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.[著者文摘]