The Main Molecular Mechanisms Underlying Methamphetamine- Induced Neurotoxicity and Implications for Pharmacological Treatment

Molecular mechanism of programmed cell death in drug-induced neuronal damage: A special focus on ketamine-induced neurotoxicity

In recent years, the abuse of ketamine as a recreational drug has been growing, and has become one of the most widely abused drugs. Continuous using ketamine poses a risk of drug addiction and complications such as attention deficit disorder, memory loss and cognitive decline. Ketamine-induced neurotoxicity is thought to play a key role in the development of these neurological complications. In this paper, we focus on the molecular mechanisms of ketamine-induced neurotoxicity. According to our analyses, drugs in causing neurotoxicity are closely associated with programmed cell death (PCD) such as apoptosis, autophagy, necroptosis, pyroptosis, and Ferroptosis. Therefore, this review will collate the existing mechanisms of programmed death in ketamine-induced neurotoxicity as well as explore the possible mechanisms by outlining the mechanisms of programmed death in other drug-induced neurotoxicity, which may be helpful in identifying potential therapeutic targets for neurotoxicity induced by ketamine abuse.

Methamphetamine and Methamphetamine-Induced Neuronal Exosomes Modulate the Activity of Rab7a via PTEN to Exert an Influence on the Disordered Autophagic Flux Induced in Neurons

Autophagy is a critical mechanism by which methamphetamine (METH) induces neuronal damage and neurotoxicity. Prolonged METH exposure can result in the accumulation of autophagosomes within cells. The autophagy process encompasses several essential vesicle-related biological steps, collectively referred to as the autophagic flux. However, the precise mechanisms by which METH modulates the autophagic flux and the underlying pathways remain to be elucidated. In this study, we utilized a chronic METH exposure mouse model and cell model to demonstrate that METH treatment leads to an increase in p62 and LC3B-II and the accumulation of autophagosomes in striatal neurons and SH-SY5Y cells. To assess autophagic flux, this study utilized autophagy inhibitors and inducers. The results demonstrated that the lysosomal inhibitor chloroquine exacerbated autophagosome accumulation; however, blocking autophagosome formation with 3-methyladenine did not prevent METH-induced autophagosome accumulation. Compared to the autophagy activator rapamycin, METH significantly reduced autophagosome-lysosome fusion, leading to autophagosome accumulation. Rab7a is a critical regulator of autophagosome-lysosome fusion. Although Rab7a expression was upregulated in SH-SY5Y cells and brain tissues after METH treatment, immunoprecipitation experiments revealed weakened interactions between Rab7a and the lysosomal protein RILP. Overexpression of active Rab7a (Rab7a Q67L) significantly alleviated the METH-induced upregulation of LC3-II and p62. PTEN, a key regulator of Rab7a dephosphorylation, was downregulated following METH treatment, resulting in decreased Rab7a dephosphorylation and reduced Rab7a activity, thereby contributing to autophagosome accumulation. We further investigated the role of neuronal exosomes in the autophagy process. Our results demonstrated that the miRNA expression profiles in exosomes released by METH-induced SH-SY5Y cells were significantly altered, with 122 miRNAs upregulated and 151 miRNAs downregulated. KEGG and GO enrichment analyses of these differentially expressed miRNAs and their target genes revealed significant associations with the autophagy pathway and potential regulation of PTEN expression. Our experiments confirmed that METH-induced exosomes reduced PTEN expression levels and decreased Rab7a dephosphorylation, thereby exacerbating autophagic flux impairment and autophagosome accumulation. In conclusion, our study indicated that METH and its induced neuronal exosomes downregulate PTEN expression, leading to reduced Rab7a dephosphorylation. This, in turn, hinders the fusion of autophagosomes and lysosomes, ultimately resulting in autophagic flux impairment and neuronal damage.

Quercitrin, the primary active ingredient of Albizia julibrissin Durazz. flowers, alleviates methamphetamine-induced hepatotoxicity through a mitochondria-mediated apoptosis pathway

Background and purpose

Methamphetamine (METH), a synthetic psychostimulant and highly addictive drug, could cause depression and acute liver injury. There have been few studies on the mechanism by which METH induces liver damage and on how to alleviate METH-induced hepatic toxicities. Albizzia julibrissin Durazz. flowers (AF) is a traditional Chinese medicine known for its ability to releve depression and soothe the liver. The extracts of AF have shown hepatoprotective effects with their anti-oxidative activities. The potential of AF extracts to alleviate METH-induced hepatic toxicity remains unclear. This study aims to investigate the effects of AF extracts and their priamry active ingredient on METH-induced hepatotoxicity and explore the potential underlying mechanisms.

Methods

Firstly, we used the MTT assay to screen the active components of AF. Then, UPLC-MS/MS was employed to analyze the effective components and identify their activities. In addition, in vitro and in vivo experiments were conducted to explore the effects of the active components on METH-induced hepatic toxicity. Moreover, flow cytometry was employed to detect the effects of the active components of AF on METH-induced hepatocyte cycle arrest and apoptosis; biochemical kits were used to detect oxidative damage; transmission electron microscopy, mitochondrial membrane potential probes, and Western blotting were used to analyze mitochondrial damage. C57/BL6J mice were used to establish a METH-mediated acute liver injury model. After 21 days of intervention with the effective components of AF, serum from mice was collected to detect the level of liver injury markers, and tissues were collected for H&E staining, oxidation index analysis, and mitochondrial-related protein expression analysis.

Results

We found that the ethyl acetate fraction of AF extracts significantly alleviated the decrase in hepatocyte activity induced by METH in vitro. Further UPLC-MS/MS analyses showed that quercitrin (QR) is the major active ingredient of AF extracts. QR alleviates METH-induced hepatocyte apoptosis, cell cycle arrest, oxidative stress, and mitochondrial damage. QR alleviates METH-induced oxidative liver damage in mice and exerts therapeutic effects by regulating the BAX/CASP3 pathway.

Conclusion

AF and its main component QR can effectively alleviate METH-induced liver injury, and its mechanism is related to the mitochondria-mediated apoptotic pathway.

Polysaccharide alleviates neurodegeneration and behavioral deficit by enhancing mitochondrial autophagy in chronic methamphetamine mice

Methamphetamine (METH) is a psychostimulant drug widely abused because of its addictive properties.Its impact on the central nervous system is a major area of interest due to its unique ability to cross the blood-brain barrier, facilitated by its dual water and lipid solubility. Studies have indicated that oxidative stress, neuroinflammation, neuronal apoptosis, and mitochondrial dysfunction are primary mechanisms of METH-induced neurotoxicity. Mitophagy, a process regulated by the phosphatase and tensin homolog deleted on chromosome 10 (PTEN) induced kinase 1 (PINK1)/Parkin signaling pathway, has emerged as a critical mechanism for preserving mitochondrial function. Polysaccharides derived from bamboo fungus have shown potential in mitigating neurotoxicity. However, the role of these polysaccharides in ameliorating methamphetamine-induced neurotoxicity remains unclear. This study aimed to investigate whether polysaccharides could alleviate neurodegeneration in a chronic METH mice model and elucidate the underlying mechanisms and elucidate the mechanisms underlying METH-induced neuronal damage.

Methamphetamine and Ecstasy-Induced Acute Reversible Cerebellar Neurotoxicity in a 3-Year-Old Child: A Case Report

The prevalence of substance use disorders is increasing among children and adolescents. We present a case of a 3-year-old girl who was admitted to our hospital with complaints of acute onset difficulty walking and speaking. Neurological examination revealed dysarthria, truncal ataxia, hypotonia, and hyporeflexia. Brain magnetic resonance imaging, cerebrospinal fluid analysis, and routine blood and urine analyses were normal. Urine drug testing revealed positive results for ecstasy and methamphetamine. The patient's symptoms improved during hospitalization. To our knowledge, this is the youngest reported case of methamphetamine and ecstasy-induced acute reversible cerebellar neurotoxicity. It is essential to carefully monitor acute reversible neurological symptoms related to methamphetamine and ecstasy.

Epidemiological patterns and therapeutic approaches of toad toxin poisoning in a retrospective case study

Toad toxin, a bioactive compound revered in traditional Chinese medicine, has been employed therapeutically for centuries. Recent studies have increasingly confirmed its pharmacological benefits, including cardioprotection, anesthetic effects, anti-inflammatory properties, enhancement of sexual function, and antineoplastic activities. This toxin is applied in the treatment of diverse medical conditions such as chronic bronchitis, pharyngitis, and colon cancer. Nonetheless, the consumption of toad-related substances-such as flesh, eggs, gallbladders-or the medicinal use of toad toxin frequently leads to poisoning incidents, some of which are fatal. This paper comprehensively reviews the principal features of toad toxin poisoning, encompassing clinical symptoms, therapeutic approaches, and other relevant factors to aid in the diagnosis and management, as well as the forensic evaluation of lethal cases. We advocate for further research into the cardiotoxic and neurotoxic effects of toad toxin to deepen our understanding of its poisoning mechanisms and pharmacological profile. Future efforts should focus on regulatory standardization of treatment practices and public education to mitigate the risks associated with toad toxin exposure.

Differential Gene Expression in the Prefrontal Cortex and Hippocampus Following Long-Access Methamphetamine Self-Administration in Male Rats

Methamphetamine (METH) is a potent psychostimulant that disrupts cognitive and neurobiological functions in brain regions such as the prefrontal cortex (PFC) and hippocampus. Chronic METH use leads to altered synaptic plasticity, neuroinflammation, and mitochondrial dysfunction, contributing to methamphetamine use disorder (MUD). This study investigates gene expression changes following long-access intravenous METH self-administration in a rodent model. RNA sequencing (RNA-Seq) was conducted on PFC and hippocampal tissue to identify differentially expressed genes (DEGs) between METH-treated and control groups. We identified 41 DEGs in the PFC and 32 in the hippocampus, many involved in synaptic plasticity, immune response, and energy metabolism. Key findings included downregulation of mitochondrial function genes and upregulation of genes related to neural development and extracellular matrix organization, highlighting the profound transcriptional effects of METH. As a proof-of-concept, we explored individual gene expression variability in relation to economic demand for METH. Rats exhibiting higher demand showed distinct molecular profiles, including upregulation of genes linked to neural signaling and transcription regulation, such as Foxd1 and Cdh1. This preliminary analysis demonstrates that individual differences in drug-seeking correlate with unique gene expression patterns. These findings suggest that both group-level and individual molecular changes contribute to the neurobiological mechanisms of METH use. A better understanding of these individual differences could potentially inform the development of personalized therapeutic approaches for MUD.

Single-Cell RNA-Seq Uncovers Robust Glial Cell Transcriptional Changes in Methamphetamine-Administered Mice

Methamphetamine is a highly addictive stimulant known to cause neurotoxicity, cognitive deficits, and immune dysregulation in the brain. Despite significant research, the molecular mechanisms driving methamphetamine-induced neurotoxicity and glial cell dysfunction remain poorly understood. This study investigates how methamphetamine disrupts glial cell function and contributes to neurodevelopmental and neurodegenerative processes. Using single-cell RNA sequencing (scRNA-seq), we analyzed the transcriptomes of 4000 glial cell-associated genes from the cortical regions of mice chronically administered methamphetamine. Methamphetamine exposure altered the key pathways in astrocytes, including the circadian rhythm and cAMP signaling; in microglia, affecting autophagy, ubiquitin-mediated proteolysis, and mitophagy; and in oligodendrocytes, disrupting lysosomal function, cytoskeletal regulation, and protein processing. Notably, several transcription factors, such as Zbtb16, Hif3a, Foxo1, and Klf9, were significantly dysregulated in the glial cells. These findings reveal profound methamphetamine-induced changes in the glial transcriptomes, particularly in the cortical regions, highlighting potential molecular pathways and transcription factors as targets for therapeutic intervention. This study provides novel insights into the glial-mediated mechanisms of methamphetamine toxicity, contributing to our understanding of its effects on the central nervous system and laying the groundwork for future strategies to mitigate its neurotoxic consequences.

Differentially Expressed Nedd4-binding Protein Ndfip1 Protects Neurons Against Methamphetamine-induced Neurotoxicity

To identify factors involved in methamphetamine (METH) neurotoxicity, we comprehensively searched for genes which were differentially expressed in mouse striatum after METH administration using differential display (DD) reverse transcription-PCR method and sequent single-strand conformation polymorphism analysis, and found two DD cDNA fragments later identified as mRNA of Nedd4 (neural precursor cell expressed developmentally downregulated 4) WW domain-binding protein 5 (N4WBP5), later named Nedd4 family-interacting protein 1 (Ndfip1). It is an adaptor protein for the binding between Nedd4 of ubiquitin ligase (E3) and target substrate protein for ubiquitination. Northern blot analysis confirmed drastic increases in Ndfip1 mRNA in the striatum after METH injections, and in situ hybridization histochemistry showed that the mRNA expression was increased in the hippocampus and cerebellum at 2 h-2 days, in the cerebral cortex and striatum at 18 h-2 days after single METH administration. The knockdown of Ndfip1 expression with Ndfip1 siRNA significantly aggravated METH-induced neurotoxicity in the cultured monoaminergic neuronal cells. These results suggest that drastic increases in Ndfip1 mRNA is compensatory reaction to protect neurons against METH-induced neurotoxicity.

Therapeutic targeting of neuroinflammation in methamphetamine use disorder

Methamphetamine (METH) is a highly addictive illicit psychostimulant with a significant annual fatality rate. Emerging studies highlight its role in neuroinflammation and a range of neurological disorders. This review examines the current landscape of potential drug targets for managing neuroinflammation in METH use disorders (MUDs), with a particular focus on the rationale behind targeting Toll-like receptor 4 (TLR4), the NLR family pyrin domain containing 3 (NLRP3) inflammasome, and other promising targets. Given the multifactorial neurological effects of METH, including cognitive impairment and neurodegeneration, addressing METH-induced neuroinflammation has shown considerable promise in partially mitigating the damaging effects on the central nervous system and improving behavioral outcomes. This article provides an overview of the existing understanding while charting a promising path forward for developing innovative MUD treatments, focusing on neuroinflammation as a therapeutic target. Targeting neuroinflammation in METH-induced neurological disorders shows significant promise in mitigating cognitive impairment and neurodegeneration, offering a potential therapeutic strategy for improving outcomes in MUD. While challenges remain in optimizing treatments, ongoing research into combination therapies, novel drug delivery systems, and neuroprotective agents suggests a positive outlook for more effective interventions.

Betaine improves METH-induced depressive-like behavior and cognitive impairment by alleviating neuroinflammation via NLRP3 inflammasome inhibition

Methamphetamine abuse has been associated with central nervous system damage, contributing to the development of neuropsychiatric disorders such as depressive-like behavior and cognitive impairment. With the escalating prevalence of METH abuse, there is a pressing need to explore effective therapeutic interventions. Thus, the objective of this research was to investigate whether betaine can protect against depressive-like behavior and cognitive impairment induced by METH. Following intraperitoneal injections of METH in mice, varying doses of betaine were administered. Subsequently, the behavioral responses of mice and the impact of betaine intervention on METH-induced neural damage, synaptic plasticity, microglial activation, and NLRP3 inflammatory pathway activation were assessed. Administration 30 mg/kg and 100 mg/kg of betaine ameliorated METH-induced depressive-like behaviors in the open field test, tail suspension test, forced swimming test, and sucrose preference test and cognitive impairment in the novel object recognition test and Barnes maze test. Moreover, betaine exerted protective effects against METH-induced neural damage and reversed the reduced synaptic plasticity, including the decline in dendritic spine density, as well as alterations in the expression of hippocampal PSD95 and Synapsin-1. Additionally, betaine treatment suppressed hippocampal microglial activation induced by METH. Likewise, it also inhibited the activation of the hippocampal NLRP3 inflammasome pathway and reduced IL-1β and TNF-α release. These results collectively suggest that betaine's significant role in mitigating depressive-like behavior and cognitive impairment resulting from METH abuse, presenting potential applications in the prevention and treatment of substance addiction.

Improving neurological and mental health outcomes for children with prenatal drug exposure

Prenatal drug exposure is a global public health problem that will never be completely eliminated. Some drugs are essential for maternal health but many others are used recreationally and for non-medical reasons. Both legal and illegal drugs of addiction and dependency have the potential to cause permanent and even intergenerational harm to the developing child and understanding the direct impact of drugs of addiction on child neurodevelopmental and mental health is difficult and confounded by many social, environmental and possibly, genetic factors. Furthermore, many drugs are not clear neuroteratogens and their impact on the child may be indolent and not appreciated for a long time after exposure has occurred. Despite this, there are numerous windows of opportunity to improve the eventual outcomes of the child including utilising the enormous benefits of neuroplasticity and general principles of basic health care and support. This chapter will discuss current understanding of the impact of drugs of addiction on the growing child and offer possible mitigation strategies to improve outcomes.

Transcranial magnetic stimulation for methamphetamine use disorder: A scoping review within the neurocircuitry model of addiction

The use of methamphetamine in the United States is increasing, contributing now to the "fourth wave" in the national opioid epidemic crisis. People who suffer from methamphetamine use disorder (MUD) have a higher risk of death. No pharmacological interventions are approved by the FDA and psychosocial interventions are only moderately effective. Transcranial Magnetic Stimulation (TMS) is a relatively novel FDA-cleared intervention for the treatment of Major Depressive Disorder (MDD) and other neuropsychiatric conditions. Several lines of research suggest that TMS could be useful for the treatment of addictive disorders, including MUD. We will review those published clinical trials that show potential effects on craving reduction of TMS when applied over the dorsolateral prefrontal cortex (DLPFC) also highlighting some limitations that affect their generalizability and applicability. We propose the use of the Koob and Volkow's neurocircuitry model of addiction as a frame to explain the brain effects of TMS in patients with MUD. We will finally discuss new venues that could lead to a more individualized and effective treatment of this complex disorder including the use of neuroimaging, the exploration of different areas of the brain such as the frontopolar cortex or the salience network and the use of biomarkers.

IL-10 and Cdc42 modulate astrocyte-mediated microglia activation in methamphetamine-induced neuroinflammation

Methamphetamine (Meth) use is known to induce complex neuroinflammatory responses, particularly involving astrocytes and microglia. Building upon our previous research, which demonstrated that Meth stimulates astrocytes to release tumor necrosis factor (TNF) and glutamate, leading to microglial activation, this study investigates the role of the anti-inflammatory cytokine interleukin-10 (IL-10) in this process. Our findings reveal that the presence of recombinant IL-10 (rIL-10) counteracts Meth-induced excessive glutamate release in astrocyte cultures, which significantly reduces microglial activation. This reduction is associated with the modulation of astrocytic intracellular calcium (Ca2+) dynamics, particularly by restricting the release of Ca2+ from the endoplasmic reticulum to the cytoplasm. Furthermore, we identify the small Rho GTPase Cdc42 as a crucial intermediary in the astrocyte-to-microglia communication pathway under Meth exposure. By employing a transgenic mouse model that overexpresses IL-10 (pMT-10), we also demonstrate in vivo that IL-10 prevents Meth-induced neuroinflammation. These findings not only enhance our understanding of Meth-related neuroinflammatory mechanisms, but also suggest IL-10 and Cdc42 as putative therapeutic targets for treating Meth-induced neuroinflammation.

Microglia contribute to methamphetamine reinforcement and reflect persistent transcriptional and morphological adaptations to the drug

Methamphetamine use disorder (MUD) is a chronic, relapsing disease that is characterized by repeated drug use despite negative consequences and for which there are currently no FDA-approved cessation therapeutics. Repeated methamphetamine (METH) use induces long-term gene expression changes in brain regions associated with reward processing and drug-seeking behavior, and recent evidence suggests that methamphetamine-induced neuroinflammation may also shape behavioral and molecular responses to the drug. Microglia, the resident immune cells in the brain, are principal drivers of neuroinflammatory responses and contribute to the pathophysiology of substance use disorders. Here, we investigated transcriptional and morphological changes in dorsal striatal microglia in response to methamphetamine-taking and during methamphetamine abstinence, as well as their functional contribution to drug-taking behavior. We show that methamphetamine self-administration induces transcriptional changes associated with protein folding, mRNA processing, immune signaling, and neurotransmission in dorsal striatal microglia. Importantly, many of these transcriptional changes persist through abstinence, a finding supported by morphological analyses. Functionally, we report that microglial ablation increases methamphetamine-taking, possibly involving neuroimmune and neurotransmitter regulation. In contrast, microglial depletion during abstinence does not alter methamphetamine-seeking. Taken together, these results suggest that methamphetamine induces both short and long-term changes in dorsal striatal microglia that contribute to altered drug-taking behavior and may provide valuable insights into the pathophysiology of MUD.

Effects of congeners of amphetamine on the human heart

Central stimulatory and hallucinogenic drugs of abuse like amphetamine and most congeners of amphetamine can have cardiac harmful effects. These cardiac side effects can lead to morbidities and death. In this paper, we review current knowledge on the direct and indirect effects of these amphetamine congeners on the mammalian heart-more specifically, the isolated human heart muscle preparation. In detail, we address the question of whether and how these drugs affect cardiac contractility and their mechanisms of action. Based on this information, further research areas are defined, and further research efforts are proposed.

STIM1 Mediates Methamphetamine-Induced Neuronal Autophagy and Apoptosis

Methamphetamine (METH) is a widely abused amphetamine-type psychoactive drug that causes serious health problems. Previous studies have demonstrated that METH can induce neuron autophagy and apoptosis in vivo and in vitro. However, the molecular mechanisms underlying METH-induced neuron autophagy and apoptosis remain poorly understood. Stromal interacting molecule 1 (STIM1) was hypothesized to be involved in METH-induced neuron autophagy and apoptosis. Therefore, the expression of STIM1 protein was measured and the effect of blocking STIM1 expression with siRNA was investigated in cultured neuronal cells, and the hippocampus and striatum of mice exposed to METH. Furthermore, intracellular calcium concentration and endoplasmic reticulum (ER) stress-related proteins were determined in vitro and in vivo in cells treated with METH. The results suggested that STIM1 mediates METH-induced neuron autophagy by activating the p-Akt/p-mTOR pathway. METH exposure also resulted in increased expression of Orai1, which was reversed after STIM1 silencing. Moreover, the disruption of intracellular calcium homeostasis induced ER stress and up-regulated the expression of pro-apoptotic protein CCAAT/enhancer-binding protein homologous protein (CHOP), resulting in classic mitochondria apoptosis. METH exposure can cause neuronal autophagy and apoptosis by increasing the expression of STIM1 protein; thus, STIM1 may be a potential gene target for therapeutics in METH-caused neurotoxicity.

The Underlying Neurobiological Mechanisms of Psychosis: Focus on Neurotransmission Dysregulation, Neuroinflammation, Oxidative Stress, and Mitochondrial Dysfunction

Psychosis, defined as a set of symptoms that results in a distorted sense of reality, is observed in several psychiatric disorders in addition to schizophrenia. This paper reviews the literature relevant to the underlying neurobiology of psychosis. The dopamine hypothesis has been a major influence in the study of the neurochemistry of psychosis and in development of antipsychotic drugs. However, it became clear early on that other factors must be involved in the dysfunction involved in psychosis. In the current review, it is reported how several of these factors, namely dysregulation of neurotransmitters [dopamine, serotonin, glutamate, and γ-aminobutyric acid (GABA)], neuroinflammation, glia (microglia, astrocytes, and oligodendrocytes), the hypothalamic-pituitary-adrenal axis, the gut microbiome, oxidative stress, and mitochondrial dysfunction contribute to psychosis and interact with one another. Research on psychosis has increased knowledge of the complexity of psychotic disorders. Potential new pharmacotherapies, including combinations of drugs (with pre- and probiotics in some cases) affecting several of the factors mentioned above, have been suggested. Similarly, several putative biomarkers, particularly those related to the immune system, have been proposed. Future research on both pharmacotherapy and biomarkers will require better-designed studies conducted on an all stages of psychotic disorders and must consider confounders such as sex differences and comorbidity.

Neonatal brain inflammation enhances methamphetamine-induced reinstated behavioral sensitization in adult rats analyzed with explainable machine learning

Neonatal brain inflammation produced by intraperitoneal (i.p.) injection of lipopolysaccharide (LPS) results in long-lasting brain dopaminergic injury and motor disturbances in adult rats. The goal of the present work is to investigate the effect of neonatal systemic LPS exposure (1 or 2 mg/kg, i.p. injection in postnatal day 5, P5, male rats)-induced dopaminergic injury to examine methamphetamine (METH)-induced behavioral sensitization as an indicator of drug addiction. On P70, subjects underwent a treatment schedule of 5 once daily subcutaneous (s.c.) administrations of METH (0.5 mg/kg) (P70-P74) to induce behavioral sensitization. Ninety-six hours following the 5th treatment of METH (P78), the rats received one dose of 0.5 mg/kg METH (s.c.) to reintroduce behavioral sensitization. Hyperlocomotion is a critical index caused by drug abuse, and METH administration has been shown to produce remarkable locomotor-enhancing effects. Therefore, a random forest model was used as the detector to extract the feature interaction patterns among the collected high-dimensional locomotor data. Our approaches identified neonatal systemic LPS exposure dose and METH-treated dates as features significantly associated with METH-induced behavioral sensitization, reinstated behavioral sensitization, and perinatal inflammation in this experimental model of drug addiction. Overall, the analysis suggests that the implementation of machine learning strategies is sensitive enough to detect interaction patterns in locomotor activity. Neonatal LPS exposure also enhanced METH-induced reduction of dopamine transporter expression and [3H]dopamine uptake, reduced mitochondrial complex I activity, and elevated interleukin-1β and cyclooxygenase-2 concentrations in the P78 rat striatum. These results indicate that neonatal systemic LPS exposure produces a persistent dopaminergic lesion leading to a long-lasting change in the brain reward system as indicated by the enhanced METH-induced behavioral sensitization and reinstated behavioral sensitization later in life. These findings indicate that early-life brain inflammation may enhance susceptibility to drug addiction development later in life, which provides new insights for developing potential therapeutic treatments for drug addiction.

GPR55 activation improves anxiety- and depression-like behaviors of mice during methamphetamine withdrawal

Methamphetamine is a potent and highly addictive neurotoxic psychostimulant that triggers a spectrum of adverse emotional responses during withdrawal. G-protein coupled receptor 55 (GPR55), a novel endocannabinoid receptor, is closely associated with mood regulation. Herein, we developed a murine model of methamphetamine-induced anxiety- and depressive-like behavior during abstinence which showed a decreased GPR55 expression in the hippocampus. Activation of GPR55 mitigated these behavioral symptoms, concomitantly ameliorating impairments in hippocampal neurogenesis and reducing neuroinflammation. These findings underscore the pivotal role of GPR55 in mediating the neuropsychological consequences of methamphetamine withdrawal, potentially via mechanisms involving the modulation of hippocampal neurogenesis and inflammation.

Crystal methamphetamine and its effects on mental and oral health: A narrative review

The purpose of this comprehensive literature review is to present the available evidence on the effects of methamphetamine on mental and oral health, as well as provide an overview of the most widely used medical and dental care strategies in the management of meth mouth. For this purpose, PubMed and Google Scholar electronic databases were searched for relevant articles, yielding 115 search results, which were further scrutinized for their relevance, leaving 55 for a detailed review. The analysis of the gathered data indicates that a comprehensive patient-centered approach that takes into consideration the physical, mental, and social aspects is crucial for mitigating the detrimental effects of increasing methamphetamine use.

Methamphetamine Use Disorder and Inflammation: A Case-Control Study

OBJECTIVE

Methamphetamine use disorder (MUD) is a global health condition that impairs a person's health which may result in morbidity and mortality. Inflammation is a crucial process playing a vital role in MUD. For this reason, it is necessary to examine biochemical parameters for follow-up and treatment alternatives.

METHODS

We aimed to reveal the relationship between inflammatory response and MUD by evaluating peripheral hemogram parameters, leukocyte count, subtypes, and their ratios to each other, systemic immune inflammation index (SII), monocyte/high-density lipoprotein (HDL) ratio, and human C-reactive protein (CRP) in adult men with MUD. We included 76 adult male participants in the patient group and 70 adult male participants in the control group. We calculated the neutrophil/lymphocyte rate (NLR), monocyte/lymphocyte rate (MLR), platelet/lymphocyte rate (PLR), and basophil/lymphocyte rate (BLR). In addition, we obtained the SII and the monocyte/HDL rate.

RESULTS

The patients' leukocyte (p<0.001), platelet (p<0.001), plateletcrit (PCT) (p=0.002), neutrophil (p<0.001), monocyte (p=0.002), CRP (p<0.001), NLR (p=0.001), PLR (p=0.004), MLR (p=0.009), SII (p<0.001) and monocyte/HDL ratio (p<0.001) were higher than the control group. We observed a significant and positive relationship between the daily methamphetamine intake, and methamphetamine use duration (p=0.002), PCT (p=0.044), neutrophil (p=0.021), NLR (p=0.001), PLR (p=0.004), MLR (p=0.029), and SII (p<0.001). Daily methamphetamine intake had a significant and positive effect on SII. A one-unit increase in daily methamphetamine intake elevated SII by 165.53 units.

CONCLUSION

The results confirm the presence of peripheral subclinical inflammation and systemic immune inflammation in adult men with MUD.

Psychosocial Risk Factors Associated with Lifetime Amphetamine-Type Stimulants (ATS) Dependence in Drug Detention Centres: Perspectives from the Multiethnicity Study

ATS dependence in Malaysia is growing tremendously across multiracial Malaysian groups, increasing concerns among public health experts and the community. This study highlighted the chronicity of ATS dependence and factors associated with ATS use. Interviewer-administered questionnaires were administered using ASSIST 3.0. A total of N = 327 multiracial people who use ATS were enrolled in this study. The study findings show that 190/327 (58.1%) respondents were ATS dependent. Malays reported the highest number of ATS-dependent (55.8%), followed by Bajau (21.6%) and Kadazan-Dusun (16.8%) ethnic. Across all races, three factors were significantly associated with the ATS dependence: respondents who had a lifetime history of needle sharing aOR = 0.023 (95% CI: 0.003, 0.183) and a lifetime history of heroin use aOR = 0.192 (95% CI: 0.093, 0.396) were at a reduced odd of ATS dependent. Meanwhile, being married reduced the likelihood of becoming dependent on ATS with aOR = 0.378 (95% CI: 0.206, 0.693) compared to being single or divorced. This study revealed that the use of ATS among multiracial Malaysians is alarmingly high, including those in detention centers. Comprehensive harm reduction strategies are urgently needed to prevent the spreading of infectious diseases and other negative health consequences associated with ATS use.

Evaluating the Protective Effects of Thymoquinone on Methamphetamine-induced Toxicity in an In Vitro Model Based on Differentiated PC12 Cells

Methamphetamine (Meth) is a highly addictive stimulant. Its potential neurotoxic effects are mediated through various mechanisms, including oxidative stress and the initiation of the apoptotic process. Thymoquinone (TQ), obtained from Nigella sativa seed oil, has extensive antioxidant and anti-apoptotic properties. This study aimed to investigate the potential protective effects of TQ against Meth-induced toxicity by using an in vitro model based on nerve growth factor-differentiated PC12 cells. Cell differentiation was assessed by detecting the presence of a neuronal marker with flow cytometry. The effects of Meth exposure were evaluated in the in vitro neuronal cell-based model via the determination of cell viability (in an MTT assay) and apoptosis (by annexin/propidium iodide staining). The generation of reactive oxygen species (ROS), as well as the levels of glutathione (GSH) and dopamine, were also determined. The model was used to determine the protective effects of 0.5, 1 and 2 μM TQ against Meth-induced toxicity (at 1 mM). The results showed that TQ reduced Meth-induced neurotoxicity, possibly through the inhibition of ROS generation and apoptosis, and by helping to maintain GSH and dopamine levels. Thus, the impact of TQ treatment on Meth-induced neurotoxicity could warrant further investigation.

Methamphetamine use shortens telomere length in male adults and rats

BACKGROUND

Methamphetamine (MA) use increases the risk of age-related diseases. However, it remains uncertain whether MA use exhibits accelerated biological aging, as indicated by telomere length (TL), a proposed marker of aging. Here we conducted studies in both humans and rats to investigate the association between MA use and TL.

METHODS

We recruited 125 male MA users and 66 healthy controls, aged 30-40 years. MA users were diagnosed using DSM-5 criteria and categorized into two groups: non-severe (n = 78) and severe (n = 47) MA use disorder (MUD). MA-treated conditioned place preference (CPP) rats were utilized to validate our clinical investigations. TL was assessed using real-time polymerase chain reaction.

RESULTS

At clinical levels, MA users exhibited significantly shorter leukocyte TL compared to healthy controls. Among MA users, individuals with severe MUD had significantly shorter leukocyte TL than those with non-severe MUD. Importantly, both univariate and multivariate linear regression analyses demonstrated a negative association between the severity of MA use and leukocyte TL. In a rat model of MA-induced CPP, leukocyte TL was also significantly shortened after MA administration, especially in rats with higher CPP expression or reinstatement scores.

CONCLUSION

MA use shortened TL, and the severity of MA use was negatively correlated with TL. These findings provide new insights into the pathophysiology of accelerated aging caused by MA use and may have implications for identifying biomarkers and developing novel treatment strategies for MUD.

Structural indices of brain aging in methamphetamine use disorder

BACKGROUND

Methamphetamine use is surging globally. It has been linked to premature stroke, Parkinsonism, and dementia, suggesting that it may accelerate brain aging.

METHODS

We performed a retrospective study to determine if structural indices of brain aging were more prevalent prior to old age (26 - 54 years) in individuals with Methamphetamine Use Disorder (MUD), who were in early abstinence (M ± SD = 22.1 ± 25.6 days) than in healthy control (HC) participants. We compared T1-weighted MRI brain scans in age- and sex-matched groups (n = 89/group) on three structural features of brain aging: the brain volume/cerebrospinal fluid (BV/CSF) index, volume of white matter hypointensities/lesions, and choroid plexus volume.

RESULTS

The MUD group had a lower mean BV/CSF index and larger volumes of white matter hypointensities and choroid plexus (p-values < 0.01). Regression analyses showed significant age-by-group effects, indicating different age trajectories of the BV/CSF index and choroid plexus volume, consistent with abnormal global brain atrophy and choroid plexus pathology in the MUD group. Significant age and group main effects reflected a larger volume of white matter hypointensities for older participants across groups and for the MUD group irrespective of age. None of the three measures of brain aging correlated significantly with recent use or duration of recent abstinence from methamphetamine.

CONCLUSIONS

Premature brain pathology, which may reflect cerebrovascular damage and dysfunction of the choroid plexus, occurs in people with MUD. Such pathology may affect cognition and thereby efficacy of behavioral treatments for MUD.

Microglia contribute to methamphetamine reinforcement and reflect persistent transcriptional and morphological adaptations to the drug

Methamphetamine use disorder (MUD) is a chronic, relapsing disease that is characterized by repeated drug use despite negative consequences and for which there are currently no FDA-approved cessation therapeutics. Repeated methamphetamine (METH) use induces long-term gene expression changes in brain regions associated with reward processing and drug-seeking behavior, and recent evidence suggests that methamphetamine-induced neuroinflammation may also shape behavioral and molecular responses to the drug. Microglia, the resident immune cells in the brain, are principal drivers of neuroinflammatory responses and contribute to the pathophysiology of substance use disorders. Here, we investigated transcriptional and morphological changes in dorsal striatal microglia in response to methamphetamine-taking and during methamphetamine abstinence, as well as their functional contribution to drug-taking behavior. We show that methamphetamine self-administration induces transcriptional changes associated with protein folding, mRNA processing, immune signaling, and neurotransmission in dorsal striatal microglia. Importantly, many of these transcriptional changes persist through abstinence, a finding supported by morphological analyses. Functionally, we report that microglial ablation increases methamphetamine-taking, possibly involving neuroimmune and neurotransmitter regulation, and that post-methamphetamine microglial repopulation attenuates drug-seeking following a 21-day period of abstinence. In contrast, microglial depletion during abstinence did not alter methamphetamine-seeking. Taken together, these results suggest that methamphetamine induces both short and long-term changes in dorsal striatal microglia that contribute to altered drug-taking behavior and may provide valuable insights into the pathophysiology of MUD.

The role of NF-κB signaling pathway in reactive astrocytes among neurodegeneration after methamphetamine exposure by integrated bioinformatics

BACKGROUND

Methamphetamine (METH) is a highly addictive stimulant that has become one of the top five risk substances cause deaths from substance abuse. METH exposure increases the risk of neurodegenerative disease (ND), such as Parkinson's disease (PD), leading to disability and death. Activation of reactive astrocytes is an essential factor in neurodegeneration, and their complex role in METH exposure remains unclear. This study explored the role of reactive astrocyte overactivation in neurodegeneration after METH exposure.

METHODS

METH bulk RNA sequencing data (GSE107015 and GSE98793) and single-cell RNA sequencing data (GSE119861) were obtained from the GEO database. We performed immune infiltration analysis on the bulk RNA data. After cell clustering using the single-cell RNA data, astrocytes were extracted for downstream analysis. Differentially expressed genes (DEGs) were identified from the bulk and single-cell RNA sequencing datasets, and GO, KEGG, and GSEA pathway analyses were performed. The PPI network and random forest methods were performed on the overlapping genes of the DEGs to screen hub genes. To explore the common ground between METH exposure and neurodegenerative diseases, we applied a random forest algorithm to PD chip data (GSE99039 and GSE72267) to establish a diagnostic model using the hub genes in METH. New object recognition and the Morris water maze were used to examine cognitive function in mice exposed to METH for 14 days in vivo. Astrocytes were cocultured with neurons for the detection of intercellular crosstalk.

RESULTS

DEGs in the METH group significantly enriched pathways related to NDs, inflammation, and the NF-κB signaling pathway. Immune infiltration analysis revealed significantly increased infiltration of monocytes, T cells, and NK cells and decreased infiltration of neutrophils in the METH group. An intersection of 44 hub genes was screened based on the PPI network and random forest algorithm. These genes suggest that there might be similar pathogenesis between METH exposure and PD. METH exposure resulted in learning memory impairment, hippocampal astrocyte activation, and upregulation of NF-κB expression in mice. Activation of reactive astrocytes cocultured with neurons causes neural damage.

CONCLUSIONS

This study explored the crosstalk between astrocytes and neurons in METH exposure, providing a potential pathogenesis to explore the altered immune microenvironment involving reactive astrocytes after METH exposure.

Protective effects of alpha-lipoic acid on anxiety-like behavior, memory and prevention of hippocampal oxidative stress in methamphetamine-treated rats

RATIONALE

Alpha-lipoic acid is an essential cofactor for aerobic metabolism and acts as a potent antioxidant in the body. It has been shown that acute exposure to methamphetamine induces oxidative stress, which is responsible for severe cognitive deficits in animals. The hippocampus plays a crucial role in the processing of memory and anxiety-like behavior.

OBJECTIVES

In this study, preventive effect of the alpha-lipoic acid on memory impairment in methamphetamine-induced neurotoxicity was investigated.

METHODS

Wistar male rats (200-220 g) were allocated to five groups (seven rats in each group): (1) saline + saline, (2) saline + vehicle (sunflower oil as alpha-lipoic acid solvent), (3) methamphetamine + vehicle, (4) methamphetamine + alpha-lipoic acid 10 mg/kg, and (5) methamphetamine + alpha-lipoic acid 40 mg/kg. Rats received intraperitoneal methamphetamine repeatedly (2 × 20 mg/kg, 2 h interval). Alpha-lipoic acid was injected 30 min, 24 h, and 48 h after the last injection of methamphetamine. The passive avoidance test and open field were used for evaluation of memory retrieval and anxiety, respectively. After behavioral test, rats were anesthetized, their brains were extracted, and after preparing hippocampal homogenates, malondialdehyde (MDA) level, catalase, and superoxide dismutase (SOD) activities were evaluated.

RESULTS

Statistical analysis showed that injection of saline or sunflower oil had no significant effect on anxiety, memory, or oxidative stress markers. Methamphetamine induced memory impairment, increased anxiety-like behavior and MDA level, but it reduced catalase and SOD activity. Treatment with alpha-lipoic acid decreased MDA, increased catalase and SOD activity, and also prevented memory impairment and anxiety-like behavior. Our results showed that alpha-lipoic acid protected the hippocampus from oxidative stress by elevating SOD and CAT activities and reduced memory impairment following acute methamphetamine injection. These findings suggest that alpha-lipoic acid may have a protective effect against the adverse effects of methamphetamine exposure on the hippocampus. Therefore, the current data indicated that ALA can reduce oxidative stress predominantly by its antioxidant property.

Lymphocyte-related ratios in methamphetamine-induced psychotic disorder in Taiwan, comparing with patients with schizophrenia

The lymphocyte-related ratios, neutrophil-to-lymphocyte ratio (NLR), monocyte-to-lymphocyte ratio (MLR) and platelet-to-lymphocyte ratio (PLR) are new measures of inflammation within the body. Few studies have investigated the inflammatory response of patients with methamphetamine-induced psychotic disorder. Clinically, the psychotic symptoms and behavioural manifestation of methamphetamine-induced psychotic disorder are often indistinguishable from paranoid schizophrenia. We aimed to determine the differences in these inflammatory markers between patients with methamphetamine-induced psychotic disorder, patients with schizophrenia and healthy individuals. A total of 905 individuals were recruited. The NLR and MLR were found to be higher in both patients with methamphetamine-induced psychotic disorders and patients with schizophrenia compared with healthy controls. There was no significant difference between the three groups in PLR. When compared with the control group, the methamphetamine-induced psychotic disorder group was significantly higher in NLR 27% (95%CI = 11 to 46%, p = 0.001), MLR 16% (95%CI = 3% to 31%, p = 0.013) and PLR 16% (95%CI = 5% to 28%, p = 0.005). NLR of the group with methamphetamine-induced psychotic disorder was 17% (95%CI = 73% to 94%, p = 0.004) less than the group with schizophrenia, while MLR and PLR did not differ significantly between the two groups. This is the first study that investigated the lymphocyte-related ratios in methamphetamine-induced psychotic disorder when compared with patients with schizophrenia and healthy individuals. The results showed that both patients with methamphetamine-induced psychotic disorder and patients with schizophrenia had stronger inflammatory responses than the healthy control. Our finding also indicated that the inflammatory response of methamphetamine-induced psychotic disorder was between those of patients with schizophrenia and healthy individuals.

Substance Use and Addiction

Efforts to reveal the molecular, cellular, and circuit mechanisms of addiction have largely focused on neurons. Yet accumulating data regarding the ability of glial cells to impact synaptic function, circuit activity, and behavior demands that we explore how these nonneuronal cells contribute to substance use disorders and addiction. Important work has shown that glial cells, including microglia, exhibit changes in phenotype following exposure to drugs of abuse and that modification of glial responses can impact behaviors related to drug seeking and drug taking. While these are critical first steps to understanding how microglia can impact addiction, there are still substantial gaps in knowledge that need to be addressed. This chapter reviews some of the key studies that have shown how microglia are affected by and can contribute to addiction. It also discusses areas where more knowledge is urgently needed to reveal new therapeutic and preventative approaches.

Modeling methamphetamine use disorder and relapse in animals: short- and long-term epigenetic, transcriptional., and biochemical consequences in the rat brain

Methamphetamine use disorder (MUD) is a neuropsychiatric disorder characterized by binge drug taking episodes, intervals of abstinence, and relapses to drug use even during treatment. MUD has been modeled in rodents and investigators are attempting to identify its molecular bases. Preclinical experiments have shown that different schedules of methamphetamine self-administration can cause diverse transcriptional changes in the dorsal striatum of Sprague-Dawley rats. In the present review, we present data on differentially expressed genes (DEGs) identified in the rat striatum following methamphetamine intake. These include genes involved in transcription regulation, potassium channel function, and neuroinflammation. We then use the striatal data to discuss the potential significance of the molecular changes induced by methamphetamine by reviewing concordant or discordant data from the literature. This review identified potential molecular targets for pharmacological interventions. Nevertheless, there is a need for more research on methamphetamine-induced transcriptional consequences in various brain regions. These data should provide a more detailed neuroanatomical map of methamphetamine-induced changes and should better inform therapeutic interventions against MUD.

Single-nucleus transcriptome profiling of prefrontal cortex induced by chronic methamphetamine treatment

Background

Methamphetamine (METH) addiction causes a huge burden on society. The prefrontal cortex (PFC), associated with emotion and cognitive behaviours, is also involved in addiction neurocircuitry. Although bulk RNA sequencing has shown METH-induced gene alterations in the mouse PFC, the impact on different cell types remains unknown.

Aims

To clarify the effects of METH treatment on different cell types of the PFC and the potential pathways involved in METH-related disorders.

Methods

We performed single-nucleus RNA sequencing (snRNA-seq) to examine the transcriptomes of 20 465 nuclei isolated from the PFC of chronic METH-treated and control mice. Main cell types and differentially expressed genes (DEGs) were identified and confirmed by RNA fluorescence in situ hybridization(FISH).

Results

Six main cell types were identified depending on the single-cell nucleus sequencing; of particular interest were the mature oligodendrocytes in the PFC. The DEGs of mature oligodendrocytes were enriched in the myelin sheath, adenosine triphosphate (ATP) metabolic process, mitochondrial function and components, and so on. The messenger RNA levels of Aldoc and Atp5l (FISH) and the protein level of the mitochondrial membrane pore subunit TOM40 (immunofluorescence) decreased in the mature oligodendrocytes. Fast blue staining and transmission electron microscopy image indicated myelin damage, and the myelin thickness decreased in METH brains.

Conclusions

snRNA-seq reveals altered transcriptomes of different cell types in mouse PFC induced by chronic METH treatment, underscoring potential relationships with psychiatric disorders.

Elevated C-reactive protein/albumin ratio in patients with methamphetamine use disorder

BACKGROUND

Methamphetamine use disorder causes significant crises, which have individual, familial, and social consequences. Identifying inflammatory biomarkers for methamphetamine use disorder may be useful for following the inflammatory status of patients in clinical assessment. In this study, we aimed to investigate whether neutrophil/lymphocyte ratio (NLR), platelet/lymphocyte ratio (PLR), monocyte/lymphocyte ratio (MLR), C-reactive protein/albumin ratio (CAR) and neutrophil/albumin ratio (NAR) levels can be used as inflammatory biomarkers in methamphetamine use disorder.

METHODS

The sample comprised 139 treatment-seeking participants who met the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) criteria for methamphetamine use disorder and 139 sociodemographically matched controls. Only hospitalised patients were included. An independent sample t-test, Pearson's correlation test, and binominal logistic regression analysis were performed.

RESULTS

CAR (p = 0.016) and NAR (p = 0.048) levels were significantly higher in individuals with methamphetamine use disorder when compared with healthy controls. The CAR level was found to be a significant predictor of group membership in regression analysis for methamphetamine use disorder.

CONCLUSION

CAR may be a potential inflammatory biomarker for patients with methamphetamine use disorder. CAR as a relatively easier-to-measure biomarker could be beneficial to follow the inflammatory status and treatment response of patients.

Distinct and Dynamic Changes in the Temporal Profiles of Neurotransmitters in Drosophila melanogaster Brain following Volatilized Cocaine or Methamphetamine Administrations

Due to similarities in genetics, cellular response, and behavior, Drosophila is used as a model organism in addiction research. A well-described behavioral response examined in flies is the induced increase in locomotor activity after a single dose of volatilized cocaine (vCOC) and volatilized methamphetamine (vMETH), the sensitivity, and the escalation of the locomotor response after the repeated dose, the locomotor sensitization. However, knowledge about how vCOC and vMETH affect different neurotransmitter systems over time is scarce. We used LC-MS/MS to systematically examine changes in the concentration of neurotransmitters, metabolites and non-metabolized COC and METH in the whole head homogenates of male flies one to seven hours after single and double vCOC or vMETH administrations. vMETH leads to complex changes in the levels of examined substances over time, while vCOC strongly and briefly increases concentrations of dopamine, tyramine and octopamine followed by a delayed degradation into N-acetyl dopamine and N-acetyl tyramine. The first exposure to psychostimulants leads to significant and dynamic changes in the concentrations relative to the second administration when they are more stable over several hours. Further investigations are needed to understand neurochemical and molecular changes post-psychostimulant administration.

A Review on the Disruption of Novel Object Recognition Induced by Methamphetamine

Background

Methamphetamine (MA), is a widely abused synthetic psychostimulant that leads to irreversible brain damage manifested as cognitive impairments in humans and animals. The novel object recognition (NOR) task is a commonly used behavioral assay for the investigation of non-spatial memory in rodents. This test is based on the natural tendency of rodents to spend more time exploring a novel object than a familiar one. NOR test has been used in many studies investigating cognitive deficits caused by MA in rodents. The objective of the present study was to review neurobiological mechanisms that might be responsible for MA-induced NOR alterations.

Methods

A PubMed search showed 83 publications using novel object recognition and methamphetamine as keywords in the past 10 years.

Findings

The present study revealed different MA regimens cause recognition memory impairment in rodents. In addition, it was found that the main neurobiological mechanism involved in MA-induced recognition deficits is the dysfunction of monoaminergic systems.

Conclusion

NOR is a useful test to assess the cognitive functions following MA administration and evaluate the efficacy of new therapeutic agents in MA-addicted individuals.

Gegen-Qinlian decoction-A traditional Chinese medicine formula-Alleviates methamphetamine withdrawal induced anxiety by targeting GABAergic interneuron-pyramidal neuron pathway in mPFC

Methamphetamine (Meth) withdrawal elicits anxiety, which is a public health concern with limited therapeutic options. Previous studies implied a strong correlation between mPFC and Meth withdrawal. Here, we examined the role of Gegen-Qinlian decoction (GQD) in Meth withdrawal anxiety and explored potential therapeutic targets in mPFC. We found that intra-gastric administration of GQD during the withdrawal period efficiently alleviated anxiety-like behaviours in Meth-withdrawn mice. Further, GQD could restore Meth withdrawal-triggered pathway of GABAergic interneurons (GABA IN)-pyramidal neurons (PN) in the mPFC of Meth-withdrawn mice, especially the prelimbic cortex (PrL) sub-region and PV-positive GABA IN. While, GQD had no obvious effects on the glial cells in the mPFC of Meth-withdrawn mice. By transcriptomic analysis and validation of several gene candidates, we found that genes in the MAPK signalling pathway, especially those related to heat shock proteins, including Hspa1a, Hspa1b and Hspb1, might be GQD-targeting genes in mPFC to treat Meth withdrawal anxiety, as indicated that these genes were up-regulated by Meth withdrawal but rescued by GQD in mPFC. Collectively, our findings identified for the first time that GQD could efficiently alleviate Meth withdrawal anxiety, partially through regulating the local GABA IN-PN pathway and transcriptomic profile of mPFC. The present study confirms that TCM, such as GQD, will be a desirable therapeutic approach in the treatment of drug addiction and related emotional deficits.

Prelimbic cortex dynorphin/κ opioid receptor system modulates methamphetamine-induced cognitive impairment

Chronic exposure to methamphetamine (METH) causes severe and persistent cognitive impairment. The present study aimed to investigate the role of dynorphin/κ opioid receptor (KOR) system in the development of METH-induced cognitive impairment. We found that mice showed significant cognitive impairment in the novel object recognition test (NOR) following daily injections of METH (10 mg/kg) for seven consecutive days. Systemic blockade of KOR prevented METH-induced cognitive impairment by pretreatment of the selective KOR antagonist norBNI (10 mg/kg, i.p.) or KOR deletion. Then, significant increased dynorphin and KOR mRNA were observed exclusively in prelimbic cortex (PL) other than infralimbic cortex. Finally, microinjection with norBNI into PL also improved cognitive memory in METH-treated mice using NOR and spontaneous alternation behaviour test. Our results demonstrated that dynorphin/KOR system activation in PL may be a possible mechanism for METH-induced cognitive impairment and shed light on KOR antagonists as a potential neuroprotective agent against the cognitive deficits induced by drug abuse.

Stimulant and hallucinogenic novel psychoactive substances; an update

INTRODUCTION

The renewed interest in considering a range of stimulants, psychedelics and dissociatives as therapeutics emphasizes the need to draft an updated overview of these drugs' clinical and pharmacological issues.

AREAS COVERED

The focus here was on: stimulants (e.g. amphetamines, methamphetamine, and pseudoephedrine; phenethylamines; synthetic cathinones; benzofurans; piperazines; aminoindanes; aminorex derivatives; phenmetrazine derivatives; phenidates); classical (e.g. ergolines; tryptamines; psychedelic phenethylamines), and atypical (e.g. PCP/ketamine-like dissociatives) psychedelics.Stimulant and psychedelics are associated with: a) increased central DA levels (psychedelic phenethylamines, synthetic cathinones and stimulants); b) 5-HT receptor subtypes' activation (psychedelic phenethylamines; recent tryptamine and lysergamide derivatives); and c) antagonist activity at NMDA receptors, (phencyclidine-like dissociatives).

EXPERT OPINION

Clinicians should be regularly informed about the range of NPS and their medical, psychobiological and psychopathological risks both in the acute and long term. Future research should focus on an integrative model in which pro-drug websites' analyses are combined with advanced research approaches, including computational chemistry studies so that in vitro and in vivo preclinical studies of index novel psychoactives can be organized. The future of psychedelic research should focus on identifying robust study designs to convincingly assess the potential therapeutic benefits of psychedelics, molecules likely to present with limited dependence liability levels.

Methamphetamine increases force of contraction in isolated human atrial preparations through the release of noradrenaline

We measured the cardiac contractile effects of the sympathomimetic amphetamine-like drug methamphetamine alone and in the presence of cocaine or propranolol in human atrial preparations. For a more comprehensive analysis, we also examined the effects of methamphetamine in preparations from the left and right atria of mice and, for comparison, analyzed the cardiac effects of amphetamine itself. In human atrial preparations, methamphetamine and amphetamine increased the contractile force, the relaxation rate, and the rate of tension development, and shortened the time to maximum tension and the time to relaxation. Likewise, in mice preparations, methamphetamine and amphetamine increased the contractile force in the left atrium and increased the beating rate in the right atrium. The effect in human atrial preparations started at 1µM, therefore methamphetamine was less effective and potent than isoproterenol in increasing contractile force. These positive inotropic effects of methamphetamine were greatly attenuated by 10µM cocaine and abolished by 10µM propranolol. The inotropic effects of methamphetamine in human atrial preparations were associated with, and are believed to be mediated at least in part by, an increase in the phosphorylation state of the inhibitory subunit of troponin. In conclusion, the sympathomimetic central stimulant drug methamphetamine (as well as amphetamine) increased contractile force and protein phosphorylation, presumably through a release of noradrenaline in isolated human atrial preparations. Thus, methamphetamine acts as an indirect sympathomimetic in the human atrium.

Maternal use of methamphetamine alters cardiovascular function in the adult offspring

Methamphetamine is one of the most commonly used illicit drugs during pregnancy. Most studies investigating the impact of maternal use of methamphetamine on children have focused on neurological outcomes. In contrast, cardiovascular outcomes in these children have not been characterized. Recent studies in rodents provide evidence that prenatal exposure to methamphetamine induces changes in cardiac gene expression, changes in the heart's susceptibility to ischemic injury, and changes in vascular function that may increase the risk of developing cardiovascular disorders later in life. Importantly, these changes are sex-dependent. This review summarizes our current understanding of how methamphetamine use during pregnancy impacts the cardiovascular function of adult offspring and highlights gaps in our knowledge of the potential cardiovascular risks associated with prenatal exposure to methamphetamine.

Histone modifications in cocaine, methamphetamine and opioids

Cocaine, methamphetamine and opioids are leading causes of drug abuse-related deaths worldwide. In recent decades, several studies revealed the connection between and epigenetics. Neural cells acquire epigenetic alterations that drive the onset and progress of the SUD by modifying the histone residues in brain reward circuitry. Histone modifications, especially acetylation and methylation, participate in the regulation of gene expression. These alterations, as well as other host and microenvironment factors, are associated with a serious of negative neurocognitive disfunctions in various patient populations. In this review, we highlight the evidence that substantially increase the field's ability to understand the molecular actions underlying SUD and summarize the potential approaches for SUD pharmacotherapy.

Effects of chronic methamphetamine exposure on rewarding behavior and neurodegeneration markers in adult mice

Recreational and medical use of stimulants among young adults have gained popularity in the United States over the last decade and their use may increase vulnerability to brain biochemical changes and addictive behaviors. The long-term effects of chronic stimulant exposure in later adulthood have not been fully elucidated.Our study investigated whether chronic exposure to methamphetamine (METH), at a dose designed to emulate human therapeutic dosing for ADHD, would promote biochemical alterations and affect sensitivity to the rewarding effects of subsequent METH dosing.Groups of 3.5-month-old male and female C57BL/6J mice were administered non-contingent intraperitoneal injections of either saline or METH (1.4 mg/kg) twice a day for 1 month (5 days/week). METH (0.5 mg/kg)-induced conditioned place preference (CPP) was tested in mice to determine the effects of previous METH exposure on reward-related behavior. Mice were randomly assigned to Experiment I (males and females) or Experiment II (females only) in which CPP testing was respectively performed either 0.5 or 5 months after the end of METH injections, at ~5 or 10 months old respectively. The midbrain and striatum, regions involved in reward circuit, were assessed for markers associated with neurotoxicity, dopaminergic function, neuroinflammation and epigenetic changes after behavioral testing.Previous exposure to chronic METH did not have significant short-term effects on CPP response but led to a decreased CPP response in 10-month-old females. Previous exposure to METH induced some short-term changes to biochemical markers measured in a brain region and sex-dependent manner, while long-term changes were only observed with GFAP and KDM5C.In conclusion, our data suggest sex- and post-exposure duration-dependent outcomes and warrant further exploration of the long-term neurobehavioral consequences of psychostimulant use in both sexes.

Overview of blood-brain barrier dysfunction in methamphetamine abuse

Methamphetamine (METH) is one of the psychostimulants most widely abused in the world. METH abuse can lead to severe neurotoxicity. The blood-brain barrier (BBB) is a natural barrier separating the central nervous system (CNS) from the peripheral blood circulation, which can limit or regulate the exchange of toxic substances, molecules, ions, etc., to maintain the homeostasis of CNS. Long-term or high dose abuse of METH can cause structural or functional abnormalities of the BBB and increase the risk of neurodegenerative diseases. In this review, we discussed the mechanisms of METH-induced BBB dysfunction, summarized the risk factors that could exacerbate METH-induced BBB dysfunction, and introduced some potential therapeutic agents. It would provide an important basis and direction for the prevention and treatment of BBB dysfunction induced by METH.

Cardiolipin and OPA1 Team up for Methamphetamine-Induced Locomotor Activity by Promoting Neuronal Mitochondrial Fusion in the Nucleus Accumbens of Mice

Mitochondria are highly dynamic organelles with coordinated cycles of fission and fusion occurring continuously to satisfy the energy demands in the complex architecture of neurons. How mitochondria contribute to addicted drug-induced adaptable mitochondrial networks and neuroplasticity remains largely unknown. Through liquid chromatography-mass spectrometry-based lipidomics, we first analyzed the alteration of the mitochondrial lipidome of three mouse brain areas in methamphetamine (METH)-induced locomotor activity and conditioned place preference. The results showed that METH remodeled the mitochondrial lipidome of the hippocampus, nucleus accumbens (NAc), and striatum in both models. Notably, mitochondrial hallmark lipid cardiolipin (CL) was specifically increased in the NAc in METH-induced hyperlocomotor activity, which was accompanied by an elongated giant mitochondrial morphology. Moreover, METH significantly boosted mitochondrial respiration and ATP generation as well as the copy number of mitochondrial genome DNA in the NAc. By screening the expressions of mitochondrial dynamin-related proteins, we found that repeated METH significantly upregulated the expression of long-form optic atrophy type 1 (L-OPA1) and enhanced the interaction of L-OPA1 with CL, which may promote mitochondrial fusion in the NAc. On the contrary, neuronal OPA1 depletion in the NAc not only recovered the dysregulated mitochondrial morphology and synaptic vesicle distribution induced by METH but also attenuated the psychomotor effect of METH. Collectively, upregulated CL and OPA1 cooperate to mediate METH-induced adaptation of neuronal mitochondrial dynamics in the NAc, which correlates with the psychomotor effect of METH. These findings propose a potential therapeutic approach for METH addiction by inhibiting neuronal mitochondrial fusion.

Long-term methamphetamine self-administration increases mesolimbic mitochondrial oxygen consumption and decreases striatal glutathione

Neurotoxic regimens of methamphetamine (METH) are known to increase reactive oxygen species (ROS), affect redox homeostasis, and lead to damage in dopamine neurons. Functional changes induced by long-term METH self-administration on mitochondrial respiratory metabolism and redox homeostasis are less known. To fill this gap, we implanted a jugular catheter into adult male mice and trained them to nose poke for METH infusions. After several weeks of METH exposure, we collected samples of the ventral striatum (vST) and the ventral midbrain (vMB). We used HPLC to determine the levels of the ROS scavenger glutathione in its reduced (GSH) and oxidized forms. Then, we used high-resolution respirometry to determine the oxygen consumption rate (OCR) of mitochondrial complexes. Finally, using in vivo electrophysiology, we assessed changes in dopamine neuron firing activity in the VTA. METH self-administration produced a decrease of the GSH pool in vST, correlating with lifetime METH intake. We observed increased mitochondrial respiration across the two mesolimbic regions. METH self-administration decreases firing rate and burst activity but increases the number of spontaneously active dopamine neurons per track. We conclude that METH self-administration progressively decreased the antioxidant pool in sites of higher dopamine release and produced an increase in mitochondrial metabolism in the mesolimbic areas, probably derived from the increased number of dopamine neurons actively firing. However, dopamine neuron firing activity is decreased by METH self-administration, reflecting a new basal level of dopamine neurotransmission.

Metformin attenuates depressive-like behaviour of methamphetamine withdrawal in mice: A mechanistic approach

OBJECTIVES

Methamphetamine (METH) as a potent psychostimulant drug with a high potency of dependence rate that results in neurotoxicity has become a major drug of abuse in many parts of the world. Unfortunately, there is limited evidence regarding treatment of METH withdrawal syndrome. Therefore, we aimed to investigate whether metformin mitigate the methamphetamine (METH) withdrawal syndrome in male mice. Based on the literature, depression and anxiety are the major METH withdrawal symptoms.

METHODS

Here, METH (2 mg/kg) was administered to mice twice a day for 14 constitutive days to induce animal model of METH-induced withdrawal syndrome. To do this, mice in control group and those with METH withdrawal syndrome were divided into treatment (receiving metformin in 3 doses of 50, 100 and 200 mg/kg for 10 days) and non-treatment sub-groups. Following the behavioural test, the animals were sacrificed; their hippocampus was dissected to measure oxidative stress parameters and expression of cellular energy homeostasis and immune-inflammatory genes.

RESULTS

Our data revealed that metformin provoked antidepressant effects in behavioural tests through AMPK overexpression as an important mitochondrial energetic sensor and inhibition of Tlr4 overexpression in the immune system gene expression. In addition, metformin was able to improve oxidative stress biomarkers and neuronal damage in the hippocampus and restore cellular energy homeostasis and immune system gene expression.

CONCLUSIONS

The data suggested that metformin can influence the hippocampus through targeting mitochondria and their performance, and consequently, neuroinflammation responses and brain metabolic changes. It is supposed to be a new therapeutic option in clinical trials of depression and anxiety following METH withdrawal treatment.

Cognitive impairment and changes of red blood cell components and serum levels of IL-6, IL-18, and L-tryptophan in methamphetamine abusers

The deficit in cognitive function is more concerning in methamphetamine (MA) users. The cognitive deficit was suspected to be the consequence of neuroinflammation-induced neurological dysregulation. In addition, activating the key enzyme in the tryptophan metabolic pathway by pro-inflammatory cytokines results in metabolite toxicity, further generating cognitive impairments. However, the evidence for the role of neuroinflammation and tryptophan metabolites involved in MA-induced cognitive deficit needs more conclusive study.

OBJECTIVES

This retrospective study aimed to determine blood-inflammatory markers, tryptophan metabolite-related molecules, and cognitive function in MA abusers compared to healthy control (HC) participants.

METHODS

The cognitive functions were evaluated using Stroop, Go/No-Go, One Back Task (OBT), and Wisconsin Card Sorting Test-64 (WCST-64). Blood samples were analyzed for complete blood count (CBC) analysis, serum inflammatory cytokines interleukin (IL)-6 and IL-18 and tryptophan metabolites.

RESULTS

MA group exhibited poor cognitive performance in selective attention, inhibition, working memory, cognitive flexibility, concept formation and processing speed compared to HC. Reduction in red blood cell (RBC) components but induction in white blood cells (WBCs) and IL-6 were observed in MA abusers, which might indicate anemia of (systemic chronic low-grade) inflammation. In addition, the depletion of precursor in the tryptophan metabolic pathway, L-tryptophan was also observed in MA users, which might represent induction in tryptophan metabolites.

CONCLUSION

These findings emphasize that blood biomarkers might be a surrogate marker to predict the role of neuroinflammation and abnormal tryptophan metabolite in MA-induced cognitive impairments.

The role of metabotropic glutamate receptors in neurobehavioral effects associated with methamphetamine use

Metabotropic glutamate (mGlu) receptors are expressed throughout the central nervous system and act as important regulators of drug-induced neuroplasticity and behavior. Preclinical research suggests that mGlu receptors play a critical role in a spectrum of neural and behavioral consequences arising from methamphetamine (meth) exposure. However, an overview of mGlu-dependent mechanisms linked to neurochemical, synaptic, and behavioral changes produced by meth has been lacking. This chapter provides a comprehensive review of the role of mGlu receptor subtypes (mGlu1-8) in meth-induced neural effects, such as neurotoxicity, as well as meth-associated behaviors, such as psychomotor activation, reward, reinforcement, and meth-seeking. Additionally, evidence linking altered mGlu receptor function to post-meth learning and cognitive deficits is critically evaluated. The chapter also considers the role of receptor-receptor interactions involving mGlu receptors and other neurotransmitter receptors in meth-induced neural and behavioral changes. Taken together, the literature indicates that mGlu5 regulates the neurotoxic effects of meth by attenuating hyperthermia and possibly through altering meth-induced phosphorylation of the dopamine transporter. A cohesive body of work also shows that mGlu5 antagonism (and mGlu2/3 agonism) reduce meth-seeking, though some mGlu5-blocking drugs also attenuate food-seeking. Further, evidence suggests that mGlu5 plays an important role in extinction of meth-seeking behavior. In the context of a history of meth intake, mGlu5 also co-regulates aspects of episodic memory, with mGlu5 stimulation restoring impaired memory. Based on these findings, we propose several avenues for the development of novel pharmacotherapies for Methamphetamine Use Disorder based on the selective modulation mGlu receptor subtype activity.