Figure 4
Comparison of the effect of σ1 agonists on capsaicin-sensitized and on nonsensitized wild-type mice.
Mice were subcutaneously (s.c.) treated with PRE-084 (PRE), (+)-pentazocine (PTZ), carbetapentane (CBP) or their solvent (saline) 30 min before the intraplantar (i.pl.) injection of capsaicin (0.125 μg) or its vehicle (DMSO 1%). The results show latency to paw withdrawal in response to a mechanical stimulus (0.5 g) applied in the hindpaw. Capsaicin-sensitized mice were stimulated in both the ipsilateral (ipsi, black bars) and contralateral (contra, hatched bars) paw to the i.pl. injection. The response in the ipsilateral paw of nonsensitized (DMSO-treated) animals (ipsi, open bars) was also evaluated. Each bar and vertical line represents the mean ± SEM of the values obtained in 8–10 animals. Statistically significant differences between the values obtained in mice treated with the σ1 agonists or its solvent and stimulated in the paw ipsilateral to the capsaicin injection: **p < 0.01; and between the values obtained in mice stimulated in the ipsilateral or contralateral paw after the administration of capsaicin in the ipsilateral paw: ##p < 0.01. There were no statistically significant differences between the groups treated s.c. with saline (administered with capsaicin or its solvent), or between any of these three groups and mice treated with the σ1 agonists and stimulated in the paw contralateral to capsaicin administration. There were no statistically significant differences between the groups treated s.c. with saline and animals treated with the σ1 agonists and stimulated in the paw in which the capsaicin solvent was injected (two-way ANOVA followed by Bonferroni test).
