Effect of Oncomodulin on Afferent Inner Hair Cell and Efferent Outer Hair Cell Synaptopathy

Abstract

Inner hair cells (IHCs) are a type of specialized sensory cell which converts the pressure gradient of the endolymph into an interpretable signal, allowing for hearing. However, there is another type of sensory cell crucial for hearing: outer hair cells (OHCs). OHCs amplify basilar membrane motion through the movement of prestin, a voltage-sensitive motor protein, resonating with its respective tonotopic frequency. The medial olivocochlear (MOC) system is part of the auditory system which synapses on OHCs with cholinergic receptors, acting antagonistically to prestin by hyperpolarizing the cell, resulting in cochlear acoustic protection through a calcium dependent mechanism. Loss of function of the MOC system has been shown to precede progression of age-related sensory deficits, but the correlation between the loss of function of the MOC system and OHC vitality is yet to be examined. This paper will examine the correlation between OHC vitality, efferent MOC synapses, and afferent glutaminergic synapses.