80 Hz电刺激伏隔核对吗啡诱导的大鼠条件性位置偏爱行为形成的影响

80 Hz electrical stimulus to nucleus accumbens influencing the formation of conditioned place preference induced by morphine in rats

目的探讨80Hz电刺激伏隔核对吗啡诱导的大鼠条件性位置偏爱形成的影响。方法雄性SD大鼠30只,随机分为吗啡-刺激组、吗啡-假刺激组、正常对照组,每组各10只。3组大鼠分别在不同条件下进行条件性位置偏爱实验,其中吗啡-刺激组、吗啡-假刺激组分别进行预测试、手术、训练、刺激、测试5个阶段实验,正常对照组进行预测试、手术、训练、测试4个阶段实验;在训练阶段,吗啡-刺激组和吗啡-假刺激组每天交替注射吗啡和生理盐水各1次,正常对照组每天注射2次生理盐水;在刺激阶段,吗啡-刺激组采用80Hz电刺激伏隔核,吗啡-假刺激组不刺激伏隔核。分别记录预测试和测试阶段3组大鼠在白箱内平均停留时间,并给予比较。结果吗啡-假刺激组训练后,在白箱内平均停留时间明显长于训练前和同期的正常对照组(P<0.01),吗啡诱导的心理依赖模型建立成功。吗啡-刺激组在伏隔核刺激条件下完成条件性位置偏爱训练后,在白箱停留时间长于吗啡-假刺激组(P<0.01),表明电刺激伏隔核显著强化了大鼠的觅药行为。结论80Hz电刺激大鼠双侧伏隔核可明显地促进吗啡诱导的位置偏爱行为的形成,表明该频率电刺激可强化吗啡诱导的心理依赖。

Objective：To investigate the influence of 80 Hz electrical stimulus to nucleus accumbens （NAc） on the formation of conditioned place preference （CPP） induced by morphine in rats. Methods： Thirty male SD rats were evenly randomized into 3 groups： the morphine stimulation group, morphine-fake stimulation group, and normal control group. The CPP test was carried out under different situations in 3 groups. Five steps were included in the morphine stimulation and morphine-fake stimulation groups, namely, the pre-test, surgery, training, stimulation or fake stimulation, and test steps. Four steps were included in the control group, namely, the pre-test, surgery, training, and test steps. During the training step, rats in morphine stimulation group and morphine-fake stimulation were respectively injected with morphine and normal saline by turns everyday, and those in normal control group were injected with normal saline twice a day. During the stimulation step, 80 Hz electrical stimulus was applied to the NAc in the morphine stimulation group and the fake-stimulation group received no stimulation. The average stay periods in the white case during the period of pre-test and test were recorded and compared in the 3 groups. Results： The average stay in the white case of morphine-fake stimulation group was longer than that before training and that of the saline control group at the same step （P〈0.01）, suggesting that the model of morphine-induced psychological dependence was successfully established. The average stay of morphine stimulation group was longer than that of morphine-fake stimulation group （P〈0.01）, indicating that the electrical simulation greatly enhanced the drug-seeking behaviors of rats. Conclusion： 80 Hz electrical stimulation of bilateral NAc can obviously promote the formation of morphine-induced CPP behaviors in rats, indi- cating that the morphine-induced psychological dependence is strengthened under 80 Hz electrical stimulus.