Figure 5.

Effects of Hmgb1 siRNA post-treatment in the right CeA on chronic neuropathic pain behaviors. (A) Hmgb1 siRNA AAV pooled viral vector (siHmgb1) or scrambled siRNA AAV control viral vector (scramble) was stereotaxically delivered into the right CeA of male (siHmgb1, n = 19; scramble, n = 20) and female (siHmgb1, n = 20; scramble, n = 20) rats as a post-treatment 1 week after SNL surgery. Pain-related behavioral assays were performed 4 weeks after SNL surgery. (B) Sensory withdrawal thresholds (measured by electronic von Frey and paw compression of the affected hind paw) were increased by siHmgb1 post-treatment in male and female SNL rats compared to the scramble control. Emotional-affective responses were measured by the duration (s) of audible (C) or ultrasonic (D) vocalizations evoked by a brief (10 s) normally innocuous (100 g/6 mm²) or noxious (500 g/6 mm²) mechanical compression of the affected hind paw. Audible and ultrasonic vocalization duration in response to normally innocuous stimulation was significantly decreased in siHmgb1 post-treatment males only; audible and ultrasonic vocalization duration evoked by noxious stimulation was significantly decreased in both males and females following siHmgb1 post-treatment when compared to the scramble control. Anxiety-like behaviors measured by center duration and number of center entries in the OFT (E) and open arm duration and open arm entries in the EPM (F) were not significantly affected by siHmgb1 post-treatment in male or female SNL rats compared to the scramble control. No significant differences were observed in the distance traveled in the OFT for male or female SNL rats following siHmgb1 post-treatment when compared to the scramble control (E). *, **, ***, **** p < 0.05, 0.01, 0.001, 0.0001, two-way ANOVA with Šidák’s post hoc tests, compared to the same-sex scramble control. Bar histograms show the mean ± SEM. Experimental protocol figure created with BioRender.com, https://www.biorender.com/ (accessed on 8 May 2023).