Morphine as a Potential Oxidative Stress-Causing Agent

Research progress on the impact of opioids on the tumor immune microenvironment (Review)

Opioids have been extensively used in cancer pain management because they can significantly improve the quality of life of patients with advanced cancer. However, recent evidence suggests that opioids can also modulate the tumor immune microenvironment by interacting with opioid receptors on immune cells, potentially regulating tumor progression and efficacy of cancer treatments. Notably, morphine can exhibit a dose-dependent effect on tumor immunity in pancreatic cancer and renal cell models, with lower doses potentially promoting tumor migration and invasion of pancreatic cancer cells, whereas higher doses shows the effect of inhibiting migration and invasion through distinct molecular pathways. The present review therefore comprehensively explored the mechanisms by which opioids can regulate the tumor immune microenvironment, focusing on their effects on immune cells, oxidative stress and angiogenesis. It also examined the interactions between opioids and other analgesics, along with their potential impact on immune modulation. All relevant articles and materials were retrieved from PubMed using the key words 'opioids', 'immune system', 'T cells', 'monocytes', 'macrophages', 'lymphocytes', 'natural killer cell', 'immunotherapy', 'immune cell function' and 'dose dependent effect'. The immunosuppressive effects of opioids, particularly through the µ-opioid receptor, can suppress the activity of natural killer cells, impair antigen presentation and promote the function of regulatory T cells (Tregs). These effects may contribute to tumor progression and metastasis. The severity of these immunosuppressive effects appears to be dose-dependent and can vary among different tumor types. There is evidence to suggest that tumors with higher immune responsiveness will experience more pronounced suppression, including the reduction of tumor angiogenesis, resulting in a decrease in tumor volume and decrease in tumor metastases. Furthermore, the combination of opioids with other analgesics, such as non-steroidal anti-inflammatory drugs, has the potential to exacerbate immunosuppression, which can in turn increase the risk of infections. Therefore, although opioids are essential for pain management in patients with cancer, their potential to modulate the immune microenvironment and promote tumor progression requires careful consideration. Clinicians should evaluate the advantages and disadvantages of opioids, especially regarding emerging immunotherapies, to minimize their potential negative effects on the outcomes of cancer treatments. Future studies are recommended to prioritize the development of strategies that optimize pain management whilst preserving immune function, such as receptor-specific opioid formulations or adjunctive therapies targeting immunosuppressive pathways.

Association of SOD1 rs36232792 with opioid use disorder and a novel PCR-RFLP method for SOD2 rs5746136

AIM

The aim of this study is to find out the effect of SOD1 rs36232792 and SOD2 rs5746136 on the risk of opioid use disorder (OUD).

METHODS

Individuals with OUD (n = 101) and controls (n = 104) were included. SOD1 rs36232792 was genotyped by PCR. A novel PCR-RFLP method for SOD2 rs5746136 was optimized.

RESULTS

A significant difference was observed between individuals with OUD and controls in view of the frequency of 'Ins/Del+Del/Del' genotypes of the SOD1 rs36232792 (p = 0.049), but not for SOD2 rs5746136 (p = 0.254). The intensity of anxiety and depressive symptoms was significantly higher in individuals with OUD compared to controls (p = 0.001).

CONCLUSION

The SOD1 rs36232792 polymorphism could contribute to the risk of OUD in a Turkish population. A novel PCR-RFLP method for SOD2 rs5746136 confirmed by sequencing can be used in a research laboratory without advanced equipment.

Network pharmacology approach to unveiling the mechanism of berberine in the amelioration of morphine tolerance

OBJECTIVE

To investigate the mechanism underlying the effect of the Huanglian decoction (, HLD) on morphine tolerance (MT), using network pharmacology, and to verify these mechanisms in vitro and in vivo.

METHODS

Available biological data on each drug in the HLD were retrieved from the Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform. The target proteins of MT were retrieved from the GeneCards, PharmGkb, Therapeutic Target Database, DrugBank, and Online Mendelian Inheritance in Man databases. Information regarding MT and the drug targets was compared to obtain overlapping elements. This information was imported into the Search Tool for the Retrieval of Interacting Genes/Proteins platform to obtain a protein-protein interaction network diagram. Then, a "component-target" network diagram was constructed using screened drug components and target information, viaCytoscape (Institute for Systems Biology, Seattle, WA, USA). The database for annotation, visualization, and integrated discovery was used for Gene Ontology enrichment and Kyoto Encyclopedia of Genes and Genomes pathways analyses. Pathway information predicted by network pharmacology was verified using animal studies and cell experiments.

RESULTS

Network pharmacology analysis identified 22 active compounds of HLD and revealed that HLD partially ameliorated MT by modulating inflammatory, apoptosis, and nuclear factor kappa B (NF-κB) signaling pathways. Berberine (BBR), one of the main components of HLD, inhibited the development of MT in mice. BBR reduced cell viability while increasing B-cell lymphoma 2 (Bcl-2) protein expression and decreasing CD86, NF-κB, Bax, and Caspase-3 protein expression in brain vascular 2 (BV2) mcroglia cells treated with morphine. Additionally, BBR contributed to a reduction in pro-inflammatory cytokine release and apoptotic cell number.

CONCLUSIONS

BBR, a key component of HLD, effectively suppressed microglial activation and neuro-inflammation by regulating the NF-κB and apoptosis signaling pathways, thereby delaying MT. This study offers a novel approach to enhance the clinical analgesic efficacy of morphine.

Inhibition of the TRPM2 cation channel attenuates morphine tolerance by modulating endoplasmic reticulum stress and apoptosis in rats

Opioid drugs such as morphine are frequently preferred drugs for severe pain in cancer and chronic diseases, but long-term use causes opioid tolerance. The mechanism of tolerance to opioids is quite complex and not fully understood. Our aim in this study was to investigate the effects of TRPM2 cation channel antagonists N-(p-amylcinnamoyl) anthranilic acid (ACA) and 2-aminoethoxydiphenyl borate (2-APB) on morphine analgesia and tolerance in rats. Forty-eight Wistar Albino male rats were included in the study and the rats were randomly divided into drug and control (saline) groups. To induce morphine tolerance, the rats were injected with 10 mg/kg morphine intraperitoneally for 7 days. After thermal analgesia tests, dorsal root ganglion (DRG) and cortex tissues were isolated. Proapoptotic mediators caspase-3 and 9, total oxidant status (TOS) and total antioxidant status (TAS) and ER stress proteins GRP78/BiP, ATF-6, p-IRE1 and pERK levels were measured by biochemical analysis of tissue homogenates. The findings showed that there was a significant decrease in morphine tolerance in rats administered ACA and 2-APB (p<0.05). In addition, biochemical tests revealed a significant decrease in ER stress proteins, proapoptotic biomarkers and TOS levels and a significant increase in TAS levels in DRG, thalamus and sensory cortex tissues (p<0.05). In conclusion, inhibition of TRPM2 cation channel by ACA and 2-APB reduces morphine tolerance by preventing ER stress and apoptosis. It may be possible to increase the analgesic potential of morphine by combined application with ACA and 2-APB in the clinic, but further experimental and molecular studies are needed.

Modulation of oxidative stress/NMDA/nitric oxide pathway by topiramate attenuates morphine dependence in mice

Morphine belongs to the class of opioids and is known for its potential to cause dependence and addiction, particularly with prolonged use. Due to the associated risks, caution must be taken when prescribing and limiting its clinical use. Overexpression of N-methyl-D-aspartate (NMDA) receptors, nitric oxide and cGMP pathway has been implicated in exacerbate the development of morphine dependence and withdrawal. Topiramate, an antiepileptic drug, interacts with various receptors, ion channels and certain enzymes. In this study, we investigated the effects of topiramate on morphine dependence in mice, specifically targeting NMDA/Nitric oxide/cGMP pathway. Mice were administered different doses of topiramate (intraperitoneally) during the development phase, 45 min prior to morphine administration. Topiramate (20 mg/kg) significantly reduced naloxone-induced withdrawal symptoms in morphine-dependent mice. Additionally, subeffective doses of topiramate, when co-administered with NMDA receptor antagonist MK-801 (0.05 mg/kg) or nitric oxide synthase inhibitors such as L-NAME (10 mg/kg, a non-specific NOS inhibitor) and 7-NI (20 mg/kg, a selective nNOS inhibitor), showed a marked reduction in withdrawal signs. However, the effect of topiramate (20 mg/kg) was abolished when co-administered with NMDA (75 mg/kg, an NMDA receptor agonist) or L-arginine (60 mg/kg, a NOS substrate). Ex-vivo analysis revealed that topiramate significantly reduced oxidative stress and downregulated the gene expression of nNOS, NR1, and NR2B in morphine-treated mice. Furthermore, the expression of NR1 and NR2B proteins in the hippocampus and cortex was significantly reduced in topiramate-pretreated mice. Hence, this finding suggest that topiramate mitigates morphine dependence and withdrawal by inhibiting oxidative stress and modulating the NMDA/NO pathway.

The Melatonin Type 2 Receptor Agonist IIK7 Attenuates and Reverses Morphine Tolerance in Neuropathic Pain Rats Through the Suppression of Neuroinflammation in the Spinal Cord

BACKGROUND

Morphine analgesic tolerance (MAT) limits the clinical application of morphine in the management of chronic pain. IIK7 is a melatonin type 2 (MT2) receptor agonist known to have antioxidant properties. Oxidative stress is recognized as a critical factor in MAT. This study sought to assess the impact of IIK7 on the progression of MAT and its potential to reverse pre-existing MAT.

METHODS

Wistar rats underwent partial sciatic nerve transection (PSNT) surgery to induce neuropathic pain (NP). Seven days post nerve transection, we implanted an intrathecal (i.t.) catheter and linked it to an osmotic pump. Rats were randomly divided into the following groups: sham-operated/vehicle, PSNT/vehicle, PSNT/IIK7 50 ng/h, PSNT/MOR 15 g/h, and PSNT/MOR 15 g + IIK7 50 ng/h. We implanted two i.t. catheters for drug administration and the evaluation of the efficacy of IIK7 in reversing pre-established MAT. We linked one to an osmotic pump for MOR or saline continuous i.t. infusion. On the 7th day, the osmotic pump was disconnected, and 50 μg of IIK7 or the vehicle was administered through the second catheter. After 3 h, 15 μg of MOR or saline was administered, and the animal behavior tests were performed. We measured the levels of mRNA for Nrf2 and HO-1, pro-inflammatory cytokines (PICs), and the microglial and astrocyte activation in the spinal cord.

RESULTS

The co-administration of IIK7 with MOR delayed MAT development in PSNT rats by restoring Nrf2 and HO-1 while also inhibiting the microglial-cell and astrocyte activation, alongside the suppression of PICs. Additionally, a single injection of high-dose 50 μg IIK7 was efficient in restoring MOR's antinociception in MOR-tolerant rats.

CONCLUSIONS

Our results indicate that the co-infusion of ultra-low-dose IIK7 can delay MAT development and a high dose can reverse pre-existing MAT.

Could chronic opioid use be an additional risk of hepatic damage in patients with previous liver diseases, and what is the role of microbiome?

Among illicit drugs, addiction from opioids and synthetic opioids is soaring in an unparalleled manner with its unacceptable amount of deaths. Apart from these extreme consequences, the liver toxicity is another important aspect that should be highlighted. Accordingly, the chronic use of these substances, of which fentanyl is the most frequently consumed, represents an additional risk of liver damage in patients with underlying chronic liver disease. These observations are drawn from various preclinical and clinical studies present in literature. Several downstream molecular events have been proposed, but recent pieces of research strengthen the hypothesis that dysbiosis of the gut microbiota is a solid mechanism inducing and worsening liver damage by both alcohol and illicit drugs. In this scenario, the gut flora modification ascribed to non-alcoholic fatty liver disease performs an additive role. Interestingly enough, HBV and HCV infections impact gut-liver axis. In the end, the authors tried to solicit the attention of operators on this major healthcare problem.

Simultaneous use of venlafaxine and calcium channel blockers on tolerance to morphine: The role of mitochondrial damage and oxidative stress in the brain

BACKGROUND

One of the reasons for tolerance to morphine is increased oxidative stress and dysfunction of cell mitochondria in the hippocampus. Venlafaxine and calcium channel blockers can protect mitochondrial function. The investigation of the role of mitochondrial damage and oxidative stress in the simultaneous use of venlafaxine and calcium channel blockers on the acute analgesic effects of morphine and the induction of tolerance to its effects in mice was assessed.

METHOD

In this experimental study, to induce tolerance to morphine, NMRI mice were treated with 50 mg/kg morphine for three consecutive days and 5 mg/kg morphine on the fourth day. Venlafaxine (20 mg/kg) alone or in combination with calcium channel blockers, nimodipine (10 mg/kg), and diltiazem (40 mg/kg) was administered 30 min before morphine, and the hot plate test was used. Then, hippocampal mitochondria were isolated by differential centrifugation method, and the levels of mitochondrial dehydrogenase activity, mitochondrial membrane potential, mitochondrial ROS production rate, as well as the content of glutathione and malondialdehyde in hippocampal mitochondria, were measured.

RESULTS

The administration of venlafaxine-nimodipine and venlafaxine-diltiazem increased morphine's acute analgesic effects (P < 0.05) and reduced the induction and expression of tolerance to the analgesic effects of morphine (P < 0.05). Morphine significantly decreased MTT and GSH and increased MDA, mitochondrial membrane damage, and ROS compared to the control group (P < 0.01). Injection of venlafaxine-nimodipine and also venlafaxine-diltiazem 30 min before morphine can improve these alterations (P < 0.05).

DISCUSSION AND CONCLUSION

Our data showed that the simultaneous use of venlafaxine with calcium channel blockers could increase the acute analgesic effects of morphine and reduce the induction and expression of tolerance to it. Also, the preventive and protective roles of simultaneous administration of venlafaxine and calcium channel blockers on morphine-induced mitochondrial oxidative stress and damage during the tolerance test were achieved.

Serum Malondialdehyde Levels Decreased Along with the Alleviating Effects of Marrubium Parviflorum on Morphine Withdrawal Syndrome in Rats

As a major concern for the clinicians, better treatment of the patients hospitalized to stop opioid abuse has always been a target for the researchers working in this field. On the other hand, the therapeutic potential of medicinal plants has become of great interest to both researchers and consumers in recent years. Among the plants, we can mention those belonging to the genus Marrubium, which have been reported to exert many therapeutic effects. The aim of this research was to investigate the effect of Marrubium parviflorum on morphine withdrawal syndrome and its possible relationship with malondialdehyde (MDA), the indicator of lipid peroxidation that is elevated during the syndrome. To perform this study, 48 rats were divided into 6 groups as follows: 1) Saline-Saline 2) Saline-Morphine; 3, 4, 5) Different doses of the Extract-Morphine (10, 20 and 40 mg.kg-1); 6) and the most effective dose of the extract-Saline. To evaluate the withdrawal syndrome, the increasing doses of morphine were injected subcutaneously for 9 days followed by a single dose of naloxone (4 mg.kg-1, i.p.). Withdrawal symptoms were then assessedand the total withdrawal score (TWS) was calculated. On the other hand, to confirm the efficacy biochemically and to investigate the possible relationship between the observed effects and lipid peroxidation, blood samples were taken for malondialdehyde (MDA) measurement. According to the data, administration of the extract (in two higher doses) significantly alleviated the syndrome-related behavioral signs as well as MDA levels significantly. Overally, based on the results, aerial parts of Marrubium parviflorum seem to be beneficial for better coping with morphine withdrawal syndrome through complex pathways such as suppressing lipid peroxidation, further preclinical and clinical studies are required.

Ferroptosis inhibitor ferrostatin-1 attenuates morphine tolerance development in male rats by inhibiting dorsal root ganglion neuronal ferroptosis

Background

Ferrostatin-1 and liproxstatin-1, both ferroptosis inhibitors, protect cells. Liproxstatin-1 decreases morphine tolerance. Yet, ferrostatin-1's effect on morphine tolerance remains unexplored. This study aimed to evaluate the influence of ferrostatin-1 on the advancement of morphine tolerance and understand the underlying mechanisms in male rats.

Methods

This experiment involved 36 adult male Wistar albino rats with an average weight ranging from 220 to 260 g. These rats were categorized into six groups: Control, single dose ferrostatin-1, single dose morphine, single dose ferrostatin-1 + morphine, morphine tolerance (twice daily for five days), and ferrostatin-1 + morphine tolerance (twice daily for five days). The antinociceptive action was evaluated using both the hot plate and tail-flick tests. After completing the analgesic tests, tissue samples were gathered from the dorsal root ganglia (DRG) for subsequent analysis. The levels of glutathione, glutathione peroxidase 4 (GPX4), and nuclear factor erythroid 2-related factor 2 (Nrf2), along with the measurements of total oxidant status (TOS) and total antioxidant status (TAS), were assessed in the tissues of the DRG.

Results

After tolerance development, the administration of ferrostatin-1 resulted in a significant decrease in morphine tolerance (P < 0.001). Additionally, ferrostatin-1 treatment led to elevated levels of glutathione, GPX4, Nrf2, and TOS (P < 0.001), while simultaneously causing a decrease in TAS levels (P < 0.001).

Conclusions

The study found that ferrostatin-1 can reduce morphine tolerance by suppressing ferroptosis and reducing oxidative stress in DRG neurons, suggesting it as a potential therapy for preventing morphine tolerance.

Unraveling the Hippocampal Molecular and Cellular Alterations behind Tramadol and Tapentadol Neurobehavioral Toxicity

Tramadol and tapentadol are chemically related opioids prescribed for the analgesia of moderate to severe pain. Although safer than classical opioids, they are associated with neurotoxicity and behavioral dysfunction, which arise as a concern, considering their central action and growing misuse and abuse. The hippocampal formation is known to participate in memory and learning processes and has been documented to contribute to opioid dependence. Accordingly, the present study assessed molecular and cellular alterations in the hippocampal formation of Wistar rats intraperitoneally administered with 50 mg/kg tramadol or tapentadol for eight alternate days. Alterations were found in serum hydrogen peroxide, cysteine, homocysteine, and dopamine concentrations upon exposure to one or both opioids, as well as in hippocampal 8-hydroxydeoxyguanosine and gene expression levels of a panel of neurotoxicity, neuroinflammation, and neuromodulation biomarkers, assessed through quantitative real-time polymerase chain reaction (qRT-PCR). Immunohistochemical analysis of hippocampal formation sections showed increased glial fibrillary acidic protein (GFAP) and decreased cluster of differentiation 11b (CD11b) protein expression, suggesting opioid-induced astrogliosis and microgliosis. Collectively, the results emphasize the hippocampal neuromodulator effects of tramadol and tapentadol, with potential behavioral implications, underlining the need to prescribe and use both opioids cautiously.

Exploring neuroadaptive cellular pathways in chronic morphine exposure: An in-vitro analysis of cabergoline and Mdivi-1 co-treatment effects on the autophagy-apoptosis axis

The complex impacts of prolonged morphine exposure continue to be a significant focus in the expanding area of addiction studies. This research investigates the effectiveness of a combined treatment using Cabergoline and Mdivi-1 to counteract the neuroadaptive changes caused by in vitro morphine treatment. The impact of Methadone, Cabergoline, and a combination of Cabergoline and Mdivi-1 on the cellular and molecular responses associated with Morphine-induced changes was studied in human Neuroblastoma (SK-N-MC) and Glioblastoma (U87-MG) cell lines that were exposed to prolong Morphine treatment. Cabergoline and Mdivi-1 combined treatment effectively influenced the molecular alterations associated with neuroadaptation in chronic morphine-exposed neural cells. This combination therapy normalized autophagy and reduced oxidative stress by enhancing total-antioxidant capacity, mitigating apoptosis, restoring BDNF expression, and balancing apoptotic elements. Our research outlines morphine's dual role in modulating mitochondrial dynamics via the dysregulation of the autophagy-apoptosis axis. This emphasizes the significant involvement of DRP1 activity in neurological adaptation processes, as well as disturbances in the dopaminergic pathway during in vitro chronic exposure to morphine in neural cells. This study proposes a novel approach by recommending the potential effectiveness of combining Cabergoline and Mdivi-1 to modulate the neuroadaptations caused by morphine. Additionally, we identified BDNF and PCNA in neural cells as potential neuroprotective markers for assessing the effectiveness of drugs against opioid toxicity, emphasizing the need for further validation. The study uncovers diverse effects observed in pretreated morphine glioblastoma cells under treatment with Cabergoline and methadone. This highlights the potential for new treatments in the DRD2 pathway and underscores the importance of investigating the interplay between autophagy and apoptosis to advance research in managing cancer-related pain. The study necessitates an in-depth investigation into the relationship between autophagy and apoptosis, with a specific emphasis on protein interactions and the dynamics of cell signaling.

Molecular mechanisms of morphine tolerance and dependence; novel insights and future perspectives

Drug addiction is a devastating condition that poses a serious burden on the society. The use of some drugs like morphine for their tremendous analgesic properties is also accompanied with developing tolerance, dependence and the withdrawal symptoms. These symptoms are frequently severe enough to reinforce the person in recovery to start over the use of drug again and hinder the clinical use of drugs like morphine for chronic pain. Research into opioid receptors and related molecular pathways has seen resurgence in the wake of the growing opioid epidemic. The current study provides a comprehensive scientific exploration of the molecular mechanisms and underlying signalling in morphine tolerance and dependence. It also critically evaluates current therapeutic approaches, shedding light on their efficacy and limitations, and future prospects.

Role of antioxidants in the neurobiology of drug addiction: An update

Relationships between protective enzymatic and non-enzymatic pro-antioxidant mechanisms and addictive substances use disorders (SUDs) are analyzed here, based on the results of previous research, as well as on the basis of our current own studies. This review introduces new aspects of comparative analysis of associations of pro-antixidant and neurobiological effects in patients taking psychoactive substances and complements very limited knowledge about relationships with SUDs from different regions, mainly Europe. In view of the few studies on relations between antioxidants and neurobiological processes acting in patients taking psychoactive substances, this review is important from the point of view of showing the state of knowledge, directions of diagnosis and treatment, and further research needed explanation. We found significant correlations between chemical elements, pro-antioxidative mechanisms, and lipoperoxidation in the development of disorders associated with use of addictive substances, therefore elements that show most relations (Pr, Na, Mn, Y, Sc, La, Cr, Al, Ca, Sb, Cd, Pb, As, Hg, Ni) may be significant factors shaping SUDs. The action of pro-antioxidant defense and lipid peroxidation depends on the pro-antioxidative activity of ions. We explain the strongest correlations between Mg and Sb, and lipoperoxidation in addicts, which proves their stimulating effect on lipoperoxidation and on the induction of oxidative stress. We discussed which mechanisms and neurobiological processes change susceptibility to SUDs. The innovation of this review is to show that addicted people have lower activity of dismutases and peroxidases than healthy ones, which indicates disorders of antioxidant system and depletion of enzymes after long-term tolerance of stressors. We explain higher level of catalases, reductases, ceruloplasmin, bilirubin, retinol, α-tocopherol and uric acid of addicts. In view of poorly understood factors affecting addiction, analysis of interactions allows for more effective understanding of pathogenetic mechanisms leading to formation of addiction and development the initiation of directed, more effective treatment (pharmacological, hormonal) and may be helpful in the diagnosis of psychoactive changes.

Amelioration of morphine withdrawal syndrome by systemic and intranasal administration of mesenchymal stem cell-derived secretome in preclinical models of morphine dependence

BACKGROUND

Morphine is an opiate commonly used in the treatment of moderate to severe pain. However, prolonged administration can lead to physical dependence and strong withdrawal symptoms upon cessation of morphine use. These symptoms can include anxiety, irritability, increased heart rate, and muscle cramps, which strongly promote morphine use relapse. The morphine-induced increases in neuroinflammation, brain oxidative stress, and alteration of glutamate levels in the hippocampus and nucleus accumbens have been associated with morphine dependence and a higher severity of withdrawal symptoms. Due to its rich content in potent anti-inflammatory and antioxidant factors, secretome derived from human mesenchymal stem cells (hMSCs) is proposed as a preclinical therapeutic tool for the treatment of this complex neurological condition associated with neuroinflammation and brain oxidative stress.

METHODS

Two animal models of morphine dependence were used to evaluate the therapeutic efficacy of hMSC-derived secretome in reducing morphine withdrawal signs. In the first model, rats were implanted subcutaneously with mini-pumps which released morphine at a concentration of 10 mg/kg/day for seven days. Three days after pump implantation, animals were treated with a simultaneous intravenous and intranasal administration of hMSC-derived secretome or vehicle, and withdrawal signs were precipitated on day seven by i.p. naloxone administration. In this model, brain alterations associated with withdrawal were also analyzed before withdrawal precipitation. In the second animal model, rats voluntarily consuming morphine for three weeks were intravenously and intranasally treated with hMSC-derived secretome or vehicle, and withdrawal signs were induced by morphine deprivation.

RESULTS

In both animal models secretome administration induced a significant reduction of withdrawal signs, as shown by a reduction in a combined withdrawal score. Secretome administration also promoted a reduction in morphine-induced neuroinflammation in the hippocampus and nucleus accumbens, while no changes were observed in extracellular glutamate levels in the nucleus accumbens.

CONCLUSION

Data presented from two animal models of morphine dependence suggest that administration of secretome derived from hMSCs reduces the development of opioid withdrawal signs, which correlates with a reduction in neuroinflammation in the hippocampus and nucleus accumbens.

Opioid Therapy and Implications for Oxidative Balance: A Clinical Study of Total Oxidative Capacity (TOC) and Total Antioxidative Capacity (TAC)

BACKGROUND

Opioids are used in pharmacotherapy for chronic pain. The phenomenon of their influence on the oxidative-antioxidant balance is poorly understood. Additionally, little is known about the oxidative status in patients receiving chronic opioid noncancer pain therapy.

METHODS

The primary goal was to explore oxidative status using the total oxidative capacity (TOC) and total antioxidative capacity (TAC) in patients with chronic lower back pain (LBP) treated with opioids. The secondary task was to present the risk factors connected with the duration of therapy or anthropometric parameters. Plasma TOC and TAC were analyzed in the study group (n = 28), i.e., patients with chronic LBP treated with opioids, and in the control group (n = 11), i.e., healthy volunteers.

RESULTS

The TAC was significantly lower in the study group compared to the control group (p < 0.05), while the TOC did not differ significantly. A statistically lower TOC for buprenorphine compared to oxycodone (p = 0.019) and tramadol (p = 0.036) was observed. The TOC did not differ between tramadol and oxycodone. The highest TAC was described for oxycodone, while the TAC for buprenorphine and tramadol was significantly lower in comparison with oxycodone (p = 0.007 and p = 0.016). The TOC/TAC ratio was higher in patients with nicotinism in both groups.

CONCLUSIONS

Patients receiving chronic opioid therapy presented a lower antioxidative capacity. There were differences in opioid-induced oxidative imbalance, which is very important clinically. Nicotinism increases the oxidative-antioxidative imbalance. The least oxidative capacity was associated with buprenorphine, while oxycodone showed the greatest antioxidant activity. The most favorable TOC/TAC ratio was observed for buprenorphine. It is suggested that buprenorphine or oxycodone has the best profile, and there is no correlation with the duration of opioid therapy or the opioid dose. However, all opioid substances can potentially enhance the oxidative-antioxidative status.

Chronic Voluntary Morphine Intake Is Associated with Changes in Brain Structures Involved in Drug Dependence in a Rat Model of Polydrug Use

Chronic opioid intake leads to several brain changes involved in the development of dependence, whereby an early hedonistic effect (liking) extends to the need to self-administer the drug (wanting), the latter being mostly a prefrontal-striatal function. The development of animal models for voluntary oral opioid intake represents an important tool for identifying the cellular and molecular alterations induced by chronic opioid use. Studies mainly in humans have shown that polydrug use and drug dependence are shared across various substances. We hypothesize that an animal bred for its alcohol preference would develop opioid dependence and further that this would be associated with the overt cortical abnormalities clinically described for opioid addicts. We show that Wistar-derived outbred UChB rats selected for their high alcohol preference additionally develop: (i) a preference for oral ingestion of morphine over water, resulting in morphine intake of 15 mg/kg/day; (ii) marked opioid dependence, as evidenced by the generation of strong withdrawal signs upon naloxone administration; (iii) prefrontal cortex alterations known to be associated with the loss of control over drug intake, namely, demyelination, axonal degeneration, and a reduction in glutamate transporter GLT-1 levels; and (iv) glial striatal neuroinflammation and brain oxidative stress, as previously reported for chronic alcohol and chronic nicotine use. These findings underline the relevance of polydrug animal models and their potential in the study of the wide spectrum of brain alterations induced by chronic morphine intake. This study should be valuable for future evaluations of therapeutic approaches for this devastating condition.

Monoclonal antibody targeting mu-opioid receptor attenuates morphine tolerance via enhancing morphine-induced receptor endocytosis

Morphine is a frequently used analgesic that activates the mu-opioid receptor (MOR), which has prominent side effects of tolerance. Although the inefficiency of morphine in inducing the endocytosis of MOR underlies the development of morphine tolerance, currently, there is no effective therapy to treat morphine tolerance. In the current study, we aimed to develop a monoclonal antibody (mAb) precisely targeting MOR and to determine its therapeutic efficacy on morphine tolerance and the underlying molecular mechanisms. We successfully prepared a mAb targeting MOR, named 3A5C7, by hybridoma technique using a strategy of deoxyribonucleic acid immunization combined with cell immunization, and identified it as an immunoglobulin G mAb with high specificity and affinity for MOR and binding ability to antigens with spatial conformation. Treatment of two cell lines, HEK293T and SH-SY5Y, with 3A5C7 enhanced morphine-induced MOR endocytosis via a G protein-coupled receptor kinase 2 (GRK2)/β-arrestin2-dependent mechanism, as demonstrated by immunofluorescence staining, flow cytometry, Western blotting, coimmunoprecipitation, and small interfering ribonucleic acid (siRNA)-based knockdown. This mAb also allowed MOR recycling from cytoplasm to plasma membrane and attenuated morphine-induced phosphorylation of MOR. We established an in vitro morphine tolerance model using differentiated SH-SY5Y cells induced by retinoic acid. Western blot, enzyme-linked immunosorbent assays, and siRNA-based knockdown revealed that 3A5C7 mAb diminished hyperactivation of adenylate cyclase, the in vitro biomarker of morphine tolerance, via the GRK2/β-arrestin2 pathway. Furthermore, in vivo hotplate test demonstrated that chronic intrathecal administration of 3A5C7 significantly alleviated morphine tolerance in mice, and withdrawal jumping test revealed that both chronic and acute 3A5C7 intrathecal administration attenuated morphine dependence. Finally, intrathecal electroporation of silencing short hairpin RNA illustrated that the in vivo anti-tolerance and anti-dependence efficacy of 3A5C7 was mediated by enhanced morphine-induced MOR endocytosis via GRK2/β-arrestin2 pathway. Collectively, our study provided a therapeutic mAb, 3A5C7, targeting MOR to treat morphine tolerance, mediated by enhancing morphine-induced MOR endocytosis. The mAb 3A5C7 demonstrates promising translational value to treat clinical morphine tolerance.

Erythrocytic Reduced/Oxidized Glutathione and Serum Thiol/Disulfide Homeostasis in Patients with Opioid Use Disorder

Background

This study aimed to evaluate oxidative damage by measuring erythrocytic reduced/oxidized glutathione as an intracellular thiol pool and serum thiol/disulfide homeostasis as an extracellular thiol pool in patients with opioid use disorder.

Methods

In this prospective cross-sectional study, 33 male patients diagnosed with opioid use disorder and 30 healthy male controls were included. Sociodemographic characteristics and psychometric analyzes were performed and addiction characteristics (duration and amount of heroin use, usage methods) were recorded. For the evaluation of oxidative balance, intracellular reduced-oxidized glutathione (reduced glutathione and oxidized glutathione), and extracellular thiol-disulfide (native thiol and disulfide) levels were measured.

Results

There was a decrease in reduced glutathione and native thiol levels and an increase in GSSG and SS levels. Similarly, while oxidized/reduced glutathione, oxidized/total glutathione%, and disulfide/native thiol % ratios increased, the ratio of reduced glutathione/total glutathione% and native thiol/total thiol% decreased. Moreover, a positive correlation was found between the level of both intracellular and extracellular oxidant molecules and the duration and amount of opioid use.

Conclusion

Impaired intracellular reduced glutathione/oxidized glutathione and extracellular disulfide/native thiol homeostasis were found in patients with opioid use disorder. The intracellular and extracellular oxidative stress may cause complications related to chronic opioid use.

The potential protective effect of melatonin and N-acetylcysteine alone and in combination on opioid-induced testicular dysfunction and degeneration in rat

Methadone (Met) is the most common treatment for opioid addiction. Although Met is effective for treatment of opioid dependence, sexual dysfunctions and infertility have been reported as a major problem in patients under Met treatment. The present study aimed to evaluate the effect of melatonin and N-acetylcysteine (N) on morphine and Met-induced oxidative stress, apoptosis, suppression of blood sexual hormones, impairment in sperm parameters, and sexual dysfunction. Adult male Wistar rats (n = 66) were randomly divided into 11 equal groups (n = 6) as follows: control, sham, morphine, Met, Met+N, Met+ melatonin, Met+melatonin+N, morphine+ Met, morphine+Met+ melatonin, morphine+Met+N, and morphine+Met+ melatonin+N groups. On day 56 post-treatment, the blood was collected from the tail and the serum levels of sex hormones were evaluated, then the rats were sacrificed, and their bilateral testes and epididymis were retrieved for histological, immunohistochemical, molecular, testicular tissue stress oxidative status, and sperm parameters assays. Exposure to morphine, Met, and shift of morphine to Met resulted in testicular degeneration that can be attributed to generating the stress oxidative-induced- apoptotic testicular cell death and impairing spermatogenesis. Melatonin and N alone and particularly, in combination with each other improved testicular degeneration, sex hormone suppression, and testicular function mediated by increasing the testicular antioxidant capacity and inhibition of the apoptosis pathway. It's suggested that oral administration of antioxidants may be an effective treatment for attenuating some opioid-related testicular dysfunction and degeneration.

Teneligliptin Co-Infusion Alleviates Morphine Tolerance by Inhibition of Spinal Microglial Cell Activation in Streptozotocin-Induced Diabetic Rats

Morphine (MOR) is a commonly prescribed drug for the treatment of moderate to severe diabetic neuropathic pain (DNP). However, long-term MOR treatment is limited by morphine analgesic tolerance (MAT). The activation of microglial cells and the release of glia-derived proinflammatory cytokines are known to play an important role in the development of MAT. In this study, we aimed to investigate the effects of the dipeptidyl peptidase-4 inhibitor (DPP-4i) teneligliptin (TEN) on MOR-induced microglial cell activation and MAT in DNP rats. DNP was induced in four groups of male Wistar rats through a single intraperitoneal injection of streptozotocin (STZ) (50 mg/kg, freshly dissolved in 5 mmol/L citrate buffer, pH 4.5). Sham rats were administered with the vehicle. Seven days after STZ injection, all rats were implanted with an intrathecal (i.t) catheter connected to a mini-osmotic pump, divided into five groups, and infused with the following combinations: sham + saline (1 µL/h, i.t), DNP + saline (1 µL/h, i.t), DNP + MOR (15 µg/h, i.t), DNP + TEN (2 µg/h, i.t), and DNP + MOR (15 µg/h, i.t) + TEN (2 µg/h, i.t) for 7 days at a rate of 1 μL/h. The MAT was confirmed through the measurement of mechanical paw withdrawal threshold and tail-flick tests. The mRNA expression of neuroprotective proteins nuclear factor erythroid 2-related factor (Nrf2) and heme oxygenase-1 (HO-1) in the dorsal horn was evaluated by quantitative PCR (qPCR). Microglial cell activation and mononucleate cell infiltration in the spinal cord dorsal horn were assessed by immunofluorescence assay (IFA) and Western blotting (WB). The results showed that co-infusion of TEN with MOR significantly attenuated MAT in DNP rats through the restoration of neuroprotective proteins Nrf2 and HO-1 and suppression of microglial cell activation in the dorsal horn. Though TEN at a dose of 2 μg has mild antinociceptive effects, it is highly effective in limiting MAT.

Evaluation of the Effect of Vitamin E on Reproductive Parameters in Morphine-Treated Male Mice

Background

Morphine is a narcotic pain reliever that is prescribed to reduce postoperative pain and can produce reactive oxygen species (ROS). Therefore, it can have negative effects on spermatogenesis and male fertility. Vitamin E is an effective antioxidant which plays an important role in membrane lipid peroxidation due to increased ROS. The present study aimed to evaluate the effects of vitamin E and morphine on sperm parameters, level of malondialdehyde (MDA), and diameter of seminiferous tubules in morphine-treated mice.

Methods

In this experimental study, 80 mice were divided into ten groups (n=8) including control, normal saline, vehicle, morphine, various doses of vitamin E (100, 200, 300 mg/kg), and morphine plus vitamin E (100, 200, 300 mg/kg) groups. The groups were followed up for 30 consecutive days. Sperm parameters, testis weight, the diameter of seminiferous tubules, and the level of MDA were analyzed and compared.

Findings

Data analysis showed seminal parameters decreased significantly (excluding sperm count) and there was an increase in the level of MDA in morphine-treated mice compared with the normal saline group (P<0.05). Administration of E100 to morphinetreated mice did not show a significant difference in the evaluated parameters compared with the morphine group. However, E200 and E300 significantly reduced MDA and improved sperm parameters (P≤0.05).

Conclusion

The results showed co-administration of vitamin E in high doses (200 & 300) could prevent the deleterious effects of morphine on some reproductive parameters and decrease the level of MDA in morphine-treated mice.

Dexmedetomidine, an α2 agonist, increases the morphine analgesic effect and decreases morphine tolerance development by suppressing oxidative stress and TNF/IL-1 signalling pathway in rats

BACKGROUND

The aim of the present study is to examine the possible effect de dexmedetomidine on the development of morphine tolerance in rats including nociception, morphine analgesia, apoptosis, oxidative stress, and tumour necrosis factor (TNF)/ interleukin-1 (IL-1) pathways.

MATERIALS AND METHODS

In this study, 36 Wistar Albino (225-245 g) rats were used. Animals were divided into 6 groups: saline (S), 20 mcg/kg dexmedetomidine (D), 5 mg/kg morphine (M), M + D, morphine tolerance (MT), and MT + D. The analgesic effect was measured with hot plate and tail-flick analgesia tests. After the analgesia tests, the dorsal root ganglia (DRG) tissues were excised. Oxidative stress parameters [total antioxidant status (TAS), total oxidant status (TOS)], TNF, IL-1 and apoptosis enzymes (Caspase-3, Caspase-9), were measured in DRG tissues.

RESULTS

Dexmedetomidine showed an antinociceptive effect when given alone (p < 0.05 to p < 0.001). In addition, dexmedetomidine increased the analgesic effect of morphine (p < 0.001), and also decreased the tolerance to morphine at a significant level (p < 0.01 to p < 0.001). Moreover, it decreased oxidative stress (p < 0.001) and TNF/IL-1 levels when given as an additional drug of single-dose morphine and morphine tolerance group (p < 0.001). Furthermore, dexmedetomidine decreased Caspase-3 and Caspase-9 levels after tolerance development (p < 0.001).

CONCLUSION

Dexmedetomidine has antinociceptive properties, and it increases the analgesic effect of morphine and also prevents tolerance development. These effects probably occur by the modulation of oxidative stress, inflammation and apoptosis.

Role of Tumor Necrosis Factor Receptor 1-Reactive Oxygen Species-Caspase 11 Pathway in Neuropathic Pain Mediated by HIV gp120 With Morphine in Rats

BACKGROUND

Recent clinical research suggests that repeated use of opioid pain medications can increase neuropathic pain in people living with human immunodeficiency virus (HIV; PLWH). Therefore, it is significant to elucidate the exact mechanisms of HIV-related chronic pain. HIV infection and chronic morphine induce proinflammatory factors, such as tumor necrosis factor (TNF)α acting through tumor necrosis factor receptor I (TNFRI). HIV coat proteins and/or chronic morphine increase mitochondrial superoxide in the spinal cord dorsal horn (SCDH). Recently, emerging cytoplasmic caspase-11 is defined as a noncanonical inflammasome and can be activated by reactive oxygen species (ROS). Here, we tested our hypothesis that HIV coat glycoprotein gp120 with chronic morphine activates a TNFRI-mtROS-caspase-11 pathway in rats, which increases neuroinflammation and neuropathic pain.

METHODS

Neuropathic pain was induced by repeated administration of recombinant gp120 with morphine (gp120/M) in rats. Mechanical allodynia was assessed using von Frey filaments, and thermal latency using hotplate test. Protein expression of spinal TNFRI and cleaved caspase-11 was examined using western blots. The image of spinal mitochondrial superoxide was examined using MitoSox Red (mitochondrial superoxide indicator) image assay. Immunohistochemistry was used to examine the location of TNFRI and caspase-11 in the SCDH. Intrathecal administration of antisense oligodeoxynucleotide (AS-ODN) against TNFRI, caspase-11 siRNA, or a scavenger of mitochondrial superoxide was given for antinociceptive effects. Statistical tests were done using analysis of variance (1- or 2-way), or 2-tailed t test.

RESULTS

Intrathecal gp120/M induced mechanical allodynia and thermal hyperalgesia lasting for 3 weeks ( P < .001). Gp120/M increased the expression of spinal TNFRI, mitochondrial superoxide, and cleaved caspase-11. Immunohistochemistry showed that TNFRI and caspase-11 were mainly expressed in the neurons of the SCDH. Intrathecal administration of antisense oligonucleotides against TNFRI, Mito-Tempol (a scavenger of mitochondrial superoxide), or caspase-11 siRNA reduced mechanical allodynia and thermal hyperalgesia in the gp120/M neuropathic pain model. Spinal knockdown of TNFRI reduced MitoSox profile cell number in the SCDH; intrathecal Mito-T decreased spinal caspase-11 expression in gp120/M rats. In the cultured B35 neurons treated with TNFα, pretreatment with Mito-Tempol reduced active caspase-11 in the neurons.

CONCLUSIONS

These results suggest that spinal TNFRI-mtROS-caspase 11 signal pathway plays a critical role in the HIV-associated neuropathic pain state, providing a novel approach to treating chronic pain in PLWH with opioids.

Opium may affect coronary artery disease by inducing inflammation but not through the expression of CD9, CD36, and CD68

The molecular mechanisms of opium action with regard to coronary artery disease (CAD) have not yet been determined. The aim of this study was to evaluate the effect of opium on the expression of scavenger receptors including CD36, CD68, and CD9 tetraspanin in monocytes and the plasma levels of tumor necrosis factor alpha (TNF-α), interferon gamma (IFN-γ), malondialdehyde (MDA), and nitric oxide metabolites (NO_x) in CAD patients with and without opium addiction. This case-control study was conducted on three groups: (1) opium-addicted CAD patients (CAD + OA, n = 30); (2) CAD patients with no opium addiction (CAD, n = 30); and (3) individuals without CAD and opium addiction as the control group (Ctrl, n = 17). The protein and mRNA levels of CD9, CD36, and CD68 were evaluated by the flow cytometry and quantitative polymerase chain reaction (RT-qPCR) methods, respectively. The consumption of atorvastatin, aspirin, and glyceryl trinitrate was found be higher in the CAD groups compared with the control group. The plasma level of TNF-α was significantly higher in the CAD + OA group than in the CAD and Ctrl groups (p = 0.001 and p = 0.005, respectively). MDA levels significantly increased in CAD and CAD + OA patients in comparison with the Ctrl group (p = 0.010 and p = 0.002, respectively). No significant differences were found in CD9, CD36, CD68, IFN-γ, and NO_x between the three groups. The findings demonstrated that opium did not have a significant effect on the expression of CD36, CD68, and CD9 at gene and protein levels, but it might be involved in the development of CAD by inducing inflammation through other mechanisms.

Efficacy of local anaesthetic infiltration via wound catheters after open hepatic surgery: a systematic review and meta-analysis

BACKGROUND

This study analysed whether local anaesthetic wound catheter infiltration (LA-WCI) as an adjunct to intravenous patient-controlled analgesia (IV-PCA) provides superior outcomes compared to IV-PCA alone following liver resection.

METHODS

A systematic review and meta-analysis was conducted for randomised control trials (RCTs) comparing LA-WCI with IV-PCA(LA-WCI group) versus IV-PCA alone (IV-PCA group). PubMed and the Cochrane Library were searched for relevant articles.

RESULTS

Six RCTs with a total of 440 patients were included. Opioid use in the initial 48 h was less in the LA-WCI group [MD -21.27 mg (-39.39,-3.15), p = 0.02]. Pain scores were lower in the LA-WCI group at rest at POD0 (post-operative day 0)6-8 h (p = 0.0009), POD1AM(p = 0.01), POD1PM(p = 0.02) and POD2 (p = 0.0006), and exertion at POD0 0-2 h (p = 0.05), POD1AM(p = 0.03), POD1PM(p = 0.03), POD2 (p = 0.03) and POD3 (p = 0.01). LA-WCI group had reduced length of hospital stay [MD -1.32 days (-2.23,-0.40),p = 0.005], time to ambulation [MD -5.94 h (-8.47,-3.42),p = 0.00001] and incidence of nausea and vomiting (PONV) [OR 0.17 (0.07,0.43),p = 0.0002]. No differences were observed in length of intensive care unit (ICU) stay or incidence of surgical site infections.

DISCUSSION

LA-WCI as an adjunct to opiate IV-PCA post-hepatectomy reduces opioid use, pain scores at multiple time points at rest and exertion, length of hospital stay, time to ambulation and PONV. However, LA-WCI use does not alter length of ICU stay or incidence of wound infection.

Effects of treadmill exercise and chronic stress on anxiety-like behavior, neuronal activity, and oxidative stress in basolateral amygdala in morphine-treated rats

The basolateral amygdala (BLA), which is sensitive to stress, is necessary for reward-seeking behavior and addiction. Regular exercise can produce various positive effects by affecting the BLA. Therefore, we aimed to investigate the effects of chronic stress and treadmill running (TR) on anxiety-like behavior, neuronal activity, lipid peroxidation (measured by malondialdehyde (MDA) levels, a marker for oxidative stress), and total thiol in BLA, in morphine-treated rats. Male Wistar rats were restricted in restraint stress and/or ran on the treadmill and treated with morphine (5 mg/kg) for 21 days. Anxiety-like behavior was evaluated using an elevated plus maze (EPM) and open field tests (OFTs), on day 22. On day 23, neuronal activity in BLA was assessed via single-unit recording. Finally, MDA and total thiol were assessed in BLA. Our results showed that chronic administration of morphine (5 mg/kg) did not affect anxiety-like behavior. However, the morphine-treated rats, subjected to chronic stress and exercise, showed fewer anxiety-like behaviors. Morphine increased BLA's MDA levels but it was prevented by TR. Glutamatergic and GABAergic basal neuronal activities were low in morphine-treated rats but after acute morphine application, there was a significant decrease in GABAergic neuronal activities in the morphine-exercise-stress (Mor-Exe-St) group. The results of this study showed that in morphine-treated rats, stress and exercise or their combination could have either co-directional or opposite effects to the chronic effects of morphine. These results indicate the existence of common pathways similar to endogenous opioids.

Oxidative Stress and Extracellular Matrix Remodeling Are Signature Pathways of Extracellular Vesicles Released upon Morphine Exposure on Human Brain Microvascular Endothelial Cells

Morphine, a commonly used antinociceptive drug in hospitals, is known to cross the blood-brain barrier (BBB) by first passing through brain endothelial cells. Despite its pain-relieving effect, morphine also has detrimental effects, such as the potential induction of redox imbalance in the brain. However, there is still insufficient evidence of these effects on the brain, particularly on the brain endothelial cells and the extracellular vesicles that they naturally release. Indeed, extracellular vesicles (EVs) are nanosized bioparticles produced by almost all cell types and are currently thought to reflect the physiological state of their parent cells. These vesicles have emerged as a promising source of biomarkers by indicating the functional or dysfunctional state of their parent cells and, thus, allowing a better understanding of the biological processes involved in an adverse state. However, there is very little information on the morphine effect on human brain microvascular endothelial cells (HBMECs), and even less on their released EVs. Therefore, the current study aimed at unraveling the detrimental mechanisms of morphine exposure (at 1, 10, 25, 50 and 100 µM) for 24 h on human brain microvascular endothelial cells as well as on their associated EVs. Isolation of EVs was carried out using an affinity-based method. Several orthogonal techniques (NTA, western blotting and proteomics analysis) were used to validate the EVs enrichment, quality and concentration. Data-independent mass spectrometry (DIA-MS)-based proteomics was applied in order to analyze the proteome modulations induced by morphine on HBMECs and EVs. We were able to quantify almost 5500 proteins in HBMECs and 1500 proteins in EVs, of which 256 and 148, respectively, were found to be differentially expressed in at least one condition. Pathway enrichment analysis revealed that the "cell adhesion and extracellular matrix remodeling" process and the "HIF1 pathway", a pathway related to oxidative stress responses, were significantly modulated upon morphine exposure in HBMECs and EVs. Altogether, the combination of proteomics and bioinformatics findings highlighted shared pathways between HBMECs exposed to morphine and their released EVs. These results put forward molecular signatures of morphine-induced toxicity in HBMECs that were also carried by EVs. Therefore, EVs could potentially be regarded as a useful tool to investigate brain endothelial cells dysfunction, and to a different extent, the BBB dysfunction in patient circulation using these "signature pathways".

Effects of Different Opioid Drugs on Oxidative Status and Proteasome Activity in SH-SY5Y Cells

Opioids are the most effective drugs used for the management of moderate to severe pain; however, their chronic use is often associated with numerous adverse effects. Some results indicate the involvement of oxidative stress as well as of proteasome function in the development of some opioid-related side effects including analgesic tolerance, opioid-induced hyperalgesia (OIH) and dependence. Based on the evidence, this study investigated the impact of morphine, buprenorphine or tapentadol on intracellular reactive oxygen species levels (ROS), superoxide dismutase activity/gene expression, as well as β2 and β5 subunit proteasome activity/biosynthesis in SH-SY5Y cells. Results showed that tested opioids differently altered ROS production and SOD activity/biosynthesis. Indeed, the increase in ROS production and the reduction in SOD function elicited by morphine were not shared by the other opioids. Moreover, tested drugs produced distinct changes in β2(trypsin-like) and β5(chymotrypsin-like) proteasome activity and biosynthesis. In fact, while prolonged morphine exposure significantly increased the proteolytic activity of both subunits and β5 mRNA levels, buprenorphine and tapentadol either reduced or did not alter these parameters. These results, showing different actions of the selected opioid drugs on the investigated parameters, suggest that a low µ receptor intrinsic efficacy could be related to a smaller oxidative stress and proteasome activation and could be useful to shed more light on the role of the investigated cellular processes in the occurrence of these opioid drug side effects.

Effect of human mesenchymal stem cell secretome administration on morphine self-administration and relapse in two animal models of opioid dependence

The present study investigates the possible therapeutic effects of human mesenchymal stem cell-derived secretome on morphine dependence and relapse. This was studied in a new model of chronic voluntary morphine intake in Wistar rats which shows classic signs of morphine intoxication and a severe naloxone-induced withdrawal syndrome. A single intranasal-systemic administration of MSCs secretome fully inhibited (&gt;95%; p &lt; 0.001) voluntary morphine intake and reduced the post-deprivation relapse intake by 50% (p &lt; 0.02). Since several studies suggest a significant genetic contribution to the chronic use of many addictive drugs, the effect of MSCs secretome on morphine self-administration was further studied in rats bred as high alcohol consumers (UChB rats). Sub-chronic intraperitoneal administration of morphine before access to increasing concentrations of morphine solutions and water were available to the animals, led UChB rats to prefer ingesting morphine solutions over water, attaining levels of oral morphine intake in the range of those in the Wistar model. Intranasally administered MSCs secretome to UChB rats dose-dependently inhibited morphine self-administration by 72% (p &lt; 0.001); while a single intranasal dose of MSC-secretome administered during a morphine deprivation period imposed on chronic morphine consumer UChB rats inhibited re-access morphine relapse intake by 80 to 85% (p &lt; 0.0001). Both in the Wistar and the UChB rat models, MSCs-secretome administration reversed the morphine-induced increases in brain oxidative stress and neuroinflammation, considered as key engines perpetuating drug relapse. Overall, present preclinical studies suggest that products secreted by human mesenchymal stem cells may be of value in the treatment of opioid addiction.

Acupuncture Inhibits Morphine Induced-Immune Suppress via Antioxidant System

Objectives

A powerful analgesic called Morphine causes addiction behaviors and immune suppression as a potential oxidative stressor. Acupuncture showed to inhibit oxidative stress-induced hepatic damage, regulate reactive oxygen species, and attenuate morphine addiction behaviors. Therefore, we investigated the potential effects of acupuncture on morphine-induced immune suppression.

Materials and Methods

Rats received morphine intravenously through implanted catheters for 3, 7, or 21 days to determine the optimal condition for morphine-induced immune suppression. Second, we examined whether intravenous (iv.) or intraperitoneal (ip.) administration produced different results. Third, the effects of acupuncture in rats who received morphine for 21 days were investigated. Spleen and submandibular lymph node (S-LN) weights and natural killer (NK) cell activity were measured, and the white pulp diameter, total and cortical spleen thicknesses, and the number of lymphoid follicles in S-LNs were examined. The number of immunoreactive cells was also measured.

Results

Decreased organ weights and increased atrophic changes were observed as morphine-induced immune suppression. However, dose-dependent increased immune suppression was not observed between 5.0 mg/kg and 10.0 mg/kg of morphine. And, 3-day withdrawal did not affect. Similar histopathological findings were observed in 5.0 and 10.0 ip. rats when compared to equal dosages of iv., respectively. The morphine induced-immune suppression evidenced by spleen and left S-LN weights, splenic NK cell activities, histopathological findings, and the immunoreactive cell number were normalized by acupuncture.

Conclusion

These results indicate that acupuncture inhibits morphine-induced immune suppression, maybe via antioxidative action.

Opioids and Vitamin C: Known Interactions and Potential for Redox-Signaling Crosstalk

Opioids are among the most widely used classes of pharmacologically active compounds both clinically and recreationally. Beyond their analgesic efficacy via μ opioid receptor (MOR) agonism, a prominent side effect is central respiratory depression, leading to systemic hypoxia and free radical generation. Vitamin C (ascorbic acid; AA) is an essential antioxidant vitamin and is involved in the recycling of redox cofactors associated with inflammation. While AA has been shown to reduce some of the negative side effects of opioids, the underlying mechanisms have not been explored. The present review seeks to provide a signaling framework under which MOR activation and AA may interact. AA can directly quench reactive oxygen and nitrogen species induced by opioids, yet this activity alone does not sufficiently describe observations. Downstream of MOR activation, confounding effects from AA with STAT3, HIF1α, and NF-κB have the potential to block production of antioxidant proteins such as nitric oxide synthase and superoxide dismutase. Further mechanistic research is necessary to understand the underlying signaling crosstalk of MOR activation and AA in the amelioration of the negative, potentially fatal side effects of opioids.

Morphine-induced modulation of Nrf2-antioxidant response element signaling pathway in primary human brain microvascular endothelial cells

Morphine is one of the most potent opioid analgesic used for pain treatment. Morphine action in the central nervous system requires crossing the blood-brain barrier. Due to the controversial relationship between morphine and oxidative stress, the potential pro- or antioxidant effects of morphine in the blood-brain barrier is important to be understood, as oxidative stress could cause its disruption and predispose to neurodegenerative diseases. However, investigation is scarce in human brain endothelial cells. Therefore, the present study evaluated the impact of morphine exposure at three different concentrations (1, 10 and 100 µM) for 24 h and 48 h on primary human brain microvascular endothelial cells. A quantitative data-independent acquisition mass spectrometry strategy was used to analyze proteome modulations. Almost 3000 proteins were quantified of which 217 were reported to be significantly regulated in at least one condition versus untreated control. Pathway enrichment analysis unveiled dysregulation of the Nrf2 pathway involved in oxidative stress response. Seahorse assay underlined mitochondria dysfunctions, which were supported by significant expression modulations of relevant mitochondrial proteins. In conclusion, our study revealed the dysregulation of the Nrf2 pathway and mitochondria dysfunctions after morphine exposure, highlighting a potential redox imbalance in human brain endothelial cells.

Alterations in the Proteome and Phosphoproteome Profiles of Rat Hippocampus after Six Months of Morphine Withdrawal: Comparison with the Forebrain Cortex

The knowledge about proteome changes proceeding during protracted opioid withdrawal is lacking. Therefore, the aim of this work was to analyze the spectrum of altered proteins in the rat hippocampus in comparison with the forebrain cortex after 6-month morphine withdrawal. We utilized 2D electrophoretic workflow (Pro-Q® Diamond staining and Colloidal Coomassie Blue staining) which was preceded by label-free quantification (MaxLFQ). The phosphoproteomic analysis revealed six significantly altered hippocampal (Calm1, Ywhaz, Tuba1b, Stip1, Pgk1, and Aldoa) and three cortical proteins (Tubb2a, Tuba1a, and Actb). The impact of 6-month morphine withdrawal on the changes in the proteomic profiles was higher in the hippocampus—14 proteins, only three proteins were detected in the forebrain cortex. Gene Ontology (GO) enrichment analysis of differentially expressed hippocampal proteins revealed the most enriched terms related to metabolic changes, cytoskeleton organization and response to oxidative stress. There is increasing evidence that energy metabolism plays an important role in opioid addiction. However, the way how morphine treatment and withdrawal alter energy metabolism is not fully understood. Our results indicate that the rat hippocampus is more susceptible to changes in proteome and phosphoproteome profiles induced by 6-month morphine withdrawal than is the forebrain cortex.

Opium may affect coronary artery disease by inducing inflammation but not through the expression of CD9, CD36, and CD68

The molecular mechanisms of opium with regard to coronary artery disease (CAD) have not yet been determined. The aim of the present study was to evaluate the effect of opium on the expression of scavenger receptors including CD36, CD68, and CD9 tetraspanin in monocytes and the plasma levels of tumor necrosis factor alpha (TNF-α), interferon gamma (IFN-γ), malondialdehyde (MDA), and nitric oxide metabolites (NO_x) in patients with CAD with and without opium addiction. This case-control study was conducted in three groups: (1) opium-addicted patients with CAD (CAD+OA, n=30); (2) patients with CAD with no opium addiction (CAD, n=30); and (3) individuals without CAD and opium addiction as the control group (Ctrl, n=17). Protein and messenger RNA (mRNA) levels of CD9, CD36, and CD68 were evaluated by flow cytometry and reverse transcription-quantitative PCR methods, respectively. Consumption of atorvastatin, aspirin, and glyceryl trinitrate was found to be higher in the CAD groups compared with the control group. The plasma level of TNF-α was significantly higher in the CAD+OA group than in the CAD and Ctrl groups (p=0.001 and p=0.005, respectively). MDA levels significantly increased in the CAD and CAD+OA groups in comparison with the Ctrl group (p=0.010 and p=0.002, respectively). No significant differences were found in CD9, CD36, CD68, IFN-γ, and NO_x between the three groups. The findings demonstrated that opium did not have a significant effect on the expression of CD36, CD68, and CD9 at the gene and protein levels, but it might be involved in the development of CAD by inducing inflammation through other mechanisms.

Morphine dependence and withdrawal-induced changes in mouse Sertoli cell (TM4) line: Evaluation of apoptotic, inflammatory and oxidative stress biomarkers

Chronic morphine exerts deleterious effects on testicular function through either suppression of germ cells or somatic including Sertoli cells, probably through the activation of inflammatory, oxidative, and apoptosis biomarkers. Thus, the present study aimed to investigate whether the damaging effects of morphine dependence were reversed by the spontaneous morphine withdrawal or incubation with methadone and/or naloxone in Sertoli (TM4) cells using an in- vitro cell model of morphine dependence. Morphine dependence in TM4 cells was induced by increasing daily doses of morphine for 10 days and then maintained for two weeks in 5 μM. The cAMP levels were measured for an evaluation of morphine dependence. The cell viability and inflammatory, oxidative, apoptosis biomarkers, and glial cell-derived neurotrophic factor (GDNF) were measured after the end of treatment following the incubation of cells with methadone and naloxone and spontaneous withdrawal from morphine. We found that morphine dependence decreased cell viability, GDNF level and increased the levels of pro-oxidant, pro-inflammatory, and apoptotic biomarkers in TM4 cells, while spontaneous withdrawal from morphine and by naloxone decreased the levels of the biomarkers of pro-inflammatory and apoptotic in TM4 cells. Also, despite the low levels of pro-inflammatory factors following morphine withdrawal by methadone, it increased the cleaved/pro-caspase3 ratio in TM4 cells. This study showed that morphine dependence increased apoptosis probably via oxidative stress and inflammation pathways in TM4 cells. Also, it seems likely that spontaneous and naloxone withdrawal have beneficial consequences in the treatment of morphine dependence than methadone therapy, although they may require longer incubation periods.

CF3-substituted diselenide modulatory effects on oxidative stress, induced by single and repeated morphine administrations, in susceptible tissues of mice

Studies reveal that oxidative stress is associated with adverse effects of long-term morphine treatment. The m-trifluoromethyl-diphenyl diselenide (CF3) is a multi-target organoselenium compound that has antioxidant properties in different experimental models. This study aimed to investigate the CF3 effects against redox imbalance in peripheral and central tissues of mice, after single or multiple morphine doses. Swiss male mice received a single dose of morphine (5 mg/kg, s.c.) and CF3 (10 mg/kg, i.g.), or morphine was repeatedly injected (5 mg/kg, s.c.) and CF3 (10 mg/kg, i.g.) administered twice daily for 7 days. Oxidative stress was determined in the hippocampus, liver, and kidney. CF3 reversed the increase in reactive species caused by single and multiple morphine doses in the peripheral tissues. CF3 increased hepatic non-protein thiol levels and the superoxide dismutase (SOD) activity decreased by a single morphine dose. CF3 reversed the reduction in SOD activity in the kidney of mice repeatedly exposed to morphine. The study demonstrates that peripheral tissues were more susceptible than the hippocampus to oxidative stress induced by morphine in mice. The results show that CF3 modulated parameters of oxidative stress modified by single and multiple morphine administrations in peripheral and central tissues of mice.

An update in toxicology of ageing

The field of ageing research has been rapidly advancing in recent decades and it had provided insight into the complexity of ageing phenomenon. However, as the organism-environment interaction appears to significantly affect the organismal pace of ageing, the systematic approach for gerontogenic risk assessment of environmental factors has yet to be established. This puts demand on development of effective biomarker of ageing, as a relevant tool to quantify effects of gerontogenic exposures, contingent on multidisciplinary research approach. Here we review the current knowledge regarding the main endogenous gerontogenic pathways involved in acceleration of ageing through environmental exposures. These include inflammatory and oxidative stress-triggered processes, dysregulation of maintenance of cellular anabolism and catabolism and loss of protein homeostasis. The most effective biomarkers showing specificity and relevancy to ageing phenotypes are summarized, as well. The crucial part of this review was dedicated to the comprehensive overview of environmental gerontogens including various types of radiation, certain types of pesticides, heavy metals, drugs and addictive substances, unhealthy dietary patterns, and sedentary life as well as psychosocial stress. The reported effects in vitro and in vivo of both recognized and potential gerontogens are described with respect to the up-to-date knowledge in geroscience. Finally, hormetic and ageing decelerating effects of environmental factors are briefly discussed, as well.

Sintocalmy, a Passiflora incarnata Based Herbal, Attenuates Morphine Withdrawal in Mice

Chronic opioid use changes brain chemistry in areas related to reward processes, memory, decision-making, and addiction. Both neurons and astrocytes are affected, ultimately leading to dependence. Passiflora incarnata L. (Passifloraceae) is the basis of frequently used herbals to manage anxiety and insomnia, with proven central nervous system depressant effects. Anti-addiction properties of P. incarnata have been reported. The aim of this study was to investigate the effect of a commercial extract of Passiflora incarnata (Sintocalmy®, Aché Laboratory) in the naloxone-induced jumping mice model of morphine withdrawal. In addition, glial fibrillary acidic protein (GFAP) and S100 calcium-binding protein B (S100B) levels were assessed in the frontal cortex and hippocampus, and DNA damage was verified on blood cells. In order to improve solubilization a Sintocalmy methanol extract (SME) was used. SME is mainly composed by flavonoids isovitexin and vitexin. The effects of SME 50, 100 and 200 mg/kg (i.p.) were evaluated in the naloxone-induced withdrawal syndrome in mice. SME 50 and SME 100 mg/kg decreased naloxone-induced jumping in morphine-dependent mice without reducing locomotor activity. No alterations were found in GFAP levels, however SME 50 mg/kg prevented the S100B increase in the frontal cortex and DNA damage. This study shows anti-addiction effects for a commercial standardized extract of P. incarnata and suggests the relevance of proper clinical assessment.

Mesoporous Polydopamine Nanoparticles Attenuate Morphine Tolerance in Neuropathic Pain Rats by Inhibition of Oxidative Stress and Restoration of the Endogenous Antioxidant System

Oxidative stress resulting from reactive oxygen species (ROS) is known to play a key role in numerous neurological disorders, including neuropathic pain. Morphine is one of the commonly used opioids for pain management. However, long-term administration of morphine results in morphine antinociceptive tolerance (MAT) through elevation of ROS and suppression of natural antioxidant defense mechanisms. Recently, mesoporous polydopamine (MPDA) nanoparticles (NPS) have been known to possess strong antioxidant properties. We speculated that morphine delivery through an antioxidant nanocarrier might be a reasonable strategy to alleviate MAT. MPDAs showed a high drug loading efficiency of ∼50%, which was much higher than conventional NPS. Spectral and in vitro studies suggest a superior ROS scavenging ability of NPS. Results from a rat neuropathic pain model demonstrate that MPDA-loaded morphine (MPDA@Mor) is efficient in minimizing MAT with prolonged analgesic effect and suppression of pro-inflammatory cytokines. Additionally, serum levels of liver enzymes and levels of endogenous antioxidants were measured in the liver. Treatment with free morphine resulted in elevated levels of liver enzymes and significantly lowered the activities of endogenous antioxidant enzymes in comparison with the control and MPDA@Mor-treated group. Histopathological examination of the liver revealed that MPDA@Mor can significantly reduce the hepatotoxic effects of morphine. Taken together, our current work will provide an important insight into the development of safe and effective nano-antioxidant platforms for neuropathic pain management.

Repositioning antispasmodic drug Papaverine for the treatment of chronic myeloid leukemia

BACKGROUND

Papaverine is a benzylisoquinoline alkaloid from the plant Papaver somniferum (Opium poppy). It is approved as an antispasmodic drug by the US FDA and is also reported to have anti-cancer properties. Here, Papaverine's activity in chronic myeloid leukemia (CML) is explored using Saccharomyces cerevisiae, mammalian cancer cell lines, and in silico studies.

METHODS

The sensitivity of wild-type and mutant (anti-oxidant defense, apoptosis) strains of S. cerevisiae to the drug Papaverine was tested by colony formation, spot assays, and AO/EB staining. In vitro cytotoxic effect was investigated on HCT15 (colon), A549 (lung), HeLa (cervical), and K562 (Bcr-Abl positive CML), and RAW 264.7 cell lines; cell cycle, mitochondrial membrane potential, ROS detection analyzed in K562 cells using flow cytometry and apoptotic markers, Bcr-Abl signaling pathways examined by western blotting. Molecular docking and molecular dynamics simulation of Papaverine against the target Bcr-Abl were also carried out.

RESULTS

Investigation in S. cerevisiae evidenced Papaverine induces ROS-mediated apoptosis. Subsequent in vitro examination showed that CML cell line K562 was more sensitive to the drug Papaverine. Papaverine induces ROS generation, promotes apoptosis, and inhibits Bcr-Abl downstream signaling. Papaverine acts synergistically with the drug Imatinib. Furthermore, the docking and molecular dynamic simulation studies supported that Papaverine binds to the allosteric site of Bcr-Abl.

CONCLUSION

The data presented here have added support to the concept of polypharmacology of existing drugs and natural compounds to interact with more than one target. This study provides a proof-of-concept for repositioning Papaverine as an anti-CML drug.

Substances of abuse and the blood brain barrier: Interactions with physical exercise

Substance use disorders pose a common medical, social and financial problem. Among the pathomechanisms of substance use disorders, the disruption and increased permeability of the blood-brain barrier has been recently revealed. Physical exercise appears to be a relatively inexpensive and feasible way to implement behavioral therapy counteracting the blood-brain barrier impairment. Concomitantly, there are also studies supporting a potential protective role of selected substances of abuse in maintaining the blood-brain barrier integrity. In this review, we aim to provide a summary on the modulatory influence of physical exercise, a non-pharmacological intervention, on the blood-brain barrier alterations caused by substances of abuse. Further studies are needed to understand the precise mechanisms that underlie various effects of physical exercise in substance use disorders.

Oxidative Stress and Neuroinflammation as a Pivot in Drug Abuse. A Focus on the Therapeutic Potential of Antioxidant and Anti-Inflammatory Agents and Biomolecules

Drug abuse is a major global health and economic problem. However, there are no pharmacological treatments to effectively reduce the compulsive use of most drugs of abuse. Despite exerting different mechanisms of action, all drugs of abuse promote the activation of the brain reward system, with lasting neurobiological consequences that potentiate subsequent consumption. Recent evidence shows that the brain displays marked oxidative stress and neuroinflammation following chronic drug consumption. Brain oxidative stress and neuroinflammation disrupt glutamate homeostasis by impairing synaptic and extra-synaptic glutamate transport, reducing GLT-1, and system X_c⁻ activities respectively, which increases glutamatergic neurotransmission. This effect consolidates the relapse-promoting effect of drug-related cues, thus sustaining drug craving and subsequent drug consumption. Recently, promising results as experimental treatments to reduce drug consumption and relapse have been shown by (i) antioxidant and anti-inflammatory synthetic molecules whose effects reach the brain; (ii) natural biomolecules secreted by mesenchymal stem cells that excel in antioxidant and anti-inflammatory properties, delivered via non-invasive intranasal administration to animal models of drug abuse and (iii) potent anti-inflammatory microRNAs and anti-miRNAs which target the microglia and reduce neuroinflammation and drug craving. In this review, we address the neurobiological consequences of brain oxidative stress and neuroinflammation that follow the chronic consumption of most drugs of abuse, and the current and potential therapeutic effects of antioxidants and anti-inflammatory agents and biomolecules to reduce these drug-induced alterations and to prevent relapse.

Glutathione and Glutathione-Like Sequences of Opioid and Aminergic Receptors Bind Ascorbic Acid, Adrenergic and Opioid Drugs Mediating Antioxidant Function: Relevance for Anesthesia and Abuse

Opioids and their antagonists alter vitamin C metabolism. Morphine binds to glutathione (l-γ-glutamyl-l-cysteinyl-glycine), an intracellular ascorbic acid recycling molecule with a wide range of additional activities. The morphine metabolite morphinone reacts with glutathione to form a covalent adduct that is then excreted in urine. Morphine also binds to adrenergic and histaminergic receptors in their extracellular loop regions, enhancing aminergic agonist activity. The first and second extracellular loops of adrenergic and histaminergic receptors are, like glutathione, characterized by the presence of cysteines and/or methionines, and recycle ascorbic acid with similar efficiency. Conversely, adrenergic drugs bind to extracellular loops of opioid receptors, enhancing their activity. These observations suggest functional interactions among opioids and amines, their receptors, and glutathione. We therefore explored the relative binding affinities of ascorbic acid, dehydroascorbic acid, opioid and adrenergic compounds, as well as various control compounds, to glutathione and glutathione-like peptides derived from the extracellular loop regions of the human beta 2-adrenergic, dopamine D1, histamine H1, and mu opioid receptors, as well as controls. Some cysteine-containing peptides derived from these receptors do bind ascorbic acid and/or dehydroascorbic acid and the same peptides generally bind opioid compounds. Glutathione binds not only morphine but also naloxone, methadone, and methionine enkephalin. Some adrenergic drugs also bind to glutathione and glutathione-like receptor regions. These sets of interactions provide a novel basis for understanding some ways that adrenergic, opioid and antioxidant systems interact during anesthesia and drug abuse and may have utility for understanding drug interactions.

Reactive Oxygen Species (ROS) are Critical for Morphine Exacerbation of HIV-1 gp120-Induced Pain

Many HIV patients develop chronic pain and use opioid-derived medicine as primary analgesics. Emerging clinical evidence suggests that chronic use of opioid analgesics paradoxically heightens pain states in patients. This side effect of opioid analgesics has a significant negative impact on clinical practice, but the underlying pathogenic mechanism remains elusive. Using a mouse model of HIV-associated pain, we simulated the development of morphine exacerbation on pain and investigated potential underlying cellular and molecular pathways. We found that repeated morphine treatment promoted astrocyte activation in the spinal dorsal horn (SDH) and up-regulation of pro-inflammatory cytokines IL-1β and TNF-α. Furthermore, we observed that morphine administration potentiated mitochondrial reactive oxygen species (ROS) in the SDH of the HIV pain model, especially on astrocytes. Systemic application of the ROS scavenger phenyl-N-t-butyl nitrone (PBN) not only blocked the enhancement of gp120-induced hyperalgesia by morphine but also astrocytic activation and cytokine up-regulation. These findings suggest a critical role of ROS in mediating the exacerbation of gp120-induced pain by morphine. Graphical abstract.

The Circadian Hormone Melatonin Inhibits Morphine-Induced Tolerance and Inflammation via the Activation of Antioxidative Enzymes

Opioids are commonly prescribed for clinical pain management; however, dose-escalation, tolerance, dependence, and addiction limit their usability for long-term chronic pain. The associated poor sleep pattern alters the circadian neurobiology, and further compromises the pain management. Here, we aim to determine the correlation between constant light exposure and morphine tolerance and explore the potential of melatonin as an adjuvant of morphine for neuropathic pain treatment. Methods: Wistar rats were preconditioned under constant light (LL) or a regular light/dark (LD) cycle before neuropathic pain induction by chronic constriction injury. An intrathecal (i.t.) osmotic pump was used for continued drug delivery to induce morphine tolerance. Pain assessments, including the plantar test, static weight-bearing symmetry, and tail-flick latency, were used to determine the impact of the light disruption or exogenous melatonin on the morphine tolerance progression. Results: constant light exposure significantly aggravates morphine tolerance in neuropathic rats. Continued infusion of low-dose melatonin (3 μg/h) attenuated morphine tolerance in both neuropathic and naïve rats. This protective effect was independent of melatonin receptors, as shown by the neutral effect of melatonin receptors inhibitors. The transcriptional profiling demonstrated a significant enhancement of proinflammatory and pain-related receptor genes in morphine-tolerant rats. In contrast, this transcriptional pattern was abolished by melatonin coinfusion along with the upregulation of the Kcnip3 gene. Moreover, melatonin increased the antioxidative enzymes SOD2, HO-1, and GPx1 in the spinal cord of morphine-tolerant rats. Conclusion: Dysregulated circadian light exposure significantly compromises the efficacy of morphine’s antinociceptive effect, while the cotreatment with melatonin attenuates morphine tolerance/hyperalgesia development. Our results suggest the potential of melatonin as an adjuvant of morphine in clinical pain management, particularly in patients who need long-term opioid treatment.

Proteomic analysis of protein composition of rat hippocampus exposed to morphine for 10 days; comparison with animals after 20 days of morphine withdrawal

Opioid addiction is recognized as a chronic relapsing brain disease resulting from repeated exposure to opioid drugs. Cellular and molecular mechanisms underlying the ability of organism to return back to the physiological norm after cessation of drug supply are not fully understood. The aim of this work was to extend our previous studies of morphine-induced alteration of rat forebrain cortex protein composition to the hippocampus. Rats were exposed to morphine for 10 days and sacrificed 24 h (groups +M10 and −M10) or 20 days after the last dose of morphine (groups +M10/−M20 and −M10/−M20). The six altered proteins (≥2-fold) were identified in group (+M10) when compared with group (−M10) by two-dimensional fluorescence difference gel electrophoresis (2D-DIGE). The number of differentially expressed proteins was increased to thirteen after 20 days of the drug withdrawal. Noticeably, the altered level of α-synuclein, β-synuclein, α-enolase and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was also determined in both (±M10) and (±M10/−M20) samples of hippocampus. Immunoblot analysis of 2D gels by specific antibodies oriented against α/β-synucleins and GAPDH confirmed the data obtained by 2D-DIGE analysis. Label-free quantification identified nineteen differentially expressed proteins in group (+M10) when compared with group (−M10). After 20 days of morphine withdrawal (±M10/−M20), the number of altered proteins was increased to twenty. We conclude that the morphine-induced alteration of protein composition in rat hippocampus after cessation of drug supply proceeds in a different manner when compared with the forebrain cortex. In forebrain cortex, the total number of altered proteins was decreased after 20 days without morphine, whilst in hippocampus, it was increased.

NADPH oxidase-mediated endothelial injury in HIV- and opioid-induced pulmonary arterial hypertension

We previously demonstrated that the combined exposure of human pulmonary microvascular endothelial cells (HPMECs) to morphine and viral protein(s) results in the oxidative stress-mediated induction of autophagy, leading to shift in the cells from early apoptotic to apoptosis-resistant proliferative status associated with the angioproliferative remodeling observed in pulmonary arterial hypertension (PAH). In this study, we tried to delineate the major source of HIV-1 protein Tat and morphine induced oxidative burst in HPMECs and its consequences on vascular remodeling and PAH in an in vivo model. We observed switch from the initial increased expression of NADPH oxidase (NOX) 2 in response to acute treatment of morphine and HIV-Tat to later increased expression of NOX4 on chronic treatment in the endoplasmic reticulum of HPMECs without any alterations in the mitochondria. Furthermore, NOX-dependent induction of autophagy was observed to play a pivotal role in regulating the endothelial cell survival. Our in vivo findings showed significant increase in pulmonary vascular remodeling, right ventricular systolic pressure, and Fulton index in HIV-transgenic rats on chronic administration of morphine. This was associated with increased oxidative stress in lung tissues and rat pulmonary microvascular endothelial cells. Additionally, endothelial cells from morphine-treated HIV-transgenic rats demonstrated increased expression of NOX2 and NOX4 proteins, inhibition of which ameliorated their increased survival upon serum starvation. In conclusion, this study describes NADPH oxidases as one of the main players in the oxidative stress-mediated endothelial dysfunction on the dual hit of HIV-viral protein(s) and opioids.

Effect of fentanyl and its three novel analogues on biochemical, oxidative, histological, and neuroadaptive markers after sub-acute exposure in mice

AIMS

Comparative sub-acute toxicity, including tolerance and dependence potential of fentanyl and its three novel and potent analogues was determined in mice.

MAIN METHODS

Comparative sub-acute (21 d, intraperitoneal; 1/10 LD₅₀) toxicity of fentanyl and its three novel analogues viz., N-(1-(2-phenoxyethyl)-4-piperidinyl) propionanilide (2), N-isopropyl-3-(4-(N-phenylpropionamido)piperidin-1-yl)propanamide (5), and N-t-butyl-3-(4-(N-phenylpropionamido)piperidin-1-yl)propanamide (6) was determined in mice. Animals were observed for additional seven days to assess the recovery. The brain, liver and kidney toxicity was assessed on the basis of various biochemical, oxidative, histological, and neuroadaptive markers. The expression levels of key neuronal markers associated with drug tolerance and dependence were investigated by western blot and immunohistochemistry.

KEY FINDINGS

Fentanyl and its analogues caused abnormal levels of liver and kidney specific biomarkers in plasma. Brain malondialdehyde (MDA) levels were raised by all the treatments and kidney MDA level by analogue 6 (21 d). Reduced glutathione levels in brain, liver, and kidney were diminished by all the treatments (21 & 28 d) and a significant change in the levels of antioxidant enzymes was also produced mainly after 21 d. The deleterious effects of fentanyl and its analogues were further substantiated by corresponding histopathological changes in brain, liver and kidney (21 & 28 d). These compounds were also found to produce neuroadaptive changes as evidenced by the increased expression levels of c-Fos, glucocorticoid receptor, N-methyl-d-aspartate receptor1 and μ-opioid receptor (21 & 28 d).

SIGNIFICANCE

Three novel analogues of fentanyl were envisaged to have alternative therapeutic potentials. However, their comparative sub-acute toxicity revealed undesirable side effects, thereby masking their therapeutic ability.

Pomegranate Seeds Extract Possesses a Protective Effect against Tramadol-Induced Testicular Toxicity in Experimental Rats

Tramadol is a centrally acting opioid analgesic that is extensively used. The chronic exposure to tramadol induces oxidative stress and toxicity especially for patients consuming it several times a day. Previously, we and others reported that tramadol induces testicular damage in rats. This study was conducted to investigate the possible protective effect of pomegranate seed extract (PgSE) against tramadol-induced testicular damage in adult and adolescent rats. Male rats were orally treated with tramadol or in a combination with PgSE for three weeks. Testes were then dissected and analyzed. Histological and ultrastructural examinations indicated that tramadol induced many structural changes in the testes of adult and adolescent rats including hemorrhage of blood vessels, intercellular spaces, interstitial vacuoles, exfoliation of germ cells in lumen, cell apoptosis, chromatin degeneration of elongated spermatids, and malformation of sperm axonemes. Interestingly, these abnormalities were not observed in tramadol/PgSE cotreated rats. The morphometric analysis revealed that tramadol disrupted collagen metabolism by elevating testicular levels of collagen fibers but that was protected in tramadol/PgSE cotreatment at both ages. In addition, DNA ploidy revealed that S phase of the cell cycle was diminished when adult and adolescent rats were treated with tramadol. However, the S phase had a normal cell population in the cotreated adult rats, but adolescent rats had a lower population than controls. Furthermore, the phytochemistry of PgSE revealed a high content of total polyphenols and total flavonoids within this extract; besides, the DPPH free radical scavenging activity was high. In conclusion, this study indicated that PgSE has a prophylactic effect against tramadol-induced testicular damage in both adult and adolescent ages, although the tramadol toxicity was higher in adolescent age to be completely protected. This prophylactic effect might be due to the high antioxidant compounds within the pomegranate seeds.