Long-term white noise exposure-induced mtDNA deletion in the auditory system

• Published in: Acta oto-laryngologica Vol. 128; no. 3; pp. 309 - 313
• Main Authors: Han, Weiju, Shi, Yongbing, Yang, Weiyan, Han, Dongyi
• Format: Journal Article
• Language: English
• Published: Stockholm Informa UK Ltd 01.01.2008; Taylor & Francis; Taylor and Francis
• Subjects: Alleles; Animals; Auditory Pathways - metabolism; Auditory Pathways - pathology; Auditory Pathways - physiopathology; Biological and medical sciences; Chromosome Deletion; Cochlea - metabolism; Cochlea - pathology; Cochlea - physiopathology; Cochlear Nucleus - metabolism; Cochlear Nucleus - pathology; Cochlear Nucleus - physiopathology; DNA deletion; DNA, Mitochondrial - genetics; Ear, auditive nerve, cochleovestibular tract, facial nerve: diseases, semeiology; Evoked Potentials, Auditory, Brain Stem - physiology; Female; hearing loss; Hearing Loss, Noise-Induced - genetics; Hearing Loss, Noise-Induced - pathology; Hearing Loss, Noise-Induced - physiopathology; Male; Medical sciences; mitochondrial DNA; Noise exposure; Non tumoral diseases; Otorhinolaryngology. Stomatology; Polymerase Chain Reaction; Rats; Rats, Wistar; Sequence Analysis, DNA; Temporal Lobe - metabolism; Temporal Lobe - pathology; Temporal Lobe - physiopathology; Acoustic trauma; Auditory disorder; White noise; Deletion; ENT disease; Mitochondrial DNA; Noise pollution; ENT; DNA deletion; Noise exposure; Long term; Hearing loss
• ISSN: 0001-6489; 1651-2251
• DOI: 10.1080/00016480601126994

Conclusion. Long-term exposure to broadband noise can lead to increased levels of mtDNA4834 deletion in the auditory system in rats. Objective. This study aimed to determine if long-term noise exposure induces mtDNA deletion in the auditory system. Materials and methods. Wistar rats aged 3 months (n =20) were exposed to 110 dB SPL white noise, 4 h per day, for 20 consecutive days. The control group included Wistar rats of the same age (n=20) with no noise exposure. Auditory brainstem responses (ABRs) were tested as an indicator of hearing function. The cochlea, cochlear nucleus, temporal lobe brain tissue, and blood specimens were collected for DNA extraction. The mtDNA was amplified to identify the highly conserved ND1 segment, as well as mtDNA4834 deletion. Results. Animals in the noise-exposed group demonstrated permanent loss of auditory sensitivity following noise exposure compared with the control animals (p<0.01). The majority of animals in the noise-exposed group demonstrated mtDNA4834 deletion in cochlea, cochlear nucleus and temporal lobe brain tissues, while only a few in the control group showed such deletion (p<0.01). In contrast, mtDNA4834 deletion in blood specimens was identified at an extremely low rate in both the noise-exposed and the control groups.