title: Low-level laser therapy for prevention of noise-induced hearing loss in rats.
abstract: Noninvasive low-level laser therapy (LLLT) is neuroprotective, but the mechanism of this effect is not fully understood. In this study, the use of LLLT as a novel treatment for noise-induced hearing loss (NIHL) is investigated. Sprague-Dawley rats were exposed to intense noise and their right ears were irradiated with an 808nm diode laser at an output power density of 110 or 165mW/cm(2) for a 30min period for 5 consecutive days. Measurement of the auditory brainstem response revealed an accelerated recovery of auditory function in the groups treated with LLLT compared with the non-treatment group at days 2, 4, 7 and 14 after noise exposure. Morphological observations also revealed a significantly higher outer hair cell survival rate in the LLLT groups. Immunohistochemical analyses for inducible nitric oxide synthase (iNOS) and cleaved caspase-3 were used to examine oxidative stress and apoptosis. Strong immunoreactivities were observed in the inner ear tissues of the non-treatment group, whereas these signals were decreased in the LLLT group at 165mW/cm(2) power density. Our findings suggest that LLLT has cytoprotective effects against NIHL via the inhibition of iNOS expression and apoptosis.
authors: Department of Otolaryngology-Head and Neck Surgery, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama 359-0042, Japan.
authors: Atsushi
authors: A
authors: Tamura
authors: Department of Otolaryngology-Head and Neck Surgery, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama 359-0042, Japan. Electronic address: t-matsunobu@shin-tokyohospital.or.jp.
authors: Takeshi
authors: T
authors: Matsunobu
authors: Department of Otolaryngology-Head and Neck Surgery, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama 359-0042, Japan.
authors: Kunio
authors: K
authors: Mizutari
authors: Department of Otolaryngology-Head and Neck Surgery, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama 359-0042, Japan.
authors: Katsuki
authors: K
authors: Niwa
authors: Department of Otolaryngology-Head and Neck Surgery, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama 359-0042, Japan.
authors: Takaomi
authors: T
authors: Kurioka
authors: Division of Biomedical Information Sciences, National Defense Medical College Research Institute, 3-2 Namiki, Tokorozawa, Saitama 359-0042, Japan.
authors: Satoko
authors: S
authors: Kawauchi
authors: Division of Biomedical Information Sciences, National Defense Medical College Research Institute, 3-2 Namiki, Tokorozawa, Saitama 359-0042, Japan.
authors: Shunichi
authors: S
authors: Satoh
authors: Department of Pathology and Laboratory Medicine, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama 359-0042, Japan.
authors: Sadayuki
authors: S
authors: Hiroi
authors: Department of Anesthesiology, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama 359-0042, Japan.
authors: Yasushi
authors: Y
authors: Satoh
authors: Department of Psychiatry, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama 359-0042, Japan.
authors: Masashi
authors: M
authors: Nibuya
authors: Department of Physiology, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama 359-0042, Japan.
authors: Risa
authors: R
authors: Tamura
authors: Department of Otolaryngology-Head and Neck Surgery, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama 359-0042, Japan.
authors: Akihiro
authors: A
authors: Shiotani
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000528:radiation effects; D053148:Caspase 3 / Q000378:metabolism; D016057:Evoked Potentials, Auditory, Brain Stem; D018072:Hair Cells, Auditory, Outer / Q000473:pathology / Q000528:radiation effects; D034381:Hearing Loss / Q000209:etiology / Q000473:pathology / Q000503:physiopathology / Q000517:prevention & control*; D028022:Low-Level Light Therapy; D008297:Male; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D009622:Noise / Q000009:adverse effects*; D018384:Oxidative Stress / Q000528:radiation effects; D017207:Rats, Sprague-Dawley
chemical_list: D052247:Nitric Oxide Synthase Type II; D053148:Caspase 3
keywords: Cleaved caspase-3; Inducible nitric oxide synthase; Low-level laser therapy; Noise-induced hearing loss