Animals ; Conditioning (Psychology) ; drug effects ; Extinction, Psychological ; drug effects ; physiology ; Fear ; drug effects ; physiology ; Male ; Mifepristone ; pharmacology ; Rats ; Rats, Sprague-Dawley

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.

Animals ; Conditioning (Psychology) ; Drug-Seeking Behavior ; Morphine ; pharmacology ; Nucleus Accumbens ; drug effects ; physiology ; Rats ; Rats, Sprague-Dawley ; Telemetry

To explore the relationship between the drug-seeking behavior, motivation of conditioned place preference (CPP) rats and the frontal association cortex (FrA) electroencephalogram (EEG) sample entropy, we in this paper present our studies on the FrA EEG sample entropy of control group rats and CPP group rats, respectively. We invested different behavior in four situations of the rat activities, i. e. rats were staying in black chamber of videoed boxes, those staying in white chamber of videoed boxes, those shuttling between black-white chambers and those shuttling between white-black chambers. The experimental results showed that, compared with the control group rats, the FrA EEG sample entropy of CPP rats staying in black chamber of video box and shuttling between white-black chambers had no significant difference. However, sample entropy is significantly smaller (P < 0.01) when heroin-induced group rats stayed in white chamber of video box and shuttled between black-white chambers. Consequently, the drug-seeking behavior and motivation of CPP rats correlated closely with the EEG sample entropy changes.
Animals ; Conditioning (Psychology) ; drug effects ; Drug-Seeking Behavior ; Electroencephalography ; Entropy ; Frontal Lobe ; drug effects ; physiology ; Heroin ; pharmacology ; Rats ; Rats, Sprague-Dawley

OBJECTIVETo establish the computer-based video-tracking conditioned place preference (CPP) system in mice.

METHODSThe CPP system was composed of computer, camera, soundproof box, shuttle box and analytical software. The results of morphine-induced conditioned place preference were used to evaluate the experiment system. And the effect of morphine-induced locomotor activity in drug-paired compartment was studied in mice.

RESULTSLow (1 mg/kg, i.p.), moderate (3 mg/kg, 5 mg/kg, i.p.) and high (10 mg/kg, i.p.) dose of morphine significantly prolonged the time mice spent in drug-paired compartment compared with saline, but there was no dose-response relation. Moderate and high dose of morphine significantly enhanced locomotor activity, among which 5 mg/kg and 10 mg/kg morphine induced behavior sensitization in drug-paired compartment during the conditioning sessions.

CONCLUSIONThe computer-based video-tracking conditioned place preference experiment system in mice established successfully is reliable and stable.

Animals ; Automatic Data Processing ; Conditioning (Psychology) ; drug effects ; physiology ; Male ; Mice ; Mice, Inbred ICR ; Models, Animal ; Morphine ; pharmacology ; Motor Activity ; drug effects ; Narcotics ; pharmacology ; Opioid-Related Disorders ; physiopathology ; psychology ; Video Recording

OBJECTIVETo study the effect of glycine site/NMDA (N-methyl-D-aspartate) receptor antagonist MRZ2/576 on the conditioned place preference (CPP) and locomotor activity induced by morphine in mice.

METHODSDifferent doses (1.25, 2.5 and 5 mg/kg, i.p.) of MRZ2/576 were used to evaluate the effect of MRZ2/576 on the acquisition and expression of CPP induced by morphine (5 mg/kg) in mice. In addition, we examined the locomotor activity of mice in conditioning and testing phase of CPP paradigm.

RESULTSMRZ2/576 alone could not establish place preference, but a 5 mg/kg dose of MRZ2/576 could block both acquisition and expression of morphine-induced CPP. In testing phase of CPP, there was no statistical difference for locomotor activity between the groups; injection of MRZ2/576 showed a dose-dependent decrease of locomotor activity on both control and morphine-treated mice, especially 5 mg/kg of MRZ2/576 significantly suppressed the locomotor activity of mice.

CONCLUSIONBased on the present results, we assume that MRZ2/576 can antagonize the rewarding effect of morphine, suggesting that this glycine site/NMDA receptor antagonist could be used to treat addictions due to its light side effect profile.

Animals ; Conditioning (Psychology) ; drug effects ; Excitatory Amino Acid Antagonists ; pharmacology ; Magnesium ; physiology ; Male ; Mice ; Mice, Inbred ICR ; Morphine ; pharmacology ; Motor Activity ; drug effects ; Phthalazines ; pharmacology ; Receptors, N-Methyl-D-Aspartate ; antagonists & inhibitors

LiCl at doses sufficient to induce conditioned taste aversion (CTA) causes c-Fos expression in the brain regions implicated in CTA formation. It has been reported that nitric oxide (NO) may play a role in CTA learning and LiCl increases both the synthesis and activity of NO synthase (NOS) in the brain. In this study, we examined the effect of central N omega-nitro-L- arginine methyl ester (L-NAME) on the brain c-Fos expression and CTA learning induced by lithium in rats. In the results, intracerebroventricular L-NAME given prior to lithium did not change either the lithium-induced CTA or c-Fos in the relevant brain regions. This suggests that the brain NO system may not be involved in the neuronal activation during lithium-induced CTA formation.
Animals ; Avoidance Learning/*drug effects/physiology ; Brain/*physiology ; Conditioning (Psychology) /*drug effects/physiology ; Immunohistochemistry ; Injections, Intraventricular ; Lithium/*pharmacology ; Male ; NG-Nitroarginine Methyl Ester/*pharmacology ; Nitric Oxide/physiology ; Proto-Oncogene Proteins c-fos/*analysis ; Rats ; Rats, Sprague-Dawley ; Support, Non-U.S. Gov't ; Taste/*drug effects/physiology