title: The aging of the middle ear in 129S6/SvEvTac and CBA/CaJ mice: measurements of umbo velocity, hearing function, and the incidence of pathology.
abstract: Measurements of umbo velocity and auditory brainstem response (ABR) were made on two different strains of mice, 129S6/SvEvTac (129S6) and CBA/CaJ (CB), within three different age ranges. The velocity measurements were made with a laser Doppler vibrometer using a semiclosed sound delivery system; the frequency range of accurate velocity measurements is from 1 to 21 kHz. The visual detection threshold of the ABR was determined at selected frequencies between 2 and 32 kHz. The velocity results suggest a small but significant change in umbo velocity with age in both strains, between the youngest (1.5-3 months) and mid-aged (12-14 months) groups. There is also a clear difference in the umbo velocity in the youngest animals of the two strains, with the 129S6 having more sensitive middle-ear function than the CB. These results support the existence of a small age-related loss in middle-ear sensitivity in the mouse that was first described in the BALB/6J strain. The age-related changes in middle-ear function observed in both CB and 129S6 are much smaller than the age-related decreases in ABR. Our results also describe a statistically significant increase in the incidence of middle-ear pathology with age in the 129S6.
authors.affiliation: Eaton-Peabody Laboratory, Massachusetts Eye and Ear Infirmary, Boston, MA 02114, USA. jjr@epl.meei.harvard.edu
authors.forename: John J
authors.initials: JJ
authors.lastname: Rosowski
authors.forename: Kelly M
authors.initials: KM
authors.lastname: Brinsko
authors.forename: Bruce I
authors.initials: BI
authors.lastname: Tempel
authors.forename: Sharon G
authors.initials: SG
authors.lastname: Kujawa
mesh_terms: D000375:Aging / Q000473:pathology / Q000502:physiology*; D000818:Animals; D001309:Auditory Threshold; D004432:Ear, Middle / Q000473:pathology* / Q000503:physiopathology*; D016057:Evoked Potentials, Auditory, Brain Stem; D015994:Incidence; D051379:Mice; D008808:Mice, Inbred CBA; D010033:Otitis Media / Q000453:epidemiology / Q000473:pathology / Q000503:physiopathology; D011304:Presbycusis / Q000453:epidemiology / Q000473:pathology* / Q000503:physiopathology*; D013045:Species Specificity