Oxidative DNA damage is associated with intense noise exposure in the rat.
Increasing evidence suggests that noise-induced hearing loss may be reduced or prevented with antioxidant therapy. Biochemical markers of reactive oxygen species (ROS)-induced damage can help elucidate possible treatment timing constraints. This study examined the time course of ROS damage following a 2-h, broad-band noise exposure resulting in permanent threshold shift in 35 Long-Evans rats. Cochlea, brain, liver, serum and urine were analyzed at 1, 3, 8, 72, and 672 h (28 days) after exposure. Oxidative DNA damage was assessed by measuring 8-hydroxy-2'-deoxyguanosine (8OHdG) by high performance liquid chromatography with electrochemical detection. Lipid peroxidation was measured via the thiobarbituric acid-reactive substances (TBARS) colorimetric assay for detection of aldehydes (e.g., malondialdehyde). Auditory brainstem response and distortion product otoacoustic emission thresholds showed progressive elevation for the 3- and 8-h groups, then notable recovery for the 72-h group, and some worsening for the 672-h group. 8OHdG was significantly elevated in cochlea in the 8-h group, and in brain and liver for the 72-h group. TBARS were significantly elevated in serum for the 72-h group. Based upon oxidative DNA damage present in cochlea following intense noise, we postulate that the first 8 h following exposure might be a critical period for antioxidant treatment.
Van Campen
Luann E
LE
Engineering and Physical Hazards Branch, Division of Applied Research and Technology, National Institute for Occupational Safety and Health, Cincinnati, OH 45226, USA. vancampen_1_e@lilly.com
Murphy
William J
WJ
Franks
John R
JR
Mathias
Patricia I
PI
Toraason
Mark A
MA
D000080242:8-Hydroxy-2'-Deoxyguanosine; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D001921:Brain / Q000378:metabolism; D003051:Cochlea / Q000293:injuries / Q000378:metabolism; D004249:DNA Damage; D003849:Deoxyguanosine / Q000031:analogs & derivatives* / Q000378:metabolism; D016057:Evoked Potentials, Auditory, Brain Stem; D006317:Hearing Loss, Noise-Induced / Q000378:metabolism* / Q000503:physiopathology / Q000517:prevention & control; D008099:Liver / Q000378:metabolism; D008297:Male; D009622:Noise / Q000009:adverse effects*; D017084:Otoacoustic Emissions, Spontaneous; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism; D017392:Thiobarbituric Acid Reactive Substances / Q000378:metabolism
D000975:Antioxidants; D017382:Reactive Oxygen Species; D017392:Thiobarbituric Acid Reactive Substances; D000080242:8-Hydroxy-2'-Deoxyguanosine; D003849:Deoxyguanosine