OBJECTIVETo analyse the relationship between the electrical activity changes of nucleus accumbens (NAc) shell and the drug-seeking behavior by recording NAc shell electrical activity in conditioned place preference (CPP) rats induced by morphine.

METHODSForty SD rats were randomly divided into operation-only control group and the morphine-induced CPP group after stereotaxic electrode was buried on rats NAc shell and the latter group was used to establish the morphine CPP model(n = 20). A CPP video system combining with the technique of electrical activity wireless telemetry was used in the study. The NAc electrical activity from each group of rats was recorded by wireless telemetry respectively, which included staying in black or white chamber of video box, shuttling between black-white chambers and between white-black chambers. The electrical activity differences were analyzed by the percentage of each wave.

RESULTSWhen the morphine-induced rats staying in black chamber, compared with the operation-only control group, the NAc shell electrical activity showed that the percentage of 0 - 10 Hz was increased(P < 0.05), meanwhile, those of 10 - 20 Hz and 30 - 40 Hz were reduced(P < 0.05, P < 0.01); when the morphine-induced rats staying in white chamber, the NAc shell electrical activity showed that the percentage of 0 - 10 Hz and 30 - 40 Hz were increased(P < 0.05 , P < 0.01) , that of 10 - 20 Hz was reduced(P < 0.05 , P < 0. 01); when the morphine-induced rats in black- white shuttling status, the NAc shell electrical activity showed that the percentage of 0 - 10 Hz was increased(P <0.05, P <0.01), that of 10- 30 Hz was reduced( P <0.05); and in the white-black shuttling status, the electrical activity showed that the percentage of 0 - 10 Hz was reduced(P <0.05), that of 10 - 30 Hz was increased(P < 0.05) ; the electrical activity was further compared between staying status and shuttling status in the morphine-induced CPP group. There was no significant difference of electrical activity between the rats in white-black shuttling status and staying in white chamber. However, when rats in black-white shuttling status, compared with staying in black chamber, the electrical activity showed that the percentage of 0 - 10 Hz and 40 - 50 Hz were increased(P < 0.05), meanwhile, those of 10 - 20 Hz and 30 - 40 Hz were reduced(P <0.05).

CONCLUSIONThe electrical activity changes of NAc shell in morphine-induced CPP rats were different from those of the operation-only control group, and these changes might be associated to the rat's drug-seeking behavior.