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. 2019 Dec 8;30(4):2185–2198. doi: 10.1093/cercor/bhz231

Figure 8.

Figure 8

SP mRNA and Arc are coexpressed in ensembles of dentate granule cells activated in a novel environment. (A–C) Fluorescent in situ hybridization for SP mRNA and immunofluorescence (IF) labeling for activity-regulated cytoskeleton-associated protein (Arc) in the dentate gyrus of control mice (A1-A4) and mice 2 h (B1-B4) and 24 h (C1-C4) after placement into a novel environment. (D) In controls, 84.5 ± 4.6% of strongly SP mRNA expressing granule cells were also Arc-positive. Conversely, 15.5 ± 4.6% of strongly SP mRNA-positive granule cells were Arc-negative. (E) In control mice (Ctrl), 1.3 ± 0.2% of all granule cells (suprapyramidal blade) showed a strong SP mRNA signal. Two hours after placement into a novel environment, the number of granule cells expressing high levels of SP mRNA significantly increased to 2.3 ± 0.2%. By 24 h, the number of strongly SP mRNA expressing cells had returned back to control level (1.4 ± 0.2%). One-way ANOVA with Bonferroni correction for multiple comparisons; F(2, 6) = 26.02; *P < 0.05, N = 3 for each time point. (F) Fraction of strongly SP mRNA-positive granule cells coexpressing Arc. (G) In controls, 81.8 ± 0.9% of Arc-positive cells were also strongly SP mRNA-positive. Conversely, 18.2 ± 0.9% of Arc-positive cells were not strongly SP mRNA-positive. (H) Arc–IF followed a similar time course (cage-control: 1.3 ± 0.1%, 2 h: 2.1 ± 0.2%, and 24 h: 1.4 ± 0.1%). One-way ANOVA with Bonferroni correction for multiple comparisons; F(2, 6) = 39.86; *P < 0.05, N = 3 for each time point. (I) Fraction of Arc-positive granule cells strongly coexpressing SP mRNA. Scale bars: 100 μm (C1) and 25 μm (C4). gcl, granule cell layer; ml, molecular layer.