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. Author manuscript; available in PMC: 2019 Dec 1.
Published in final edited form as: Pain. 2018 Dec;159(12):2512–2521. doi: 10.1097/j.pain.0000000000001355

Figure 3. Morphine administration in the RVM but not the ACC reverses mechanical hyperalgesia in SNL rats.

Figure 3.

Noxious mechanical withdrawal thresholds of the ipsilateral hindpaws were measured using the Randall-Selitto test before surgery (PRE), post-surgery at baseline (Time=0) and during a 90 min time course after brain microinjections. All SNL groups developed mechanical hyperalgesia #P<0.0001 (unpaired t-test). (A) Morphine (20 μg/0.5 μl) or saline into the ACC site 1 of SNL and sham rats had no effect (N=8–13) on paw withdrawal thresholds. (B) Morphine (20 μg/0.5 μl) or saline into the ACC site 2 had no effect (N=9–18). (C) Morphine (20 μg/0.5 μl) or saline into the ACC site 3 had no effect (N=7–12). (D) Compared to saline, microinjection of morphine (10 μg/0.5 μl) into the RVM significantly increased paw withdrawal thresholds in both SNL (N=8; *P<0.05) and sham (N=8; +P<0.05) rats. (2-way ANOVA with Tukey’s post hoc test). Data are means ± SEM.