Identification of activity-induced Npas4-regulated genes in cortical inhibitory and excitatory neurons (array)

To identify the activity-induced gene expression programs in inhibitory and excitatory neurons, we analyzed RNA extracted from cultured E14 mouse MGE- and CTX-derived neurons (DIV 10) after these cultures were membrane-depolarized for 0, 1 and 6 hrs with 55mM extracellular KCl. To identify the gene programs regulated in these cells by the activity-induced early-response transcription factor Npas4, we repeated the same experiment in the MGE- and CTX-cultures lacking Npas4 (Npas4-KO). Littermate mouse E14 MGE- or CTX-derived neurons (WT or KO for Npas4) were cultured for 9 days, quieted overnight with TTX and AP-5 and then membrane-depolarized for 0, 1 or 6 hours by raising the extracellular KCl-concentration to 55mM. RNA was then extracted and analyzed using Affymetrix GeneChip Mouse Expression Set 430 2.0 microarray platform.