Journal: bioRxiv
Article Title: Progressive remote memory decline coincides with parvalbumin interneuron hyperexcitability and enhanced inhibition of cortical engram cells in a mouse model of Alzheimer’s disease
doi: 10.1101/2025.03.26.645537
Figure Lengend Snippet: a. Schematic coronal brain section indicating the mPFC prelimbic region in dark grey, where tdTomato + parvalbumin (PV) cells and pyramidal (PYR) cells were recorded in APP/PS1 PV-Cre tdTomato (APP/PS1) and PV-Cre tdTomato (control) mice. Representative differential interference contrast images (left) and a corresponding fluorescent image (right). fmi= forceps minor of the corpus callosum. ML= midline. Recordings were performed in 16 ( b-i ) and 20 ( j-q ) week-old mice. b . Resting membrane potential was unaltered in PV cells at 16 weeks of age. Mann-Whitney test: U = 433, p = 0.98, n = 29/30 cells, N = 4 mice/genotype. Ctr= control. c . Action potential (AP) firing of PV cells upon a depolarizing current step (250 pA). d. AP frequency in PV cells in response to 0-425 pA depolarizing current steps did not differ between genotypes. Two-way repeated measures ANOVA genotype x current F (10,390) = 0.44, p = 0.93, n = 29/30 cells, N = 4 mice/genotype. e. Rheobase was unchanged in PV cells. Unpaired t-test: t 57 = 0.08, p = 0.93, n = 29/30 cells, N = 4 mice/genotype. Ctr= control. f . Resting membrane potential of PYR cells did not differ between genotypes. Unpaired t-test: t 36 = 0.51, p = 0.61, n = 17/21 cells from N = 4/6 control vs. APP/PS1 mice, respectively. Ctr= control. g. AP firing of PYR cells upon a depolarizing current step (250 pA). h. AP frequency in PYR cells in response to 0-250 pA depolarizing current steps did not differ between genotypes. Two-way repeated measures ANOVA genotype x current F (10,370) = 0.25, p = 0.99, n = 17/21 from N = 4/6 control vs. APP/PS1 mice, respectively. i. APP/PS1 mice show a lower rheobase in PYR cells. Mann-Whitney test: U = 111, * p = 0.048, n = 17/21 cells from N = 4/6 control vs. APP/PS1 mice, respectively. Ctr= control. j . Resting membrane potential was unaltered in PV cells at 20 weeks of age. Unpaired t-test: t 35 = 0.93, p = 0.36, n = 22/15 cells from N = 6/7 control and APP/PS1 mice, respectively. Ctr= control. k. AP firing of PV cells upon a depolarizing current step (250 pA). l. APP/PS1 mice show an increased AP frequency in PV cells in response to 0-425 pA depolarizing current steps. Two-way repeated measures ANOVA genotype x current F (17,595) = 4.05, * p < 0.0001, n = 22/15 cells, N = 6/7 control and APP/PS1 mice, respectively. m . Rheobase was unchanged in PV cells. Unpaired t-test: t 35 = 1.67, p = 0.10, 22/15 cells, N = 6/7 control and APP/PS1 mice, respectively. Ctr= control. n. Resting membrane potential of PYR cells did not differ between genotypes. Unpaired t-test: t 74 = 0.92, p = 0.36, n = 37/39 cells, N = 9 mice/genotype. Ctr= control. o . AP firing of PYR cells upon a depolarizing current step (250 pA). p . AP frequency in PYR cells in response to 0-250 pA depolarizing current steps did not differ between genotypes. Two-way repeated measures ANOVA genotype x current F (10,740) = 1.80, p = 0.08, n = 37/39 cells, N = 9 mice/genotype. q. APP/PS1 mice show a decrease in PYR cell rheobase. Unpaired t-test: t 74 = 2.34, * p = 0.022, n = 37/39 cells, N = 9 mice/genotype. Ctr= control. Graphs show mean ± s.e.m.
Article Snippet: Pyramidal, PV and SST cells were recorded in the mPFC using a Multiclamp 700B amplifier (Molecular devices, Sunnyvale, CA) and sampled at 10 kHz low pass filter at 4 kHz and digitized with Axon Digidata 1440 A (Molecular Devices).
Techniques: Control, Membrane, MANN-WHITNEY