title: Metabolic changes in the auditory cortex in presbycusis demonstrated by MR spectroscopy.
abstract: In humans, aging is accompanied by the deterioration of the hearing function--presbycusis. The major etiology for presbycusis is the loss of hair cells in the inner ear; less well known are changes in the central auditory system. Therefore, we used 1H magnetic resonance spectroscopy at 3T tomograph to examine metabolite levels in the auditory cortex of three groups of subjects: young healthy subjects less than 30 years old and subjects older than 65 years either with mild presbycusis corresponding to their age or with expressed presbycusis. Hearing function in all subjects was examined by pure tone audiometry (125-16,000 Hz). Significant differences were found in the concentrations of glutamate and N-acetylaspartate, with lower levels in aged subjects. Lactate was particularly increased in subjects with expressed presbycusis. Significant differences were not found in other metabolites, including GABA, between young and elderly subjects. The results demonstrate that the age-related changes of the inner ear are accompanied by a decrease in the excitatory neurotransmitter glutamate as well as a lactate increase in the auditory cortex that is more expressed in elderly subjects with large hearing threshold shifts.
authors: Department of Auditory Neuroscience, Institute of Experimental Medicine, Academy of Sciences of the Czech Republic, Prague, Czech Republic. profant@biomed.cas.cz
authors: Oliver
authors: O
authors: Profant
authors: Zuzana
authors: Z
authors: Balogová
authors: Monika
authors: M
authors: Dezortová
authors: Dita
authors: D
authors: Wagnerová
authors: Milan
authors: M
authors: Hájek
authors: Josef
authors: J
authors: Syka
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000378:metabolism*; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D001301:Audiometry, Pure-Tone; D001303:Auditory Cortex / Q000378:metabolism*; D016022:Case-Control Studies; D005260:Female; D005971:Glutamates / Q000378:metabolism; D006801:Humans; D007773:Lactates / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D011304:Presbycusis / Q000378:metabolism*
chemical_list: D005971:Glutamates; D007773:Lactates; D001224:Aspartic Acid; C000179:N-acetylaspartate
keywords: Auditory cortex; EP; GABA; Glutamate; Lactate; MP; MR spectroscopy; N-acetylaspartate; NAA; Presbycusis; VOI; YC; elderly subjects with expressed presbycusis; elderly subjects with mild presbycusis; volume of interest; young subjects with physiologic hearing