Fig. 2.

Effects of intra-nucleus accumbens shell (NASh) microinjections of SKF 82958 on place conditioning in morphine-dependent (black bars) and nondependent (gray bars) rats. Rats with bilateral cannulae in the NASh or just dorsal to the NASh were implanted with placebo or morphine pellets and, 3 days later, underwent place conditioning with systemic naloxone (0.01 mg/kg, SC), intracranial SKF 82958 (1 μg/side, intra-NASh or dorsal control), or a combination of intracranial SKF 82958 and systemic naloxone. Data from bilateral microinjections of SKF 82958 into dorsal control regions are shown to the right of the dashed line. Data are expressed as the change in time spent in the drug-paired side after conditioning minus the time spent in the drug-paired side before conditioning (means+SEM). Significant changes in time spent in the drug-paired chamber after conditioning compared to before conditioning are: *p< 0.05, **p<0.01, Fisher’s protected t tests, 7–21 rats per group. Nal naloxone, SKF SKF 82958, Veh vehicle, m morphine, p placebo