Calcium signaling in neuronal motility: pharmacological tools for investigating specific pathways

Migration of neurons and neuronal precursors from the site of origin to their final location is a key process in the development of the nervous system and in the correct organization of neuronal structures and circuits. Different modes of migration (mainly radial and tangential) have been described in the last 40 years; for these, as for motility processes involving other cellular types, calcium signaling plays a key role, with influx from the extracellular medium representing the main mechanism, and a more delimited but specific role played by release from intracellular stores. Deciphering the involvement of the different calcium influx pathways has been a major task for cellular neurobiologists, and the availability - or lack - of reliable and selective pharmacological tools has represented the main limiting factor. This review addresses the strategies employed to investigate the role of voltage-dependent calcium channels and of neurotransmitter activated channels, either calcium permeable or not, that directly or indirectly can elicit cytosolic calcium increases; in addition, reference to recent findings on the involvement of other families of calcium permeable channels (such as the transient receptor potential superfamily) is presented. Finally, a brief description of the present - and limited - knowledge of the perturbations of calcium signaling involved in neuronal migration pathologies is provided.