The purinergic receptors 2X3 on spiral ganglion neurons enhance the medial olivocochlear reflex in mice after long-term moderate noise exposure.

Our purpose was to study the expression of purinergic receptors 2X2 (P2X2) and purinergic receptors 2X3 (P2X3) in spiral ganglion neurons (SGNs), the afferent nerves of medial olivocochlear (MOC) reflex, after long-term moderate noise exposure, and its relationship with the enhancement of MOC reflex. Mice were exposed a moderate broadband noise for 4 weeks consecutively. Then mouse hearing functions, including threshold auditory brainstem responses, distortion-product otoacoustic emissions, and MOC reflex, were evaluated and the expression of P2X2 and P2X3 on SGNs were assessed by cochlear immunofluorescence. AF-353 was injected before each noise exposure. Four weeks later, mice were also tested for hearing functions and expression of P2X2 and P2X3 on SGNs. The long-term moderate noise strengthened MOC reflex, and AF-353 reduced it in mice and P2X3 expression on SGNs increased after long-term moderate noise exposure, and AF-353 can downregulate it. The P2X3 on SGNs of mice increased after long-term moderate noise exposure, and the upregulation of it mediated the enhancement of MOC reflex.