Cochlear kainate receptors.
Synaptic transmission between the cochlear hair cell and its afferent fiber is mediated by glutamate receptors. While kainate receptors are known to be present in the spiral ganglion, little is known of their distribution or functional role. We have detected all five kainate receptor subunits in the mouse cochlea with quantitative RT-PCR and with immunohistochemistry. We observed kainate receptors on afferent terminals co-localized with α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA: ) receptors at the afferent synapse. Individual terminals innervating a single hair cell varied in their ratios of AMPA:  to kainate receptor immunoreactivity. Infusion of the mouse cochlea via the scala tympani with UBP296, a recently developed antagonist with high specificity for the GluK1 kainate receptor (compared to the AMPA:  receptor), reduced the compound action potential and elevated auditory neural thresholds without affecting the distortion product otoacoustic emission thresholds. Thus, the pharmacological evidence suggests that kainate receptors may contribute to the response to transmitter released from the hair cell during acoustic stimulation. It is plausible that afferent transmission at this synapse is mediated by a mix of AMPA:  and kainate receptors.
Department of Otology and Laryngology, Eaton Peabody Laboratory, Massachusetts Eye and Ear Infirmary and Harvard Medical School, 243 Charles Street, Boston, MA, 02114, USA.
Marcello
M
Peppi
Department of Otology and Laryngology, Eaton Peabody Laboratory, Massachusetts Eye and Ear Infirmary and Harvard Medical School, 243 Charles Street, Boston, MA, 02114, USA.
Melissa
M
Landa
Department of Otology and Laryngology, Eaton Peabody Laboratory, Massachusetts Eye and Ear Infirmary and Harvard Medical School, 243 Charles Street, Boston, MA, 02114, USA. wfs@epl.meei.harvard.edu.
William F
WF
Sewell
D018750:6-Cyano-7-nitroquinoxaline-2,3-dione / Q000494:pharmacology; D000409:Alanine / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D003051:Cochlea / Q000502:physiology*; D005260:Female; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D008808:Mice, Inbred CBA; D012333:RNA, Messenger / Q000032:analysis; D018092:Kainic Acid Receptors / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D009435:Synaptic Transmission / Q000502:physiology
D018750:6-Cyano-7-nitroquinoxaline-2,3-dione; D000409:Alanine; D012333:RNA, Messenger; D018092:Kainic Acid Receptors; C490221:UBP296