TY - JOUR T1 - GluA2-Containing AMPA Receptors Distinguish Ribbon-Associated from Ribbonless Afferent Contacts on Rat Cochlear Hair Cells JF - eneuro JO - eneuro DO - 10.1523/ENEURO.0078-16.2016 VL - 3 IS - 2 SP - ENEURO.0078-16.2016 AU - Rodrigo Martinez-Monedero AU - Chang Liu AU - Catherine Weisz AU - Pankhuri Vyas AU - Paul Albert Fuchs AU - Elisabeth Glowatzki Y1 - 2016/03/01 UR - http://www.eneuro.org/content/3/2/ENEURO.0078-16.2016.abstract N2 - Mechanosensory hair cells release glutamate at ribbon synapses to excite postsynaptic afferent neurons, via AMPA-type ionotropic glutamate receptors (AMPARs). However, type II afferent neurons contacting outer hair cells in the mammalian cochlea were thought to differ in this respect, failing to show GluA immunolabeling and with many “ribbonless” afferent contacts. Here it is shown that antibodies to the AMPAR subunit GluA2 labeled afferent contacts below inner and outer hair cells in the rat cochlea, and that synaptic currents in type II afferents had AMPAR-specific pharmacology. Only half the postsynaptic densities of type II afferents that labeled for PSD-95, Shank, or Homer were associated with GluA2 immunopuncta or presynaptic ribbons, the “empty slots” corresponding to ribbonless contacts described previously. These results extend the universality of AMPAergic transmission by hair cells, and support the existence of silent afferent contacts. ER -