Electrical activity regulates neuronal maturation in the adult dentate gyrus

M GEORGINA DAVIES SALA; M SOLEDAD ESPOSITO; LUCAS A MONGIAT; ALEJANDRO F SCHINDER

Huerta Grande, Còrdoba

Congreso; Second Joint Meeting of the argentine society for neursciences; 2010

Newborn granule cells (GCs) of the adult hippocampus develop over several weeks. Little is known about the role of intrinsic activity in GC development. To answer this question we designed a strategy to decrease intrinsic excitability of adult-born GCs and analyze their morphological and functional properties. We built a retrovirus encoding an inward rectifying potassium channel (Kir2.1) and green fluorescent protein (GFP), and delivered it into the dentate gyrus of young adult mice. Labeled cells were analyzed in brain slices by electrophysiology and confocal imaging after 2, 3 or 5 weeks. Electrophysiological recordings confirmed that Kir-expressing neurons displayed larger inward rectifier currents, decreased input resistance, hyperpolarized resting potential, and diminished levels of subthreshold depolarization. In regard to neuronal phenotype, Kir neurons expressed higher levels doublecortin and reduced levels of calbindin at all time points, which was also associated to a reduced dendritic length. Kir neurons also exhibited a reduced frequency of both excitatory and inhibitory miniature events, and a striking reduction in survival. Our results demonstrate that intrinsic electrical activity is essential for the correct maturation, integration and survival of adult-born GCs.