loss using clinically available antioxidant compounds.
authors.affiliation: Department of Defense Spatial Orientation Center, Naval Medical Center San Diego, San Diego, CA 92134-2200, USA. rkopke@nmcsd.med.navy.mil
authors.forename: R D
authors.initials: RD
authors.lastname: Kopke
authors.forename: P A
authors.initials: PA
authors.lastname: Weisskopf
authors.forename: J L
authors.initials: JL
authors.lastname: Boone
authors.forename: R L
authors.initials: RL
authors.lastname: Jackson
authors.forename: D C
authors.initials: DC
authors.lastname: Wester
authors.forename: M E
authors.initials: ME
authors.lastname: Hoffer
authors.forename: D C
authors.initials: DC
authors.lastname: Lambert
authors.forename: C C
authors.initials: CC
authors.lastname: Charon
authors.forename: D L
authors.initials: DL
authors.lastname: Ding
authors.forename: D
authors.initials: D
authors.lastname: McBride
mesh_terms: D000111:Acetylcysteine / Q000627:therapeutic use*; D000818:Animals; D001299:Audiometry; D001309:Auditory Threshold / Q000187:drug effects; D002452:Cell Count; D002682:Chinchilla; D004338:Drug Combinations; D006198:Hair Cells, Auditory / Q000187:drug effects / Q000473:pathology; D006317:Hearing Loss, Noise-Induced / Q000188:drug therapy* / Q000503:physiopathology; D012459:Salicylates / Q000627:therapeutic use*
chemical_list: D004338:Drug Combinations; D012459:Salicylates; D000111:Acetylcysteine