Transmitter release at the hair cell ribbon synapse.
Neurotransmitters are released continuously at ribbon synapses in the retina and cochlea. Notably, a single ribbon synapse of inner hair cells provides the entire input to each cochlear afferent fiber. We investigated hair cell transmitter release in the postnatal rat cochlea by recording excitatory postsynaptic currents (EPSCs) from afferent boutons directly abutting the ribbon synapse. EPSCs were carried by rapidly gating AMPA receptors. EPSCs were clustered in time, indicating the possibility of coordinate release. Amplitude distributions of spontaneous EPSCs were highly skewed, peaking at 0.4 nS and ranging up to 20 times larger. Hair cell depolarization increased EPSC frequency up to 150 Hz without altering the amplitude distribution. We propose that the ribbon synapse operates by multivesicular release, possibly to achieve high-frequency transmission.
Glowatzki
Elisabeth
E
The Center for Hearing and Balance, Department of Otolaryngology-Head and Neck Surgery, The Johns Hopkins University School of Medicine, Baltimore, MD 21205-2195, USA. eglowatz@bme.jhu.edu
Fuchs
Paul A
PA
D000200:Action Potentials / Q000502:physiology; D000818:Animals; D002118:Calcium / Q000502:physiology; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology; D006198:Hair Cells, Auditory / Q000378:metabolism* / Q000502:physiology; D006199:Hair Cells, Auditory, Inner / Q000502:physiology; D066298:In Vitro Techniques; D009412:Nerve Fibers / Q000502:physiology; D018377:Neurotransmitter Agents / Q000378:metabolism*; D051381:Rats; D018091:Receptors, AMPA / Q000502:physiology; D012146:Rest; D013569:Synapses / Q000378:metabolism*
D018377:Neurotransmitter Agents; D018091:Receptors, AMPA; D002118:Calcium