Fig. 5. Mechanical hyperalgesia in mice after a first incision preceded (or not) by a remifentanil infusion. Each point represents the mean changes in nociceptive thresholds compared with baseline, standardized to the control group (represented by the broken line , n = 5). Vertical bars show the SD. Negative values indicate pronociceptive effects. Empty squares represent results obtained after a first incision + saline without previous treatment (n = 5), whereas filled rhombs show the effects of a first incision + saline performed in mice previously exposed to 2.66 μg · kg−1· min−1remifentanil (n = 7). Remifentanil was administered 27 days before surgery (see Materials and Methods). * P < 0.05 compared with the control group.