Noise induces up-regulation of P2X2 receptor subunit of ATP-gated ion channels in the rat cochlea.
Regulation of P2X(2) receptor (P2X(2)R) expression in the rat cochlea in response to noise was analysed. Sustained loud sound (90-120 dB white noise, > 6 h), increased P2X(2)R mRNA and protein levels in rat organ of Corti and spiral ganglion (primary auditory neurones). P2X(2)R expression by the type I spiral ganglion neurones, which innervate the inner hair cells via the inner spiral plexus, was confirmed by confocal immunofluorescence. This also revealed increased P2X(2)R labelling of outer hair cell (OHC) stereocilia and cuticular plates, reflecting trafficking of greater numbers of ATP-gated ion channels assembled with P2X(2)R subunits to the transducer site. Whole-cell voltage clamp of OHC confirmed the noise-induced up-regulation of ATP-gated inward currents. These data indicate that regulation of P2X(2) receptor gene expression in the cochlea is adaptive, with sustained loud sound promoting increased transcription and translation specifically at sites regulating hearing sensitivity and auditory neurotrans-mission.
Wang
Julie C-C
JC
Department of Physiology, University of Auckland, Private Bag 92019, New Zealand.
Raybould
Nicholas P
NP
Luo
Lin
L
Ryan
Allen F
AF
Cannell
Mark B
MB
Thorne
Peter R
PR
Housley
Gary D
GD
D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D003051:Cochlea / Q000378:metabolism* / Q000502:physiology; D005455:Fluorescent Antibody Technique; D018072:Hair Cells, Auditory, Outer / Q000378:metabolism* / Q000502:physiology; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D007473:Ion Channels / Q000378:metabolism* / Q000502:physiology; D009622:Noise; D009925:Organ of Corti / Q000378:metabolism; D018408:Patch-Clamp Techniques; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D017208:Rats, Wistar; D018048:Receptors, Purinergic P2 / Q000378:metabolism*; D058476:Receptors, Purinergic P2X2; D013136:Spiral Ganglion / Q000378:metabolism; D015854:Up-Regulation
D007473:Ion Channels; C546403:P2rx2 protein, rat; D012333:RNA, Messenger; D018048:Receptors, Purinergic P2; D058476:Receptors, Purinergic P2X2; D000255:Adenosine Triphosphate