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Cinnamomi Cortex is a commonly used herb with a variety of pharmacological effects. We investigated the molecular mechanisms by which Cinnamomi Cortex antagonises morphine addiction (MA) using network pharmacology and molecular docking techniques in a morphine-dependent rat withdrawal model. The antagonistic effect of Cinnamomi Cortex was observed by inducing withdrawal symptoms in morphine-dependent rats through a dose-escalation method. Network pharmacology and molecular docking techniques were further employed to analyze the substance basis and mechanism of Cinnamomi Cortex in antagonizing MA. Cinnamomi Cortex was screened to contain 10 active ingredients, 127 active targets and 1724 MA-related targets. Among them, 52 targets overlapped between Cinnamomi Cortex and MA and 13 core targets were identified by metric analysis. Cinnamomi Cortex had a significant inhibitory effect on withdrawal symptoms in MA rats, with the most pronounced effect at a moderate dose. The active ingredients of Cinnamomi Cortex (including oleic acid) can act on multiple targets related to MA and regulate multiple pathways to treat MA. The present study reveals the material basis and mechanism of cinnamon's action on MA, and provides insights and references for subsequent experiments exploring the potential therapeutic approach of Cinnamomi Cortex on MA. [ABSTRACT FROM AUTHOR]

Opioids are known to be used medically as analgesia and illegally as recreational drugs. Morphine, a semi-synthetic opioid is used widely in managing pain. Despite knowing the side-effect of the usage, the number of illegal users of opioids or morphine, specifically, is statistically still growing. Long-term usage of opioids, especially morphine, induces addiction that is expressed as dependence, tolerance, and withdrawal behaviour. Currently, with expanding research on anti-addiction studies, many loopholes in the basic mechanism of addiction were found, providing a setback for the researchers to overcome the problem. Thus, this review is aimed to present the latest update on the cellular modifications caused by chronic morphine treatment. By understanding and updating the knowledge, research can focus on the recent postulation and suggestions. [ABSTRACT FROM AUTHOR]

Abstract Background Chronic morphine usage induces lasting molecular and microcellular adaptations in distinct brain areas, resulting in addiction-related behavioural abnormalities, drug-seeking, and relapse. Nonetheless, the mechanisms of action of the genes responsible for morphine addiction have not been exhaustively studied. Methods We obtained morphine addiction-related datasets from the Gene Expression Omnibus (GEO) database and screened for Differentially Expressed Genes (DEGs). Weighted Gene Co-expression Network Analysis (WGCNA) functional modularity constructs were analyzed for genes associated with clinical traits. Venn diagrams were filtered for intersecting common DEGs (CDEGs). Gene Ontology (GO) enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis for functional annotation. Protein–protein interaction network (PPI) and CytoHubba were used to screen for hub genes. Potential treatments for morphine addiction were figured out with the help of an online database. Results Sixty-five common differential genes linked to morphine addiction were identified, and functional enrichment analysis showed that they were primarily involved in ion channel activity, protein transport, the oxytocin signalling pathway, neuroactive ligand-receptor interactions, and other signalling pathways. Based on the PPI network, ten hub genes (CHN2, OLIG2, UGT8A, CACNB2, TIMP3, FKBP5, ZBTB16, TSC22D3, ISL1, and SLC2A1) were checked. In the data set GSE7762, all of the Area Under Curve (AUC) values for the hub gene Receiver Operating Characteristic (ROC) curves were greater than 0.8. We also used the DGIdb database to look for eight small-molecule drugs that might be useful for treating morphine addiction. Conclusions The hub genes are crucial genes associated with morphine addiction in the mouse striatum. The oxytocin signalling pathway may play a vital role in developing morphine addiction.

• Morphine induced inflammation requires the crosstalk between neuron, astrocyte, and microglia. • Morphine causes abnormal glycolysis in astrocytes, which leads to excessive mitochondrial fragmentation of astrocytes. • Inhibiting abnormal glycolysis of astrocytes with FK866 could attenuates morphine induced neuroinflammatory responses. Chronic morphine exposure causes the development of addictive behaviors, accompanied by an increase in neuroinflammation in the central nervous system. While previous researches have shown that astrocytes contribute to brain diseases, the role of astrocyte in morphine addiction through induced neuroinflammation remain unexplored. Here we show that morphine-induced inflammation requires the crosstalk among neuron, astrocyte, and microglia. Specifically, astrocytes respond to morphine-induced neuronal activation by increasing glycolytic metabolism. The dysregulation of glycolysis leads to an increased in the generation of mitochondrial reactive oxygen species and causes excessive mitochondrial fragmentation in astrocytes. These fragmented, dysfunctional mitochondria are consequently released into extracellular environment, leading to activation of microglia and release of inflammatory cytokines. We also found that blocking the nicotinamide adenine dinucleotide salvage pathway with FK866 could inhibit astrocytic glycolysis and restore the mitochondrial homeostasis and effectively attenuate neuroinflammatory responses. Importantly, FK866 reversed morphine-induced addictive behaviors in mice. In summary, our findings illustrate an essential role of astrocytic immunometabolism in morphine induced neural and behavioral plasticity, providing a novel insight into the interactions between neurons, astrocytes, and microglia in the brain affected by chronic morphine exposure. [ABSTRACT FROM AUTHOR]

Background: Chronic morphine usage induces lasting molecular and microcellular adaptations in distinct brain areas, resulting in addiction-related behavioural abnormalities, drug-seeking, and relapse. Nonetheless, the mechanisms of action of the genes responsible for morphine addiction have not been exhaustively studied. Methods: We obtained morphine addiction-related datasets from the Gene Expression Omnibus (GEO) database and screened for Differentially Expressed Genes (DEGs). Weighted Gene Co-expression Network Analysis (WGCNA) functional modularity constructs were analyzed for genes associated with clinical traits. Venn diagrams were filtered for intersecting common DEGs (CDEGs). Gene Ontology (GO) enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis for functional annotation. Protein–protein interaction network (PPI) and CytoHubba were used to screen for hub genes. Potential treatments for morphine addiction were figured out with the help of an online database. Results: Sixty-five common differential genes linked to morphine addiction were identified, and functional enrichment analysis showed that they were primarily involved in ion channel activity, protein transport, the oxytocin signalling pathway, neuroactive ligand-receptor interactions, and other signalling pathways. Based on the PPI network, ten hub genes (CHN2, OLIG2, UGT8A, CACNB2, TIMP3, FKBP5, ZBTB16, TSC22D3, ISL1, and SLC2A1) were checked. In the data set GSE7762, all of the Area Under Curve (AUC) values for the hub gene Receiver Operating Characteristic (ROC) curves were greater than 0.8. We also used the DGIdb database to look for eight small-molecule drugs that might be useful for treating morphine addiction. Conclusions: The hub genes are crucial genes associated with morphine addiction in the mouse striatum. The oxytocin signalling pathway may play a vital role in developing morphine addiction. [ABSTRACT FROM AUTHOR]

Aim: Morphine is one of the most preferred opioids in treatment of chronic pain. Recurrent use can cause addiction. There is no consensus on cardiovascular system treatment/side effects of opioids. In order to investigate effects of opioid addiction on heart, myocardial contractility/histological changes were investigated in rats via experimental morphine addiction/withdr awal. Materials and Methods: 32 adult male Wistar albino rats used for study, which was officially completed on 28-05-2021, were divided into Control(C), Morphine(M), Morphine+Naloxone(MN) groups randomly. In GroupC 10mg/kg 0.9% NaCl solution, in GroupM-MN 10mg/kg morphine were administered subcutaneously for 7 days. After the last administration of morphine, 3mg/kg NaCl was given to GroupC-M, 3mg/kg naloxone was given to GroupMN intraperitoneally. Signs of morphine withdrawal were observed for 30 minutes and scored. 3-4mm strips of atria were hung in isolated organ bath chambers. Tension was adjusted to 2g. Adrenaline-induced contractions (0.001M) were observed. Changes in tension were recorded. SAS University Edition 9.4 program was used for statistical analysi s. Results: Morphine withdrawal behaviours were observed in GroupMN. There was no statistically significant difference between atrial contractility tension values of GroupC-M-MN(p>0.05). Pre-adrenaline tension values were higher in GroupM-MN than in GroupC. But the greatest contraction increase between 15minutes before/after adrenaline-induced data was in GroupC. Conclusion: Morphine addiction/withdrawal didn't cause inotropic/chronotropic changes. No histological differences were observed in mast cells. These results may constitute a positive resource for the heart for systems analysis in morphine addicts. [ABSTRACT FROM AUTHOR]

Morphine, the main component of opium, is a commonly used analgesic in clinical practice, but its abuse potential limits its clinical application. Nicotinic acetylcholine receptors (nAChRs) in the mesolimbic circuitry play an important role in the rewarding effects of abused drugs. Previous studies have showed that α6β2* (* designated other subunits) nAChRs are mainly distributed in dopaminergic neurons in the midbrain area, which regulates the release of dopamine. So α6β2* nAChRs are regarded as a new target to treat drug abuse. α-Conotoxin TxIB was discovered in our lab, which is the most selective ligand to inhibit α6β2* nAChRs only. Antagonists of α6β2* nAChRs decreased nicotine, cocaine, and ethanol rewarding effects previously. However, their role in morphine addiction has not been reported so far. Thus, it is worth evaluating the effect of α-conotoxin TxIB on the morphine-induced conditioned place preference (CPP) and its behavioral changes in mice. Our results showed that TxIB inhibited expression and acquisition of morphine-induced CPP and did not produce a rewarding effect by itself. Moreover, repeated injections of TxIB have no effect on learning, memory, locomotor activity, and anxiety-like behavior. Therefore, blocking α6/α3β2β3 nAChRs inhibits the development of morphine-induced CPP. α-Conotoxin TxIB may be a potentially useful compound to mitigate the acquisition and/or retention of drug-context associations. [ABSTRACT FROM AUTHOR]

The usage of morphine for analgesia purposes is widely known, usually for the post-operation procedure and as chronic pain management. However, addiction and overdose liabilities before morphine usage are also common. Morphine addiction is observed and studied from various perspectives; tolerance, dependence, and withdrawal. With growing and expending research field, researches on addiction were done using in vivo and in vitro model. However, the scientific evidence of morphine addiction using human neuroblastoma cell lines is uncommon. Thus, the present study was designed and conducted to observe the liability of SK-N-SH, as a model for morphine addiction. The cells were administrated with morphine for 24 hr before being treated with methadone. The cytosolic fraction of the cell was collected and used for determining the addiction mechanism. Data showed the involvement of the µ-opioid receptor in expressing the addictive properties of morphine. Exposure to 24 hr morphine had increased the protein level responsible for addiction and reduce the protein levels expressing the endocytic machinery, desensitization of receptors, and cellular adaptation. The altered proteins level was normalized by the treatment of methadone. The study proposed the use of SK-N-SH as an addiction model, as it showed morphine addiction and methadone anti-addiction properties. [ABSTRACT FROM AUTHOR]

Morphine, the main component of opium, is a commonly used analgesic in clinical practice, but its abuse potential limits its clinical application. Nicotinic acetylcholine receptors (nAChRs) in the mesolimbic circuitry play an important role in the rewarding effects of abused drugs. Previous studies have showed that α6β2* (* designated other subunits) nAChRs are mainly distributed in dopaminergic neurons in the midbrain area, which regulates the release of dopamine. So α6β2* nAChRs are regarded as a new target to treat drug abuse. α-Conotoxin TxIB was discovered in our lab, which is the most selective ligand to inhibit α6β2* nAChRs only. Antagonists of α6β2* nAChRs decreased nicotine, cocaine, and ethanol rewarding effects previously. However, their role in morphine addiction has not been reported so far. Thus, it is worth evaluating the effect of α-conotoxin TxIB on the morphine-induced conditioned place preference (CPP) and its behavioral changes in mice. Our results showed that TxIB inhibited expression and acquisition of morphine-induced CPP and did not produce a rewarding effect by itself. Moreover, repeated injections of TxIB have no effect on learning, memory, locomotor activity, and anxiety-like behavior. Therefore, blocking α6/α3β2β3 nAChRs inhibits the development of morphine-induced CPP. α-Conotoxin TxIB may be a potentially useful compound to mitigate the acquisition and/or retention of drug-context associations.

Drug addiction is a global health problem and continues to place an enormous financial burden on society. This addiction is characterized by drug dependence sensitization and craving. Morphine has been widely used for pain relief, but chronic administration of morphine causes analgesic tolerance, hyperalgesia, and addiction, all of which limit its clinical usage. Alterations of multiple molecular pathways have been reported to be involved in the development of drug addiction, including mitochondrial dysfunction, excessive oxidative stress and nitric oxide stress, and increased levels of apoptosis, autophagy, and neuroinflammation. Preclinical and clinical studies have shown that the co-administration of melatonin with morphine leads to a reversal of these affected pathways. In addition, murine models have shown that melatonin improves morphine-induced analgesic tolerance and addictive behaviors, such as behavioral sensitization, reward effect, and physical dependence. In this review, we attempt to summarize the recent findings about the beneficial effect and molecular mechanism of melatonin on mitochondrial dysfunction, uncontrolled autophagy, and neuroinflammation in morphine addiction and morphine analgesic tolerance. We propose that melatonin might be a useful supplement in the treatment opiate abuse. [ABSTRACT FROM AUTHOR]

Drug addiction is a recurrent, chronic brain disease. The existing treatment methods have limitations, such as poor adherence and inability to completely avoid relapse. Histidine triad nucleotide-binding protein 1 (HINT1) is involved in many neuropsychiatric diseases, such as schizophrenia, pain, and drug dependence. Studies have confirmed that there is a genetic link between HINT1 and addictions such as nicotine and cocaine. However, there is no research on the role of HINT1 protein in morphine addiction at home and abroad. Thus, we designed this project by constructing different types of morphine addiction animal models, including conditioned place preference and behavioral sensitization. We comprehensively examined the participation of HINT1 protein in key brain regions associated with addiction, including prefrontal cortex, nucleus accumbens, corpus striatum, and hippocampus, in different stages of different models. In addition, we used HINT1 knockout mice to establish the above models and physical dependence model to investigate the effect of HINT1 protein deletion on morphine addiction-related behaviors. We found that HINT1 has varying degrees of involvement in different stages of multiple addictive animal models. The absence of HINT1 can attenuate morphine-mediated addictive behavior to a certain extent and can alleviate the withdrawal symptoms of morphine. [ABSTRACT FROM AUTHOR]

Environmental cues associated with drug abuse are powerful mediators of drug craving and relapse in substance-abuse disorders. Consequently, attenuating the strength of cue-drug memories could reduce the number of factors that cause drug craving and relapse. Interestingly, impairing cue-drug memory reconsolidation is a generally accepted strategy aimed at reducing the intensity of cues that trigger drug-seeking and drug-taking behaviors. In addition, the agranular insular cortex (AI) is an important component of the neural circuits underlying drug-related memory reconsolidation. GABAB receptors (GABABRs) are potential targets for the treatment of addiction, and baclofen (BLF) is the only prototypical GABAB agonist available for application in clinical addiction treatment. Furthermore, ΔFosB is considered a biomarker for the evaluation of potential therapeutic interventions for addiction. Here, we used the morphine-induced conditioned place preference (CPP) paradigm to investigate whether postretrieval microinjections of BLF into the AI could affect reconsolidation of drug-reward memory, reinstatement of CPP, and the level of ΔFosB in mice. Our results showed that BLF infused into the AI immediately following morphine CPP memory retrieval, but not 6 h postretrieval or following nonretrieval, could eliminate the expression of a morphine CPP memory. This effect persisted in a morphine-priming–induced reinstatement test, suggesting that BLF in the AI was capable of preventing the reconsolidation of the morphine CPP memory. Our results also showed that the elimination of morphine CPP memory was associated with reduced morphine-associated ΔFosB expression in the longer term. Taken together, the results of our research provide evidence to support that GABABRs in the AI have an important role in drug-cue memory reconsolidation and further our understanding of the role of the AI in drug-related learning and memory.

Long-term administration of morphine for the management of chronic pain will result in tolerance to its analgesic effect and could even cause drug dependence. Numerous studies have demonstrated significant redox alteration in morphine dependence and addiction. Thioredoxin-1 (Trx-1) play important roles in controlling the cellular redox balance. In recent years, several recent studies have demonstrated that Trx-1 may be a promising novel therapeutic target for morphine addiction. In this article, we firstly review the redox alteration in morphine addiction. We also summarize the expression and the protective roles of Trx-1 in morphine dependence. We further highlight the protection of geranylgeranylacetone (GGA), a noncytotoxic pharmacological inducer of Trx-1, in morphine-induced conditioned place preference. In conclusion, Trx-1 may be very promising for clinical therapy of morphine addiction in the future.

Environmental cues associated with drug abuse are powerful mediators of drug craving and relapse in substance-abuse disorders. Consequently, attenuating the strength of cue-drug memories could reduce the number of factors that cause drug craving and relapse. Interestingly, impairing cue-drug memory reconsolidation is a generally accepted strategy aimed at reducing the intensity of cues that trigger drug-seeking and drug-taking behaviors. In addition, the agranular insular cortex (AI) is an important component of the neural circuits underlying drug-related memory reconsolidation. GABAB receptors (GABABRs) are potential targets for the treatment of addiction, and baclofen (BLF) is the only prototypical GABAB agonist available for application in clinical addiction treatment. Furthermore, ΔFosB is considered a biomarker for the evaluation of potential therapeutic interventions for addiction. Here, we used the morphine-induced conditioned place preference (CPP) paradigm to investigate whether postretrieval microinjections of BLF into the AI could affect reconsolidation of drug-reward memory, reinstatement of CPP, and the level of ΔFosB in mice. Our results showed that BLF infused into the AI immediately following morphine CPP memory retrieval, but not 6 h postretrieval or following nonretrieval, could eliminate the expression of a morphine CPP memory. This effect persisted in a morphine-priming–induced reinstatement test, suggesting that BLF in the AI was capable of preventing the reconsolidation of the morphine CPP memory. Our results also showed that the elimination of morphine CPP memory was associated with reduced morphine-associated ΔFosB expression in the longer term. Taken together, the results of our research provide evidence to support that GABABRs in the AI have an important role in drug-cue memory reconsolidation and further our understanding of the role of the AI in drug-related learning and memory. [ABSTRACT FROM AUTHOR]

Long-term administration of morphine for the management of chronic pain will result in tolerance to its analgesic effect and could even cause drug dependence. Numerous studies have demonstrated significant redox alteration in morphine dependence and addiction. Thioredoxin-1 (Trx-1) play important roles in controlling the cellular redox balance. In recent years, several recent studies have demonstrated that Trx-1 may be a promising novel therapeutic target for morphine addiction. In this article, we firstly review the redox alteration in morphine addiction. We also summarize the expression and the protective roles of Trx-1 in morphine dependence. We further highlight the protection of geranylgeranylacetone (GGA), a noncytotoxic pharmacological inducer of Trx-1, in morphine-induced conditioned place preference. In conclusion, Trx-1 may be very promising for clinical therapy of morphine addiction in the future. [ABSTRACT FROM AUTHOR]

Aim: Although the effects of morphine on renal functions and bladder have been investigated, it has not been studied yet whether the long-term morphine dependence and related withdrawal syndrome have a different effect on the bladder. Aim of the study is to investigate the effects of morphine addiction and morphine withdrawal on bladder smooth muscle. Material and Methods: Adult male Wistar-Albino rats (n:30) included in the study were randomly divided into 3 groups. 10 mg/kg 0.9% NaCl solution was injected subcutaneously once a day for 7 days. 10 mg/kg morphine was injected subcutaneously once a day for 7 days in morphine and morphine-withdrawal group. After two hours of the last injections, 3 mg/kg 0.9% NaCl solution was injected intraperitoneally in both control and morphine groups, while 3 mg/kg naloxone for morphine-withdrawal group. Then the behavior of the animals was observed for thirty hours. Afterwards, the bladders were rapidly extracted and their tension was recorded in the isolated organ bath. Results: Morphine withdrawal behaviors were observed in rats in the morphine withdrawal group. When the bladder contractions of the groups were examined, no statistically significant difference was found between the tension values (p>0.05). Conclusion: In summary the study carried out in rats with morphine addiction, it was observed that being addicted to morphine or being on morphine withdrawal did not affect bladder contractions. [ABSTRACT FROM AUTHOR]

Abstract Opioid addiction is a growing problem for public health, and opioids have correspondingly become more heavily regulated over time. We have previously shown that TRPV1 plays a critical role in morphine addiction using a self-administration paradigm in rats, and the current study evaluates the effects of the TRPV1 signaling pathway on morphine self-administration (SA). We found that treatment with a selective TRPV1 antagonist, SB366791, significantly decreased the morphine SA-induced activation of Ca2+/calmodulin-dependent protein kinase II (CaMKII), Akt and the cAMP response element binding protein (CREB) in the nucleus accumbens (NAc). In addition, phospho-PKA and phospho-PKC expression levels were significantly increased in the NAc of the morphine-SA groups, regardless of SB366791 treatment. Finally, local microinjection of SB366791 into the NAc significantly suppressed the maintenance of morphine SA. Taken together, our findings highlight that TRPV1 plays an important role in morphine addiction, likely via activation of the CaMKII-CREB pathway in the NAc. Highlights • TRPV1 antagonist, SB366791, decreased the activation of CaMKII, Akt, and CREB induced by morphine SA. • p-PKA and p-PKC expression levels were significantly increased in the NAc of the morphine-SA groups, regardless of SB366791 treatment. • Local microinjection of SB366791 into the NAc suppressed the maintenance of morphine SA. [ABSTRACT FROM AUTHOR]

Objective(s):To determine the effect of acetylcholine (ACh), pilocarpine, and atropine on pain evoked responses of pain excited neurons (PEN) and pain inhibited neurons (PIN) in hippocampal CA3 region of morphine addicted rats. Materials and Methods:Female Wistar rats, weighing between 230-260 g were used in this study. Morphine addicted rats were generated by subcutaneous injection of increasing concentrations of morphine hydrochloride for six days. Trains of electrical impulses applied to the sciatic nerve were used as noxious stimulation and the evoked electrical activities of PEN or PIN in hippocampal CA3 area were recorded using extracellular electrophysiological recording techniques in hippocampal slices. The effect of acetylcholine receptor stimulation byACh, the muscarinic agonist pilocarpine, and the muscarinic antagonist atropine on the pain evoked responses of pain related electrical activities was analyzed in hippocampal CA3 area of morphine addicted rats. Results:Intra-CA3 microinjection of ACh (2 μg/1 μl) or pilocarpine (2 μg/1 μl) decreased the discharge frequency and prolonged the firing latency of PEN, but increased the discharge frequency and shortened the firing inhibitory duration (ID) of PIN. The intra-CA3 administration of atropine (0.5 μg/1 μl) produced opposite effect. The peak activity of cholinergic modulators was 2 to 4 min later in morphine addicted rats compared to peak activity previously observed in normal rats. Conclusion: ACh dependent modulation of noxious stimulation exists in hippocampal CA3 area of morphine addicted rats. Morphine treatment may shift the sensitivity of pain related neurons towards a delayed response to muscarinergic neurotransmission in hippocampal CA3 region.

The nucleus accumbens (NAc) plays a critical role in addictive drug-induced behavioral changes. d-serine is present at high levels in the brain and is involved in the regulation of N-methyl-d-aspartate glutamate (NMDA)-dependent synaptic activity. In this study, we aimed to examine the involvement of d-serine in morphine addiction. Morphine decreased the NMDA receptor-mediated excitatory postsynaptic currents and excitability of GABAergic neurons in the NAc, while exogenous d-serine alleviated the effects of morphine. Morphine reduced extracellular d-serine levels in rat NAc or in primary culture of astrocytes through inhibition of intracellular Ca2+ signals and blockade of d-serine release from cell vesicles. Morphine induced robust internalization of α-amino-3-hydroxy-5-methyl-4-isoxazole-propionate acid receptor (AMPAR) in primary cultured astrocytes. Moreover, administration of exogenous d-serine to rats inhibited the development of locomotor sensitization to morphine, attenuated the morphine-induced potentiation on conditioned place preference and suppressed the morphine-enhanced expression of p-CREB and ΔFosB in the NAc. Overall, our results showed that morphine inhibited d-serine release from astrocytes through modulation of AMPAR-mediated Ca2+ influx, and led to the inhibition of postsynaptic excitability of GABAergic neurons in the NAc. This work may provide a new insight into the underlying mechanisms of morphine addiction. [ABSTRACT FROM AUTHOR]

Background: There is only little information about the effects of GABA receptors agonist and antagonist on morphine self-administration. Present study was designed to assess role of GABAB receptors in the regulation of morphine-reinforced self-administration. Methods: This study was performed in four groups of rats: (1) Saline group, which received saline in the self-administration session. (2) Morphine group, which received morphine in saline solution in the self-administration session. (3) Baclofen + Morphine group, which received both baclofen 20 min before self- administration test and morphine in the self-administration session. (4) Phaclofen + Morphine group, which received both phaclofen 20 min before self- administration test and morphine in the self-administration session. The number of lever pressing and self-infusion were recorded. Results: Morphine significantly increased the number of active lever pressing dose dependently in self-administration session in comparative with saline group. Administration of baclofen, 20 min before morphine self-administration produced significant decrease in the initiation of morphine self-administration during all session. Conversely, pre-treatment of phaclofen increased the number of active lever pressing and self-infusion in this test. Conclusion: Our results indicated a short-term treatment by baclofen, reduced morphine-maintenance response in a dose-dependent manner, suggesting that GABAB receptor agonists could be useful for reversing the neuroadaptations related to opiates.

5-aza-2-deoxycytidine (5-aza), an inhibitor of DNA methyltransferases (DNMTs), has been implicated in aversive memory and the function of brain region which processing affect. However, little is known about the role of 5-aza in the reconsolidation of opiate withdrawal memory. In the present study, using the morphine-naloxone induced conditioned place aversion (CPA) model in rats, we injected 5-aza into agranular insular (AI), granular insular (GI), basolateral amygdala (BLA) and central amygdala (CeA) immediately after the memory retrieval and tested the behavioral consequences at 24hours, 7 days and 14days after retrieval test. We found that 5-aza injection into AI disrupted the reconsolidation of morphine-associated withdrawal memory, but 5-aza injection into GI had no impact on the reconsolidation. Meanwhile, 5-aza injection into BLA but not CeA attenuated the withdrawal memory trace 14 days later. However, 5-aza administration to rats, in the absence of memory reactivation, had no effect on morphine-associated withdrawal memory. These findings suggest that 5-aza interfere with the reconsolidation of opiate withdrawal memory, and the roles of insular and amygdala in reconsolidation are distinctive.

AIM: Neuritin, which was first identified in the rat hippocampal dentate gyrus, is known as the candidate plasticity gene 15. The effects of neuritin on neurite development, dendritic branching, synaptic activity and neuronal survival in the nervous system in some neurodegenerative diseases and psychopathologies have been determined. However, there is no research finding on how neuritin expression is affected in processes related to opioid addiction. In this study, we aimed to determine the neurogenesis status and neuritin gene expression level in the hippocampus in morphine-dependent and naloxone administered rats. METHODS: Morphine addiction was constituted by subcutaneously administering morphine to adult male rats for 7 days in the study. In the morphine withdrawal group, in addition to morphine administration, naloxone was injected 1.5 hours after the last injection. Hippocampus tissues were removed from all animals. Neuritin and neurogenesis biomarkers such as doublecortin, brainderived neurotrophic factor, NeuN and MASH1 gene expression levels were evaluated by using quantitative RT-PCR. One-way ANOVA was used for statistical evaluation. RESULTS: The expression level of hippocampal neuritin in the morphine addiction group was significantly lower compared to control (p<0.05). Neuritin expression in naloxone group significantly increased compared to the addiction group (p<0.001). Brain derived neurotrophic factor, doublecortin and NeuN expression levels were significantly higher in the morphine withdrawal group compared to the addiction group (p<0.05, p<0.001 and p<0.05, respectively). There was no significant difference in MASH1 expression level. CONCLUSION: The results of this study show that administration of naloxone significantly increases the return of hippocampal neurogenesis biomarkers in morphine-dependent rats. The fact that morphine addiction lowers the level of neuritin in the hippocampus and that morphine withdrawal significantly increases its expression suggests that neuritin may play a mediating role in the opioidergic modulation of neurogenesis and neuroplasticity in the hippocampal dentate gyrus. [ABSTRACT FROM AUTHOR]

Background: Although opioid agonist-based treatments are considered the first-line treatment for opioid use disorders, nonopioid alternatives are urgently needed to combat the inevitable high relapse rates. Compound 511 is a formula derived from ancient traditional Chinese medical literature on opiate rehabilitation. Previously, we observed that Compound 511 could effectively prevent the acquisition of conditioned place preference (CPP) during early morphine exposure. However, its effects on drug-induced reinstatement remain unclear.Purpose: This study aims to estimate the potential of Compound 511 for the therapeutic intervention of opioid relapse in rodent models and explore the potential mechanisms underlying the observed actions.Study Design/methods: The CPP and locomotor sensitization paradigm were established to evaluate the therapeutic effect of Compound 511 treatment on morphine-induced neuroadaptations, followed by immunofluorescence and western blot (WB) analysis of the synaptic markers PSD-95 and Syn-1. Furthermore, several addiction-associated transcription factors and epigenetic marks were examined by qPCR and WB, respectively. Furthermore, the key active ingredients and targets of Compound 511 were further excavated by network pharmacology approach and experimental validation.Results: The results proved that Compound 511 treatment during abstinence blunted both the reinstatement of morphine-evoked CPP and locomotor sensitization, accompanied by the normalization of morphine-induced postsynaptic plasticity in the nucleus accumbens (NAc). Additionally, Compound 511 was shown to exert a selectively repressive influence on morphine-induced hyperacetylation at H3K14 and a reduction in H3K9 dimethylation as well as ΔFosB activation and accumulation in the NAc. Finally, two herbal ingredients of Compound 511 and six putative targets involved in the regulation of histone modification were identified.Conclusion: Our findings indicated that Compound 511 could block CPP reinstatement and locomotor sensitization predominantly via the reversal of morphine-induced postsynaptic plasticity through epigenetic mechanisms. Additionally, 1-methoxy-2,3-methylenedioxyxanthone and 1,7-dimethoxyxanthone may serve as key ingredients of Compound 511 by targeting specific epigenetic enzymes. This study provided an efficient nonopioid treatment against opioid addiction. [ABSTRACT FROM AUTHOR]

Bacosides are the main biologically active components derived from the plant bacopa monnieri ( Bacopa monnieri (L.) Wettst.), which has been used as a nootropic in Indian medicine for many centuries. In recent years, these compounds have attracted attention because of their wide range of neurobiological effects. The neuroprotective effects of bacosides on brain neurons under the influence of various damaging factors (neurotoxins, oxidative stress, beta-amyloid deposition, cigarette smoke, etc.) have been established. It was shown that these substances reduce the levels of inflammatory cytokines and inhibit the processes of demyelination of neurons. The anticonvulsant effect of bacosides has been established. These compounds also improve cognitive functions, including memory and learning abilities. The effects associated with the influence on the dopaminergic and serotonergic systems of the striatum are of interest for the therapy of morphine addiction. The theoretical justifications for the future use of bacosides as a multipurpose means of complex therapy of individual diseases in neurological and psychiatric practice are presented.

Objectives To study the role of microRNA-873 (miR-873) in suppressing morphine-induced macrophage apoptosis and morphine dependence, and to identify molecular targets within the miR-873 pathway for the treatment of immune suppression and morphine addiction. Methods As morphine elevates TLR9 expression and induces TLR9-mediated apoptosis, we used TLR9 knockout Balb/C mice to study TLR9-independent effects of miR-873 on morphine-induced macrophage apoptosis. Forty TLR9-knockout mice were randomly and equally assigned to morphine group and control group. Following the administration of morphine, miR-873 mimics or miR negative control was injected into mice in each group. Using freshly isolated macrophages from mice and RAW264.7 murine macrophage cell line, miR-873 level was determined by qRT-PCR and morphine induced apoptosis was measured by TUNEL assays. Western blotting was used to detect and quantify the expression level of A20, a protein that negatively regulates inflammation and TNF-induced apoptosis. Results qRT-PCR analysis revealed a markedly lower expression of miR-873 in freshly isolated peritoneal macrophages, liver tissue and spleen tissue in the morphine group compared with the corresponding tissues in the control group. TUNEL assays showed that the apoptosis rates in the morphine groups treated with miR-873 mimics was markedly lower than their respective control groups. Western blotting results showed that A20 expression level was sharply elevated in the experimental groups treated with miR-873 mimics than the negative and blank control groups. Conclusions Our results show that miR-873 elevates A20 levels and inhibits morphine-induced macrophage apoptosis. [ABSTRACT FROM AUTHOR]

Aims The alteration of ROS level is frequently observed in the course of morphine addiction, and ROS is proverbially involved in this process. This study aims to explore the relationship among morphine addiction, reactive oxygen species (ROS) and expression of μ-opioid receptor (MOR) in differentiated SH-SY5Y cells. Main methods SH-SY5Y cells were induced to differentiation by treatment with retinoic acid (RA); the activity of lactate dehydrogenase (LDH) and the nitro blue tetrazolium (NBT) reduction were assessed by spectrophotometry. Intracellular reactive oxygen species (ROS) was measured with the 2,7-dichlorofluorescin diacetate (DCFH-DA) assay. Cellular cAMP was determined by using a competitive protein binding kit. The mRNA expression of μ-opioid receptor (MOR) was evaluated by qRT-PCR. Key findings Morphine-induced ROS are generated in a concentration- and time-dependent manner and inhibited by naloxone. Exogenous oxidants increase the level of ROS and aggravate morphine addiction, while the exogenous antioxidants efficiently reverse these effects. Morphine decreases the mRNA level of MOR in a concentration-dependent manner. And the mRNA level of MOR is remarkably reduced in the presence of exogenous oxidants and effectively promoted by antioxidants. Significance This study indicates that ROS can affect morphine addiction through involving MOR. Treatment with ROS scavenging can serve as a medical therapy for morphine addiction. [ABSTRACT FROM AUTHOR]

Recent studies indicated that epigenetic modification, especially DNA methylation, play an important role in the persistence of addiction-related memory. 5-aza-2-deoxycytidine (5-aza), an inhibitor of DNA methyltransferases, was approved for clinical treatment. However, it is not clear whether 5-aza is involved in opiate addiction. In this study, using the morphine-induced conditioned place preference (mCPP) model in rats, we injected 5-aza into hippocampus (CA1) and prelimbic cortex (PL), and tested the behavioral consequences at various stages of consolidation, acquisition and retrieval. Moreover, to test whether protein phosphatase regulates the effects of 5-aza, protein phosphatase (PP) 1/2A inhibitor okadaic acid (OA) was infused before 5-aza injection. We found that 5-aza injection into CA1 but not into PL significantly attenuated the consolidation and acquisition of mCPP, however, the inhibition of DNA methylation in PL but not in CA1 enhanced the retrieval of mCPP. All these behavioral effects were absent when OA was infused before 5-aza injection. These findings suggest that 5-aza interfere opiate-related memory, and protein phosphatase plays an important role in this process. [ABSTRACT FROM AUTHOR]

Various impacts of exercise on brain performance following the induction of morphine dependence have been documented; however, the underlying neuronal mechanisms are still unclear. The present research was done to investigate the impact of different exercise training modes on apoptosis, neuronal maturation, and synaptic plasticity in the perforant pathway (PP)-dentate gyrus (DG) synapses in the morphine-dependent rats. Five groups, including a control group (Con, ten healthy rats) and forty morphine-dependent rats were considered as follows (n = 10/group): 1) sedentary-dependent (Sed-D); 2) endurance exercise-dependent (En-D); 3) strength exercise-dependent (St-D); and 4) concurrent exercise-dependent (Co-D). The exercise training groups were subjected to endurance, strength, and concurrent training five days a week for ten weeks. After training sessions, the field excitatory postsynaptic potential (fEPSP) slope and population spike (PS) amplitude in the DG were determined in response to high-frequency stimulation (HFS) of the PP. For assessing neurogenesis and apoptosis, NeuroD and Caspase-3 expression levels were evaluated after all experiments. Concurrent training increased PS amplitude and EPSP compared to the control group. NeuroD in the morphine-dependent rats significantly decreased, but concurrent training returned the NeuroD to its levels in healthy rats. Furthermore, Caspase-3 expression levels in morphine-dependent rats remarkably increased and concurrent training significantly reduced Caspase-3 expression levels compared to the Sed-D group. Concurrent training can ameliorate synaptic plasticity impairment in morphine-dependent rats through neurogenesis promotion and apoptosis reduction. According to the results, concurrent training can be an appropriate novel candidate for treating opioid addiction. • Exercise training reverses memory deficit in morphine-dependent rats. • Different types of exercise exert differential effects on brain function. • Concurrent training prevents morphine-induced neurodegenerative. • Concurrent training increases synaptic plasticity in morphine-dependent rats. • Exercise training may be a new therapy for opioid dependence. [ABSTRACT FROM AUTHOR]

Abstract: It is well established that brain-derived neurotrophic factor (BDNF) plays a pivotal role in brain plasticity-related processes, such as learning, memory and drug addiction. However, changes in expression of BDNF splice variants after acquisition, extinction and reinstatement of cue-elicited morphine seeking behavior have not yet been investigated. Real-time PCR was used to assess BDNF splice variants (I, II, IV and VI) in various brain regions during acquisition, extinction and reinstatement of morphine-conditioned place preference (CPP) in mice. Repeated morphine injections (10mg/kg, i.p.) increased expression of BDNF splice variants II, IV and VI in the hippocampus, caudate putamen (CPu) and nucleus accumbens (NAcc). Levels of BDNF splice variants decreased after extinction training and continued to decrease during reinstatement induced by a morphine priming injection (10mg/kg, i.p.). However, after reinstatement induced by exposure to 6min of forced swimming (FS), expression of BDNF splice variants II, IV and VI was increased in the hippocampus, CPu, NAcc and prefrontal cortex (PFC). After reinstatement induced by 40min of restraint, expression of BDNF splice variants was increased in PFC. These results show that exposure to either morphine or acute stress can induce reinstatement of drug-seeking, but expression of BDNF splice variants is differentially affected by chronic morphine and acute stress. Furthermore, BDNF splice variants II, IV and VI may play a role in learning and memory for morphine addiction in the hippocampus, CPu and NAcc. [Copyright &y& Elsevier]

Background: There is only little information about the effects of GABA receptors agonist and antagonist on morphine self administration. Present study was designed to assess role of GABAB receptors in the regulation of morphine reinforced self administration. Methods: This study was performed in four groups of rats: (1) Saline group, which received saline in the self administration session. (2) Morphine group, which received morphine in saline solution in the self administration session. (3) Baclofen + Morphine group, which received both baclofen 20 min before self administration test and morphine in the self administration session. (4) Phaclofen + Morphine group, which received both phaclofen 20 min before self administration test and morphine in the self administration session. The number of lever pressing and self infusion were recorded. Results: Morphine significantly increased the number of active lever pressing dose dependently in self administration session in comparative with saline group. Administration of baclofen, 20 min before morphine self administration produced significant decrease in the initiation of morphine self administration during all session. Conversely, pre treatment of phaclofen increased the number of active lever pressing and self infusion in this test. Conclusion: Our results indicated a short term treatment by baclofen, reduced morphine maintenance response in a dose dependent manner, suggesting that GABAB receptor agonists could be useful for reversing the neuroadaptations related to opiates. [ABSTRACT FROM AUTHOR]

Abstract: Opioid addiction modulates the extracellular signal-regulated kinase (ERK) leading to synaptic plasticity in the brain. ERK1/2 are stimulated by mitogen-activated protein kinase kinases (MEK1/2), but little is known about the regulation of MEK activity by opioid drugs. This study was designed to assess the acute effects of selective μ-, δ-, and κ-opioid receptor agonists, as well as those induced by chronic morphine and opioid withdrawal, on the content of phosphorylated MEK1/2 in the rat brain. Sufentanil (1–30 μg/kg, 30–120 min) induced dose- and time-dependent increases in MEK1/2 phosphorylation in the cerebral cortex and corpus striatum (30–177%) through a naloxone-sensitive mechanism. Morphine (100 mg/kg, 2 h) also augmented MEK1/2 phosphorylation in the both brain regions (50–70%). Similarly, the selective δ-opioid receptor agonist SNC-80 (10 mg/kg, 30 min) increased MEK1/2 activity in the cortex (60%) that was antagonized by naltrindole. In contrast, the selective κ-opioid receptor agonist (−)-U50488H (10 mg/kg, 30–120 min) did not modify significantly MEK1/2 phosphorylation in the cortex. Chronic morphine (10–100 mg/kg, 5 days) was not associated with alterations in the content of phosphorylated MEK1/2 in the brain (induction of tachyphylaxis to the acute effects). In morphine-dependent rats, however, naloxone (2 mg/kg)-precipitated withdrawal (2–6 h) induced robust increases in MEK1/2 phosphorylation in cortex (27–49%) and striatum (83–123%). Spontaneous opioid withdrawal (24 h) in morphine-dependent rats did not alter MEK1/2 activity in the brain. The findings may be relevant in the context of the pivotal role played by the MEK/ERK pathway in various long-lasting forms of synaptic plasticity associated with opioid addiction. [Copyright &y& Elsevier]

Abstract: This study was designed to determine the affinity and binding profile of β-carbolines for imidazoline I2 receptors and catalytic sites of monoamine oxidase (MAO)-A/B in rat brain and liver. The aim was also directed to assess the in vivo effects of norharman (β-carboline) and LSL 60101 (I2 ligand) on brain 3,4-dihydroxyphenylalanine (DOPA) synthesis in morphine-dependent rats. Competition experiments against [3H]2-BFI revealed that β-carbolines recognize the high- and low-affinity components of the brain imidazoline I2 receptor with the rank order of potency (K iH in nM): noreleagnine (12)>norharman (20)>harmalol (82)>harmaline (177)≫harmine (630)>harman (700)≫FG-7142 (>100,000). In liver, this rank was different: harmine (51)>harmaline (103)=noreleagnine (103)≫harmalol (1290)>harman (2000)≫norharman (12,382)≫FG-7142 (>100,000). In brain and liver, competition curves for β-carbolines against [3H]Ro41-1049 (MAO-A) and [3H]Ro19-6327 (MAO-B) were monophasic and resulted in different drug potencies for the two MAO isozymes (higher affinities for MAO-A) and in similar pharmacological profiles in both tissues. In morphine-dependent rats, naloxone (2 mg/kg, 2 h)-precipitated withdrawal increased the synthesis of DOPA in the cerebral cortex and hippocampus (50%). Pretreatment with norharman (20 mg/kg) or LSL 60101 (20 mg/kg) (30 min before naloxone) fully prevented the stimulatory effect of opiate withdrawal on DOPA synthesis. Norharman and LSL 60101 also attenuated the severity of the withdrawal syndrome. The results indicate that β-carbolines bind with high affinity to imidazoline I2B receptors, and similarly to I2 ligands (LSL 60101) can block the behavioural and biochemical effects of opiate withdrawal. [Copyright &y& Elsevier]

This study was designed to immunodetect and characterize Fas receptor aggregates (oligomerization) in the brain and to assess its possible modulation in opiate addiction. High molecular mass, sodium dodecyl sulfate (SDS)- and β-mercaptoethanol-resistant Fas aggregates (∼110/120 and ∼203 kDa specific peptides) were immunodetected with a cytoplasmic domain-specific antibody in brain tissue (rat, mouse and human) and SH-SY5Y cells by Western blot analysis. Preincubation of rat cortical membranes with N-ethylmaleimide (NEM; 1 mM for 1 h at 37 °C) reduced the immunodensity of ∼203 kDa Fas aggregates (51%) and increased that of 35 kDa native Fas (172%) and 51/48 kDa glycosylated Fas (47%), indicating that disulfide bonds are involved in Fas dimerization. Enzymatic N-deglycosylation of Fas receptor increased the content of Fas aggregates (∼110/120 kDa: five- to sixfold, and ∼203 kDa: two- to threefold), suggesting that Fas glycosylation is involved in regulating receptor dimerization. Chronic (10–100 mg/kg for 5 days), but not acute (30 mg/kg for 2 h), treatment with morphine (a μ-opioid peptide receptor agonist) induced up-regulation of Fas aggregates in the brain (∼110/120 kDa: 39%, and ∼203 kDa: 89%). The acute and/or chronic treatments with δ- and κ-opioid peptide receptor agonists and with a σ1-receptor agonist did not readily alter the content of Fas aggregates in the rat brain. The results indicate that Fas aggregates are natively expressed in the brain and that its density is regulated by the state of Fas glycosylation. These forms of Fas (receptor homodimerization) are functionally relevant because they were up-regulated in the brain of morphine-dependent rats. [Copyright &y& Elsevier]

Chronic experiments on rats with experimental morphine addiction demonstrated that injections of comenic acid are capable of significantly arresting the withdrawal syndrome after morphine discontinuation. Neither habituation nor addiction to comenic acid were developed. Optimum doses of comenic acid have been selected (34 to 50 mg/kg per day). [ABSTRACT FROM AUTHOR]

The sensitivity of 5-HT1A serotonin receptors and α2-adrenoceptors (autoreceptors and heteroreceptors) modulating brain monoamine synthesis was investigated in rats during morphine treatment and after naloxone-precipitated withdrawal. The accumulation of 5-hydroxytryptophan (5-HTP) and 3,4-dihydroxyphenylalanine (DOPA) after decarboxylase inhibition was used as a measure of the rate of tryptophan and tyrosine hydroxylation in vivo. Acute morphine (3–100 mg/kg, 1 h) increased the synthesis of 5-HTP/5-HT in various brain regions (15%–35%) and that of DOPA/dopamine (DA) in striatum (28%–63%), but decreased the synthesis of DOPA/noradrenaline (NA) in hippocampus and cortex (20%–33%). Naloxone (2–60 mg/kg, 1 h) did not alter the synthesis of 5-HTP or DOPA in brain. Tolerance to the inhibitory effect of morphine on DOPA/NA synthesis and a sensitization to its stimulatory effects on DOPA/DA and 5-HTP/5-HT synthesis were observed after chronic morphine and/or in morphine-withdrawn rats. In morphine-dependent rats (tolerant and withdrawn states) the inhibitory effects of the 5-HT1A agonists 8-OH-DPAT and buspirone (0.1 mg/kg, 1 h), and that of the α2-adrenoceptor agonist clonidine (0.1 mg/kg, 1 h), on the synthesis of 5-HTP/5-HT were potentiated (25%–50%). Moreover, the effect of 8-OH-DPAT was antagonized by WAY 100135, a selective 5-HT1A antagonist. In morphine-dependent rats (tolerant state), the inhibitory effects of clonidine on the synthesis of DOPA/NA (hippocampus, hypothalamus) and DOPA/DA (striatum) also were potentiated (35%–55%). In summary, we conclude that morphine addiction is associated with supersensitivity of 5-HT1A serotonin receptors and α2-adrenoceptors (autoreceptors and heteroreceptors) that modulate the synthesis of monoamines in brain. [ABSTRACT FROM AUTHOR]