SEXUAL DIMORPHISM AND LATERALIZED ACTIVATION OF THE BASOLATERAL AMYGDALA IN A MOUSE MODEL OF HYPERALGESIC PRIMING

The study aimed to evaluate sex differences in basolateral amygdala (BLA) activation in male and female mice subjected to the hyperalgesic priming model. Male and female Swiss Webster mice (60 days old) were assigned to either control or hyperalgesic priming groups (n=3-4/group). The priming protocol consisted of a plantar incision followed by a local injection of prostaglandin E2 (PGE2) to induce persistent hypersensitivity. Nociceptive responses were assessed using the Von Frey test and the Mouse Grimace Scale (MGS). Subsequently, brain tissues were processed for immunofluorescence to evaluate BLA activation by DeltaFosB expression. Regarding the behavioral assessments, the repeated measures ANOVA for the Von Frey test revealed a significant main effect of Time (F_5,25=20,68; p<0.05), with Tukey’s post-hoc test showing a significant increase in mechanical hypersensitivity compared to the baseline for both sexes. Furthermore, for the MGS, significant main effects were observed for both Time (F_5,25=12,90; p<0.05) and Group (F_5,25=6,86; p<0.05). Post-hoc analysis confirmed that facial expressions of pain were significantly increased compared to baseline levels throughout the experimental period. Additionally, the group effect revealed that males exhibited significantly higher facial pain scores compared to females. Preliminary immunofluorescence results showed that: for females, the repeated measures ANOVA revealed a significant interaction between Condition and Side (F_1,6=6,59; p<0.05). Tukey's post-hoc test demonstrated that females in the priming group exhibited a significant increase in DeltaFosB expression in the left BLA compared to the contralateral side. In contrast, no significant differences in BLA activation were observed for males.