Fig. 2

Oxycodone produced a significant and dose-dependent acute effect on SNL-induced allodynia. The ipsilateral paw withdrawal pressure was determined every other day after SNL by von Frey test. (a) acute effect determined 30 min after daily saline or oxycodone administration, or (c) chronic effect determined 1 h before saline or oxycodone administration. The area under curve (AUC) values of corresponding curves of the von Frey tests are shown in (b) and (d). Data are presented as means ± S.E.M. (n = 5–9). One-way ANOVA and Newman-Keuls test were used to analyze the data. ^* P < 0.05, ^*** p < 0.001 vs. Sham + saline group; ^# p < 0.05, ^### p < 0.001 vs. SNL + saline group