Fig. 3
WT1 effect is mediated by enhanced activity and excitability of CA1 neurons. a In the mouse hippocampus WT1 localizes predominantly within the cell bodies layer. Scale bar = 500 μm. b Immunostaining of the mouse CA1 region shows WT1 expression mainly in cell bodies but also in proximal dendrites. Scale bar = 50 μm. c In the rat CA1 region WT1 is expressed in pyramidal neurons and not in GFAP positive astrocytes. Scale bar = 50 μm. d Scheme for the electrophysiology experiments. Reduction in WT1 expression after a single intrahippocampal injection of WT1-AS (paired t test: *p = 0.0202). A weak stimulus (delivered at arrow) induced LTP in WT1-AS group (two-way ANOVA RM: F(1,12) = 10.58, **p = 0.0069). Calibrations: 0.5 mV/10 ms. e, Bicuculline (10 μM) did not block WT1-AS-mediated LTP enhancement (two-way ANOVA RM: F(1,9) = 6.039, *p = 0.0363). Calibrations: 0.5 mV/10 ms. f Whole-cell patch recordings in rats CA1 pyramidal neurons. Right inset: probability of evoking at least one spike in response to a weak (20–50 pA) or a stronger (60–90 pA) current step in WT1-depleted or control groups (two-tailed Chi-square test, **p = 0.0041). Resting membrane potential and input resistance measured −63.75 ± 3.15 mV and 105.8 ± 21.76 MΩ in the WT1-AS group, and −60.80 ± 2.85 mV and 109.3 ± 20.04 MΩ in the SC-ODN group. Left inset: representative traces in cells from WT1-AS or SC-ODN. Calibration: 50 mV/100 ms. g Upon weak stimulus (delivered at arrow) LTP was induced in Wt1∆ mice but not in control group (two-way ANOVA RM: F(1,23) = 5.125, *p = 0.0333). Calibrations: 0.5 mV/10 ms. h Wt1∆ mice showed increased basal synaptic efficiency (left panel: input/output; linear regression unpaired t test, **p = 0.0077) but did not affect paired-pulse ratio (right panel; two-way ANOVA RM, p = 0.0878). Representative fEPSPs graphs show traces recorded during baseline and 60 min post-HFS. Dot blot graphs display final 10 min of fEPSP slope. Data are expressed as mean ± s.e.m
