Induced biosynthesis of Arc in the skin depends on the presence of intact primary afferents. A, Intraplantar administration of inflammatory mediators in the ipsilateral (IPL) paw of mice triggered a rapid translation of arc in skin that is not modified by the transcription inhibitor Act D (300 ng/25 μl); n = 6 animals per group. Ordinary one-way ANOVA: F_(2,15) = 11.33, p = 0.0010. Bonferroni's multiple comparisons test: NGF/IL-6, IPL versus NGF/IL-6, CL; **p = 0.0022. IPL, ipsilateral or injected side; CL, contralateral or uninjected side. B, Intraplantar administration of inflammatory mediators, in the presence or absence of Act D (300 ng/25 μl), did not alter Arc abundance in the DRG. C, Intraplantar administration of inflammatory mediators, in the presence or absence of Act D (300 ng/25 μl), did not modify Arc abundance in the spinal dorsal horn (SDH). D, A cartoon detailing the experimental protocol for sciatic nerve transection (SNT). Sciatic nerve was axotomized, and 10 d later, animals received an intraplantar injection of the inflammatory mediators. One hour after injection, Arc protein expression was analyzed in DRG and glabrous skin from injected (ipsilateral, IPL) and noninjected (contralateral, CL) paws. E, Increase in Arc abundance in the skin caused by intraplantar administration of inflammatory mediators requires intact primary afferent fibers; n = 4 animals per group. Ordinary one-way ANOVA: F_(3,12) = 15.14, p = 0.0002. Tukey's multiple comparisons test: naive, NGF/IL-6, IPL versus SNT, NGF/IL-6, IPL; **p = 0.0094. n.s., non-significant. F, SNT surgery transection did not alter Arc abundance in the DRG.