FIGURE 7.

Evaluation of potential rewarding or aversive properties of cyclo[Pro‐Sar‐Phe‐d‐Phe]. cyclo[Pro‐Sar‐Phe‐d‐Phe] alone did not produce conditioned place preference or aversion. After determination of initial preconditioning preferences, C57BL/6J mice were place conditioned daily for 2 days with 0.9% saline (i.c.v.), morphine (30 nmol, i.c.v.), U50,488 (100 nmol, i.c.v.), or cyclo[Pro‐Sar‐Phe‐d‐Phe] (0.1–10 nmol, i.c.v.) with a counterbalanced design as described in Section 2. Data are presented as mean difference in time spent in the drug‐paired chamber ± SEM (n = 16–28). P < .05, significantly different from matching preconditioning preference; two‐way ANOVA with Sidak's multiple comparison post hoc test. Data from 109 animals are shown in this figure