New cells expressing neuronal markers are generated postnatally at the subventricular zone of the forebrain, and from there they migrate into the olfactory bulb (OB) following a well defined pathway, the rostral migratory stream (RMS). However, it is still unclear whether newly generated cells (NGC) that express neuronal markers become functional neurones. To fill this gap we combined a retroviral mediated cell lineage and patch-clamp electrophysiology. We have identified one-month old neurones with functional properties similar to those of mature periglomerular (PG) and granule cells in the adult OB. From these cells we recorded action potentials in response to the injection of depolarising currents, and we have isolated and characterised Na+ and K+ currents. About 50% of the NGC were PG cells; the remaining ended their migration between internal plexiform and mitral cell layers, or in the granule cell layer. The migrating neuroblasts within the RMS show only a small delayed rectifier K-current, to which an A-current is added when the OB is reached. The mature cells lose the delayed rectifier K+-current, and only display A- and Na+ currents. Finally, by recordings action potentials and excitatory synaptic currents in response to stimulation of the olfactory nerve. These results show that endogenous neuronal progenitors produce new neurons that integrate into previously established and functioning circuits. Supported by grants from Fondazione Caricento (O.B.) and NIH (MH56524, J.J.L.).
Functional aspects of neurogenesis in the adult olfactory bulb
BELLUZZI, Ottorino;BENEDUSI, Mascia;
2003
Abstract
New cells expressing neuronal markers are generated postnatally at the subventricular zone of the forebrain, and from there they migrate into the olfactory bulb (OB) following a well defined pathway, the rostral migratory stream (RMS). However, it is still unclear whether newly generated cells (NGC) that express neuronal markers become functional neurones. To fill this gap we combined a retroviral mediated cell lineage and patch-clamp electrophysiology. We have identified one-month old neurones with functional properties similar to those of mature periglomerular (PG) and granule cells in the adult OB. From these cells we recorded action potentials in response to the injection of depolarising currents, and we have isolated and characterised Na+ and K+ currents. About 50% of the NGC were PG cells; the remaining ended their migration between internal plexiform and mitral cell layers, or in the granule cell layer. The migrating neuroblasts within the RMS show only a small delayed rectifier K-current, to which an A-current is added when the OB is reached. The mature cells lose the delayed rectifier K+-current, and only display A- and Na+ currents. Finally, by recordings action potentials and excitatory synaptic currents in response to stimulation of the olfactory nerve. These results show that endogenous neuronal progenitors produce new neurons that integrate into previously established and functioning circuits. Supported by grants from Fondazione Caricento (O.B.) and NIH (MH56524, J.J.L.).I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
