Figure 6

Opioid-dependent LPS-induced antinociception in inflammatory pain. All rats were injected with CFA i.pl. 4 d before further treatment. (A) Mechanical nociceptive thresholds were measured before and 5–120 min after injection of 100 μl LPS (0.01-1 μg) i.pl. (n = 6, * vs. 0 min, p < 0.05, Two way RM ANOVA, Student-Newman-Keuls). (B, C) Rats were treated with 1 μg LPS i.pl. and thermal nociceptive as well as mechanical thresholds were determined after indicated time points (n = 6, * vs. 0 min, * p < 0.05, Two way RM ANOVA, Student-Newman-Keuls). (D) Thermal nociceptive thresholds were measured after 5 min – 1 d in rats after 1 μg LPS i.pl. and as well as NLX (0.56 ng) or anti-β-endorphin antibody (anti-END, 2 μg) compared to control antibody (IgG2 μg, all black symbols). Contralateral paws from rats in each treatment group are shown for comparison (white symbols). (E,F) The effect of the small molecule TLR4 inhibitor, TAK-242 i.pl. (1, 10 μg/ml) on LPS-induced antinociception was evaluated in mechanical and thermal nociceptive thresholds. (E) Paw pressure thresholds in inflamed paws (ipsi, black symbols) were obtained after 5–120 min (n = 3–7). (F) Thermal nociceptive thresholds were measured in inflamed paws (ipsi, black symbols) rats after 1 μg LPS and 10 μg TAK-242 i.pl. at indicated time points compared to solvent (n = 6, * vs. 0 min, p < 0.05, Two way RM ANOVA, Student-Newman-Keuls). Contralateral (contra) paws are shown seen for comparison (white symbols). The data from the treatment group LPS + control IgG (black circles) is displayed for comparison from graph 6D. All data are presented as MEAN ± SEM. always n = 6 except when indicated otherwise, * vs. 0 min, p < 0.05, Two way RM ANOVA, Student-Newman-Keuls).