A High-Fat Diet Delays Age-Related Hearing Loss Progression in C57BL/6J Mice

Abstract

ObjectiveAge-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).MethodsForty 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.ResultsThe 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.ConclusionsThe 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.

Induced Short-Term Hearing Loss due to Stimulation of Age-Related Factors by Intermittent Hypoxia, High-Fat Diet, and Galactose Injection

“…By determining the expression of Ucp2 under all environmental stimuli, it was confirmed that mitochondrial dysfunction was caused by oxidative stress [ 12 , 14 ]. Mitochondrial dysfunction has been observed to induce apoptosis in many studies [ 9 , 19 ], and we obtained similar results through histological analysis in this study. Thus, we discussed that the reduction of frequencies was influenced when the blood vessels were damaged, and substance exchange in the bloodstream was poor because of the hypoxic condition and HFD.…”

“…However, when two or more stimuli were added, hearing loss was observed to occur over a short period of time. HFD significantly increases the content of fat in the body, affects sugar metabolism, restricts blood vessels, and causes metabolic diseases [ 19 ]. These effects could be demonstrated by the expression of Edn1 and ApoE in cells within the hearing organ.…”

“…Therefore, based on relevant factors identified in the literature, we designed an aging animal model resulting from the exposure to a combination of three different lifestyles [ 9 , 18 ]. It has been reported that mitochondrial dysfunction can be induced by diet modification [ 19 ]. A high-fat diet (HFD) results in increased intracellular lipid content, diabetes-induced symptoms, and impairment of mitochondrial function due to oxidative stress.…”

Altered vesicular glutamate transporter distributions in the mouse cochlear nucleus following cochlear insult

“…Since the animals used in this study were 5 weeks of age upon surgery and 8 to 9 weeks of age upon euthanasia, the presence of sensorineural hearing loss is unlikely. Indeed, ABR thresholds of the mice in the current study are similar to thresholds of normal hearing C57Bl6 mice (Fujita et al, 2015, Shi et al, 2015). Moreover, VGLUT changes occurred only in the CN ipsilateral to the kanamycin injection, whereas sensorineural hearing loss would presumably affect both sides equally.…”

“…However, post-hoc tests were not significant for any of the tested frequencies (one-way ANOVA: p = 0.278, p = 0.128, p = 0.236, p = 0.241 for 12, 16, 20, and 30 kHz, respectively, corrected for multiple comparisons). ABR thresholds of age-matched control animals were similar to ABR thresholds of normal-hearing C57Bl6 mice (Fujita et al, 2015, Shi et al, 2015). …”