Sex differences in body composition, voluntary wheel running activity, balance performance, and auditory function in CBA/CaJ mice across the lifespan

Hearing loss is the third most prevalent chronic health condition affecting older adults and age-related hearing loss (ARHL) is the most common form of hearing impairment. Significant sex differences in hear-ing have been documented in humans and rodents. In general, the results of these studies show that men lose their hearing more rapidly than women. However, the cellular mechanism underlying sex dif-ferences in hearing or hearing loss remains largely unknown, and to our knowledge, there is no well-established animal model for studying sex differences in hearing. In the current study, we examined sex differences in body composition, voluntary wheel running activity, balance performance, auditory func-tion, and cochlear histology in young, middle-age, and old CBA/CaJ mice, a model of age-related hearing loss. As expected, body weight of young females was lower than that of males. Similarly, lean mass and total water mass of young, middle-age, and old females were lower than those of males. Young females showed higher voluntary wheel running activity during the dark cycle, an indicator of mobility, physical activity, and balance status, compared to males. Young females also displayed higher auditory brainstem response (ABR) wave I amplitudes at 8 kHz, wave II, III, V amplitudes at 8 and 48 kHz, and wave IV/I and V/I amplitude ratios at 48 kHz compared to males. Collectively, our findings suggest that the CBA/CaJ mouse strain is a useful model to study the cellular mechanisms underlying sex differences in physical activity and hearing.(c) 2022 Elsevier B.V. All rights reserved.

Automated summary

Hearing loss is a common chronic health condition in older adults, and age-related hearing loss (ARHL) is the most prevalent form of hearing impairment. Research has shown significant differences in hearing between males and females, with men experiencing more rapid hearing loss. However, the cellular mechanism underlying these sex differences in hearing remains unknown, and there is currently no well-established animal model for studying this phenomenon. In this study, the researchers investigated sex differences in body composition, physical activity, balance performance, auditory function, and cochlear histology in CBA/CaJ mice of different ages. The findings suggest that the CBA/CaJ mouse strain is a valuable model for studying the cellular mechanisms underlying sex differences in physical activity and hearing.