Fig. 3.

The presynaptic component of inhibitory synapses made onto newborn dentate granule cells (DGCs) is altered in GSK-3β-overexpressing (OE) mice. A Schematic diagram illustrating patch-clamp whole-cell recordings and showing 8-week-old newborn dentate granule cells in red and embryonic dentate granule cells in purple. B, C Representative miniature inhibitory postsynaptic currents (mIPSCs) traces recorded from 8-week-old WT (B) and GSK-3β-OE (C) dentate granule cells. Vertical deflections represent mIPSCs. D Representative normalized traces showing faster rising kinetics in GSK-3β-OE mice. E–G Frequency (E), amplitude (F), and slope (G) of mIPSCs in developmentally generated (embryonic) and 8-week-old newborn dentate granule cells (adult-born) in wild-type (WT) (gray and white symbols) and GSK-3β-OE (dark and light blue symbols) mice. H Length of the axon initial segment (AIS). I: AIS starting point. J–K Representative images and high-power magnifications showing the AIS of 8-week-old newborn dentate granule cells transduced with a Venus-encoding retrovirus in WT and GSK-3β-OE mice. L–M Representative images and high-power magnifications of 8-week-old newborn dentate granule cells transduced with a Synaptophysin (Syn):GFP-encoding retrovirus in WT and GSK-3β-OE mice. N–O Area of CA3 (N) and CA2 (O) mossy fiber terminals occupied by Syn⁺ clusters (colocalization Mander´s coefficient). P Total exploratory time (s) during the second day of the Novel location preference test. Q: Memory index on the third day of the Novel location preference test. In (J–M), Z-projection images are shown. In (E–G), a two-way ANOVA, followed by a Bonferroni post hoc test, was used. A two-way ANOVA, followed by a Tukey post hoc test, was used to analyze the data shown in (H, I, N, and O). A Student t-test was applied to analyze the data depicted in (P, Q). In (B–G), nine developmentally generated (embryonic) and 15 8-week-old dentate granule cells were obtained from eight GSK-3β-OE. These cells were compared to 11 developmentally generated (embryonic) and 10 8-week-old dentate granule cells obtained from four WT mice. In (H, I), a minimum of 30 newborn dentate granule cells of each age, obtained from 4–5 animals per genotype, were analyzed. In (N, O), a minimum of 10–15 stacks of images per region (CA3 and CA2) and cell age, obtained from 4–5 animals per genotype, were analyzed. In (P, Q), eight WT and 10 GSK-3β-OE animals were used. Graphs represent mean values ± SEM. ML: Molecular layer. GCL: Granule cell layer. H: Hilus. White scale bar: 50 μm. Light blue scale bar: 5 μm. Yellow scale bar: 25 μm. Magenta scale bar: 2 µm. Yellow triangles: AIS. White triangles: Syn⁺ clusters. ⁺ 0.09 > p ≥ 0.05; * 0.05 > p ≥ 0.01; ** 0.01 > p ≥ 0.001; and *** 0.001 > p ≥ 0.0001