Noise-induced hearing loss: the effect of melanin in the stria vascularis

• Published in: Hearing research Vol. 154; no. 1; pp. 116 - 123
• Main Authors: Bartels, Sande, Ito, Shosuke, Trune, Dennis R, Nuttall, Alfred L
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.04.2001; Elsevier
• Subjects: Animals; Auditory Threshold; Biological and medical sciences; Ear, auditive nerve, cochleovestibular tract, facial nerve: diseases, semeiology; Female; Hearing Loss, Noise-Induced - etiology; Hearing Loss, Noise-Induced - metabolism; Hearing Loss, Noise-Induced - physiopathology; Medical sciences; Melanin; Melanins - metabolism; Mice; Mice, Inbred C57BL; Non tumoral diseases; Otorhinolaryngology. Stomatology; Pigment; Pigmentation; Sensorineural; Species Specificity; Stria vascularis; Stria Vascularis - metabolism; Stria Vascularis - ultrastructure; Sensorineural; Pigment; Stria vascularis; Melanin; Albinism; Noise; Internal ear disease; Rodentia; Auditory disorder; Acoustic trauma; Vertebrata; Mammalia; Guinea pig; Mouse; Animal; Auditory evoked potential; Pigments; ENT disease; Perception hearing loss; Noise pollution; Protection; Sensory hearing loss
• ISSN: 0378-5955; 1878-5891
• DOI: 10.1016/S0378-5955(01)00213-1

Conflicting investigations regarding the potential protective effect of melanin against noise-induced sensorineural hearing loss have suggested that eumelanin and pheomelanin may have differing effects within the stria vascularis. Three strains of C57BL/ 6J mice, (+/+, a/ a) wild-types (dark coats/black eyes), ( c2j/ c2j, a/ a), albinos (white coats/pink eyes), and (+/+, Ay/ Ay) yellow mice (yellow coats/black eyes), were subjected to five consecutive days of broad band noise exposure at 112 dB(A) SPL for 3 h/day. Cochlear function was evaluated with auditory brainstem response audiometry to pure tones immediately pre-exposure, 5–6 h post-exposure, and 14 days post-exposure. No significant difference in the degree of sensorineural hearing loss induced in the three strains of mice was identified. The eumelanin and pheomelanin content of each stria vascularis and amount of protein per stria for both mouse and guinea pig ( 2/ NCR) were determined via high performance liquid chromatography. No pheomelanin was found in the stria of yellow mice, suggesting that coat color is not an accurate predictor of strial melanin content. The melanin content per mg of strial protein was higher in mice than in guinea pigs. A species-specific difference in melanin content does not explain the absence of a protective effect in mice.