Abstract
Calcium plays a key role in nervous system formation. Calcium is involved in many functions enabling the setting up of organs work. The aim of the present study was to characterize theT-type voltage-dependent calcium channels transiently expressed in primary vestibular neurons and to understand the role of calcium entries during perinatal mouse development. By means of electrophysiological and pharmacological studies, T-type subunits Cav3.1 and Cav3.2 properties were characterized. Cav3.2 induced a large current during the earlier developmental stage. Neuronal electrical activity studies showed the presence of an after-depolarisation component which was correlated with Cav3.2 expression.<br />Electrical activity properties analyses at an early development stage (E17) revealed an increase of the repolarisation decay time during the action potential. This enlargement was blocked by cadmium. Action potentials became faster at more mature stages. These early phenomena occured during the periods of neuritogenesis and synaptogenesis of the peripheral vestibular system. The physiological role of the Cav3.2 subunit and its related electrical activity were determined by use of antisens on neuronal cultures. When Cav3.2 was blocked, a decrease in the neuritis growth was observed. These results show that the T-type calcium current, especially that linked to the activation of Cav3.2, has an crucial implication in vestibular system ontogenesis