Figure 5.

Overexpression of REST/NRSF reduces neuronal excitability and I_Na current density. (A) Representative images of hippocampal neurons (16 div) co-transfected with GFP together with either a myc-tagged REST/NRSF expression vector (GFP+mycREST; left panels) or an empty vector (GFP; right panels). From left to right: GFP fluorescence (green), myc immunoreactivity (red), and DAPI staining (blue). Scale bar: 25 μm. (B) (Left panels) Representative traces of electrically evoked Ca²⁺ transients recorded at the cell body of non-transfected neurons (grey traces) or of neurons expressing either GFP alone (black trace) or GFP+mycREST (red trace). (Right panel) Quantitative analysis of the evoked Ca²⁺ influx recorded in non-transfected neurons (n=30) or in neurons expressing either GFP alone (n=17) or GFP+MycREST (n=18) (*P<0.05, GFP+MycREST versus GFP+empty vector; one-way ANOVA followed by the Bonferroni’s test). (C) Plots of the mean instantaneous frequency versus injected current (iF/I curve) for pyramidal neurons expressing either GFP alone (black) or GFP+mycREST (red) (n=16). (D) Mean (±s.e.m.) firing rate, maximum rising slope, action potential peak, and current threshold density. Significant changes were observed in the firing rate, action potential peak, and current threshold density of GFP+mycREST versus GFP-expressing neurons (*P<0.05, Student’s unpaired two-tailed t-test; n=16). (E) (Left) Mean (±s.e.m.) normalized I_Na density versus voltage measured in hippocampal pyramidal neurons expressing either GFP alone (black, n=30) or GFP+mycREST (red, n=16). A significant decrease in the I_Na density was observed in GFP+mycREST-expressing neurons (*P<0.05, **P<0.01, Student’s unpaired two-tailed t-test with Welch’s correction). (F) Average I_Na activation (squares) and inactivation (circles) curves for neurons expression either GFP (empty symbols, n=30) or GFP+mycREST (red symbols; n=16).