title: A high-fat diet delays age-related hearing loss progression in C57BL/6J mice.
abstract: OBJECTIVE
  Age-related hearing loss (AHL), or presbycusis, is the most common sensory disorder among the elderly. We used C57BL/6J mice as an AHL model to determine a possible association between AHL and a high-fat diet (HFD).
  
  
  METHODS
  Forty C57BL/6J mice were randomly assigned to a control or HFD group. Each group was divided into the following subgroups: 1-, 3-, 5- and 12-month groups (HFD, n = 5/subgroup; control, n = 5/subgroup). Nine CBA/N-slc mice were also used as a 12-month control (n = 5) or 12-month HFD (n = 4) group. The mice were fed a HFD or normal (control) diet throughout this study. Hearing function was evaluated at 1, 3, 5 and 12 months using auditory evoked brainstem responses (ABRs). Spiral ganglion cells (SGCs) were also counted.
  
  
  RESULTS
  The elevation of ABR thresholds (at 4 and 32 kHz) at 3 and 5 months was significantly suppressed in the HFD group compared with the control groups for C57BL/6J mice. After 12 months, the elevation of ABR thresholds was significantly suppressed in the HFD group at all frequencies for C57BL/6J mice. In contrast, CBA/N-slc mice displayed opposite outcomes, as ABR thresholds at all frequencies at 12 months were significantly elevated in the HFD group compared with the control group. For the C57BL/6J mice at 12 months, SGC numbers significantly decreased in all parts of the cochleae in the control group compared with the HFD groups. In contrast, for the CBA/N-slc mice, SGC numbers significantly decreased, particularly in the upper parts of the cochleae in the HFD group compared with the control groups.
  
  
  CONCLUSIONS
  The elevation in ABR thresholds and SGC loss associated with aging in the HFD-fed C57BL/6J mice were significantly suppressed compared with those in the normal diet-fed mice. These results suggest that HFD delays AHL progression in the C57B/6J mice.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Kobe University Graduate School of Medicine, Kobe, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Fujita
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Kobe University Graduate School of Medicine, Kobe, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Yamashita
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Kobe University Graduate School of Medicine, Kobe, Japan.
authors.forename: Natsumi
authors.initials: N
authors.lastname: Uehara
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Kobe University Graduate School of Medicine, Kobe, Japan.
authors.forename: Go
authors.initials: G
authors.lastname: Inokuchi
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Kobe University Graduate School of Medicine, Kobe, Japan.
authors.forename: Shingo
authors.initials: S
authors.lastname: Hasegawa
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Kobe University Graduate School of Medicine, Kobe, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Otsuki
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Kobe University Graduate School of Medicine, Kobe, Japan.
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Nibu
mesh_terms: D000161:Acoustic Stimulation; D000818:Animals; D003051:Cochlea / Q000473:pathology / Q000503:physiopathology; D059305:Diet, High-Fat; D018450:Disease Progression; D016057:Evoked Potentials, Auditory, Brain Stem; D008297:Male; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D011304:Presbycusis / Q000178:diet therapy* / Q000473:pathology / Q000503:physiopathology