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. Author manuscript; available in PMC: 2011 Aug 22.
Published in final edited form as: Brain Res. 2007 Jan 13;1142:28–36. doi: 10.1016/j.brainres.2007.01.028

Figure 3. Morphine antinociception in opioid-naïve and morphine tolerant P17 rats tested in the 49 °C tail-immersion assay.

Figure 3

Rats were infused with isotonic saline (■, 1 μl/h) or morphine (▲, 2 mg/kg/h) for 72-h from implanted osmotic minipumps. Baseline latencies were then obtained in the 49 °C tail-immersion test before treatment with morphine s.c. for test latencies for dose-response curves 30-min later. The antinocicpetive effect of morphine was reduced in the morphine-infused rats to 67% MPE at the highest dose tested. n=6 rats per dose per treatment group.