Acoustics ; Animals ; Behavior, Animal ; radiation effects ; Conditioning (Psychology) ; Cytokines ; blood ; Male ; Microwaves ; Rats, Wistar

OBJECTIVETo study the correlation between EEG characteristics of medial prefrontal cortex (mPFC) and drug-seeking behavior of rats with morphine dependent place preference under shuttling condition.

METHODSForty rats were randomly divided into four groups (n = 10): morphine PL group, NS PL group, morphine IL group and NS IL group. After embeding the electrode in prelimbic (PL) or infralimbic (IL) cortex of each group by brain stereotaxic operation, the model of morphine dependent conditioned place preference (CPP) in rats was established. The differences of EEG wave percentage in mPFC were telemetered and analyzed when rats shuttled before and after the model.

RESULTSAfter the model, the withdrawal symptoms were evident in morphine PL and IL group, and the activity time and distance in white box were increased obviously. Compared with control group, after the model, the EEG in morphine PL group showed that: when the rats shuttled to white box, 8 wave decreased obviously, P wave increased obviously. When the rats shuttled to black box, brain waves showed opposite changes. The EEG in morphine IL group showed that: when the rats shuttled to white box, a wave increased obviously, P and a wave decreased obviously. When the rats shuttled to black box, the brain wave had no significant differences compared with control group.

CONCLUSIONThe EEG changes are different in PL and IL cortex of morphine CPP rats under shuttling condition, and the EEG changes are also different when rats shuttling to white or black box. There is possibly different mechanism, when different drug-seeking environmental cues caused EEG changes in different regions of mPFC.

Animals ; Conditioning (Psychology) ; Cues ; Drug-Seeking Behavior ; Electroencephalography ; Morphine Dependence ; physiopathology ; Prefrontal Cortex ; physiopathology ; Rats ; Telemetry

OBJECTIVEConditioned taste preference (CTP) is a taste learning reflex by which an animal learns to prefer a substance which tastes not well and has been studied with much interest in recent years. However, the neural substrates of CTP are less known. This study aimed to determine the possible neural path- ways of CTP and whether serum leptin level and the leptin receptor (OB-Rb) in the hind brain are involved following CTP formation.

METHODSWe established CTP of quinine in rats with a 2-bottle preference test. The serum leptin concentrations were detected, the expression of c-fos in the rat brain was tested to determine the nuclei in relation with establishment of CTR Finally, the OB-Rb mRNA expression was examined by RT-qPCR assay in parabrachial nucleus (PBN) and the nucleus of the solitary tract (NST) of the hind brain.

RESULTSCompared with control group, the level of serum leptin was higher in the CTP group (4.58 ± 0.52 vs 1.67 ± 0.25 µg/L, P < 0.01); increased c-fos positive cells were found in the anterior hypothalamus (AH, 221.75 ± 4.96 vs. 178.50 ± 6.63 cells/mm², P < 0.05), the basal lateral amygdala (BLA, 70.75 ± 6.17 vs 56.50 ± 3.62 cells/ mm², P < 0.05) and the nucleus of the solitary tract (NST, 41.25 ± 1.32 vs 32.50 ± 1.02 cells/mm², P < 0.05). But in ventromedial nucleus of the hypothalamus (VMH, 20.75 ± 2.73 vs 38.5 ± 1.54 per 1 mm², P < 005), PBN (21.50 ± 2.24 vs 36.25 ± 1.49 cells/mm², P < 0.05) and the central nucleus of the amygdala (CeA, 22.25 ± 1.53 vs 35.50 ± 2.11 cells/mm², P < 0.05), the number of c-fos positive cells was decreased in the CTP group. In addition, we found OB-Rb mRNA expression in PBN of CTP group rats was higher than that of control group (0.95 ± 0.055 vs 0.57 ± 0.034, P < 0.05), while there was no significant difference of OB-Rb mRNA expression in NST between the two groups.

CONCLUSIONNuclei AH, BLA, NST, VMH, PBN and CeA participate in the formation of CTP. Leptin and its receptor in PBN may be involved in the formation and maintenance of CTP.

Animals ; Conditioning (Psychology) ; Leptin ; blood ; Rats ; Receptors, Leptin ; physiology ; Rhombencephalon ; physiology ; Taste ; physiology

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 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

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

The purpose of the present study is to analyze the relationship between the telemetry electroencephalogram (EEG) changes of the prelimbic (PL) cortex and the drug-seeking behavior of morphine-induced conditioned place preference (CPP) rats by using the wavelet packet extraction and entropy measurement. The recording electrode was stereotactically implanted into the PL cortex of rats. The animals were then divided randomly into operation-only control and morphine-induced CPP groups, respectively. A CPP video system in combination with an EEG wireless telemetry device was used for recording EEG of PL cortex when the rats shuttled between black-white or white-black chambers. The telemetry recorded EEGs were analyzed by wavelet packet extraction, Welch power spectrum estimate, normalized amplitude and Shannon entropy algorithm. The results showed that, compared with operation-only control group, the left PL cortex's EEG of morphine-induced CPP group during black-white chamber shuttling exhibited the following changes: (1) the amplitude of average EEG for each frequency bands extracted by wavelet packet was reduced; (2) the Welch power intensity was increased significantly in 10-50 Hz EEG band (P < 0.01 or P < 0.05); (3) Shannon entropy was increased in β, γ₁, and γ₂waves of the EEG (P < 0.01 or P < 0.05); and (4) the average information entropy was reduced (P < 0.01). The results suggest that above mentioned EEG changes in morphine-induced CPP group rat may be related to animals' drug-seeking motivation and behavior launching.
Animals ; Conditioning (Psychology) ; Drug-Seeking Behavior ; Electroencephalography ; Entropy ; Morphine ; pharmacology ; Prefrontal Cortex ; drug effects ; Rats ; Telemetry ; Wavelet Analysis

The intense associative memories that develop between cocaine-paired contexts and rewarding stimuli make addiction hard to cure by contributing to cocaine seeking and relapse. So it's of great importance to examine the neurobiological basis of addiction memory. Cocaine conditioned place preference (CPP) used in this study is a form of Pavlovian conditioning which can establish associations between drug and contextual factors. c-Fos and Zif268 are commonly used immediate early gene (IEG) makers to identify neurons that are activated after a stimulus or behavioral conditioning. This study was designed to reveal neuronal c-Fos, Zif268 expression pattern in 10 brain regions following cocaine context-associated reward memory retrieval in mice, combining animal behavioral study and immunofluorescence method. C57BL/6 mice were randomly divided into 3 groups: Saline retrieval, Cocaine retrieval, and No retrieval of cocaine groups. Cocaine retrieval and No retrieval of cocaine underwent CPP training (one side paired with cocaine, and the other side with saline) except that No retrieval of cocaine group didn't undergo CPP test. Saline retrieval group received saline injections (i.p) on both sides. The results showed that: Neuronal c-Fos, Zif268 protein expression levels in nucleus accumbens (NAc) core both were elevated in Cocaine retrieval group compared with those in Saline retrieval (Control) group during cocaine context-associated reward memory retrieval. Zif268 protein expression level in basolateral amygdala (BLA) was also elevated in Cocaine retrieval group compared with that in control mice. Elevation was not seen in other regions such as hippocampus, prefrontal cortex (PFC). Thus, NAc core and BLA were activated during cocaine context-associated reward memory retrieval. The results suggest that neurons that are activated in NAc core and BLA are crucial basis of cocaine context-associated reward memory.
Animals ; Basolateral Nuclear Complex ; cytology ; Cocaine ; pharmacology ; Conditioning (Psychology) ; Early Growth Response Protein 1 ; metabolism ; Hippocampus ; Memory ; Mice ; Mice, Inbred C57BL ; Neurons ; metabolism ; Nucleus Accumbens ; metabolism ; Prefrontal Cortex ; Proto-Oncogene Proteins c-fos ; metabolism ; Reward

Amygdala ; drug effects ; metabolism ; Animals ; Conditioning (Psychology) ; Morphine ; adverse effects ; Rats ; Receptors, Opioid, kappa ; metabolism

OBJECTIVETo study and compare the effect of Corydalis yanhusuo and L-THP on dopamine neurotransmitter and D2 receptor of reward circuitry in various cerebral areas of conditioned place preference model rats and the comparison of their effects.

METHODThe CPP model was established by injecting morphine in rats with increasing doses for 10 days. The initial dose of 10 mg x kg(-1), and the final dose of 100 mg x kg(-1), with 10 mg x kg(-1) increased each day. At 48 h after the final training, CPP was adopted to detect the successful establishment of the model. On the same day (12 d), they were orally administered with 2, 1, 0.5 g x kg(-1) C. yanhusuo (containing 0.153, 0.077 and 0.038 mg L-THP) and L-THP (3.76, 1.88, 0.94 mg x kg(-1)) for six days. On 18 d, CPP test was performed again. Next day, HPLC was adopted to determine the content of dopamine neurotransmitters of reward circuitry in VTA-NAc-PFC; Immunohistochemistry and Western blotting were adopted to detect the expression of D2 receptors.

RESULTCompared with the physiological saline treatment group, C. yanhusuo (2, 1 g x kg(-1)) and L-THP (3.76, 1.88 mg x kg(-1)) groups showed that rats stayed in a notably shorter period in white boxes (morphine-accompanied boxes) (P < 0.01 or P < 0.05), and revealed a remarkably lower dopamine content in VTA, NAc and PFC and the significant increase in the expression of D2 receptor (P < 0.01 or P < 0.05).

CONCLUSIONThe down-regulation of the increased dopamine content in reward nervous circuitry and the up-regulation of the expression of D2 receptor may be one of mechanisms of C. yanhusuo and L-THP in accelerating the recession of morphine's CPP effect Regarding the inhibition of morphine's CPP effect and the effect on dopamine system, the effect of C. yanhusuo traditional Chinese medicine containing one-fold L-THP monomer is equal to that of the independent application of around 24-fold L-THP monomer.

Animals ; Berberine Alkaloids ; administration & dosage ; Brain ; drug effects ; metabolism ; physiopathology ; Conditioning, Operant ; drug effects ; Corydalis ; chemistry ; Dopamine ; metabolism ; Humans ; Male ; Morphine ; adverse effects ; Plant Extracts ; administration & dosage ; Rats ; Rats, Sprague-Dawley ; Receptors, Dopamine D2 ; genetics ; metabolism ; Substance-Related Disorders ; drug therapy ; genetics ; metabolism ; psychology