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. 2013 Sep 12;8(9):e74706. doi: 10.1371/journal.pone.0074706

Figure 4. Conditional mu-cKO and control mice show comparable systemic morphine analgesia in nociceptive assays.

Figure 4

Top. Morphine induced dose-dependent antinociception in both mu-cKO and mufl mice in the three heat assays, (A) tail immersion, (B) tail flick and (C) hot plate. Morphine-induced analgesia was abolished in conventional mu-KO animals (tail immersion, n=10/genotype; tail flick, n=10-14/genotype; hot plate, n=6-17/ genotype), confirming the selective effect of morphine on mu receptor. Bottom. Mu-cKO and mufl control mice show similar systemic morphine analgesia in the tail pressure (n=9-13/genotype) and acetic acid-induced visceral nociceptive (n=13-14/genotype) assays. Two-way ANOVA, post-hoc Fisher test for individual time points, ✰ P <0.05, ✰✰ P<0.01, ✰✰✰ P<0.001, morphine vs saline.