title: Photobiomodulation rescues the cochlea from noise-induced hearing loss via upregulating nuclear factor κB expression in rats.
abstract: Photobiomodulation (PBM) is a noninvasive treatment that can be neuroprotective, although the underlying mechanisms remain unclear. In the present study, we assessed the mechanism of PBM as a novel treatment for noise-induced hearing loss, focusing on the nuclear factor (NF)-κB signaling pathway. Sprague-Dawley rats were exposed to 1-octave band noise centered at 4kHz for 5h (121dB). After noise exposure, their right ears were irradiated with an 808nm diode laser beam at an output power density of 165mW/cm(2) for 30min a day for 5 consecutive days. Measurement of the auditory brainstem response revealed an accelerated recovery of auditory function in the groups treated with PBM compared with the non-treatment group at 4, 7, and 14 days after noise exposure. Immunofluorescent image analysis for inducible nitric oxide synthase and cleaved caspase-3 showed lesser immunoreactivities in outer hair cells in the PBM group compared with the non-treatment group. However, immunofluorescent image analysis for NF-κB, an upstream protein of inducible nitric oxide synthase, revealed greater activation in the PBM group compared with the naïve and non-treatment groups. Western blot analysis for NF-κB also showed stronger activation in the cochlear tissues in the PBM group compared with the naïve and non-treatment groups (p<0.01, each). These data suggest that PBM activates NF-κB to induce protection against inducible nitric oxide synthase-triggered oxidative stress and caspase-3-mediated apoptosis that occur following noise-induced hearing loss.
authors.affiliation: Department of Otolaryngology - Head and Neck Surgery, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama 359-0042, Japan. Electronic address: morningconference@r8.dion.ne.jp.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Tamura
authors.affiliation: Department of Otolaryngology - Head and Neck Surgery, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama 359-0042, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Matsunobu
authors.affiliation: Department of Physiology, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama 359-0042, Japan.
authors.forename: Risa
authors.initials: R
authors.lastname: Tamura
authors.affiliation: Division of Bioinformation and Therapeutic Systems, National Defense Medical College Research Institute, 3-2 Namiki, Tokorozawa, Saitama 359-0042, Japan.
authors.forename: Satoko
authors.initials: S
authors.lastname: Kawauchi
authors.affiliation: Division of Bioinformation and Therapeutic Systems, National Defense Medical College Research Institute, 3-2 Namiki, Tokorozawa, Saitama 359-0042, Japan.
authors.forename: Shunichi
authors.initials: S
authors.lastname: Sato
authors.affiliation: Department of Otolaryngology - Head and Neck Surgery, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama 359-0042, Japan.
authors.forename: Akihiro
authors.initials: A
authors.lastname: Shiotani
mesh_terms: D000818:Animals; D017209:Apoptosis; D053148:Caspase 3 / Q000378:metabolism; D003051:Cochlea / Q000378:metabolism*; D016057:Evoked Potentials, Auditory, Brain Stem; D006317:Hearing Loss, Noise-Induced / Q000378:metabolism* / Q000628:therapy; D028022:Low-Level Light Therapy; D008297:Male; D016328:NF-kappa B / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D015854:Up-Regulation
chemical_list: D016328:NF-kappa B; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat; D051057:Proto-Oncogene Proteins c-akt; D053148:Caspase 3
keywords: Cleaved caspase-3; Inducible nitric oxide synthase; Noise-induced hearing loss; Nuclear factor κB; Photobiomodulation