Journal: bioRxiv

Article Title: Microglia Depletion Selectively Eliminates a Singular Form of Hippocampal Long-Term Potentiation

doi: 10.1101/2022.07.29.501926

Figure Lengend Snippet: A , A’) Images of the same hippocampal cross section viewed in different color channels showing DAPI-labeling of cellular nuclei (A, inverse contrast image) and Iba1 immunoreactivity (A’) in a slice from a vehicle-treated mouse fixed promptly after preparation (SG: dentate gyrus stratum granulosum; CA1 stratum pyramidale at right). Microglia appear white in A’-C. The dashed rectangle in A indicates the placement of the higher magnification images from which the Iba1-immunoreactive cells were quantified. B, C) Representative images of the quantification field showing Iba1 immunoreactivity in slices from vehicle- (B) and PLX5622- (C) treated mice: a severe depletion of Iba1-immunoreactive cells is evident in the PLX5622 case (arrow in C indicates the single immunolabeled cell in the field). Calibration bar in C indicates 200 μm for A and A’, 100 μm for B and C.

Article Snippet: To deplete brain microglia, mice were provided chow containing PLX5622 (1200 ppm) (Cayman Chemical Company, Ann Arbor, MI, USA), an antagonist of the CSF1R which is critical for microglial survival ( ; ).

Techniques: Labeling, Immunolabeling

Journal: bioRxiv

Article Title: Microglia Depletion Selectively Eliminates a Singular Form of Hippocampal Long-Term Potentiation

doi: 10.1101/2022.07.29.501926

Figure Lengend Snippet: Acute hippocampal slices from mice fed either control (VEH) or PLX5622- (PLX) chow for 7-12 days were assessed for treatment effects on LPP transmission and LTP. A ) Input-output curves from the outer molecular layer of the DG for VEH and PLX treated animals; VEH n=8, PLX n=5. B) The response profile to a ten-pulse, 40 Hz train of stimulation was comparable between VEH and PLX groups, both showing the typical response facilitation followed by depression (F 9,135 =0.3653, p=0.9497, VEH n=7; PLX n=10; two-way RM ANOVA). C ) After recording stable baseline responses, a single 100 Hz HFS train was used to induce LTP (at arrow). Both VEH and PLX groups exhibited an initial short-term potentiation and decline to a stable potentiated response, but the magnitude of potentiation was markedly reduced in the PLX group relative to VEH-controls. Representative traces show responses before (solid) and after (dashed) induction of LTP. Scale bars: x=1 mV, y=10 ms. D) Plot of the mean potentiation at 55-60 min post-induction showed mice treated with PLX had significantly reduced LPP-DG LTP relative to VEH mice (**p=0.0029, VEH n=9; PLX n=9; two-tailed unpaired t-test).

Article Snippet: To deplete brain microglia, mice were provided chow containing PLX5622 (1200 ppm) (Cayman Chemical Company, Ann Arbor, MI, USA), an antagonist of the CSF1R which is critical for microglial survival ( ; ).

Techniques: Transmission Assay, Two Tailed Test

Journal: bioRxiv

Article Title: Microglia Depletion Selectively Eliminates a Singular Form of Hippocampal Long-Term Potentiation

doi: 10.1101/2022.07.29.501926

Figure Lengend Snippet: A) Input/output curves for the MPP were comparable in slices from VEH- and PLX5622- (PLX) chow treated mice. B) Plot shows MPP-fEPSP responses to a ten pulse, 40 Hz train were comparable in VEH and PLX mice: in both groups responses were depressed by about 30% over the course of the train (F 9,108 = 1.09, p= 0.379; VEH n=5, PLX n=9; two-way RM ANOVA). C) After recording stable baseline responses for 20 min, MPP potentiation was induced using three, 500ms high frequency stimulation trains (100Hz each) separated by 20 sec (at arrow). Both VEH and PLX treated animals exhibited a marked potentiation. Scale bars: x=1 mV, y=10 ms. D) Plot of the mean fEPSP response recorded 55-60 min post-induction showed no difference in the degree of potentiation in slices from VEH and PLX mice (p=0.2768; VEH n=7, PLX n=6; two-tailed unpaired t-test).

Article Snippet: To deplete brain microglia, mice were provided chow containing PLX5622 (1200 ppm) (Cayman Chemical Company, Ann Arbor, MI, USA), an antagonist of the CSF1R which is critical for microglial survival ( ; ).

Techniques: Two Tailed Test

Journal: bioRxiv

Article Title: Microglia Depletion Selectively Eliminates a Singular Form of Hippocampal Long-Term Potentiation

doi: 10.1101/2022.07.29.501926

Figure Lengend Snippet: A) SC input/output curves were comparable between treatment groups. B) Plot shows SC fEPSP responses to a 10 pulse, 40 Hz train were comparable in VEH and PLX mice (F 9,99 = 0.3022, p=0.9725; VEH n=6, PLX5622 n=7; two-way RM ANOVA). C) There was no reliable effect of PLX on the area of the response to individual theta bursts used to induce LTP (F 4,52 =0.0812, p=0.988; VEH n=8, PLX n=7). D) A single train of 5 theta bursts elicited comparable potentiation in slices from VEH- and PLX-mice. Representative fEPSP traces collected before (solid line) and after (dotted line) LTP are shown for the two groups. The bar graph (right) summarizes the normalized slopes at 55-60 post TBS (p=0.2365; VEH n=7, PLX n=9; two-tailed unpaired t-test). Scale bars: x=1 mV, y=10 ms.

Article Snippet: To deplete brain microglia, mice were provided chow containing PLX5622 (1200 ppm) (Cayman Chemical Company, Ann Arbor, MI, USA), an antagonist of the CSF1R which is critical for microglial survival ( ; ).

Techniques: Two Tailed Test

Journal: bioRxiv

Article Title: Microglia Depletion Selectively Eliminates a Singular Form of Hippocampal Long-Term Potentiation

doi: 10.1101/2022.07.29.501926

Figure Lengend Snippet: LPP fEPSP responses were collected from slices from naiive mice and were infused with VEH or 1μM of PLX5622 (solid bar). A) After infusion of VEH or PLX for 1 hour, a HFS (1 sec, 100Hz) was applied to induce LPP-LTP; the two groups exhibited similar levels of potentiation. Scale bars: x=1 mV, y=10 ms. B) Plot of the mean percent potentiation at 55-60 min after HFS shows comparable LPP-LTP in the Veh and PLX groups (p=0.590; VEH n=11, PLX n=8; two-tailed unpaired t-test).

Article Snippet: To deplete brain microglia, mice were provided chow containing PLX5622 (1200 ppm) (Cayman Chemical Company, Ann Arbor, MI, USA), an antagonist of the CSF1R which is critical for microglial survival ( ; ).

Techniques: Two Tailed Test