Bin Wang, Fei Luo, Ying-Qiu Xia and Ji-Sheng HanCA
Neuroscience Research Institute, Beijing Medical University, 38 Xueyuan Road, Beijing 100083, P.R. China
CACorresponding Author
Received 14 December 1999; accepted 25 January 2000
Acknowledgements: The authors want to thank Professor Nan Sui and Dr Jing Chen from the Institute of Psychology, Chinese
Academy of Science, for their constructive advice on the establishment of the animal model, and generous supply of the apparatus for electric foot shock.
Conditioned place preference (CPP) is a commonly used model to detect rewarding effect of drugs. To observe the effect of peripheral electric stimulation (PES) on morphine-induced CPP, we trained the rats with morphine in a CPP paradigm. Twelve hours before the testing phase, rats were given PES via stainless-steel needles with frequencies of 2, 100, or 2/100 Hz, respectively. PES of 2 and 2/100 Hz signi®cantly decreased CPP in morphine-trained animals in a naloxone reversible manner, while PES of 100 Hz, foot shock, needle insertion, or plain restraining, showed no effect. Thus, PES with a low-frequency component (2 Hz) could speci®cally inhibit the expression of morphine-induced CPP, presumably via activation of opioid
receptors. NeuroReport 11:1017±1020 & 2000 Lippincott Williams & Wilkins.
Key words: Acupuncture; Conditioned place preference; Frequency dependence; Morphine; Opioid; Opioid addiction; Peripheral electric stimulation; Psychological dependence; Rewarding effect
