Fig. 6. The effect of inflammatory agents on the sensory modalities response of DRG neurons in vivo.

(Ai) Heatmap response profiles for individual GCaMP3-expressing mechanically sensitive (pinch) neurons tested for sensitivity toward mechanical (pinch), 0°, and 55°C stimuli (left), as well as neurons responsive to 0° or 55°C stimuli (right), before (basal; n = 31 and n = 146, respectively) or 24 hours after administration of FCA (n = 90 or n = 102, respectively). (Aii) Summary of mechanically sensitive neurons responding to thermal stimuli as well as thermal-sensitive neurons responding to 55° or 0°C before and 24 hours after the administration of FCA, respectively. Baseline (n = 13 animals) and after FCA (n = 10 animals). (B) In vivo confocal images showing levels of GCaMP3 fluorescence from L4 DRG neurons that respond to 55°C before (pre-PGE₂) and 10 min after administration of PGE₂ (55°C + PGE₂). Basally responsive (white arrowheads) and basally silent (red arrowheads) neurons are shown. Scale bars, 50 μm. (C) Example raw traces of neuronal modality profiles before and after PGE₂ administration. (Di) Heatmap response profile for individual neurons responsive to 55°C before or after PGE₂ administration. Trace showing the average change in GCaMP3 fluorescence following peripheral noxious heat stimulation (green application bar) from basally heat-responsive neurons (Dii) or basally silent neurons (Diii). AUC, area under the curve. (Ei) Heatmap response profile for individual neurons responsive to 0°C before or after PGE₂ administration. (Eii) Trace showing the average change in GCaMP3 fluorescence following peripheral noxious cold stimulation (0°C; green application bar) from basally cold-responsive neurons. Changes in relative maximal fluorescence and AUC (insets). n.s., not significant. (F) Summary of the number of cells displaying discrete modalities before and after PGE₂ administration (n = 75) [*P < 0.05, **P < 0.01, and ***P < 0.001 (comparisons made to baseline); #P < 0.05 and ###P < 0.001 (comparisons made between groups)]. Pre- and post-PGE₂ recordings were made from five animals. M, mechano; C, cold; H, heat; M/H, mechano-heat; M/C/H, mechano-cold-heat; C/H, cold and hot.