Spontaneous activity patterns emerge in networks of neurons during the maturation process in many central nervous system regions. In the course of postnatal development of the hippocampus, several neurons display spontaneous activity characterized by an increase in the intracellular calcium events. These changes manifest as a coherent and recurrent electrical activity within hippocampal neuronal networks (synchronous plateau assemblies, - SPAs, and giant depolarizing potentials - GDPs). This spontaneous activity of hippocampal neurons is responsible for the proper conduct of neuronal connections during local network shaping in this crucial period of development. Some studies have demonstrated that neuronal gap junctions (GJ) are essential for SPAs generation and propagation, since specific and non-specific neuronal blockers reduce SPAs. GJ are comprised of protein subunits called connexins (Cx) which allow the passage of small molecules, including charged ions, up to 1 kDa between connected cells. Our previous results demonstrated the presence of transcripts and protein of Cx36 and Cx45 during postnatal hippocampal development. Using calcium imaging and multielectrode array (MEA) recordings we will evaluate the neuronal GJ contribution to GDPs events during hippocampal development of rats, since these events are important modulators of several processes, such as synaptic connectivity, enhancement of synaptic efficacy of mossy fiber-CA3 and CA3-CA1 connections, neuronal survive mediated by neurotrophin release, functional GABAergic synapse formation, control of number of functional synapses and neuronal network excitability. With this project, we expect to identify the specific contribution of neuronal Cxs, Cx45 and Cx36, to GDPs pattern during the hippocampal development of rodents. All reagents necessary for the achievement of this project were provided by aid project FAPESP (2014/16711-6).
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