Supplementary Figure 3: Repeated systemic (i.p.) injections of minocycline (MCL) reverse SNI- and CFA‑induced mechanical allodynia in male but not female mice.
From: Different immune cells mediate mechanical pain hypersensitivity in male and female mice
Symbols represent mean ± SEM mechanical withdrawal thresholds (g) before (BL) and after SNI surgery (a) or CFA injection (b), and one day after three daily injections of MCL at 25 mg/kg/day (i.p.); n=6–8 mice/sex/drug in each experiment. In both experiments, a significant sex x drug x repeated measure (post-BL time points only) was observed (F1,20 = 7.6, p=0.01; F1,26 = 68.0, p<0.001, respectively). *p<0.05, ***p<0.001 compared to all other groups. Single injections of MCL produced no effects even at high doses (data not shown); repeated injections have previously shown to increase the anti-allodynic efficacy of MCL (Nazemi et al., Pharmacol. Biochem. Behav., 2012). Note that these observations are in contradiction to those of Bastos and colleagues, who observed partial reversal of chronic constriction injury (CCI)‑mediated mechanical allodynia by 100 mg/kg minocycline in female C57BL/6 mice (Bastos et al., Neurosci. Lett., 543:157-162, 2013) and partial reversal of late‑phase (15–30 min post-injection) formalin test responding by 50 and 100 mg/kg minocycline in male and female mice (Bastos et al., Neurosci. Lett., 553:110-114, 2013). In experiments by another group, 50 mg/kg minocycline was found to reverse thermal hyperalgesia induced by interleukin-1β in female heterozygous G-protein-coupled receptor kinase 2 (GRK2) mutant mice on a C57BL/6 genetic background (Willemen et al., Pain, 2010). It is unclear whether the differences are due to assay, dose, measures or test parameters.
