Figure 4.

The dynorphin/κ-opioid system mediates the aversive properties of CRF. A, Schematic showing the conditioning paradigm used to assess aversion. B, CPA scores (drug compartment posttest minus pretest) showed that mice injected with saline in both compartments did not develop aversion (gray bar, left) and that norBNI (10 mg/kg, i.p.; white bars) with saline did not affect place preference. CRF (1 μg, i.c.v.) injection induced significant CPA (gray bar, right) that was blocked by norBNI pretreatment (white bar). *p < 0.05, significantly different from other groups at (n = 9–16 animals per group). C, CRF (1 μg, i.c.v.) produced significant CPA in wild-type Pdyn (+/+) mice but not in Pdyn(−/−) littermates. *p < 0.05, significantly different from Pdyn(−/−); n = 5–8 animals per group.