OBJECTIVETo study the correlation between EEG characteristics of medial prefrontal cortex (mPFC) and drug-seeking behavior of rats with morphine dependent place preference under shuttling condition.

METHODSForty rats were randomly divided into four groups (n = 10): morphine PL group, NS PL group, morphine IL group and NS IL group. After embeding the electrode in prelimbic (PL) or infralimbic (IL) cortex of each group by brain stereotaxic operation, the model of morphine dependent conditioned place preference (CPP) in rats was established. The differences of EEG wave percentage in mPFC were telemetered and analyzed when rats shuttled before and after the model.

RESULTSAfter the model, the withdrawal symptoms were evident in morphine PL and IL group, and the activity time and distance in white box were increased obviously. Compared with control group, after the model, the EEG in morphine PL group showed that: when the rats shuttled to white box, 8 wave decreased obviously, P wave increased obviously. When the rats shuttled to black box, brain waves showed opposite changes. The EEG in morphine IL group showed that: when the rats shuttled to white box, a wave increased obviously, P and a wave decreased obviously. When the rats shuttled to black box, the brain wave had no significant differences compared with control group.

CONCLUSIONThe EEG changes are different in PL and IL cortex of morphine CPP rats under shuttling condition, and the EEG changes are also different when rats shuttling to white or black box. There is possibly different mechanism, when different drug-seeking environmental cues caused EEG changes in different regions of mPFC.