A review of the clinical pharmacology of methamphetamine

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.

The influence of drug class on reward in substance use disorders

In the United States, the societal costs associated with drug use surpass $500 billion annually. The rewarding and reinforcing properties that drive the use of these addictive substances are typically examined concerning the neurobiological effects responsible for their abuse potential. In this review, terms such as "abuse potential," "drug," and "addictive properties" are used due to their relevance to the methodological, theoretical, and conceptual framework for understanding the phenomenon of drug-taking behavior and the associated body of preclinical and clinical literature. The use of these terms is not intended to cast aspersions on individuals with substance use disorders (SUD). Understanding what motivates substance use has been a focus of SUD research for decades. Much of this corpus of work has focused on the shared effects of each drug class to increase dopaminergic transmission within the central reward pathways of the brain, or the "reward center." However, the precise influence of each drug class on dopamine signaling, and the extent thereof, differs considerably. Furthermore, the aforementioned substances have effects on several neurobiological targets that mediate and modulate their addictive properties. The current manuscript sought to review the influence of drug class on the rewarding effects of each of the major pharmacological classes of addictive drugs (i.e., psychostimulants, opioids, nicotine, alcohol, and cannabinoids). Our review suggests that even subtle differences in drug effects can result in significant variability in the subjective experience of the drug, altering rewarding and other reinforcing effects. Additionally, this review will argue that reward (i.e., the attractive and motivational property of a stimulus) alone is not sufficient to explain the abuse liability of these substances. Instead, abuse potential is best examined as a function of both positive and negative reinforcing drug effects (i.e., stimuli that the subject will work to attain and stimuli that the subject will work to end or avoid, respectively). Though reward is central to drug use, the factors that motivate and maintain drug taking are varied and complex, with much to be elucidated.

Methamphetamine and REM sleep deprivation interact to affect behavioral performance in adult and adolescent rats

Drug addiction may result in sleep problems. Importantly, sleep deprivation (SD) is known as an important risk factor for relapse to drug abuse as SD mimics the effects of psychostimulants on dopamine system of the brain. Moreover, aging may affect sleep and drug addiction. This study, therefore, set out to assess the effects of methamphetamine (METH) and REM sleep deprivation (RSD) on locomotor activity, anxiety-like behavior and spatial memory in adult and adolescent rats. Adult and adolescent male Wistar rats received a neurotoxic METH regimen; four subcutaneous injections of 6 mg/kg, at 2 h intervals. Five days later, the animals underwent a 48-h RSD episode using the multiple platforms method. They were then examined using the open field (OF), elevated plus maze (EPM) and Y-maze tasks. We found that the METH and RSD paradigms showed synergistic effects to increase locomotion and risk-taking behavior in both adult and adolescent animals, while only adolescent rats revealed RSD-induced anxiety-like behavior. Moreover, adolescent animals revealed greater sensitization for vertical activity following METH plus RSD episode. In addition, METH and RSD paradigms revealed synergistic effects to impair spatial working memory, but neither METH nor RSD alone affected performance of animals in the Y-maze task. Our findings may indicate that there are important relationships between METH and RSD to induce hyperlocomotion, risk-taking behavior and spatial memory impairment, particularly in adolescent animals. Moreover, it seems that adolescent rats may be more susceptible to anxiety-like behavior and hyperlocomotion than adults.

Dopaminergic dominance in the ventral medial hypothalamus: A pivotal regulator for methamphetamine-induced pathological aggression

Methamphetamine (METH) abuse is associated with a spectrum of behavioral consequences, among which heightened aggression presents a significant challenge. However, the causal role of METH's impact in aggression and its target circuit mechanisms remains largely unknown. We established an acute METH exposure-aggression mouse model to investigate the role of ventral tegmental area (VTA) dopaminergic neurons and ventral medial hypothalamus VMH glutamatergic neuron. Our findings revealed that METH-induced VTA dopamine excitability activates the ventromedial hypothalamus (VMH) glutamatergic neurons, contributing to pathological aggression. Notably, we uncovered a dopaminergic transmission within the VTA-VMH circuit that exclusively functioned under METH influence. This dopaminergic pathway emerged as a potential key player in enabling dopamine-related pathological aggression, with heightened dopaminergic excitability implicated in various psychiatric symptoms. Also, the modulatory function of this pathway opens new possibilities for targeted therapeutic strategies for intervention to improve treatment in METH abuse and may have broader implications for addressing pathological aggression syndromes.

Serotonin Syndrome After Prolonged Remifentanil and Propofol Infusion for Craniotomy: A Case Report

Serotonin syndrome (SS) is a life-threatening condition caused by serotonergic medications. We describe a unique case of SS likely caused by prolonged exposure to propofol and remifentanil alone. A young male presented for vestibular schwannoma resection. Several hours into the case, the patient demonstrated hyperthermia and hemodynamic instability, followed by clonus, rigidity, shivering, and tachycardia after emergence. SS was diagnosed using Hunter's criteria and improved with supportive measures. While the patient endorsed a history of methamphetamine use, his urine drug screen was negative. The possibility of SS should be considered when administering propofol and remifentanil, particularly with prolonged infusions.

Methamphetamine increases risky choice in rats, but only when magnitude and probability of reinforcement are manipulated within a session

Risky choice is associated with maladaptive behaviors, particularly substance use disorders. Current animal models of risky choice are often confounded by other constructs like behavioral flexibility and suboptimal choice. The purpose of the current experiment was to determine if the psychostimulant methamphetamine, a drug whose popularity has increased in recent years, increases risky choice in an equivalent expected value (EEV) task. In the EEV task, rats are given a choice between two reinforcer alternatives that differ in magnitude and probability of delivery, but have equivalent expected value. Forty-eight Sprague Dawley rats were tested in three versions of the EEV task. In the first version of the EEV task, both reinforcer magnitude and probability were adjusted across blocks of trials for both alternatives. In the second and the third versions of the EEV task, reinforcer magnitude was held constant across each block of trials (either 1 vs. 2 pellets or 4 vs. 5 pellets). We found that male rats preferred the "riskier" option, except when reinforcer magnitudes were held constant at 4 and 5 pellets across each block of trials. Methamphetamine (0.5 mg/kg) increased preference for the risky option in both males and females, but only when both reinforcer magnitude and probability were manipulated across blocks of trials for each alternative. The current results demonstrate that both magnitude of reinforcement and probability of reinforcement interact to influence risky choice. Overall, this study provides additional support for using reinforcers with expected value to measure risky choice.

Natural products as the therapeutic strategies for addiction

World Drug Report 2023 concluded that 296 million people abused drugs, 39.5 million became addiction and 494,000 died as a direct or indirect result of addiction. Addiction has become a growing problem that affects individuals, their families, societies, countries and even the world. However, treatment for addiction is only limited to some developed countries because of the high cost, difficult implementation, and time consuming. Therefore, there is an urgent need to develop a low-cost, effective drug for the development of addiction treatment in more countries, which is essential for the stability and sustainable development of the world. In this review, it provided an overview of the abuse of common addictive drugs, related disorders, and current therapeutic regimen worldwide, and summarized the mechanisms of drug addiction as reward circuits, neuroadaptation and plasticity, cognitive decision-making, genetics, and environment. According to their chemical structure, 43 natural products and 5 herbal combinations with potential to treat addiction were classified, and their sources, pharmacological effects and clinical trials were introduced. It was also found that mitragine, ibogine, L-tetrahydropalmatine and crocin had greater potential for anti-addiction.

Effects of chronic aerobic exercise on attentional bias among women with methamphetamine addiction

Objective

To explore the effects of chronic exercise on attentional bias toward drug-related stimuli and on brain electrophysiological characteristics among women with methamphetamine addiction.

Methods

In total, 63 women with methamphetamine addiction were randomized to participate in a dance (n = 21; mean age, 32.16 ± 2.07 years), bicycle (n = 21; mean age, 32.59 ± 2.12 years), or control (maintained regular activities with little exercise; n = 21; mean age, 30.95 ± 2.81 years) group for 12 weeks. The participants in the three groups were not significantly different in terms of methamphetamine use or detoxification. Before and after the intervention, attentional bias was assessed using the dot-probe task, and event-related potentials were recorded during the task.

Results

The mean attentional bias scores decreased significantly after the intervention in both exercise groups but not in the control group. After 12 weeks of dance exercise, the amplitudes of the N170, N2, P2, and P3 components of the event-related potentials decreased significantly during attentional bias processing. In addition, differences in N170 amplitudes for congruent vs. incongruent conditions in the dot-probe task were no longer observed. After 12 weeks of cycling exercise, N2 and P2 amplitudes decreased significantly. By contrast, there were no significant differences in N170, N2, P2, and P3 amplitudes in the control group before vs. after the intervention.

Conclusions

Chronic (12 weeks of) aerobic exercise reduced attentional bias toward drug-related cues by improving attentional inhibition and reducing the maintenance of extra attention to drug-related cues among women with methamphetamine addiction. Both dance and bicycle exercise improved the early recognition of drug-related cues, weakened the influence of the memory of previous drug use, and improved attentional bias behavior by strengthening attention control. Dance exercise, but not bicycling, also regulated emotional control and improved the attention selection process. These results provide theoretical and empirical evidence that chronic aerobic exercise may reduce the attentional bias toward drug-related cues to assist in the recovery of women with methamphetamine addiction.

Unraveling the protective effects of curcumin against drugs of abuse

Curcumin, a natural compound derived from the turmeric plant (Curcuma longa), has garnered significant attention for its diverse neuroprotective properties. Curcumin has been widely recognized for its remarkable anti-inflammatory, antioxidant, and anti-apoptotic effects, which have shown great potential in the treatment of various disorders, encompassing psychiatric and neurodegenerative diseases. In this review, we delve into the protective effects of curcumin against drugs of abuse, including morphine, methamphetamine, cocaine, nicotine, and alcohol, with a particular focus on the underlying mechanisms from a neuroscience perspective. Overall, curcumin demonstrates promising effects against the neurotoxicity induced by abused drugs through a wide range of mechanisms. These include the modulation of inflammatory cytokines, maintenance of ion homeostasis, epigenetic regulation, enhancement of antioxidant capacity, as well as the activation of the cAMP response element-binding protein (CREB) and brain-derived neurotrophic factor (BDNF) signaling pathways. These findings suggest that curcumin emerges as a promising therapeutic agent in combatting the detrimental effects induced by drugs of abuse, and further research is warranted to fully comprehend the molecular pathways and optimize its utilization for the prevention and treatment of substance abuse-related neurotoxicity.

Enantiomeric contributions to methamphetamine's bidirectional effects on basal and fentanyl-depressed respiration in mice

RATIONALE

Fentanyl remains the primary cause of fatal overdoses, and its co-use with methamphetamine (METH) is a growing concern. We previously demonstrated that racemic METH can either enhance or mitigate opioid-induced respiratory depression (OIRD) dependent upon whether a low or high dose is administered. The optical isomers of METH, dextromethamphetamine (d-METH) and levomethamphetamine (l-METH), differ substantially in their selectivity and potency to activate various monoamine (MA) receptors, and these pharmacological differences may underlie the bidirectional effects of the racemate. Since it is unknown which of METH's MA receptor mechanisms mediate these respiratory effects, examination of METH's pharmacologically distinct enantiomers may provide insight into treatment targets for OIRD.

METHODS

The two optical isomers of METH, d-METH and l-METH, were tested in adult male mice to determine their effects on basal and fentanyl-depressed respiratory frequency, tidal volume, and minute ventilation (MVb; i.e., respiratory frequency x tidal volume) using whole-body plethysmography.

RESULTS

When tested at dose ranges of 1.0-10 mg/kg, d-METH elevated MVb and l-METH decreased basal MVb. A dose of 30 mg/kg l-METH increased basal MVb. Under fentanyl-depressed conditions, the bidirectional effects of racemic METH were observed with d-METH treatment while l-METH significantly exacerbated OIRD at 1.0 and 3.0 mg/kg.

CONCLUSIONS

d-METH and l-METH differentially contribute to the bidirectional respiratory modulation observed by the racemate, with d-METH exhibiting predominantly stimulatory effects and l-METH exhibiting primarily depressant effects depending on dose.

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 Poisoning After "Plugging" Intentional Recreational Rectal Use

BACKGROUND

Methamphetamine is a commonly used illicit substance. The route of administration is usually parenteral, oral ingestion, or snorting. A less common route of administration is placing in the rectum.

CASE REPORT

A 28-year-old man presented to the emergency department with acute methamphetamine toxicity within 30 min after intentional rectal administration of methamphetamine for recreational purposes. The patient had hypertension, tachycardia, drug-induced psychosis, elevated creatine kinase, and required rapid sequence intubation and admission to the intensive care unit. Our patient had no clinical evidence of bowel ischemia or injury at the time of discharge. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Rectal administration of methamphetamine is known as "plugging," "booty bumping," "keestering," and "butt whacking." The rectal administration of methamphetamine has the increased risk of severe acute methamphetamine toxicity, as rectal administration bypasses first-pass metabolism, allowing for a more acute onset and higher bioavailability of methamphetamine compared with oral administration. There is the potential for mesenteric ischemia and bowel injury after rectal methamphetamine. Close clinical monitoring for bowel and rectal ischemia or injury are recommended, in addition to management of the sympathomimetic toxidrome.

Alterations in the fecal microbiota of methamphetamine users with bad sleep quality during abstinence

BACKGROUND

Methamphetamine (MA) abuse has resulted in a plethora of social issues. Sleep disturbance is a prominent issue about MA addiction, which serve as a risk factor for relapse, and the gut microbiota could play an important role in the pathophysiological mechanisms of sleep disturbances. Therefore, improving sleep quality can be beneficial for treating methamphetamine addiction, and interventions addressing the gut microbiota may represent a promising approach.

METHOD

We recruited 70 MA users to investigate the associations between sleep quality and fecal microbiota by the Pittsburgh Sleep Quality Index (PSQI), which was divided into MA-GS (PSQI score < 7, MA users with good sleep quality, n = 49) and MA-BS group (PSQI score ≥ 7, MA users with bad sleep quality, n = 21). In addition, we compared the gut microbiota between the MA-GS and healthy control (HC, n = 38) groups. 16S rRNA sequencing was applied to identify the gut bacteria.

RESULT

The study revealed that the relative abundances of the Thermoanaerobacterales at the order level differed between the MA-GS and MA-BS groups. Additionally, a positive correlation was found between the relative abundance of the genus Sutterella and daytime dysfunction. Furthermore, comparisons between MA users and HCs revealed differences in beta diversity and relative abundances of various bacterial taxa.

CONCLUSION

In conclusion, the study investigated alterations in the gut microbiota among MA users. Furthermore, we demonstrated that the genus Sutterella changes may be associated with daytime dysfunction, suggesting that the genus Sutterella may be a biomarker for bad sleep quality in MA users.

Vesicular monoamine transporter-2 inhibitor JPC-141 prevents methamphetamine-induced dopamine toxicity and blocks methamphetamine self-administration in rats

Previous research has demonstrated therapeutic potential for VMAT2 inhibitors in rat models of methamphetamine use disorder. Here, we report on the neurochemical and behavioral effects of 1-(2-methoxyphenethyl)-4-phenethypiperazine (JPC-141), a novel analog of lobelane. JPC-141 potently inhibited (Ki = 52 nM) [3H]dopamine uptake by VMAT2 in striatal vesicles with 50 to 250-fold greater selectivity for VMAT2 over dopamine, norepinephrine and serotonin plasmalemma transporters. Also, JPC-141 was 57-fold more selective for inhibiting VMAT2 over [3H]dofetilide binding to hERG channels expressed by HEK293, suggesting relatively low potential for cardiotoxicity. When administered in vivo to rats, JPC-141 prevented the METH-induced reduction in striatal dopamine content when given either prior to or after a high dose of METH, suggesting a reduction in METH-induced dopaminergic neurotoxicity. In behavioral assays, JPC-141 decreased METH-stimulated locomotor activity in METH-sensitized rats at doses of JPC-141 which did not alter locomotor activity in the saline control group. Moreover, JPC-141 specifically decreased iv METH self-administration at doses that had no effect on food-maintained responding. These findings support the further development of VMAT2 inhibitors as pharmacotherapies for individuals with methamphetamine use disorder.

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.

Focused ultrasound stimulation of infralimbic cortex attenuates reinstatement of methamphetamine-induced conditioned place preference in rats

Methamphetamine (MA) use disorder poses significant challenges to both the affected individuals and society. Current non-drug therapies like transcranial direct-current stimulation and transcranial magnetic stimulation have limitations due to their invasive nature and limited reach to deeper brain areas. Transcranial focused ultrasound (FUS) is gaining attention as a noninvasive option with precise spatial targeting, able to affect deeper areas of the brain. This research focused on assessing the effectiveness of FUS in influencing the infralimbic cortex (IL) to prevent the recurrence of MA-seeking behavior, using the conditioned place preference (CPP) method in rats. The study involved twenty male Sprague-Dawley rats. Neuronal activation by FUS was first examined via electromyography (EMG). Rats received alternately with MA or saline, and confined to one of two distinctive compartments in a three compartment apparatus over a 4-day period. After CPP test, extinction, the first reinstatement, and extinction again, FUS was applied to IL prior to the second MA priming-induced reinstatement. Safety assessments were conducted through locomotor and histological function examinations. EMG data confirmed the effectiveness of FUS in activating neurons. Significant attenuation of reinstatement of MA CPP was found, along with successful targeting of the IL region, confirmed through acoustic field scanning, c-Fos immunohistochemistry, and Evans blue dye staining. No damage to brain tissue or impaired locomotor activity was observed. The results of the study indicate that applying FUS to the IL markedly reduced the recurrence of MA seeking behavior, without harming brain tissue or impairing motor skills. This suggests that FUS could be a promising method for treating MA use disorder, with the infralimbic cortex being an effective target for FUS in preventing MA relapse.

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.

Smart Nanoscale Extracellular Vesicles in the Brain: Unveiling their Biology, Diagnostic Potential, and Therapeutic Applications

Information exchange is essential for the brain, where it communicates the physiological and pathological signals to the periphery and vice versa. Extracellular vesicles (EVs) are a heterogeneous group of membrane-bound cellular informants actively transferring informative calls to and from the brain via lipids, proteins, and nucleic acid cargos. In recent years, EVs have also been widely used to understand brain function, given their "cell-like" properties. On the one hand, the presence of neuron and astrocyte-derived EVs in biological fluids have been exploited as biomarkers to understand the mechanisms and progression of multiple neurological disorders; on the other, EVs have been used in designing targeted therapies due to their potential to cross the blood-brain-barrier (BBB). Despite the expanding literature on EVs in the context of central nervous system (CNS) physiology and related disorders, a comprehensive compilation of the existing knowledge still needs to be made available. In the current review, we provide a detailed insight into the multifaceted role of brain-derived extracellular vesicles (BDEVs) in the intricate regulation of brain physiology. Our focus extends to the significance of these EVs in a spectrum of disorders, including brain tumors, neurodegenerative conditions, neuropsychiatric diseases, autoimmune disorders, and others. Throughout the review, parallels are drawn for using EVs as biomarkers for various disorders, evaluating their utility in early detection and monitoring. Additionally, we discuss the promising prospects of utilizing EVs in targeted therapy while acknowledging the existing limitations and challenges associated with their applications in clinical scenarios. A foundational comprehension of the current state-of-the-art in EV research is essential for informing the design of future studies.

Neuropharmacological Evidence Implicating Drug-Induced Glutamate Receptor Dysfunction in Affective and Cognitive Sequelae of Subchronic Methamphetamine Self-Administration in Mice

Methamphetamine (MA) is a highly addictive drug, and MA use disorder is often comorbid with anxiety and cognitive impairment. These comorbid conditions are theorized to reflect glutamate-related neurotoxicity within the frontal cortical regions. However, our prior studies of MA-sensitized mice indicate that subchronic, behaviorally non-contingent MA treatment is sufficient to dysregulate glutamate transmission in mouse brain. Here, we extend this prior work to a mouse model of high-dose oral MA self-administration (0.8, 1.6, or 3.2 g/L; 1 h sessions × 7 days) and show that while female C57BL/6J mice consumed more MA than males, MA-experienced mice of both sexes exhibited some signs of anxiety-like behavior in a behavioral test battery, although not all effects were concentration-dependent. No MA effects were detected for our measures of visually cued spatial navigation, spatial learning, or memory in the Morris water maze; however, females with a history of 3.2 g/L MA exhibited reversal-learning deficits in this task, and mice with a history of 1.6 g/L MA committed more working-memory incorrect errors and relied upon a non-spatial navigation strategy during the radial-arm maze testing. Relative to naïve controls, MA-experienced mice exhibited several changes in the expression of certain glutamate receptor-related proteins and their downstream effectors within the ventral and dorsal areas of the prefrontal cortex, the hippocampus, and the amygdala, many of which were sex-selective. Systemic pretreatment with the mGlu1-negative allosteric modulator JNJ 162596858 reversed the anxiety-like behavior expressed by MA-experienced mice in the marble-burying test, while systemic pretreatment with NMDA or the NMDA antagonist MK-801 bi-directionally affected the MA-induced reversal-learning deficit. Taken together, these data indicate that a relatively brief history of oral MA is sufficient to induce some signs of anxiety-like behavior and cognitive dysfunction during early withdrawal that reflect, at least in part, MA-induced changes in the corticolimbic expression of certain glutamate receptor subtypes of potential relevance to treating symptoms of MA use disorder.

Methamphetamine spasm in the large caliber arteries-the severity is likely underestimated

This report describes two cases of rarely reported, severe large arterial vascular spasms seen on computed tomography images after methamphetamine abuse. Although the effects of methamphetamine on the central nervous system and smaller arteries are relatively well known, its effects on large caliber arteries are rarely discussed. We present two cases of severe large arterial multisegmented vasospasm, captured on contrast-enhanced computed tomography, several hours after methamphetamine abuse. One of the patients was discharged without apparent tissue loss or organ failure. The other developed severe heart failure, liver failure, and toe gangrene. The publication of the de-identified images has been approved by the VA Central California Health Care System's Research and Development Committee and Privacy Officer. Vascular surgeons and, perhaps, acute care physicians, who are usually aware of small arterial vasospastic conditions, should also be aware of this methamphetamine-induced large arterial finding, which can be quite dramatic in appearance on imaging.

The Exploration of Joint Toxicity and Associated Mechanisms of Primary Microplastics and Methamphetamine in Zebrafish Larvae

The co-existence of microplastics (MPs) and methamphetamine (METH) in aquatic ecosystems has been widely reported; however, the joint toxicity and associated mechanisms remain unclear. Here, zebrafish larvae were exposed individually or jointly to polystyrene (PS) and polyvinyl chloride (PVC) MPs (20 mg/L) and METH (1 and 5 mg/L) for 10 days. The mortality, behavioral functions, and histopathology of fish from different groups were determined. PS MPs posed a stronger lethal risk to fish than PVC MPs, while the addition of METH at 5 mg/L significantly increased mortality. Obvious deposition of MPs was observed in the larvae's intestinal tract in the exposure groups. Meanwhile, treatment with MPs induced intestinal deposits and intestinal hydrops in the fish, and this effect was enhanced with the addition of METH. Furthermore, MPs significantly suppressed the locomotor activation of zebrafish larvae, showing extended immobility duration and lower velocity. METH stimulated the outcome of PS but had no effect on the fish exposed to PVC. However, combined exposure to MPs and METH significantly increased the turn angle, which declined in individual MP exposure groups. RNA sequencing and gene quantitative analysis demonstrated that exposure to PS MPs and METH activated the MAPK signaling pathway and the C-type lectin signaling pathway of fish, while joint exposure to PVC MPs and METH stimulated steroid hormone synthesis pathways and the C-type lectin signaling pathway in zebrafish, contributing to cellular apoptosis and immune responses. This study contributes to the understanding of the joint toxicity of microplastics and pharmaceuticals to zebrafish, highlighting the significance of mitigating microplastic pollution to preserve the health of aquatic organisms and human beings.

Uncovering transcriptomic biomarkers for enhanced diagnosis of methamphetamine use disorder: a comprehensive review

Introduction

Methamphetamine use disorder (MUD) is a chronic relapsing disorder characterized by compulsive Methamphetamine (MA) use despite its detrimental effects on physical, psychological, and social well-being. The development of MUD is a complex process that involves the interplay of genetic, epigenetic, and environmental factors. The treatment of MUD remains a significant challenge, with no FDA-approved pharmacotherapies currently available. Current diagnostic criteria for MUD rely primarily on self-reporting and behavioral assessments, which have inherent limitations owing to their subjective nature. This lack of objective biomarkers and unidimensional approaches may not fully capture the unique features and consequences of MA addiction.

Methods

We performed a literature search for this review using the Boolean search in the PubMed database.

Results

This review explores existing technologies for identifying transcriptomic biomarkers for MUD diagnosis. We examined non-invasive tissues and scrutinized transcriptomic biomarkers relevant to MUD. Additionally, we investigated transcriptomic biomarkers identified for diagnosing, predicting, and monitoring MUD in non-invasive tissues.

Discussion

Developing and validating non-invasive MUD biomarkers could address these limitations, foster more precise and reliable diagnostic approaches, and ultimately enhance the quality of care for individuals with MA addiction.

The effect of CNQX on self-administration: present in nicotine, absent in methamphetamine model

Objective

Addiction is a chronic disease with limited pharmacological options for intervention. Focusing on reducing glutamate levels in the brain seems to be a promising strategy in addiction treatment research. Our research aimed to evaluate the effects of CNQX, an antagonist that targets AMPA and kainate glutamatergic receptors while also exhibiting affinity for the NMDA receptor, especially by modulating its glycine site. We conducted this assessment on the self-administration of nicotine and methamphetamine via intravenous (IV) administration in rats.

Methods

An operant IV self-administration model was used in male Wistar rats. When animals maintained a stable intake of nicotine or methamphetamine, we administered a single injection of CNQX (in the dose of 3 or 6 mg/kg IV) to evaluate its effect on drug intake. Subsequently, the rats were forced to abstain by staying in their home cages for 2 weeks. The period of abstinence was followed by a context-induced relapse-like session before which animals were pretreated with the injection of CNQX (3 or 6 mg/kg IV) to evaluate its effect on drug seeking.

Results

CNQX significantly reduced nicotine intake during the maintenance phase, but no effect was revealed on nicotine seeking after forced abstinence. CNQX did not affect methamphetamine taking or seeking.

Conclusion

The effect of reducing nicotine taking but not seeking could be explained by different involvement of glutamatergic receptors in various stages of nicotine dependence.

Paternal methamphetamine exposure differentially affects first and second generations in mice

Amphetamine-type stimulants are abused worldwide, and methamphetamine (METH) accounts for a large majority of seized abused drug cases. Recently, the paternal origin of health and disease theory has been proposed as a concept wherein paternal factors influence descendants. Although METH abuse is more common among males, its effects on their descendants were not examined. Therefore, we investigated the effects of paternal METH exposure on F1 and F2 levels in a mouse model. Sires were administered METH for 21 days and mated with female mice to obtain F1 mice. Growth evaluations (number of births, survival rate, body weight, righting reflex, cliff avoidance tests, and wire-hanging maneuver) were performed on F1 mice. Upon reaching six weeks of age, the mice were subjected to spontaneous locomotion, elevated plus-maze, acute METH treatment, and passive avoidance tests. Additionally, RNA-seq was performed on the striatum of male mice. Male F1 mice were mated with female mice to obtain F2 mice. They were subjected to the same tests as the F1 mice. Paternal METH exposure resulted in delayed growth and decreased memory function in F1 mice, overweight in F2 mice, decreased METH sensitivity, and reduced anxiety-related behaviors in female F2 mice. Enrichment analysis revealed significant enrichment of terms related to behavior in F1 and protein folding in F2. These results indicated that the effects of paternal METH exposure vary across generations. The effects of paternal factors need to be examined not only in F1, but also in F2 and beyond.

Differences in the prevalence and clinical correlates of depressive symptoms in male patients with methamphetamine and heroin use disorder in a Chinese Han population

BACKGROUND AND OBJECTIVES

Comorbidity of substance use disorders and depression is a common phenomenon. It is well known that opioid addiction is neurobiologically distinct from psychostimulant addiction. However, direct comparisons of comorbid depressive symptoms in patients with methamphetamine (METH) use disorder (MAUD) and heroin use disorders (HUD) have been lacking until now.

METHODS

A total of 353 patients with methamphetamine use disorder, 76 patients with HUD, and 203 healthy controls were recruited. The Beck Depression Inventory (BDI-SF), the Desires for Drug Questionnaire (DDQ) and the short form of the Childhood Trauma Questionnaire (CTQ-SF) were used to measure participants' depressive symptoms, drug craving, and childhood abuse or neglect, respectively.

RESULTS

The prevalence of depressive symptoms was 35.41% (125/353) in MAUD and 56.57% (43/76) in MAUD, significantly higher than the 22.66% (46/203) in healthy controls. Furthermore, there was a significant difference in the total BDI score between the MAUD and HUD groups (F = 5.02, df = 1, 372, p = .026). Among MAUD, years of education, history of incarceration, month of abstinence and negative reinforcement scores were associated with depressive symptoms (all p < .05). Among HUD, duration of drug use, childhood emotional abuse and sexual abuse were associated with depressive symptoms (all p < .05).

CONCLUSIONS AND SCIENTIFIC SIGNIFICANCE

The prevalence and correlates of depressive symptoms differ between MAUD and HUD, adding to the existing literature. Therefore, treatment and intervention programs should be designed to address these unique correlates in HUD and MAUD patients.

Predictive role of impulsivity, anxiety, and depression in the efficacy of intermittent theta burst transcranial magnetic stimulation modalities for treating methamphetamine use disorder: A randomized clinical trial

INTRODUCTION

Methamphetamine use disorder (MUD) can cause impulsive behavior, anxiety, and depression. Stimulation of the left dorsolateral prefrontal cortex in MUD patients by intermittent theta burst repetitive transcranial magnetic stimulation (iTBS-rTMS) is effective in reducing cravings, impulsive behavior, anxiety, and depression. The purpose of this study was to explore whether these psychological factors helped to predict MUD patients' responses to iTBS-rTMS treatment.

METHODS

Fifty MUD patients and sixty healthy subjects matched for general conditions were used as study subjects. The study randomly divided MUD patients into iTBS-rTMS and sham stimulation groups and received 20 sessions of real or sham iTBS-rTMS treatment, and the study collected cue-related evoked craving data before and after treatment. All subjects completed the Barratt Impulsiveness Scale (BIS-11), Self-rating Anxiety Scale (SAS), and Self-rating Depression Scale (SDS).

RESULTS

The MUD patients showed significantly higher levels of impulsivity, anxiety, and depression than the healthy subjects. The MUD patients who received the real treatment had significantly lower impulsivity, anxiety, and depression scores, and better treatment effects on cravings than the sham stimulation group. The Spearman rank correlation and stepwise multiple regression analyses showed that the baseline BIS-11 and the reduction rate (RR) of BIS-11 and RR of SDS were positively correlated with the decrease in cravings in the iTBS-rTMS group. ROC curve analysis showed that RR of SDS (AUC = 91.6 %; 95 % CI = 0.804-1.000) had predictive power to iTBS- rTMS therapeutic efficacy, the cutoff value is 15.102 %.

CONCLUSIONS

iTBS-rTMS had a good therapeutic effect in MUD patients and the baseline impulsivity, the improved depression and impulsivity were associated with therapeutic effect of iTBS-rTMS. The improved depression had the potential to predict the efficacy of the iTBS-rTMS modality for MUD treatment.

Initiation of Antipsychotic Treatment for Amphetamine Induced Psychosis and Its Impact on Length of Stay

Introduction: A risk of amphetamine use is amphetamine-induced psychosis (AIP). Symptoms of AIP include hallucinations, delusions, and agitation. While AIP may resolve with abstinence from amphetamines, antipsychotics are commonly used despite not being FDA approved. The primary objective of this study was to compare length of stay (LOS) for patients with AIP treated with antipsychotics vs untreated. Secondary aims were to determine antipsychotic prescribed, proportion of patients utilizing as needed doses, time to initiation, and readmissions. Methods: A retrospective chart review conducted at an academic medical center identified adult participants who were diagnosed with AIP, admitted to inpatient psychiatry service, and had a urine drug screen (UDS) positive for amphetamines. Patients were excluded if they were already taking an antipsychotic, had active prescriptions for amphetamine salts, or were in the emergency department for more than 48 hours. Demographics were assessed with descriptive statistics. Length of stay was compared between treatment groups using Kruskal-Wallis. Secondary aims were assessed using chi-square, Mann-Whitney U, and Kruskal-Wallis. Results: Sixty-nine patients were included. Median LOS for patients treated with antipsychotics (n = 35) was longer than untreated patients (n = 34), (5 days vs 2.5 days, P = .001). Type of antipsychotic used and time to initiation of antipsychotic were not found to affect LOS. There was no difference in readmissions rates and positive UDS on readmission between groups. Conclusion: This study found patients with scheduled antipsychotics for AIP had a longer LOS than patients who did not receive scheduled antipsychotics. Future studies are needed to evaluate antipsychotic use in AIP.

Mucocutaneous alterations and complications in amphetamine abusers: a narrative review

Amphetamines are the second most commonly used illicit drug worldwide. Amphetamine use can result in significant cutaneous morbidity. This review highlights the dermatological manifestations of amphetamine abuse.

Methamphetamine (MA) use and MA-induced psychosis are associated with increasing aberrations in the compensatory immunoregulatory system, interleukin-1α, and CCL5 levels

There are only a few studies reporting on the immunological profiles of methamphetamine (MA) use, MA dependency, or MA-induced psychosis (MAP). This study measured M1 macrophage, T helper (Th)-1, Th-2, growth factor, and chemokine profiles, as well as the immune inflammatory response system (IRS) and compensatory immunoregulatory system (CIRS) in peripheral blood samples from patients with MA use (n = 51), MA dependence (n = 47), and MAP (n = 43) in comparison with controls (n = 32). We discovered that persistent MA use had a robust immunosuppressive impact on all immunological profiles. The most reliable biomarker profile of MA use is the combination of substantial CIRS suppression and a rise in selected pro-inflammatory cytokines, namely CCL27 (CTACK), CCL11 (eotaxin), and interleukin (IL)-1α. In addition, MA dependency is associated with increased immunosuppression, as demonstrated by lower stem cell factor levels and higher IL-10 levels. MAP is related to a significant decrease in all immunological profiles, particularly CIRS, and an increase in CCL5 (RANTES), IL-1α, and IL-12p70 signaling. In conclusion, long-term MA use and dependency severely undermine immune homeostasis, whereas MAP may be the consequence of increased IL-1α - CCL5 signaling superimposed on strongly depleted CIRS and Th-1 functions. The widespread immunosuppression established in longstanding MA use may increase the likelihood of infectious and immune illness or exacerbate disorders such as hepatitis and AIDS. Furthermore, elevated levels of CCL5, CCL11, CCL27, IL-1α, and/or IL-12p70 may play a role in the peripheral (atherosclerosis, cutaneous inflammation, immune aberrations, hypospermatogenesis) and central (neuroinflammation, neurotoxic, neurodegenerative, depression, anxiety, and psychosis) side effects of MA use.

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.

Methylamphetamine toxicity and its involvement in death: A retrospective observational study of deaths reported to the Victorian Coroner, Australia

A retrospective observational study of Victorian deaths involving MA between 2010 and 2019 was conducted to determine the prevalence and contribution of methylamphetamine (MA) toxicity to death in the absence of other factors. Demographics, autopsy findings, toxicology, and the cause of death were reviewed. Coronial cases were categorized into five groups: deaths due to MA toxicity in the absence of other factors (Group A1); deaths due to MA toxicity in the setting of other potentially contributing factors (Group A2); deaths due to MA toxicity in the setting of significant natural disease (Group B); deaths primarily due to multiple-drug toxicity (Group C); and deaths primarily due to natural causes (Group D). There were 506 deaths involving MA categorized into Group A1 (n = 1, 0.6%), Group A2 (n = 8, 1.6%), Group B (n = 28, 5.5%), Group C (n = 229, 45%), and Group D (n = 240, 47%). Significant natural disease was prevalent among deaths involving MA and mainly concerned forms of cardiovascular disease (n = 277, 55%). The MA concentration in the one death included in Group A1 was 2.1 mg/L. The median MA concentrations of Group A2 (1.6 mg/L) and Group B (0.5 mg/L) were significantly higher than Group C (0.2 mg/L) and Group D (0.2 mg/L). Additionally, many other toxicologically significant drugs were detected and mostly comprised of central nervous system depressants. Deaths due to MA toxicity in the absence of other factors were rare despite the greater availability of crystal MA in the Australian community. The study highlights the interpretative challenges of MA blood concentrations and the continuing harms of this drug in Australia.

A systematic review and meta-analysis of health, functional, and cognitive outcomes in young people who use methamphetamine

Methamphetamine use typically starts in adolescence, and early onset is associated with worse outcomes. Yet, health, functional, and cognitive outcomes associated with methamphetamine use in young people are not well understood. The aim of this study was to comprehensively assess the evidence on health, functional, and cognitive outcomes in young people (10-25 years-old) who use methamphetamine. Sixty-six studies were included. The strongest association observed was with conduct disorder, with young people who use methamphetamine some 13 times more likely to meet conduct disorder criteria than controls. They were also more likely to have justice system involvement and to perpetrate violence against others. Educational problems were consistently associated with youth methamphetamine use. The cognitive domain most reliably implicated was inhibitory control. Key limitations in the literature were identified, including heterogenous measurement of exposure and outcomes, lack of adequate controls, and limited longitudinal evidence. Outcomes identified in the present review - suggesting complex and clinically significant behavioural issues in this population - are informative for the development of future research and targeted treatments.

Efficacy of On-line Hemodiafiltration for Rhabdomyolysis Presenting with Acute Kidney Injury Due to Unexpected Drug Abuse

Myoglobin is a well-known cause of acute kidney injury (AKI) due to rhabdomyolysis. However, whether or not removing serum myoglobin by on-line hemodiafiltration (OHDF) improves the kidney function remains unclear. We herein report a patient with a history of methamphetamine abuse who developed AKI due to rhabdomyolysis. A urinalysis and blood collection results obtained before and after OHDF demonstrated that OHDF improved the kidney function by removing a large amount of serum myoglobin rather than via urinary excretion. In conclusion, OHDF may prevent AKI progression effectively when the urine volume is insufficient.

A Case Report of Treatment With Cariprazine in a Recurrent Psychosis Presumably Induced by Methamphetamine

This case report describes a 31-year-old male patient with psychosis presumably related to methamphetamine-associated psychosis (MAP). Our patient was experiencing persistent symptoms of visual, tactile, and auditory hallucinations after cessation of methamphetamine. He has a medical history of a substance use disorder, post-traumatic stress disorder, attention-deficit hyperactivity disorder, nicotine dependence and major depressive disorder. Previously, he received a wide range of antipsychotic drug treatment regimens at other psychiatric facilities, all with some degree of effect, but never with complete symptom relief. At the time of admission to our inpatient clinic, he was started on cariprazine and reported a significant decrease in visual, auditory, and tactile hallucinations with complete cessation for a period of two weeks. There appears to be a unique ability of cariprazine's mechanism of action to reverse symptoms of the presumable diagnosis of MAP that is unable to be achieved with other antipsychotic medications.

Methamphetamine-induced region-specific transcriptomic and epigenetic changes in the brain of male rats

Psychostimulant methamphetamine (METH) is neurotoxic to the brain and, therefore, its misuse leads to neurological and psychiatric disorders. The gene regulatory network (GRN) response to neurotoxic METH binge remains unclear in most brain regions. Here we examined the effects of binge METH on the GRN in the nucleus accumbens, dentate gyrus, Ammon's horn, and subventricular zone in male rats. At 24 h after METH, ~16% of genes displayed altered expression and over a quarter of previously open chromatin regions - parts of the genome where genes are typically active - showed shifts in their accessibility. Intriguingly, most changes were unique to each area studied, and independent regulation between transcriptome and chromatin accessibility was observed. Unexpectedly, METH differentially impacted gene activity and chromatin accessibility within the dentate gyrus and Ammon's horn. Around 70% of the affected chromatin-accessible regions in the rat brain have conserved DNA sequences in the human genome. These regions frequently act as enhancers, ramping up the activity of nearby genes, and contain mutations linked to various neurological conditions. By sketching out the gene regulatory networks associated with binge METH in specific brain regions, our study offers fresh insights into how METH can trigger profound, region-specific molecular shifts.

Drug-induced social connection: both MDMA and methamphetamine increase feelings of connectedness during controlled dyadic conversations

MDMA is a stimulant-like drug with distinctive empathogenic effects. Its pro-social effects, such as feelings of connectedness, may contribute to both its popularity as a recreational drug and its apparent value as an adjunct to psychotherapy. However, little is known about the behavioral processes by which MDMA affects social interactions. This investigation examined the effects of MDMA (100 mg versus placebo; N = 18) on feelings of connectedness with an unfamiliar partner during a semi-structured casual conversation. A separate study examined the effects of a prototypic stimulant methamphetamine (MA; 20 mg versus placebo; N = 19) to determine the pharmacological specificity of effects. Oxytocin levels were obtained in both studies. Compared to placebo, both MDMA and MA increased feelings of connection with the conversation partners. Both MDMA and MA increased oxytocin levels, but oxytocin levels were correlated with feeling closer to the partner only after MDMA. These findings demonstrate an important new dimension of the pro-social effects of MDMA, its ability to increase feelings of connectedness during casual conversations between two individuals. Surprisingly, MA had a similar effect. The findings extend our knowledge of the social effects of these drugs, and illustrate a sensitive method for assessing pro-social effects during in-person dyadic encounters.

Methamphetamine exposure drives cell cycle exit and aberrant differentiation in rat hippocampal-derived neurospheres

Introduction: Methamphetamine (METH) abuse by pregnant drug addicts causes toxic effects on fetal neurodevelopment; however, the mechanism underlying such effect of METH is poorly understood. Methods: In the present study, we applied three-dimensional (3D) neurospheres derived from the embryonic rat hippocampal tissue to investigate the effect of METH on neurodevelopment. Through the combination of whole genome transcriptional analyses, the involved cell signalings were identified and investigated. Results: We found that METH treatment for 24 h significantly and concentration-dependently reduced the size of neurospheres. Analyses of genome-wide transcriptomic profiles found that those down-regulated differentially expressed genes (DEGs) upon METH exposure were remarkably enriched in the cell cycle progression. By measuring the cell cycle and the expression of cell cycle-related checkpoint proteins, we found that METH exposure significantly elevated the percentage of G0/G1 phase and decreased the levels of the proteins involved in the G1/S transition, indicating G0/G1 cell cycle arrest. Furthermore, during the early neurodevelopment stage of neurospheres, METH caused aberrant cell differentiation both in the neurons and astrocytes, and attenuated migration ability of neurospheres accompanied by increased oxidative stress and apoptosis. Conclusion: Our findings reveal that METH induces an aberrant cell cycle arrest and neuronal differentiation, impairing the coordination of migration and differentiation of neurospheres.

The gut microbiota as a potential biomarker for methamphetamine use disorder: evidence from two independent datasets

Background

Methamphetamine use disorder (MUD) poses a considerable public health threat, and its identification remains challenging due to the subjective nature of the current diagnostic system that relies on self-reported symptoms. Recent studies have suggested that MUD patients may have gut dysbiosis and that gut microbes may be involved in the pathological process of MUD. We aimed to examine gut dysbiosis among MUD patients and generate a machine-learning model utilizing gut microbiota features to facilitate the identification of MUD patients.

Method

Fecal samples from 78 MUD patients and 50 sex- and age-matched healthy controls (HCs) were analyzed by 16S rDNA sequencing to identify gut microbial characteristics that could help differentiate MUD patients from HCs. Based on these microbial features, we developed a machine learning model to help identify MUD patients. We also used public data to verify the model; these data were downloaded from a published study conducted in Wuhan, China (with 16 MUD patients and 14 HCs). Furthermore, we explored the gut microbial features of MUD patients within the first three months of withdrawal to identify the withdrawal period of MUD patients based on microbial features.

Results

MUD patients exhibited significant gut dysbiosis, including decreased richness and evenness and changes in the abundance of certain microbes, such as Proteobacteria and Firmicutes. Based on the gut microbiota features of MUD patients, we developed a machine learning model that demonstrated exceptional performance with an AUROC of 0.906 for identifying MUD patients. Additionally, when tested using an external and cross-regional dataset, the model achieved an AUROC of 0.830. Moreover, MUD patients within the first three months of withdrawal exhibited specific gut microbiota features, such as the significant enrichment of Actinobacteria. The machine learning model had an AUROC of 0.930 for identifying the withdrawal period of MUD patients.

Conclusion

In conclusion, the gut microbiota is a promising biomarker for identifying MUD and thus represents a potential approach to improving the identification of MUD patients. Future longitudinal studies are needed to validate these findings.

Acute neurocognitive and subjective effects of oral methamphetamine with low doses of alcohol: A randomised controlled trial

BACKGROUND

Methamphetamine is often recreationally co-consumed with alcohol due to desirable off-target effects; however, the acute neurocognitive and subjective consequences of combined use are unclear.

METHODS

In a randomised, placebo-controlled, counterbalanced, cross-over study design, the effects of acute oral methamphetamine (0.42 mg/kg) were assessed with and without low doses of alcohol (target 0.04% blood-alcohol concentration, BAC) on subjective intoxication, alertness, physiological outcomes and neurocognition during the ascending and descending phases of the BAC curve. Sixteen healthy adults (mean age = 30.4 years, SD ± 4.4, 67% male) completed four experimental sessions over 4 weeks involving a one-week washout period.

RESULTS

Cardiovascular measures [heart rate (beats/minute), blood pressure (mmHg)] were predictably elevated following methamphetamine, but unaffected by combined alcohol use. Methamphetamine and alcohol produce divergent effects on subjective alertness and sedation across time, yet their combination produced predominantly sustained stimulative effects independent of the biphasic alcohol curve. At a peak BAC of 0.029%, alcohol alone impaired performance across most functional neurocognitive domains relative to placebo and methamphetamine only, and the addition of methamphetamine attenuated these effects. Methamphetamine alone produced isolated improvement in psychomotor speed consistent with peak drug effects.

CONCLUSION

Methamphetamine combined with alcohol does not substantially alter the physiological or metabolic profile compared to either drug alone. Strong stimulative effects of methamphetamine appear to mask the biphasic sedative and performance effects of low doses of alcohol, which may underlie motivations for co-consumption in recreational settings and increase propensity for harm.

Effects of 8 months of high-intensity interval training on physical fitness and health-related quality of life in substance use disorder

Objective

This study aimed to investigate the effect of 8 months of high-intensity interval training (HIIT) on physical fitness and health-related quality of life in substance use disorder.

Methods

Sixty substance use disorder were randomly assigned to either the HIIT group or the control group according to a random sampling method. The HIIT group received 8 months of four 60-min sessions per week under supervision. Weight, waist circumference, body fat percentage, heart rate, blood pressure, VO2max, reaction time, grip strength, standing on one foot with eyes closed, sitting forward flexion, and quadrant jumping, standing on one foot with eyes closed, the number of push-ups, quality of life (SF-36) score, and craving (VAS) scored were monitored in the HIIT and control groups at baseline, 4 months, and 8 months. SPSS 22.0 was used to conduct repeated measurement analysis of variance and Pearson correlation analysis on the collected subject data.

Results

Compared with baseline, weight (p < 0.001), waist circumference (p < 0.001), body fat percentage (p < 0.001), heart rate (p < 0.05), Systolic blood pressure (p < 0.01), systolic blood pressure (p < 0.05), reaction time (p < 0.001),PSQI (p < 0.001), Total cholesterol (p < 0.001), Triglyceride (p < 0.001), Blood sugar (p < 0.001) and VAS score (p < 0.001) were significantly decreased after 8 months of exercise intervention. Contrastingly, VO2max (p < 0.05), grip strength (p < 0.05), eyes closed and one foot Standing (p < 0.001), sitting forward flexion (p < 0.001), quadrant jumping (p < 0.001), push-ups (p < 0.001), PCS (p < 0.001), and MCS (p < 0.001) were significantly increased. VO2max was significantly negatively correlated with VAS (r = -0.434, p < 0.001), and significantly positively correlated with PCS (r = 0.425, p < 0.001). There was a positive correlation between standing on one foot with closed eyes and MCS (r = 0.283, p < 0.05).

Conclusion

Eight months of HIIT can comprehensively improve the physical health level and health-related quality of life of men with substance use disorders, reduce the desire for drugs, and lay the foundation for better starting a happy life.

Methamphetamine enhances neural activation during anticipation of loss in the monetary incentive delay task

Stimulants like methamphetamine (MA) affect motivated behaviors via actions on circuits mediating mood, attention, and reward. Few studies examined the effects of single doses of stimulants on reward circuits during anticipation and receipt of rewards and losses. Here, we examined the effects of MA (20 mg) or placebo in a within-subject, double-blind study with healthy adults (n = 43). During 2 fMRI sessions, participants completed the monetary incentive delay task. Primary outcome measures were BOLD activation in selected regions of interest during anticipation and receipt of monetary rewards and losses. Secondary analyses included behavioral measures, whole brain analysis, and arterial spin labeling. MA produced its expected behavioral effects and increased neural activation in the ventral striatum and anterior insula during anticipation of monetary loss versus non-loss. MA did not affect activation during anticipation of gains, or during receipt of wins or losses. MA significantly reduced cerebral blood flow in the striatum and insula. The present finding that a stimulant enhances the responses of striatal and insular regions to upcoming loss suggests that this system may be sensitive to the salience of upcoming events. The finding adds to a complex body of evidence regarding the effects of stimulant drugs on neural processes during motivated behaviors.

Revolutionizing Precision Medicine: Exploring Wearable Sensors for Therapeutic Drug Monitoring and Personalized Therapy

Precision medicine, particularly therapeutic drug monitoring (TDM), is essential for optimizing drug dosage and minimizing toxicity. However, current TDM methods have limitations, including the need for skilled operators, patient discomfort, and the inability to monitor dynamic drug level changes. In recent years, wearable sensors have emerged as a promising solution for drug monitoring. These sensors offer real-time and continuous measurement of drug concentrations in biofluids, enabling personalized medicine and reducing the risk of toxicity. This review provides an overview of drugs detectable by wearable sensors and explores biosensing technologies that can enable drug monitoring in the future. It presents a comparative analysis of multiple biosensing technologies and evaluates their strengths and limitations for integration into wearable detection systems. The promising capabilities of wearable sensors for real-time and continuous drug monitoring offer revolutionary advancements in diagnostic tools, supporting personalized medicine and optimal therapeutic effects. Wearable sensors are poised to become essential components of healthcare systems, catering to the diverse needs of patients and reducing healthcare costs.

Methamphetamine dependence in Australia-why is 'ice' (crystal meth) so addictive?

Australia has one of the highest rates in the world of the use of the crystalline form of methamphetamine, a highly addictive stimulant that is often associated with a chronic, relapsing dependency. Methamphetamine use is associated with both acquisitive and violent offending, which cause substantial personal and societal costs. Whilst the short-term euphoria and stimulation provide a positive reinforcement to methamphetamine use, the aversive states of withdrawing from methamphetamine and the associated craving, which may last up to five weeks into abstinence, underlie the negative reinforcement to continued methamphetamine use. Although many methamphetamine-dependent users experience high levels of psychological distress, it is likely that less than half engage with treatment or support services, and current intervention and treatment programmes have high discontinuation rates. Stigma and discrimination, even from paramedics and health clinicians, are prominent barriers to methamphetamine-dependent users accessing treatment in Australia.

Differential alterations in brain structural network organization during addiction between adolescents and adults

BACKGROUND

The adolescent brain may be susceptible to the influences of illicit drug use. While compensatory network reorganization is a unique developmental characteristic that may restore several brain disorders, its association with methamphetamine (MA) use-induced damage during adolescence is unclear.

METHODS

Using independent component (IC) analysis on structural magnetic resonance imaging data, spatially ICs described as morphometric networks were extracted to examine the effects of MA use on gray matter (GM) volumes and network module connectivity in adolescents (51 MA users v. 60 controls) and adults (54 MA users v. 60 controls).

RESULTS

MA use was related to significant GM volume reductions in the default mode, cognitive control, salience, limbic, sensory and visual network modules in adolescents. GM volumes were also reduced in the limbic and visual network modules of the adult MA group as compared to the adult control group. Differential patterns of structural connectivity between the basal ganglia (BG) and network modules were found between the adolescent and adult MA groups. Specifically, adult MA users exhibited significantly reduced connectivity of the BG with the default network modules compared to control adults, while adolescent MA users, despite the greater extent of network GM volume reductions, did not show alterations in network connectivity relative to control adolescents.

CONCLUSIONS

Our findings suggest the potential of compensatory network reorganization in adolescent brains in response to MA use. The developmental characteristic to compensate for MA-induced brain damage can be considered as an age-specific therapeutic target for adolescent MA users.

Urinary profiles of methoxyphenamine and its metabolite after inhalation of methoxyphenamine smoke in humans: aiming to distinguish between active and passive exposure

PURPOSE

Methamphetamine (METH) is commonly abused through smoking. However, the lack of evidence regarding differences in urinary METH excretion after its active and passive inhalation has resulted in complications where the accused claims passive exposure. This study aimed to determine the differences in urinary excretion after active and passive inhalation of the drug, using methoxyphenamine (MPA) as a model for METH.

METHODS

Body temperature and locomotor activity were measured in mice as indicators of central nervous system toxicity. Six healthy adult male subjects were exposed to passive or active inhalation of MPA smoke in a small room, and urine samples were taken. MPA concentrations were measured using liquid chromatography-tandem mass spectrometry (LC-MS/MS).

RESULTS

There were no signs of toxicity in mice exposed to MPA smoke, ensuring the safety of the clinical study. Urinary MPA concentrations were significantly lower with passive inhalation compared with those of active inhalation. The maximum urinary MPA concentration in passive inhalation was 13.4 ng/mL, which was 1/60 of active inhalation with 800 ng/mL. The urinary excretion in passive inhalation until 24 h was 8.21 μg, which was 1/76 of active inhalation with 625 μg.

CONCLUSIONS

Since METH and MPA are expected to be excreted similarly, urinary METH concentrations in passively exposed persons are expected to be lower than the cutoff value of the screening kit. If the urine screening test is positive, the suspect should be considered a METH user.

TRIAL REGISTRATION NUMBER

jRCTs031210604, registration date: Feb. 9, 2022.

An uncharted territory of sexualized drug use: exploring the dynamics of chemsex among young and adolescent MSM including self-identified gay men in urban Dhaka, Bangladesh

Global and local literature depicted the pervasiveness of chemsex among men who have sex with men (MSM), yet there is limited evidence on adolescents and youth. Though literature showed their engagement in chemsex, further exploration is warranted about their socio-sexual contexts and implications. Therefore, this article explored the contexts and implications of chemsex on young and adolescent MSM. This article is extracted from qualitative research evidence, and research data are triangulated by programmatic evidence on adolescent and young MSM from two ongoing pilot interventions. The key motivational factors for engaging in chemsex were primarily rooted in the dynamics of their peer networks. Specifically, the onset of drug use is predominantly attributed to curiosity toward experimentation with methamphetamine, peer influence, propensity to lose weight, and increasing courage to approach potential sexual partners. Moreover, they continued taking drugs as it enhanced their sexual performance, thus perpetuating chemsex. Additionally, the findings revealed several sexual implications of methamphetamine, e.g., bolstering their sexual "stamina," increasing their propensity toward sexual violence, and reducing their decision-making abilities and judgment, thus collectively decreasing condom use. In essence, chemsex is considerably driven by their socio-sexual contexts, thus perpetuating sexual risk behaviors and compromising sexual health outcomes. Therefore, harm reduction interventions targeted need to be designed keeping in mind their socio-sexual dynamics and age.

From metabolism to behaviour - Multilevel effects of environmental methamphetamine concentrations on fish

Methamphetamine (METH) is a concerning drug of abuse that produces strong psychostimulant effects. The use of this substance, along with the insufficient removal in the sewage treatment plants, leads to its occurrence in the environment at low concentrations. In this study, brown trout (Salmo trutta fario) were exposed to 1 μg/L of METH as environmental relevant concentration for 28 days in order to elucidate the complex effects resulting from the drug, including behaviour, energetics, brain and gonad histology, brain metabolomics, and their relations. Trout exposed to METH displayed lowered activity as well as metabolic rate (MR), an altered morphology of brain and gonads as well as changes in brain metabolome when compared to controls. Increased activity and MR were correlated to an increased incidence of histopathology in gonads (females - vascular fluid and gonad staging; males - apoptotic spermatozoa and peritubular cells) in exposed trout compared to controls. Higher amounts of melatonin in brain were detected in exposed fish compared to controls. Tyrosine hydroxylase expression in locus coeruleus was related to the MR in exposed fish, but not in the control. Brain metabolomics indicated significant differences in 115 brain signals between control and METH exposed individuals, described by the coordinates within the principal component analyses (PCA) axes. These coordinates were subsequently used as indicators of a direct link between brain metabolomics, physiology, and behaviour - as activity and MR varied according to their values. Exposed fish showed an increased MR correlated with the metabolite position in PC1 axes, whereas the control had proportionately lower MR and PC1 coordinates. Our findings emphasize the possible complex disturbances in aquatic fauna on multiple interconnected levels (metabolism, physiology, behaviour) as a result of the presence of METH in aquatic environments. Thus, these outcomes can be useful in the development of AOP's (Adverse Outcome Pathways).

Transcriptional and epigenetic regulation of microglia in substance use disorders

Microglia are widely known for their role in immune surveillance and for their ability to refine neurocircuitry during development, but a growing body of evidence suggests that microglia may also play a complementary role to neurons in regulating the behavioral aspects of substance use disorders. While many of these efforts have focused on changes in microglial gene expression associated with drug-taking, epigenetic regulation of these changes has yet to be fully understood. This review provides recent evidence supporting the role of microglia in various aspects of substance use disorder, with particular focus on changes to the microglial transcriptome and the potential epigenetic mechanisms driving these changes. Further, this review discusses the latest technical advances in low-input chromatin profiling and highlights the current challenges for studying these novel molecular mechanisms in microglia.

Methamphetamine: Mechanism of Action and Chinese Herbal Medicine Treatment for Its Addiction

With the proliferation of synthetic drugs, research on the mechanism of action of addictive drugs and treatment methods is of great significance. Among them, methamphetamine (METH) is the most representative amphetamine synthetic drug, and the treatment of METH addiction has become an urgent medical and social problem. In recent years, the therapeutic effects of Chinese herbal medicines on METH addiction have gained widespread attention because of their non-addictiveness, multiple targets, low side effects, low cost, and other characteristics. Previous studies have identified a variety of Chinese herbal medicines with effects on METH addiction. Based on the research on METH in recent years, this article summarizes the mechanism of action of METH as the starting point and briefly reviews the Chinese herbal medicine-based treatment of METH.

A wide range of Deep Brain Stimulation of the nucleus accumbens shell time independently reduces the extinction period and prevents the reinstatement of methamphetamine-seeking behavior in rats

Methamphetamine (METH) addiction is a significant public health issue, and standard medical therapies are often not curative. Deep Brain Stimulation (DBS) has recently shown the potential to cure addiction by modulating neural activity in specific brain circuits. Recent studies have revealed that the nucleus accumbens shell (NAcSh) could serve as a promising target in treating addiction. Therefore, the present study aimed to investigate the therapeutic effects of NAcSh high- or low-frequency stimulation (HFS or LFS) in the different time points of application on the extinction and reinstatement of the METH-conditioned place preference (CPP). LFS or HFS (10 or 130 Hz, 150-200 μA, 100 μs) was delivered to the NAcSh for 30 min non-simultaneous (in a distinct non-drug environment) or simultaneous (in a drug-paired context) of the drug-free extinction sessions. The obtained results showed that both non-simultaneous and simultaneous treatments by HFS and LFS notably reduced the extinction period of METH-induced CPP. Furthermore, the data indicated that both non-synchronous and synchronous HFS prevented METH-primed reinstatement, while only the LFS synchronized group could block the reinstatement of METH-seeking behavior. The results also demonstrated that HFS was more effective than LFS in attenuating METH-primed reinstatement, and applying HFS synchronous was significantly more effective than HFS non-synchronous in reducing the relapse of drug-seeking. In conclusion, the current study's results suggest that DBS of the NAcSh in a wide range of frequencies (LFS and HFS) could affect addiction-related behaviors. However, it should be considered that the frequency and timing of DBS administration are among the critical determining factors.