Early sensorineural hearing loss in ob/ob mouse, an animal model of type 2 diabetes.
OBJECTIVE
There have been many studies on the relationship between diabetes mellitus and presbycusis. Microangiopathy and neuropathy that's caused by chronic hyperglycemia may lead to damage to the inner ear. Several clinical studies on humans and animal studies have been performed to investigate the association between diabetes and hearing loss, however, this relationship is still a matter of debate. We investigated the association of diabetes and sensorineural hearing loss in an animal model of type-2 diabetes and obesity (the ob/ob mouse [OM]).


METHODS
The auditory brainstem response (ABR) thresholds were obtained in the OM and the wild type mice (C57BL/6J mice) up to 25 weeks after birth. After the animals were sacrificed, their cochleae were retrieved and then subjected to histopathologic observations.


RESULTS
The OM exhibited significantly elevated ABR thresholds at 21 weeks of age, yet the C57BL/6J mice exhibited no significant change until 25 weeks of age. On the histological findings, outer hair cell degeneration and loss of spiral ganglion cells were observed in the middle and basal turns of the OM. On the contrary, no degenerative change was observed until 25 weeks of age in the C57BL/6J mice.


CONCLUSIONS
This study suggests that chronic hyperglycemia and obesity may lead to early sensorineural hearing loss.
Department of Otorhinolaryngology-Head and Neck Surgery, Bundang Jesaeng Hospital, Daejin Medical Center, Seongnam, Korea.
Hyun-Seok
HS
Lee
Ki Ryung
KR
Kim
Won-Ho
WH
Chung
Yang-Sun
YS
Cho
Sung Hwa
SH
Hong