Fig 1: Reduced axonal GBR expression and presynaptic inhibition in APP-/- mice. a Representative traces of evoked EPSC recordings in CA1 neurons of acute hippocampal slices of APP-/- mice under baseline conditions (control, black) and during 50 µM baclofen application (red). Bar graphs show reduced baclofen-mediated EPSC amplitude inhibition in APP-/- mice (**P < 0.01, unpaired Student’s t-test) while EPSC amplitude inhibition in AJAP-1-/-, PIANP-/- mice and WT littermate mice did not differ (P > 0.05). The n number of neurons is indicated. b Bar graphs showing reduced baclofen-mediated inhibition of the mEPSC frequency in CA1 pyramidal neurons of APP-/- mice (***P < 0.001, unpaired Student’s t-test). Baclofen had no effect on the mEPSC amplitude in APP-/- and WT littermate mice. Baseline mEPSC frequency and amplitude were similar in APP-/- and WT littermate mice (P > 0.05, unpaired t-test). c Top: Immunofluorescence of endogenous GB1 protein in axons of hippocampal WT (left) and APP-/- (right) neurons. Neurons expressing GFP were fixed at DIV10, permeabilized, and immunostained for endogenous GB1 (green) and the presynaptic marker piccolo (magenta). GFP served as a volume marker. Merged images show GB1 and piccolo co-localization. Scale bar 5 µm. Bottom: Intensity gray value profile graphs of GB1 (green) and piccolo (magenta). Source data are provided as a Source Data file. Data are presented as mean ± s.e.m