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. Author manuscript; available in PMC: 2018 Jan 11.
Published in final edited form as: J Neurosci. 2005 Mar 23;25(12):3229–3233. doi: 10.1523/JNEUROSCI.0332-05.2005

Figure 1.

Figure 1

Dose–response effect of morphine- and naltrexone-induced analgesia in WT and KI animals after chronic placebo, morphine, or naltrexone treatment. WT (A) or KI (B, C) animals were implanted with a placebo, morphine,or naltrexone pellet for 72 h, and morphine-induced (A, B) or naltrexone-induced (C) analgesia was measured by the tail-withdrawal test 8 h after pellet withdrawal. There is a significant difference between the placebo-treated and the morphine-treated group in all three experiments. *p < 0.05, significant difference from the placebo-treated group (Student’s t test). Each dose was tested on at least 8–10 animals. % MPE, Percentage of maximum possible effect. Error bars represent SEM.