Figure 5From: The differential contribution of tumour necrosis factor to thermal and mechanical hyperalgesia during chronic inflammationPrearthritic treatment with etanercept reduces postarthritic macrophage accumulation in the dorsal root ganglion (DRG). (a) Inflammation due to complete Freund's adjuvant (CFA) induced a 10-fold increase in perineuronal macrophages (n = 4) by 7 days after inflammation. Infiltration of macrophages was restricted to the ipsilateral side, except for 7 days after inflammation, when a threefold increase in perineuronal macrophages was observed in the contralateral DRG. Nerve damage was assessed through double immunohistochemistry using the macrophage marker, ED1 (b) and a neuropathic marker, ATF-3 (activating transcription factor-3) (c). A maximum of two ATF-3-positive cells was detected per DRG, indicating that little nerve damage occurs in this model. (d) Prearthritic treatment with etanercept reduced macrophage numbers in the ipsilateral DRG by 75% 7 days after inflammation in comparison with controls treated with denatured etanercept (n = 4). No differences in macrophage numbers were detected with etanercept treatment commencing 3 days after inflammation induction. (e) A significant correlation between macrophage numbers in the DRG and mechanical hyperalgesia was observed 7 days after inflammation (n = 12). All treatment groups and controls were plotted. R2 = 0.667, P < 0.01. *P < 0.05,**P < 0.01, ***P < 0.005.Back to article page