Figure 2: Impaired spine development in ARHGAP33 KO mice.
(a–c) Decreased total and mature spine densities in ARHGAP33 KO mice. Examples of Golgi staining of granule cells in the hippocampal dentate gyri from 12-week-old ARHGAP33 KO and WT mice (a). Scale bars, 10 μm. Z-stacks were imaged, and individual spines were measured (WT, n=33 cells, KO, n=29 cells; each n=4 mice; total spine density, P=4.4 × 10−5; percentage of mature spines, P=7.7 × 10−17, one-way ANOVA; b,c). *P<0.05. Bars show mean values. Note that dendritic protrusions with widths larger than half their length were classified as mature spines49. (d–h) Decreased mEPSC frequency and amplitude in ARHGAP33 KO dentate gyrus granule cells. Representative traces of mEPSCs obtained from hippocampal slices of 12-week-old WT and ARHGAP33 KO mice (d). Scale bar, 10 pA, 100 ms. Cumulative probability plot and summary of average mEPSC frequency and amplitude of the same neurons (e–h). mEPSC frequency (cumulative probability plot, WT, n=2,937 events, KO, n=2,139 events, P=1.3 × 10−11, Kolmogorov–Smirnov test; average (scatterplot), WT, n=15 cells, KO, n=15 cells, P=0.017, Mann–Whitney U-test; e); mEPSC amplitude (cumulative probability plot, WT, n=2,937 events, KO, n=2,139 events, P=8.7 × 10−7, Kolmogorov–Smirnov test; average (scatterplot), WT, n=15 cells, KO, n=15 cells, P>0.05, Mann–Whitney U-test; f); rise time (g) and decay time (h; WT, n=15 cells, KO, n=15 cells, P>0.05, Mann–Whitney U-test). *P<0.05. Bars in the summary plots show median values. (i) No change in the paired-pulse ratio of evoked EPSCs from ARHGAP33 KO dentate gyrus granule cells. Representative traces of EPSCs (left). Scale bars, 100 pA, 20 ms. Summary graph showing the ratio of the second to the first EPSC amplitude (WT, n=20 cells; KO, n=17 cells, P>0.05, Mann–Whitney U-test; right). NS, not significant.
