Figure 2

A. CFA reduced withdrawal latency within 24 hrs post-CFA. Popliteal fossa lidocaine (4% w/v, 200 μl) reversed CFA-induced hypersensitivity, elevating paw withdrawal latencies to noxious thermal stimulation to almost cut-off in both CFA and control (saline) treated rats at the 15 min time-point. Elevated paw-flick latencies were observed throughout the 60 min testing period in the CFA treated rats, and returned to pre-lidocaine latencies within 45 min in the control rats, *p < 0.05 vs. post-CFA, ^#p < 0.05 vs. pre-CFA, n = 5-6. B. CFA decreased withdrawal thresholds to noxious mechanical stimulation within 24 hrs. Popliteal fossa lidocaine elevated paw-withdrawal thresholds to almost cut-off in both the CFA and saline (control) groups at the 15 min time-point. Paw-withdrawal thresholds returned to pre-lidocaine values within 30 min for control rats, and within 45 min in the CFA treated rats, *p < 0.05 vs. post-CFA, ^#p < 0.05 vs. pre-CFA, n = 5-6. C. Popliteal fossa lidocaine induced CPP 24 hrs, but not 4-days post-CFA injection. *p < 0.05 vs. pre-conditioning, p < 0.05, n = 5-6. D. Difference scores calculated as test time - preconditioning time spent in lidocaine chamber confirm that only rats treated with CFA 24 hours prior to conditioning showed CPP in response to peripheral nerve block by lidocaine. *p < 0.05 vs. saline treated group.