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. 2021 Sep 15;41(37):7712–7726. doi: 10.1523/JNEUROSCI.0440-21.2021

Figure 3.

Figure 3.

Arc is constitutively expressed in peripheral and spinal sites important for nociceptive signaling. A, Single DRG neuron-sequencing tSNE clusters showing expression of Arc with the light neurofilament expressed in large diameter neurons (Nefl) and across DRG sensory neurons of peptidergic; Calca (CGRP) and non-peptidergic [P2x3 (P2X3)] subclusters (Li et al., 2016). B, In situ hybridizations of Arc and markers for L4–L5 DRGs together with large diameter neurons expressing neurofilament protein NF200 (NF200, blue), Calca (CGRP, green), and neurons expressing P2x3 (P2X3 red). Validation for negative control probes is provided in Extended Data Figure 3-1. C, Quantification of Arc expression in the DRG. Expression of Arc is greatest in NF200 expressing large diameter neurons. Intraplantar administration of the inflammatory mediators increased Arc mRNA in ipsilateral (IPL) DRGs expressing Calca (CGRP) mRNA; n = 3 animals per group; multiple slices from L4–L5 DRGs. Two-way ANOVA: cell-type factor, F(2,55) = 35.80, p < 0.0001; treatment factor, F(1,55) = 4.545, p = 0.0375. Bonferroni's multiple comparisons test: NF200 versus CGRP, ***p < 0.0001; NF200 versus P2XR, ***p < 0.0001; CGRP-IPL versus CGRP-CL, *p = 0.0113. D, In situ hybridization of Arc in the dorsal horn of the spinal cord (Lamina I–VI). E, Quantification of D. Arc expression is highest in Laminal Layer II. Intraplantar administration of inflammatory mediators did not significantly impact arc mRNA expression.