Figure 2. Increased mIPSC frequency in Nf1^+/−; mutants in high KCl.

A. Representative traces of sIPSCs and mIPSCc recorded from CA1 pyramidal neurons of WT and Nf1^+/− mice with normal ACSF (2.5mM KCl). Calibration: 100 pA, 100 ms; B. Average of more than 100 events of sIPSCs or mIPSCs from WT or Nf1^+/− neurons. Calibration: 50 ms and 10pA. C and D: Frequency of mIPSC(e) and mEPSCs(f) recorded in normal and high K+ ACSF. The individual points represent recordings from different neurons. Solid black squares represent WT and open squares represent Nf1^+/− neurons. Solid lines (WT) and dashed lines (Nf1^+/−) represent the change ratio of the mIPSC or mEPSC frequency of neurons in 12.5 mM KCl versus 2.5 mM KCl ACSF. E and F. Comparison of normalized mIPSC (C) frequencies and mEPSC (D) in WT and Nf1^+/−; Data are presented as mean ± SEM. C. High KCl (12.5 mM) in ACSF resulted in a significant increase in mIPSC frequency in both WT and Nf1^+/− mice (WT: 13.89 ±0.69Hz vs. 21.98±0.95 Hz, n=30, paired t-test, t=8.306, P<0.001; Nf1^+/−: 16.26±0.65Hz vs. 43.21±1.11 Hz, n=29, t=36.525, p<0.001). E. The ratio of mIPSC frequency recorded in high KCl to that in control solution was significantly larger in Nf1^+/− mice (2.76 ± 0.34 n=29) than in their WT littermates (1.65 ± 0.229 n=30) (t=7.906; P<0.001). D. High KCl (12.5 mM) in ACSF increased the frequency of mEPSC in both WT (1.15± 0.14 Hz in normal ACSF and 2.12±0.17 in ACSF with 12.5 mM KCl, n=19, paired t-test, t=−13.585, p<0.001) and Nf1^+/− (1.25±0.104 Hz in normal ACSF and 2.25±0.16 in ACSF with 12.5 mM KCl, n=16, paired t-test, t=−7.906, p<0.001). F. The ratio of mEPSC frequency recorded in 12.5 mM KCl to that in control solution was not significantly different between WT and Nf1^+/− neurons (2.12±0.15, n=19 in WT and 2.03±0.24 n=16, in Nf1^+/−, Student’s t-test, t=0.294, p=0.7708). G and H: Deletion of the Nf1 gene from inhibitory neurons caused increased mIPSC frequency(G and H). G. Representative traces of mIPSCc recorded from CA1 pyramidal neurons of WT and Cre-mediated Nf1 mutants mice with normal ACSF (2.5mM KCl) and 12.5mM KCl ACSF. Calibration: 50 pA, 100 ms; H. The figure shows normalized frequency changes of miniature IPSCs recorded from CA1 pyramidal neurons in 12.5 mM KCl versus 2.5 mM KCl ACSF of different Nf1 mice with Cre-driven deletions (WT, n=20; Nf1^floxed/+, n=19; Syn-Cre, n=14; αCaMKII-Cre, n=18; Dlx5/6-Cre, n=13; Nf1^{syn I+/−}, n=15; Nf1^{αCaMKII+/−}, n=15; Nf1^Dlx5/6+/−, n=14) Nf1^{syn I+/−} and Nf1^Dlx5/6+/−, showed higher mIPSC frequencies than WT when the KCl concentration in ACSF was 12.5 mM KCl (WT: 13.52±0.35Hz vs. 24.31±0.71Hz; Nf1^{syn I+/−}: 15.27±0.62Hz vs. 41.26±0.37Hz; Nf1^Dlx5/6+/−: 12.46±0.42Hz vs. 35±0.51 Hz; the first value listed for each mutant line is for 2.5 mM and the second is for 12.5 mM KCl). In contrast, mIPSCs in Nf1^GFAP+/− and Nf1^{αCaMKII+/−} mice, as well as in all controls lines, did not differ from WT mice in either normal or 12.5 mM KCl ACSF