Figure 3.
Inhibition of PKMζ activity by ZIP injections into nucleus accumbens core after the first CPP test blocks the subsequent expression of morphine CPP. A, Timeline of the experimental procedure. B, C, Effect of bilateral vehicle or ZIP (30 nmol/side) injections that were given 1 d after a drug-free morphine CPP test (day 9). CPP was assessed in drug-free rats 1, 7, and 14 d after ZIP or vehicle injections. During CPP training, rats learned to associate the effects of morphine injections (10 mg/kg, s.c.) with one environmental context and the effects of saline injections with a different context. Data are mean ± SEM of preference score in seconds (time spent in the morphine-paired chamber minus time spent in the saline-paired chamber) during the CPP tests. *Different from vehicle, p < 0.05; n = 9–10 per experimental condition.