Spatial patterns of noise-induced inner hair cell ribbon loss in the mouse mid-cochlea
Yan Lu,
Jing Liu,
Bei Li,
Haoyu Wang,
Fangfang Wang,
Shengxiong Wang,
Hao Wu,
Hua Han,
Yunfeng Hua
Affiliations
Yan Lu
Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People’s Hospital, Shanghai 200125, China; Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai 200125, China; Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai 200125, China; Shanghai Institute of Precision Medicine, Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200125, China
Jing Liu
Laboratory of Brain Atlas and Brain-inspired Intelligence, Institute of Automation, Chinese Academy of Sciences, Beijing 100190, China
Bei Li
Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People’s Hospital, Shanghai 200125, China; Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai 200125, China; Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai 200125, China
Haoyu Wang
Shanghai Institute of Precision Medicine, Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200125, China
Fangfang Wang
Shanghai Institute of Precision Medicine, Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200125, China
Shengxiong Wang
Shanghai Institute of Precision Medicine, Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200125, China
Hao Wu
Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People’s Hospital, Shanghai 200125, China; Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai 200125, China; Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai 200125, China; Shanghai Institute of Precision Medicine, Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200125, China
Hua Han
Laboratory of Brain Atlas and Brain-inspired Intelligence, Institute of Automation, Chinese Academy of Sciences, Beijing 100190, China; School of Future Technology, University of Chinese Academy of Sciences, Beijing 101408, China; State Key Laboratory of Multimodal Artificial Intelligence Systems, Institute of Automation, Chinese Academy of Sciences, Beijing 100190, China; Corresponding author
Yunfeng Hua
Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People’s Hospital, Shanghai 200125, China; Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai 200125, China; Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai 200125, China; Shanghai Institute of Precision Medicine, Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200125, China; Corresponding author
Summary: In the mammalian cochlea, moderate acoustic overexposure leads to loss of ribbon-type synapse between the inner hair cell (IHC) and its postsynaptic spiral ganglion neuron (SGN), causing a reduced dynamic range of hearing but not a permanent threshold elevation. A prevailing view is that such ribbon loss (known as synaptopathy) selectively impacts the low-spontaneous-rate and high-threshold SGN fibers contacting predominantly the modiolar IHC face. However, the spatial pattern of synaptopathy remains scarcely characterized in the most sensitive mid-cochlear region, where two morphological subtypes of IHC with distinct ribbon size gradients coexist. Here, we used volume electron microscopy to investigate noise exposure-related changes in the mouse IHCs with and without ribbon loss. Our quantifications reveal that IHC subtypes differ in the worst-hit area of synaptopathy. Moreover, we show relative enrichment of mitochondria in the surviving SGN terminals, providing key experimental evidence for the long-proposed role of SGN-terminal mitochondria in synaptic vulnerability.
