Figure 5. Intra-CeA administration of naltrexone reinstated mechanical hyperalgesia in male but not female mice.
(a) Effect of bilateral intra-CeA injection of NTX (1 μg, 0.2 μL) on mechanical thresholds 21 days after plantar incision model (PIM) or sham surgery in male and female mice. Males: n = 6–7; Females: n = 5–6. * P < 0.05, ** P < 0.01, Bonferroni post-tests compared to sham + saline after 2-way ANOVA). (b) Effect of bilateral intra-CeA injection of saline. Males: n = 6–7; Females: n = 4–6. (c, d) Injection sites in males (c; PIM + NTX;
PIM + saline;
Sham + NTX;
Sham + saline) or females (d:
Sham,
PIM) and representative image of guide cannula tracts and India ink injections. (e, f, g) Incidence of intra-CeA NTX-induced withdrawal behaviors in male and female mice, including (e) jumping, (f) rearing and (g) paw flutters.