Fig. 3. Nerve injury–induced hypersensitivities and peripheral opioid antinociception in B1/B2KO mice. (A ) Chronic constriction injury (CCI) of the sciatic nerve was induced and thermal thresholds were measured with Hargreaves test, mechanical thresholds by von Frey test, and sensitivities to cool temperatures by the acetone test. (B ) Peripheral antinociceptive effects of opioid agonists were measured 2 days after CCI. Von Frey tests were performed before CCI and 2 days later, before and 30 min after near nerve injection of DAMGO (μ-receptor agonist, 2 μg/30 μl/mouse), DPDPE (δ-receptor agonist, 150 μg/30 μl/mouse), and U50488 (κ-receptor agonist, 50 μg/30 μl/mouse). Two-way repeated measures ANOVA followed by Bonferroni test were performed. *P < 0.05 vs. WT. N = 8 mice per group. Blue symbols : wild type (WT) mice; red symbols : B1/B2 knockout (B1/B2KO).