Periodic Inward Currents Triggered by NMDA in Immature CA3 Hippocampal Neurones

摘要: There is widespread interest in the function of N-methyl-D-aspartate (NMDA) receptors CNS, especially hippocampus where they are higly concentrated and may contribute to long term potentiation, a model memory. More recent studies performed primarily visual system suggest preferential involvement NMDA developmental plasticity (Tsumoto et al., 1987; Kleinschmidt al. 1987). Using single electrode voltage clamp technique, we have found that generates slow inward currents immature CA3 hippocampal neurones, already few hours after birth, confirming present active very early postnatal life. In addition, repeated applications NMDA, initiated (but not adult) TTX-insensitive periodic (PICs), which persisted for as prominent on-going phenomenon, whose frequency was independent membrane potential. These were observed under conditions K+ conductances much reduced by external Cs+, tetraethylammonium (TEA) or 4-aminopyridine (4-AP). Though TTX-insensitive, PICs appear synaptic origin, since bicuculline abolished excitatory amino acid antagonist kynurenic acid. It suggested generate initiating neurones fluctuations intracellular calcium, leading pulsatile release glutamate GABA from nerve terminals.