HISTOLOGY AND HISTOPATHOLOGY

From Cell Biology to Tissue Engineering

 

Characterization of the early pathology of cochlear stereocilia in four inbred mouse strains with progressive hearing loss

Xiang Liu1,3, Yi Xie1,2, Shanshan Huang1, Ang Xu1, Mengmeng Zhao1,2, Xiaoxia Kang1, Aiwei Yan1, Ping Li1, Changzhu Jin1,3 and Fengchan Han1,2

1Key Laboratory for Genetic Hearing Disorders in Shandong, 2Department of Biochemistry and Molecular Biology and 3Department of Human Anatomy and Histology and Embryology, Binzhou Medical University, Yantai, Shandong, P.R. China

Offprint requests to: Dr. Fengchan Han or Changzhu Jin, Key Laboratory for Genetic Hearing Disorders in Shandong, Binzhou Medical University, 346 Guanhai Road, Yantai 264003, Shandong, P.R. China. e-mail: hanfengchan@gmail.com or Jincz63@hotmail.com


Summary. Objective. Inbred strains of mice offer promising models for understanding the genetic basis of age-related hearing loss (AHL). NOD/LtJ, A/J, DBA/2J and C57BL/6J mice are classical models of age-related hearing loss and exhibit early onset of pathology of AHL. This study was carried out to characterize the early pathology of cochlear stereocilia in the four mouse strains with age-related hearing loss. Methods. The structural features of stereocilia in NOD/LtJ, A/J, DBA/2J and C57BL/6J mice were observed by scanning electron microscopy (SEM) at age of 2, 4, 6 or 8, and 10 or 12 weeks. Meanwhile, auditory-evoked brainstem response (ABR) and distortion product otoacoustic emission (DPOAE) amplitudes of the mice were measured at various intervals (3, 4, 6, 8, 10 and 12 weeks of age). Results. The ABR thresholds in NOD/LtJ, A/J and DBA/2J mice increased with age from 3 to 12 weeks. DPOAE amplitudes in NOD/LtJ, A/J, DBA/2J mice were very low at 4 weeks and became negative at 8 weeks at f2 frequency of 17 672 Hz. In addition to the progressive hearing loss, the four mouse strains displayed early onset (at 2 weeks of age) and progressive degeneration of stereocilia in hair cells. Conclusion. Early degeneration of stereocilia contributes to the functional impairment of hair cells and hearing loss in NOD/LtJ, A/J, DBA/2J and C57BL/6J mice. Histol Histopathol 34, 811-820 (2019)

Key words: Age-related hearing loss, Mouse model, Hair cells, Stereocilia, Scanning electron microscope

DOI: 10.14670/HH-18-086