INGEBI   02650
INSTITUTO DE INVESTIGACIONES EN INGENIERIA GENETICA Y BIOLOGIA MOLECULAR "DR. HECTOR N TORRES"
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Evaluating a possible crosstalk between inhibitory and excitatory calcium signals in inner hair cells of the developing inner ear.
Autor/es:
MARCELO J. MOGLIE; PAUL A. FUCHS; A. BELEN ELGOYHEN; JUAN D. GOUTMAN
Lugar:
Mar del Plata
Reunión:
Congreso; XXX Congreso Anual Sociedad Argentina de Investigación en Neurociencia; 2015
Resumen:
Altricial rodents do not respond to sound until their second postnatal week. Before the onset of hearing, cochlear inner hair cells (IHCs) fire sensory-independent action potentials sustained by voltage-dependent calcium channels. The influx of calcium triggers the release of glutamate to afferent dendrites of the auditory nerve, determining an excitatory role for calcium ions. At this stage, IHC are also innervated by efferent cholinergic neurons, projecting from the brainstem. This synapse combines the entry of calcium through α9α10 nicotinic receptors with the activation of nearby SK2, calcium dependent potassium channels, to hyperpolarize and inhibit IHCs. Thus, calcium can have these two contrary roles within a diffusionally compact cell. Electron-micrographs of IHC exhibited thin near-membrane cisterns juxtaposed to efferent synaptic contacts. Imaging experiments have shown multiple calcium entry hotspots following activation of efferent fibers. These domains would be spatially segregated from those observed after IHC depolarization. In order to understand the physiological implications of such proximity, we have performed whole cell patch clamp recordings of afferent terminals. We found that upon high frequency stimulation of efferent fibers, calcium was capable of eliciting release of glutamate to afferent terminals. Thus, we suggest that intracellular mechanisms in IHC are adapted to prevent crosstalk between these synapses.