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. 2018 Oct 12;10:35. doi: 10.3389/fnsyn.2018.00035

Figure 1.

Figure 1

A novel social stimulus causes aberrant c-Fos activation in the medial prefrontal cortex (mPFC) in the adenomatous polyposis coli (APC) conditional knockout (cKO) mouse. (A) Schematic for social vs. non-social exposure experiment. During the 5-day habituation period, the mouse is singly housed and exposed to the investigator’s hand twice, separated by 3 min, for 1 s each time. During the exposure trial, the mice are separated into one of two test groups: exposure to either a novel, non-social object for 3 min before it is removed; or exposure to a novel, juvenile mouse for 3 min before it is removed. Ninety minutes after removal of the novel stimulus, the mice were perfused and brain sections containing the mPFC were immunostained for c-Fos as a marker of neuronal activity. (B) Representative images and quantification of c-Fos positive cells in prelimbic and infralimbic sub-regions (delineated by box lines) of the mPFC shows that social exposure induces increased activation of neurons in the infralimbic cortex of APC cKO mice. In contrast novel object exposure causes less activation in the prelimbic sub-region in APC cKOs, compared with control littermates (arrowheads on c-Fos positive cells are included to highlight the significantly different activation patterns, for the novel object: n = 3 mice for each genotype, for the novel mouse: n = 3 mice for each genotype, two slices per mouse; *p < 0.05). (C) Representative image of double labeling showing that the c-Fos immuno-positive cells (green) also stain for neuronal nuclei (NeuN; red) [overlap (yellow) indicated by arrowheads]. (D) The c-Fos staining is detected in relatively few GAD67-EGFP marked parvalbumin (PV) interneurons (n = 3 control mice, six slices; APC cKO-GAD67-EGFP six mice, 12 slices [overlap (yellow) indicated by arrowheads]). Note that, to make the color for c-Fos consistent across the images shown in (C), we switched the GAD67-EGFP to red and the c-Fos to green in this panel. (E) Quantification of the c-Fos positive neurons (n = 3 mice for each genotype, ***p < 0.001), identified as pyramidal cells given their large nuclear diameter (>10 μm), NeuN staining and localization in layers 2/3 and 5 of the infralimbic sub-region, or as interneurons (<10 μm nuclear diameter) and NeuN or GAD67-EGFP positive.