Figure 3.

Responses to acute painful stimuli. A, Warm-water tail-flick assay assessed at 45, 47, and 49°C. B, Effect of the pretreatment with NLX (1 mg/kg, i.p.) on tail-flick latencies. C, Hotplate licking and jump latencies at 50°C. D, Cumulative time spent licking the hindpaw after subcutaneous injection of Formalin (20 μl of 2% Formalin) into the plantar surface from 0–5 min (first phase) and 20–30 min after injection (second phase). E, Mechanical stimulation test (von Frey monofilaments). Values are the percentage of hindpaw withdrawals in response to stimuli of increasing strength. F, Effect of NLX (1 mg/kg, i.p.) on the mechanical sensitivity threshold. Note that, after naloxone treatment, BAMBI^−/− mice showed a normalization in the withdrawal response to both thermal and mechanical stimuli, whereas no changes were evident in wild-type mice. Data are means ± SEM. *p < 0.05, **p < 0.01, and ***p < 0.001 versus BAMBI^+/+ mice (two-tailed Student's t test).