INGEBI   02650
INSTITUTO DE INVESTIGACIONES EN INGENIERIA GENETICA Y BIOLOGIA MOLECULAR "DR. HECTOR N TORRES"
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Both pre and post-synaptic mechanisms contribute to adaptation at the inner hair cell ribbon synapse.
Autor/es:
JUAN D. GOUTMAN
Reunión:
Congreso; 2nd FALAN Congress - SAN; 2016
Institución organizadora:
FALAN - Sociedad Argentina de Investigación en Neurociencia
Resumen:
Inner hair cell (IHC) are specialized sensory cells responsible for converting sounds into synaptic signals. Auditory nerve neurons receive input form this synapse, representing the output of the cochlea. As in other sensory modalities, persistent acoustic stimuli produce adaptation, observed as a reduction in spike rate at the auditory nerve. This phenomenon would contribute to setting the dynamic range for sensing varying sound intensities. We evaluated the hypothesis that the IHC-auditory nerve neurons synapse was responsible for adaptation, by performing simultaneous recordings from these two cell types.Upon IHC depolarization, we observed an initial increase, followed by a fast decay in synaptic responses, closely resembling adaptation in the auditory nerve. Interestingly, this phenomenon was invariant with presynaptic stimulation strength. Also, decay kinetics did not change even though the response amplitude varied ~5-fold. The application of a second depolarizing step shortly after adaptation occurred, showed an additional burst of activity, indicating that vesicles remained. The role of postsynaptic receptors desensitization was evaluated by applying similar protocols in the presence of cyclothiazide (CTZ). In CTZ, adaptation occurred with a ~5-fold slower decay time, but differences emerged when comparing IHC stimulation strengths. Both pre-(vesicle depletion) and post-synaptic (desensitization) mechanisms would contribute to synaptic adaptation at IHC synapses.