[Identification of the status of individual drug-administration behavior in heroin-withdrawal rats based on FrA EEG].

Objective: To identify the compulsive drug-seeking behavior of the individual in the heroin-addicted rat, a novel analysis method of telemetering electroencephalogram (EEG) in the frontal association cortex (FrA) induced by heroin-dependent position preference in rats. Methods: Thirty clean-grade Wistar rats after implantation of prefrontal cortex electrodes, were randomly divided into the surgical control group (n=10) and heroin-inducing group (n=20). The heroin-induced group was subcutaneously injected with heroin 0.5 mg/(kg.d), and then increased daily by 0.25 mg/kg for seven days. The control group was injected with the same amount of normal saline at the same time. Using the CPP video system combined with electroencephalogram (EEG) wireless telemetry technology, EEG signals in FrA areas of the addicted rats were recorded simultaneously in four behaviors: white-black shuttle, black-white shuttle, black-chamber stay and white-chamber stay. The areas with EMG and other noisy signals in the original EEG were identified, and wavelet decomposition and amplitude threshold denoising pre-processing were used. The sample entropy values of EEG data and wavelet coefficients corresponding to 4 rhythm frequencies under different behavioral states standard deviation were extracted, and support vector machine algorithm (SVM) was used to achieve real-time identification of different behavioral states of heroin-addicted rats. Results: SVM real-time classification recognition rate of 20 heroin abstinence rats, which are staying in black or white chamber of video box, shuttling between black-white chambers or between white - black chambers, was about 80%. Among them, the real-time recognition rate of black-white shuttle, which is closely related to drug-seeking behavior, reached 83.88%. Conclusion: In this paper, the real-time identification method of heroin-induced obsessive-compulsive drug-seeking behavior in rats can be used as an effective method to detect the initiation and occurrence of heroin-seeking drug-seeking behavior in rats. It can be used for the clinical observation of heroin-dependent patients and the prevention of drug-seeking behavior.

[EEG characteristics of medial prefrontal cortex in rats with morphine dependent place preference under shuttling condition].

OBJECTIVE: To 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. METHODS: Forty 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. RESULTS: After 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. CONCLUSION: The 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.

[The changes of electric shock avoidance response and local field potentials on hippocampal CA3 region of the adolescent rats with high fat feeding].

OBJECTIVE: To investigate the changes of shock avoidance response in Y maze and the real-time local field potentials (LFPs) on hippocampal CA3 region in adolescent rats with high fat feeding. METHODS: The juvenile rats of weaning 1 week were fed separately on basic feed (BF) and high fat diet (HFD) for 4 weeks until the puberty. Using the electric shock avoidance training method, the relevant parameters of reaching the learning standard of two groups of rats were recorded, and the LFPs of CA3 region in hippocampus were explored simultaneously by wireless telemetry. RESULTS: Compared with the BF group, the body weight of HFD rats were increased significantly(P<0.05), the rats percentage of reaching the learning standard within 1 to 2 days and the various parameters of shock avoidance recorded in training were all superior to those of BF group rat,the LFP rhythm of bilateral hippocampal CA3 region appeared to the desynchronizd fast wave. The θ and γ1 rhythms of right hippocampal CA3 region shown synchronous increase, but there was no coupling formation in phase-amplitude of the θ and γ1 rhythms. CONCLUSIONS: From juvenile to adolescent with HFD intake, the adolescent rat gained an increase significantly in weight,but the ability of shock avoidance and the function of hippocampus-dependent spatial cognition in Y maze had not be expected decline.

[Changes of theta oscillation of prelimbic cortex in heroin-induced CPP rats].

OBJECTIVE: To investigate the relationship between the changes of neural oscillations and the drug-seeking motivation,record the telemetric local field potentials (LFPs) of the prelimbic cortex (PrL) in the latency of drug-seeking behavior of conditioned place preference (CPP) rats induced by heroin. METHODS: The recording electrode was stereotactically implanted intothe PrL cortex of rats. The animals were then randomly divided into operation-only control and heroin-induced CPP groups, respectively. A CPP video system in combination with awireless telemetry device was used for recording LFPs when the rats shuttled between black-white chamber for drug-seeking. The LFPs were analyzed by fast Fourier transform (FFT) and wavelet packet extraction. RESULTS: Compared with operation-only control group, the LFPs recorded in PrL area of heroin-induced CPP group of rat during black-white chamber shuttling showed that the percentage of θ rhythm were increased in right and left PrL, the percentage of γ3 rhythm was increased in left PrL, the phase-amplitude coupling of θ and γ3 was increased in left PrL. After MK-801 Maleate micro injection to PrL area,drug-seeking behavior of rat was markedly reduced and the percentage of θ oscillation was depressed,the phase-amplitude coupling of θ and γ3 was depressed in left PrL compared with operation-only control group. CONCLUSIONS: These results suggest that increase of θ oscillations of PrL area may be related to the drug-seeking motivation and behavior launching in heroin-induced CPP groups of rat. The changes of θ oscillations also have close relationship with glutamatergic neuron and the receptor of it on PrL area.

[Alteration of neural oscillations in hippocampal CA3 area in the fast avoidance response rat before and after electric shock avoidance training].

The purpose of the present study is to explore the relationship of spatial learning ability and specific electrical activities of neural oscillations in the rat. The fast and general avoidance response groups were selected on the basis of the animals' responses to the electric shock in Y type maze, and their local field potentials (LFPs) of hippocampal CA3 area were recorded by wireless telemetry before and after shock avoidance training, respectively. The components of neural oscillations related to spatial identifying and learning ability were analyzed. The results showed that, compared with the general avoidance response group, the fast avoidance response group did not show any differences of LFPs in hippocampal CA3 area before electric shock avoidance trial, but showed significantly increased percentages of 0-10 Hz and 30-40 Hz rhythm in right hippocampal CA3 area after the shock avoidance training (P < 0.01 or P < 0.05). Fast Fourier transform showed that percentage increase of 0-10 Hz band occurred mainly in θ (3-7 Hz) frequency, and 30-40 Hz frequency change was equivalent to the γ1 band. Furthermore, compared with those before training, only the percentages of ß, ß2 (20-30 Hz) and γ1 rhythm increased (P < 0.01 or P < 0.05) in fast avoidance response rats after training, while the θ rhythm percentage remained unchanged. In contrast, θ rhythm percentage and the large amplitude (intensity: +2.5 - -2.5 db) θ waves in right CA3 area of general avoidance response rats were significantly reduced after training (P < 0.01). These results suggest that the increased percentages of ß2 and γ1 rhythm and high-level (unchanged) percentage of θ rhythm in the right hippocampus CA3 area might be related to strong spatial cognition ability of fast avoidance response rats.

[Wireless telemetry electrical activity of nucleus accumbens shell in morphine-induced CPP rats].

OBJECTIVE: To 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. METHODS: Forty 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. RESULTS: When 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). CONCLUSION: The 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.

[Wavelet packet extraction and entropy analysis of telemetry EEG from the prelimbic cortex of medial prefrontal cortex in morphine-induced CPP rats].

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 ß, 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.

[A wireless telemetry study on the electrical activity in nucleus accumbens of heroin-induced place preference rats].

OBJECTIVE: To analyze the electrical activity property changes in nucleus accumbens (NAc) of heroin-induced conditioned place preference (CPP) rats during different stages of heroin dependence and to explore NAc's roles in the formation of drug dependence. METHODS: Recording electrodes were bilaterally embedded into the NAcs of rats with the aid of stereotaxic apparatus, followed by establishment of heroin-dependent rat model. The NAc electrical activity during 3 different stages of heroin dependence, including heroin pre-exposure, immediate post-exposure and heroin withdrawal, were respectively recorded using EEG wireless telemetry techniques. The frequency distribution (ranging from 0.5 to 30 Hz) and the amplitude of NAc electrical activity were analyzed and measured. RESULTS: Heroin-dependent rat models were successfully established and their withdrawal symptoms were evident. All rats showed a conditioned place preference (CPP) for the white box after 5-10 days of heroin-exposure, and displayed a maximum withdrawal symptoms on 2d after heroin- withdrawal. During all statges of heroin-dependence, the NAc electrical activity contained the highest proportion of delta rhythm and the lowest proportion of alpha2 rhythm. The discharge frequence band was similar across different stages. There was a significantly increased ratio of low-frequency discharges (delta rhythm) and decreased ratio of high-frequency discharges (beta rhythm) in NAc of rats during the immediate post- heroin exposure stage when compared with that during pre-exposure and heroin withdrawal stages. During the withdrawal stage, the ratio of at rhythm was significantly lower than during pre- and post-heroin exposure stages (P < 0.01). Further, the mean discharge amplitude in NAcs during immediate post-exposure and withdrawal stages was significantly increased relative to pre-exposure stage. However, the mean discharge amplitude during heroin withdrawal stage was significantly lower than during immediate post-exposure stage. CONCLUSION: The electrical activity properties in rat NAcs showed a significant change during different stages of heroin-dependence, which suggested that neuronal activities in NAcs might contribute to the modulation of drug-dependence.

[Telemetry EEG of parietal association cortex in heroin-induced CPP rats].

OBJECTIVE: To determine the relationship between EEG changes of parietal association cortex (PtA) and drug-seeking behaviors of heroin-induced conditioned place preference (CPP) rats. METHODS: Stereotaxic electrode was buried in the PtA of rats, which were then divided randomly into heroin-induced CPP group and operation-only control group. A CPP video system in combination with EEG wireless telemetry was used for recording PtA EEG and the behaviors of the rats-staying in black or white chamber of the video box; shuttling between black-white chambers or between white-black chambers. RESULTS: No significant difference in percentage of the telemetry EEG waves was found between the two groups of rats when they stayed in the black or white chambers. The heroin-induced CPP rats had increased percentage of delta waves (P < 0.05) on the right PtA and decreased percentage of beta and beta2 waves on both right and left PtA (P < 0.05) when they shuttled between two chambers. Compared with the operation-only controls, significant decrease in the percentage of delta waves on both left and right PtA and increase in theta, alpha and alpha1 waves were evident (P < 0.05) only when the heroin-induced CPP rats shuttled between white-black chambers. CONCLUSION: EEG changes on PtA of heroin-induced CPP rats differ between staying and shuttling states. Such changes may not be associated with drug-seeking behaviors.

Sources of calcium in agonist-induced contraction of rat distal colon smooth muscle in vitro.

AIM: To study the origin of calcium necessary for agonist-induced contraction of the distal colon in rats. METHODS: The change in intracellular calcium concentration ([Ca2+]i) evoked by elevating external Ca2+ was detected by fura 2/AM fluorescence. Contractile activity was measured with a force displacement transducer. Tension was continuously monitored and recorded using a Powerlab 4/25T data acquisition system with an ML110 bridge bioelectric physiographic amplifier. RESULTS: Store depletion induced Ca2+ influx had an effect on [Ca2+]i. In nominally Ca2+-free medium, the sarco-endoplasmic reticulum Ca2+-ATPase inhibitor thapsigargin (1 mumol/L) increased [Ca2+]i from 68 to 241 nmol/L, and to 458 (P < 0.01) and 1006 nmol/L (P < 0.01), respectively, when 1.5 mmol/L and 3.0 mmol/L extracellular Ca2+ was reintroduced. Furthermore, the change in [Ca2+]i was observed with verapamil (5 micromol/L), La3+ (1 mmol/L) or KCl (40 mmol/L) in the bathing solution. These channels were sensitive to La3+ (P < 0.01), insensitive to verapamil, and voltage independent. In isolated distal colons we found that in normal Krebs solution, contraction induced by acetylcholine (ACh) was partially inhibited by verapamil, and the inhibitory rate was 41% (P < 0.05). On the other hand, in Ca2+-free Krebs solution, ACh induced transient contraction due to Ca2+ release from the intracellular stores. The transient contraction lasted until the Ca2+ store was depleted. Restoration of extracellular Ca2+ in the presence of atropine produced contraction, mainly due to Ca2+ influx. Such contraction was not inhibited by verapamil, but was decreased by La3+ (50 micromol/L) from 0.96 to 0.72 g (P < 0.01). CONCLUSION: The predominant source of activator Ca2+ for the contractile response to agonist is extracellular Ca2+, and intracellular Ca2+ has little role to play in mediating excitation-contraction coupling by agonists in rat distal colon smooth muscle in vitro. The influx of extracellular Ca2+ is mainly mediated through voltage-, receptor- and store-operated Ca2+ channels, which can be used as an alternative to develop new drugs targeted on the dysfunction of digestive tract motility.