Skip to main content
. 2020 Aug 7;11:3935. doi: 10.1038/s41467-020-17824-y

Fig. 8. Cl– homeostasis impacts mechanical and thermal nociceptive processing.

Fig. 8

a, b Confocal images of the distribution of YFP + projections in the superficial dorsal horn of MRGPRD-ChR2 (a) and TRPV1-ChR2 (b) mice. Laminar boundaries were delineated by CGRP (red) and IB4 (blue) staining. The white line represents the IB4 barycentre in the SDH. c Distribution of YFP + fluorescence intensity from eight MRGPRD-ChR2 and nine TRPV1-ChR2 mice as a function of the IB4 barycentre (white line in a, b). Dashed line indicates the boundary between laminae I and II. d The peak of YFP-intensity associated with MRGPRD afferents (gray) is closer to the IB4 barycentre (LII) than TRPV1 afferents (red, t = 5.1, P < 0.001). e, f Time course of mechanical sensitization induced by blue light illumination (5 min, 2 Hz) of the hindpaw in MRGPRD-ChR2 (e, n = 10) and TRPV1-ChR2 (f, n = 8) mice. The insets schematically illustrate the experimental procedure. g Effect of orally administered KCC2 enhancer CLP290 (100 mg kg–1) on laser-induced sensitization (time 1h = 1 h after laser stimulation). CLP290 has no effect on MRGPRD-ChR2 mechanical sensitivity, while it prevents sensitization in TRPV1-ChR2 mice. h Effect of the activation of ChR2-expressing GAD2+ SDH interneurons by blue light stimulation on mechanical (n = 13, grey) and thermal (n = 7, red) sensitivity. Nociceptive threshold was measured at different laser powers and normalized to baseline. Inset shows a schematic diagram illustrating epidural stimulation of ChR2. i.u. intensity units, CGRP  calcitonin gene-related peptide, IB4 isolectin B4, MRGPRD Mas-related G-protein coupled receptor member D, TRPV1 transient receptor potential vanilloid 1, ChR2  channelrhodopsin-2, YFP yellow fluorescent protein, Contra contralateral, ipsi  ipsilateral, GAD2  glutamate decarboxylase 2. Data are expressed as mean ± S.E.M. *P < 0.05, **P < 0.01, ***P < 0.001.