Age-related changes in the auditory function and the histopathological observation on guinea pig temporal bone.

1998 Fiscal Year Final Research Report Summary

• Project/Area Number: 08671958
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Otorhinolaryngology
• Research Institution: Yamanashi Medical University
• Principal Investigator: NOZAWA Izuru Yamanashi Medical University, Department of Otolaryngology, Assistant Professor, 医学部, 講師 (40172788)
• Co-Investigator(Kenkyū-buntansha): SHIMOMURA Shin-ichi Yamanashi Medical University, Department of Otolaryngology, Lecturer, 医学部, 助手 ; IMAMURA Shun-ichi Yamanashi Medical University, Department of Otolaryngology, Lecturer, 医学部, 助手 (20232613)
• Project Period (FY): 1996 – 1998
• Keywords: Auditory brainstem response / Compound action potentials / Aging / Guinea pig / Corti / OHC_S / IHC_S

Research Abstract

The auditory brainstem response (ABR) and the compound action potentials (CAP) were measured using click stimuli to investigate the age-related alteration in the auditory function in guinea pigs. With advancing age, a gradual elevation on the thresholds in both the ABR and CAP was clearly seen, together with the prolonged latencies for waves I, II, III, and IV to click at 95 dBpeSPL in the ABR.The negative peak (N1) latencies of the CAP were prolonged, and the amplitudes of the CAP decreased.
Degenerative changes in the organ of corti were not found in the 2 months of age. Thresholds were clearly elevated and some hair cell losses of OHCs and IHCs were found at 4 years. However, changes in the organ of corti in 15-month-old guinea pigs depend on each subject. These findings suggest that the effect of individual differences on degenerative aging processes of the auditory system should be considered in the selected animals, although a significant elevation of the neural auditory threshold and a degenerative changes in the inner ear are clearly found with advancing age as a whole.