Figure 3. Ablation of Kcnq2 from PV⁺ interneurons leads to increased excitatory transmission in pyramidal neurons.

For simplicity we refer Pvalb-Cre;Kcnq2;Ai9 mice in the figure as Pvalb-Cre;Kcnq2^f/f or Pvalb-Cre;Kcnq2^+/+. (a) Left, representative voltage responses from a + 200 pA current injection step (1 s; Vh= −75 to −77 mV) in PV⁺ interneurons from the CA1 region of the hippocampus (P23–P25). Right, summary graph showing the effect of deleting Kcnq2 on action potential number from PV⁺ interneurons (Pvalb-Cre;Kcnq2^+/+;Ai9 n = 15/4; Pvalb-Cre;Kcnq2^f/f;Ai9 n = 14/3; F_(9,243)=3.558, p=0.0004). Significance was determined using a two-factor mixed ANOVA. (b) Left, representative voltage responses from a + 200 pA current injection step (1 s; Vh=-75mV) in pyramidal neurons from the CA1 region of the hippocampus (P30–P32). Right, summary graph showing the effect of deleting Kcnq2 from pyramidal neurons in action potential number (Pvalb-Cre;Kcnq2^+/+;Ai9 n = 15/3; Pvalb-Cre;Kcnq2^f/f;Ai9 n = 12/2; F_(9,225)=0.4891, p=0.88). Significance was determined using a two-factor mixed ANOVA. (c) Left, representative sEPSC traces recorded from CA1 pyramidal neurons (P32–P35) in acute hippocampal slices from control and Kcnq2 null PV⁺ interneurons. Right, summary bar graphs of sEPSC frequency (Pvalb-Cre;Kcnq2^+/+;Ai9 1.165 ± 0.12 Hz, n = 13/4; Pvalb-Cre;Kcnq2^f/f;Ai9: 2.108 ± 0.22 Hz, n = 19/3; p=0.0098 Mann-Whitney test) and amplitude (Pvalb-Cre;Kcnq2^+/+;Ai9 15.9 ± 0.86 pA, n = 13/4; Pvalb-Cre;Kcnq2^f/f;Ai9: 15.3 ± 0.68 pA, n = 19/3; DF = 30 t = 0.62 p=0.5394). Statistical comparisons were performed with two-tailed unpaired Student’s t-test or Mann-Whitney when the variance between the two groups was significantly different. ‘n’ designates number of cells followed by number of animals. Each data point represents recording from one neuron. Data in summary graphs are represented as mean and s.e.m.