吗啡依赖位置偏爱大鼠穿梭状态下内侧前额皮层的脑电特征

EEG characteristics of medial prefrontal cortex in rats with morphine dependent place preference under shuttling condition

目的:研究吗啡依赖位置偏爱大鼠穿梭状态下内侧前额皮层(m PFC)脑电特征与觅药行为的相关性。方法:将40只大鼠随机分为4组(n=10):吗啡PL组、盐水PL组、吗啡IL组、盐水IL组。采用脑立体定位术在各组大鼠m PFC的边缘前区(PL区)或边缘下区(IL区)埋置电极,建立吗啡依赖条件性位置偏爱(CPP)大鼠模型,遥测分析各组大鼠建模前后穿梭时m PFC脑电各波百分比的差异。结果:吗啡PL组和IL组大鼠建模后戒断症状明显,在白箱活动时间和路程明显增加。吗啡PL组大鼠建模后与对照组相比,向白箱穿梭时,脑电δ波比例明显减少,β波比例明显增加;向黑箱穿梭时,上述脑波出现相反的改变。吗啡IL组大鼠建模后与对照组比较,向白箱穿梭时,脑电δ波比例明显增加,β波及α波比例明显减少;向黑箱穿梭时,各脑波比例与对照组相比无明显差异。结论:吗啡CPP大鼠穿梭状态下m PFC的PL区和IL区脑电改变不同,且向伴药箱穿梭与非伴药箱穿梭发生的脑电变化也不同,提示不同觅药环境线索在m PFC不同脑区产生的脑电改变可能存在不同机制。

Objective： To 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. Methods： Forty 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. Results： After 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, δ wave decreased obviously, β 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, δ wave increased obviously, β and α wave decreased obviously. When the rats shuttled to black box, the brain wave had no significant differences compared with control group. Conclusion： The 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.