The effect of low and high freqency electroacupuncture (EA) on the cocaine cravi ng was evaluated based on conditioned place preference (CPP) paradigm. Drug ind uced CPP in animals has been considered as a model of drug craving. In the prese nt experiments, rats were trained with an injection (i.p.) of different doses of cocaine under a "biased" CPP schedule and preference scores (PSs) were recorde d on the test session and used as the indicator of preference. 2 and 100 Hz of E A were given respectively before testing, with treatment of foot shock, needle i nsertion, restriction in the holder and no treatment being as the different kind s of control. The timecourse of the effect of EA on 5 mg/kg cocaine induced CPP was also observed. The results showed: ① The PSs after saline (0.27±0.08,n=12) and 0.5 mg/kg of cocaine (0 .26±0.10, n=12) conditioning had no difference from that of natural preference (0.38±0.12, n=12) (P>0.05), while the PSs of 1 ( 0.65±0.12, n=12), 5 (0.70± 0.09, n=12) and 10 mg/kg (0. 71± 0.09, n=12) of cocaine conditioning were significantly higher than tha t of natural preference (P<0.001), indicating that the 1 mg/kg and hig her doses of cocaine can induce significant place preference, which represents c ocaine craving. ② The PSs of 0.5 mg/kg of cocaine conditioning were similar wit h each other (P>0.05, compared with initial expression of CPP) when tes ting daily for at least 10 consecutive days, indicating that the cocaine craving is maintained for a long time once acquired. ③ 100 Hz EA significantly decreas ed the PSs of cocaine conditioning (P<0.05, compared with control grou p), while the treatment of 2 Hz of EA and all other kinds of control we used did n’t (P>0.05). ④ 100 Hz EA inhibited cocaine induced CPP when tested 10, 24 and 48 hours after stimulation. The results of the present study suggest that EA inhibits the cocaine craving in a frequency specific way and the effect of one treatment of EA maintains at least 48 hours.
