Figure 4.

Repeated propranolol treatment causes a long-lasting disruption in the retrieval of a conditioned place preference (CPP). (a) All rats expressed a CPP for the previously cocaine-paired chamber over the previously saline-paired chamber during the first CPP trial. Propranolol but not saline injections (arrows) before the second, third, and fourth CPP trials prevented the rats from expressing a CPP during those trials and a subsequent propranolol-free CPP trial. (b) Propranolol but not saline treatment resulted in a lack of expression of a CPP during a CPP trial 14 days later. Prop, propranolol. ^***p<0.001, ^**p<0.01, and ^*p<0.05.