OBJECTIVETo 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.

METHODSRecording 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.

RESULTSHeroin-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.

CONCLUSIONThe 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.

Animals ; Conditioning, Operant ; Heroin ; pharmacology ; Heroin Dependence ; physiopathology ; Male ; Nucleus Accumbens ; physiopathology ; Rats ; Rats, Sprague-Dawley ; Telemetry

OBJECTIVETo study the changes of neutral alpha-glucoside activity in the epididymis of heroin-dependent and heroin-withdrawal rats, and to investigate the effects of intervention with purine nucleotide (AMP and GMP).

METHODSEighty Wistar rats were randomly divided into 8 groups of equal number, control, nucleotide, heroin, heroin + nucleotide, 3 d withdrawal, 9 d withdrawal, 3 d nucleotide (nucleotide administrated for 3 days after heroin withdrawal) and 9 d nucleotide (nucleotide administrated for 9 days after heroin withdrawal). Neutral alpha-glucosidase activity in the epididymis was detected in each group of rats.

RESULTSCompared with the control group, neutral alpha-glucoside activity was markedly decreased in the heroin group (P < 0.05), and also in the 3 d and 9 d withdrawal groups, although with no significant differences (P > 0.05).

CONCLUSIONHeroin reduces neutral alpha-glucoside activity in the epididymis of rats, and this effect may continue for some time after drug withdrawal, while purine nucleotide can keep neutral alpha-glucosidase activity in a relatively stable state.

Animals ; Epididymis ; chemistry ; Heroin ; adverse effects ; Heroin Dependence ; metabolism ; Male ; Purine Nucleotides ; pharmacology ; Rats ; Rats, Wistar ; alpha-Glucosidases ; metabolism

OBJECTIVE: To observe the expression of discs large homolog 4 (DLG4) protein in hippocampus, amygdala and frontal cortex of rats and evaluate postsynaptic density in heroin dependence. METHODS: The rat heroin dependent model was established by increasing intraperitoneal injection of heroin. DLG4 proteins in hippocampus, amygdala and frontal cortex of heroin dependent 9, 18, 36 days rats were detected with immunohistochemical staining and compared with that in the control group. RESULTS: DLG4 proteins in hippocampus, amygdala and frontal cortex were gradually reduced with extension of heroin dependent time. CONCLUSION Heroin dependence can affect postsynaptic density of hippocampus, amygdala and frontal cortex. The changes become more apparent with extension of heroin dependence time.
Amygdala/metabolism* ; Animals ; Disks Large Homolog 4 Protein ; Frontal Lobe/metabolism* ; Heroin/pharmacology* ; Heroin Dependence ; Hippocampus/metabolism* ; Injections, Intraperitoneal ; Intracellular Signaling Peptides and Proteins/metabolism* ; Membrane Proteins/metabolism* ; Rats

Opioid use disorder (OUD) has become a considerable global public health challenge; however, potential medications for the management of OUD that are effective, safe, and nonaddictive are not available. Accumulating preclinical evidence indicates that antagonists of the dopamine D₃ receptor (D₃R) have effects on addiction in different animal models. We have previously reported that YQA14, a D₃R antagonist, exhibits very high affinity and selectivity for D₃Rs over D₂Rs, and is able to inhibit cocaine- or methamphetamine-induced reinforcement and reinstatement in self-administration tests. In the present study, our results illustrated that YQA14 dose-dependently reduced infusions under the fixed-ratio 2 procedure and lowered the breakpoint under the progressive-ratio procedure in heroin self-administered rats, also attenuated heroin-induced reinstatement of drug-seeking behavior. On the other hand, YQA14 not only reduced morphine-induced expression of conditioned place preference but also facilitated the extinguishing process in mice. Moreover, we elucidated that YQA14 attenuated opioid-induced reward or reinforcement mainly by inhibiting morphine-induced up-regulation of dopaminergic neuron activity in the ventral tegmental area and decreasing dopamine release in the nucleus accumbens with a fiber photometry recording system. These findings suggest that D₃R might play a very important role in opioid addiction, and YQA14 may have pharmacotherapeutic potential in attenuating opioid-induced addictive behaviors dependent on the dopamine system.
Rats ; Mice ; Animals ; Analgesics, Opioid ; Dopamine ; Heroin/pharmacology* ; Dopamine Antagonists/pharmacology* ; Receptors, Dopamine D3/metabolism* ; Morphine/pharmacology* ; Behavior, Addictive/drug therapy* ; Self Administration

OBJECTIVETo investigate the effects of purine nucleotide on the expressions of follicle-stimulating hormone (FSH) and luteotrophic hormone (LH) and the ultrastructures of the distal somatotrophic and gonadotrophic cells in the pituitary gland of heroin-addicted and -withdrawal rats.

METHODSNinety-two male Wistar rats were randomly divided into a control group (ip saline for 14 d), a nucleotide group (ip AMP and GMP for 10 d), a heroin group (ip heroin for 10 d), a heroin + nucleotide group (ip AMP and GMP + heroin for 10 d), a 3 d withdrawal group (ip heroin for 10 d and killed at 14 d), a 9 d withdrawal group (ip heroin for 10 d and killed at 20 d), a 3 d nucleotide group (ip nucleotide for 3 d after 10 d heroin administration and killed at 14 d), and a 9 d nucleotide group (ip nucleotide for 9 d after 10 d heroin administration and killed at 20 d). Changes in the mRNA expressions of FSH and LH in the pituitary gland of the rats were analyzed by semi-quantitative RT-PCR, and alterations in the ultrastructures of the distal somatotrophic and gonadotrophic cells were observed under the microscope.

RESULTSThe expression of FSH mRNA was significantly increased in the nucleotide, heroin + nucleotide, 3 d nucleotide and 9 d nucleotide groups (0.099 +/- 0.018, 0.177 +/- 0.046, 0.151 +/- 0.030 and 0.184 +/- 0.028) as compared with the control group (0.045 +/- 0.009) (P < 0.01); and so was that of LH mRNA in the heroin + nucleotide, 3 d nucleotide and 9 d nucleotide groups (0.950 +/- 0.169, 0.990 +/- 0.171 and 0.960 +/- 0.147) in comparison with the control group (0.700 +/- 0.099) (P < 0.01). In the heroin group, the nuclei of the distal somatotrophic and gonadotrophic cells exhibited morphological abnormality, unclear membrane, slightly pyknotic matrix, marginal and agglutinated heterochromatin, dilated rough endoplasmic reticula, swollen mitochondria, broken and vacuolated cristae in the cytoplasm, obviously decreased number of secretory granules, and myelin bodies in some cells. However, the heroin + nucleotide group showed no significant changes in the ultrastructures of somatotrophic and gonadotrophic cells compared with the control group.

CONCLUSIONShort-term use of heroin does not obviously affect the expressions of FSH and LH mRNA in the pituitary gland of rats, while heroin + nucleotide, or nucleotide following heroin withdrawal can enhance their expressions significantly. Heroin damages the ultrastructures of the distal somatotrophic and gonadotrophic cells in the pituitary gland of male rats, and purine nucleotide can diminish or inhibit this damage.

Animals ; Follicle Stimulating Hormone ; genetics ; metabolism ; Gene Expression ; drug effects ; Heroin ; adverse effects ; Heroin Dependence ; genetics ; metabolism ; Luteinizing Hormone ; genetics ; metabolism ; Male ; Pituitary Gland ; drug effects ; metabolism ; ultrastructure ; Purine Nucleotides ; pharmacology ; Rats ; Rats, Wistar ; Substance Withdrawal Syndrome ; genetics ; metabolism

OBJECTIVE: To observe the effects of heroin on intracellular free Ca2+ in rat myocardium. METHODS: The effects of heroin on intracellular free Ca2+ were observed in cultured neonatal rat myocardium by measuring intracellular free Ca2+ concentration using calcium fluorescent probe Flou-3/AM and laser scanning confocal microscope. RESULTS: Different doses and concentrations of heroin appeared to have different effects on intracellular free Ca2+ concentrations, with a dosage dependent short linear increase in the fluorescence intensity (i.e., Ca2+ concentration) leading to [Ca2+]i peak. CONCLUSION Heroin could affect concentrations of [Ca2+]i in myocardium and its dosage related effect needs further investigation.
Animals ; Calcium/metabolism* ; Calcium Signaling ; Cells, Cultured ; Dose-Response Relationship, Drug ; Heroin/pharmacology* ; Microscopy, Confocal/methods* ; Microscopy, Fluorescence ; Myocytes, Cardiac/metabolism* ; Rats ; Rats, Sprague-Dawley

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

OBJECTIVE: To investigate whether heroin can directly induce apoptosis in primary cultured cortical neurons of rat's brain. METHODS: Cultured primary neurons cultures were obtained from cerebral cortex of embryo rats. After 7 days, the cells were incubated with different concentrations of heroin (purity-80%) for 24 hours. The neuronal survival was assessed by cell viability counting with fluorescent diacetate (FDA) staining. The morphological and biochemical changes were observed with Hoechst 33258 fluorescent staining and then analyzed by agarose gel electrophoresis, respectively. RESULTS: After treatment with different concentrations of heroin, the neurons showed a decreased survival rate in a dose dependent manner, and there was a significant difference in the survival rate between the heroin group and the control group (P < 0.05). When exposed to different concentrations of heroin, neurons exhibited the morphological and biochemical features of apoptosis, including cell shrinkage, neurite degeneration, network disappearance, condensation and aggregation of nuclear chromatin, and the formation of DNA ladders. With the increase of heroin concentration of rat's brain more apoptotic bodies were seen. CONCLUSION Heroin can directly induce apoptosis in primary cultured cortical neurons in rat's brain.
Animals ; Apoptosis/drug effects* ; Cell Nucleus/pathology* ; Cell Survival/drug effects* ; Cells, Cultured ; Cerebral Cortex/pathology* ; DNA Fragmentation/drug effects* ; Dose-Response Relationship, Drug ; Electrophoresis, Agar Gel/methods* ; Female ; Heroin/pharmacology* ; Male ; Neurons/pathology* ; Rats ; Rats, Sprague-Dawley ; Staining and Labeling

OBJECTIVETo investigate the effect of M(5) muscarinic receptor subtype on the locomotor sensitization induced by heroin priming, and it's effect on the FosB expression in the nucleus accumbens (NAc) and the hippocampus in the heroin sensitized rats.

METHODSLocomotor activity was measured every 10 min for 1 h after subcutaneous injection of heroin. FosB expression was assayed by immunohistochemistry, and the antisense oligonucleotides (AS-ONs) targeting M(5) muscarinic receptor was transferred with the lipofectin.

RESULTSMicroinjection of AS-ONs targeting M(5) muscarinic receptor in the ventral tegmental area (VTA) blocked the expression of behavioral sensitization induced by heroin priming in rats. Meanwhile, the expression of FosB-positive neurons in either the NAc or the dentate gyrus (DG) of the hippocampus increased in heroin-induced locomotor sensitized rats. The enhancement of FosB-positive neurons in the NAc or DG could be inhibited by microinjection of M(5) muscarinic receptor AS-ONs into the VTA before the heroin-induced locomotor sensitization was performed. In contrast, microinjection of M(5) muscarinic receptor sense oligonucleotide (S-ONs) into the VTA did not block the expression of behavioral sensitization or the expression of FosB in the NAc or DG in the heroin sensitized rats.

CONCLUSIONBlocking M(5) muscarinic receptor in the VTA inhibits the expression of heroin-induced locomotor sensitization, which is associated with the regulation of FosB expression in the NAc and hippocampus neurons. M(5) muscarinic receptor may be a useful pharmacological target for the treatment of heroin addiction.

Acetylcholine ; metabolism ; Animals ; Brain ; drug effects ; metabolism ; physiopathology ; Heroin ; adverse effects ; Heroin Dependence ; drug therapy ; metabolism ; physiopathology ; Hippocampus ; drug effects ; metabolism ; Immunohistochemistry ; Male ; Microinjections ; Motor Activity ; drug effects ; physiology ; Narcotics ; adverse effects ; Neural Pathways ; drug effects ; metabolism ; physiopathology ; Neurons ; drug effects ; metabolism ; Nucleus Accumbens ; drug effects ; metabolism ; physiopathology ; Oligonucleotides, Antisense ; pharmacology ; Proto-Oncogene Proteins c-fos ; drug effects ; metabolism ; Rats ; Rats, Sprague-Dawley ; Receptor, Muscarinic M5 ; antagonists & inhibitors ; genetics ; metabolism ; Synaptic Transmission ; drug effects ; physiology ; Ventral Tegmental Area ; drug effects ; metabolism ; physiopathology

OBJECTIVE: To explore the changes of c-fos in apoptosis of cerebellar granular neuron of neonatal SD rats induced by heroin and the mechanisms of neuronal injury caused by heroin. METHODS: Primary cerebellar granular neuron were cultured in vitro, the model of apoptosis induced by heroin was established. Reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting were adopted to investigate the changes of c-fos in cell models. RESULTS: Ten microg/mL of heroin was the optimal dose to induce the apoptosis of cerebellar granular neuron at 48 h. Both Western blotting and RT-PCR showed down regulation of c-fos expression. CONCLUSION Heroin could induce apoptosis of cerebellar granular neuron and down regulation of c-fos, which may be one of the apoptosis mechanisms.
Animals ; Animals, Newborn ; Apoptosis/drug effects* ; Blotting, Western ; Cells, Cultured ; Cerebellum/metabolism* ; Dose-Response Relationship, Drug ; Down-Regulation ; Gene Expression Regulation/drug effects* ; Heroin/pharmacology* ; Male ; Neurons/metabolism* ; Proto-Oncogene Proteins c-fos/metabolism* ; RNA, Messenger/metabolism* ; Rats ; Rats, Sprague-Dawley ; Reverse Transcriptase Polymerase Chain Reaction