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. Author manuscript; available in PMC: 2016 Sep 1.
Published in final edited form as: Cell Signal. 2015 Jun 5;27(9):1799–1806. doi: 10.1016/j.cellsig.2015.05.019

FIGURE 1.

FIGURE 1

JNK2 is Required for Hotplate Analgesic Tolerance to Morphine. A, Animals were treated with 20mg/kg morphine or saline as a control for 3 days to induce tolerance. On Day 1 and Day 3 all mice were challenged with 10mg/kg morphine 4 hr after their morning dose and tested on a 55°C hot plate pre and post 10mg/kg injection to assess analgesia, which was measured as the latency for hind paw withdrawal/flicks. Animals did not show robust analgesic tolerance on Day 1 (data not shown). B, WT animals pretreated with saline show a robust analgesic response to morphine (10mg/kg) (as indicated by an increased latency to withdraw) on Day 3 whereas animals pretreated with morphine (20mg/kg) do not. JNK2−/− animals show robust analgesia, as indicated by an increased latency to withdraw, to morphine regardless of pretreatment with saline or morphine, demonstrating that JNK2 is required for morphine analgesic tolerance on the hotplate. Data presented were calculated as the response latency 30 min post drug administration minus baseline withdrawal latency resulting in the post-pre value presented. Baseline responses did not vary across groups (data summarized in text). n=10–18; Data analyzed by two-way ANOVA with Bonferroni posttest.