Compartmentalization of antagonistci calcium signals in developing cochlear hair cells

MARCELO J. MOGLIE; PAUL A. FUCHS; A. BELEN ELGOYHEN; JUAN D. GOUTMAN*

PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA

NATL ACAD SCIENCES

Lugar: Washington DC, USA; Año: 2018

0027-8424

During a critical developmental period, cochlear inner hair cells exhibit sensory-independent activity, featuring action potentials in which Ca2+ ions play a fundamental role in driving both spiking and glutamate release onto synapses with afferent auditory neurons. This spontaneous activity is controlled by a cholinergic input to the IHC, activating a specialized nicotinic receptor with high Ca2+ permeability, and coupled to the activation of hyperpolarizing SK channels. The mechanisms underlying distinct excitatory and inhibitory Ca2+ roles within a small, compact IHC, are unknown. Making use of Ca2+ imaging, afferent auditory bouton recordings and electron microscopy, the present work shows that unusually high intracellular Ca2+ buffering and ?sub-synaptic? cisterns provide efficient compartmentalization and tight control of cholinergic Ca2+ signals. Thus, synaptic efferent Ca2+ spillover and crosstalk is prevented and the cholinergic input preserves its inhibitory signature to ensure normal development of the auditory system.