Abstract
The earliest organized intrinsic activity in the hippocampal network appears during the perinatal period, which is characterized by slow synchronized bursting of the pyramidal neurons and interneurons in forms of giant depolarizing potentials (GDPs) in the slices and "sharp waves" in vivo. These activities are proposed to be involved in the maturation of the interneuronal networks (Ben-Ari et al., 2004). Since the generation of GDP requires depolarisation of pyramidal neurons by GABA released from interneurons and since exogenous ATP excites inhibitory interneurons in the CA3 through activation of P2Y1 receptors (Kawamura et al., J Neurosci, 2004), we examined whether activation of interneuronal purinoceptors by endogenous ATP and subsequent excitation of interneurons underlie the GDP generation. The spontaneous GDP activities were recorded by patch-clamp recording from CA3 pyramidal neurons and by imaging of [Ca2+]i with fluo-4 in the coronal hippocampal slice of the rats (P4-8). The responses of GDPs to pharmacological manipulations of ATP and adenosine receptors and their metabolism suggest a possible involvement of activation of interneuronal purinoceptors by endogenous extracellular ATP in the maintenance of GDP, which might provide an important mechanism linking on-going metabolic condition and large-scale network activities in the early development. [J Physiol Sci. 2006;56 Suppl:S15]
