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. Author manuscript; available in PMC: 2008 Mar 18.
Published in final edited form as: Behav Neurosci. 2006 Feb;120(1):10–15. doi: 10.1037/0735-7044.120.1.10

Figure 1.

Figure 1

Morphine-induced conditioned place preference was not altered in preproenkephalin knockout mice. Mice were tested for baseline (preconditioning) preference on Day 1 (upper panel), received conditioning sessions on Days 2−9, and were tested for postconditioning preference on Day 10 (lower panel). Data reported are the means (± SEM, indicated by the vertical lines) of six mice per treatment per genotype. VPCH = vehicle-paired chamber; NCH = neutral chamber; DPCH = drug-paired chamber; PENK +/+ = wild type mice; PENK −/− = knockout mice.