Fig. 2: Adult-onset human APP expression reduces LEC PV interneuron excitability.
From: Entorhinal cortex vulnerability to human APP expression promotes hyperexcitability and tau pathology
a Graphical summary of AAV.E2.tdTom and AAV.EF1a.hAPP (or for Ctrl, saline) stereotactic injection in the Lateral Entorhinal Cortex. PV-interneurons were fluorescently targeted (tdTom + ) for whole-cell current clamp recordings. b AP firing elicited by square pulse current injections of varying magnitude normalized to cellular capacitance during recording in tdTom+ PV-INT from L2 LEC at 12 pA/pF. c Group data summary of AP firing frequency in L2 LEC from Ctrl (black) and hAPP injected mice (magenta). LEC PV interneurons from hAPP injected mice show a significant reduction in AP Frequency (Hz) when compared to Ctrl(Ctrl: Max: 156.6 ± 13.52 Hz, hAPP: Max: 91.84 ± 8.74 Hz, p < 0.0001, Two-Way ANOVA). d Summary data of AP properties. L2 LEC PV interneurons after hAPP injection display a significantly decreased input resistance (Ctrl: 145.7 ± 11.61 MΩ, minimum: 82.33, 25% percentile: 125.8, median: 148.4, 75% percentile: 175.3, maximum: 192.9, range: 110.6; hAPP: 88.78 ± 15.11 MΩ, minimum: 43.02, 25% percentile: 56.95, median: 80.93, 75% percentile: 139.1, maximum: 189.9, range: 146.8; p = 0.01, t = 2.73, df = 21) and an insignificant increase in membrane capacitance (Ctrl: 68.83 ± 5.34 pF, minimum: 40.49, 25% percentile: 60.14, median: 75.62, 75% percentile: 86.40, maximum: 99.78, range 59.26, hAPP: 90.21 ± 9.77 pF, minimum: 39.90, 25% percentile: 66.88, median: 90.51, 75% percentile: 115.2, maximum: 152.4, range: 112.5; p = 0.07, t = 1.92, df = 21). e. Graphical summary of AAV.E2.tdTom and AAV.EF1a.hAPP (or for Ctrl, saline) stereotactic injection in the Somatosensory Cortex. PV-interneurons were fluorescently targeted (tdTom + ) for whole-cell current clamp recordings. f AP firing elicited by square pulse current injections of varying magnitude normalized to cellular capacitance during recording in tdTom+ PV-INT from L5 SS Ctx at 12 pA/pF. g Group data summary of AP firing frequency in L5 SS Ctx from Ctrl (black) and hAPP injected mice (magenta). SS Ctx PV interneurons from hAPP injected mice show no significant change in AP Frequency (Hz) when compared to Ctrl (Ctrl: Max: 301.1 ± 27.59 Hz, hAPP: Max: 257.2 ± 24.06 Hz). h Summary data of AP properties. SS Ctx interneurons after hAPP injection display an unchanged Membrane Capacitance (Ctrl: 71.91 ± 9.514, minimum: 34.82, 25% percentile: 46.09, median: 67.31, 75% percentile: 104.9, maximum: 124.2, range 89.40; hAPP: 73.14 ± 7.327, minimum: 44.84, 25% percentile: 50.37, median: 68.69, 75% percentile: 98.70, maximum: 117.7, range: 72.83; p = 0.9180, t = 0.1041, df = 23) and input resistance (Ctrl: 121.2 ± 17.14, minimum: 65.09, 25% percentile: 68.17, median: 112.1, 75% percentile: 137.5, maximum: 240.6, range: 175.5; hAPP: 109.1 ± 10.56, minimum: 64.34, 25% percentile: 80.07, median: 89.76, 75% percentile: 148.6, maximum: 177.9, range: 113.6; p = 0.5475, t = 0.6106, df = 23). i RNAscope representative images at 40x magnification for Ctrl injected (top) and hAPP injected mice (bottom): mAPP mRNA (cyan), Parvalbumin mRNA (gold), human APP mRNA (magenta), and a final merged image. j RNAscope quantification for hAPP copies per PV+ cell comparing control to hAPP injected. hAPP injected show a significant increase in hAPP copies per PV+ cell (p = 0.0039, t = 5.987, df = 4; two-tailed paired t-test). For all summary graphs, data are expressed as mean ( ± SEM). For c, g, and i: Statistical significance is denoted as *p < 0.05, as determined by Two-way ANOVA with Sidak’s multiple comparison test. For d, h: Individual data points (technical replicates, LEC: Ctrl n = 10, hAPP n = 13; SS: Ctrl n = 12, hAPP n = 13; all data collected from 3 biological replicates each) and box plots are displayed. Statistical significance is denoted as *p < 0.05, as determined by two-tailed unpaired t-test. Source data are provided as a Source Data File.
