Recent advances in methamphetamine neurotoxicity mechanisms and its molecular pathophysiology

Genes, Cognition, and Their Interplay in Methamphetamine Use Disorder

Methamphetamine use disorder is a pressing global health issue, often accompanied by significant cognitive deficits that impair daily functioning and quality of life and complicate treatment. Emerging evidence highlights the potential role of genetic factors in methamphetamine use disorder, particularly in association with cognitive function. This review examines the key genetic and cognitive dimensions and their interplay in methamphetamine use disorder. There is converging evidence from several studies that genetic polymorphisms in BDNF, FAAH, SLC18A1, and SLC18A2 are associated with protection against or susceptibility to the disorder. In addition, people with methamphetamine use disorder consistently displayed impairments in cognitive flexibility and inhibitory control compared with people without the disorder. These cognitive domains were associated with reactivity to methamphetamine cues that were positively correlated with total years of methamphetamine use history. Emerging research also suggests that inhibitory control is negatively correlated with lower blood FAAH mRNA levels, while cognitive flexibility positively correlates with higher blood SLC18A2 mRNA levels, highlighting how genetic and cognitive dimensions interact in methamphetamine use disorder. We also include some future directions, emphasizing potential personalized therapeutic strategies that integrate genetic and cognitive insights. By drawing attention to the interplay between genes and cognition, we hope to advance our understanding of methamphetamine use disorder and inform the development of targeted interventions.

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.

The Role of Sgt1 in Methamphetamine/Hyperthermia-induced Necroptosis

INTRODUCTION

Methamphetamine (METH) is a synthetic drug widely abused globally and can result in hyperthermia (HT) and psychiatric symptoms. Our previous studies showed that heat shock protein 90 alpha (HSP90α) plays a vital role in METH/HT-elicited neuronal necroptosis; however, the detailed mechanism of HSP90α regulation remained obscure.

METHODS

Herein, we demonstrated a function of the suppressor of G-two allele of SKP1 (Sgt1) in METH/HT-induced necroptosis. Sgt1 was mainly expressed in neurons, co-located with HSP90α, and increased in rat striatum after METH treatment. METH/HT injury triggered necroptosis and increased Sgt1 expression in PC-12 cells.

RESULTS

Data from computer simulations indicated that Sgt1 might interact with HSP90α. Geldanamycin (GA), the specific inhibitor of HSP90α, attenuated the interaction between Sgt1 and HSP90α. Knockdown of Sgt1 expression did not affect the expression level of HSP90α. Still, it inhibited the expression of receptor-interacting protein 3 (RIP3), mixed lineage kinase domain-like protein (MLKL), p-RIP3, and p-MLKL, as well as necroptosis induced by METH/HT injury.

CONCLUSION

In conclusion, Sgt1 may regulate the expression of RIP3, p-RIP3, MLKL, and p-MLKL by assisting HSP90α in affecting the METH/HT-induced necroptotic cell death.

Branch retinal artery occlusion in a 49-year-Old woman taking phentermine

Purpose

This report describes the presentation of a 49-year-old woman with a branch retinal artery occlusion of the right eye in the setting of taking phentermine, a commonly used weight loss medication.

Observations

A 49-year-old woman presented with acute painless vision loss in her right eye and was found to have a branch retinal artery occlusion after taking prescribed dosages of phentermine for weight loss therapy. Fundus examination revealed retinal whitening in the distribution of the superior temporal branch retinal artery, and spectral domain optical coherence tomography demonstrated macular edema. Systemic evaluation was negative for cardiovascular, infectious, or autoimmune etiologies. Based on the retinal findings, the patient was diagnosed with phentermine associated branch retinal artery occlusion. She was followed for nine years with no further complications and her vision remained stable in the right eye.

Conclusions and Importance

This case highlights that phentermine, a commonly used weight loss medication, could be associated with ischemic retinopathies. Thus, clinicians should be aware that retinal vascular occlusions may not only occur in those who use recreational amphetamines but also in patients taking the prescribed dosages of a weight loss medication like phentermine.

Inhibition of GSDMD-dependent pyroptosis decreased methamphetamine self-administration in rats

It is widely believed that the activation of the central dopamine (DA) system is crucial to the rewarding effects of methamphetamine (METH) and to the behavioral outcomes of METH use disorder. It was reported that METH exposure induced gasdermin D (GSDMD)-dependent pyroptosis in rats. The membrane pore formation caused by METH-induced pyroptosis may also contribute to the overflow of DA into the extracellular space and subsequently increase the DA levels in the brain. The present study firstly investigated whether the membrane pore information induced by GSDMD-dependent pyroptosis was associated with the increased DA levels in the ventral tegmental area (VAT) and nucleus accumbens (NAc) of rats self-administering METH and SY-SH5Y cells treated by METH. Subsequently, the effect of pore formation blockade or genetic inhibition of GSDMD on the reinforcing and motivational effect of METH was determined in rats, using the animal model of METH self-administration (SA). METH exposure significantly increased the activity of NLRP1/Cas-1/GSDMD pathway and the presence of pyroptosis, accompanied by the significantly increased DA levels in VTA and NAc. Moreover, intraperitoneal injections of disulfiram (DSF) or microinjection of rAAV-shGSDMD into VTA/NAc significantly reduced the reinforcing and motivational effect of METH, accompanied by the decreased level of DA in VTA and NAc. The results provided novel evidence that METH-induced pyroptosis could increase DA release in VTA and NAc via the NLRP1/Cas-1/GSDMD pathway. Additionally, membrane pores or GSDMD blockade could significantly reduce the reinforcing and motivational effect of METH. In conclusion, blocking GSDMD and membrane pore formation could be a promising potential target for the development of agents to treat METH use disorder.

Cognitive functioning of adolescents using Methamphetamine: The impact of inflammatory and oxidative processes

BACKGROUND

Methamphetamine is a substance that causes neurotoxicity and its use is increasing in recent years. Literature highlights cognitive impairment resulting from Methamphetamine use. The aim of the present study is to evaluate the relationship between cognitive impairment and inflammatory processes in adolescents with Methamphetamine use disorder.

METHODS

The study included 69 adolescents aged 15-19 years, comprising 37 participants with Methamphetamine Use Disorder and 32 healthy controls. Central Nervous System Vital Signs was used to detect cognitive impairment. Childhood Trauma Questionnaire-33 and The Children's Depression Inventory scales were used. In addition, venous blood was collected from the volunteers. Biochemical parameters (IL-1beta, IL-6, TNF-a, BDNF, FAM19A5, TAS, TOS) were analyzed.

RESULTS

Our study showed that (I) IL-6 and TNF-a levels of Methamphetamine users were lower than the healthy group; (II) BDNF levels of Methamphetamine users were higher than the healthy group; (III) mean Neurocognitive Index in cognitive tests of Methamphetamine using adolescents was negatively correlated with duration of Methamphetamine use and BDNF levels.

CONCLUSIONS

Our study suggests that Methamphetamine use may have a negative effect on cognitive functions.

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.

Daphnia magna an emerging environmental model of neuro and cardiotoxicity of illicit drugs

Cocaine, methamphetamine, ectasy (3,4-methylenedioxy amphetamine (MDMA)) and ketamine are among the most consumed drugs worldwide causing cognitive, oxidative stress and cardiovascular problems in humans. Residue levels of these drugs and their transformation products may still enter the aquatic environment, where concentrations up to hundreds of ng/L have been measured. In the present work we tested the hypothesis that psychotropic effects and the mode of action of these drugs in D. magna cognitive, oxidative stress and cardiovascular responses are equivalent to those reported in humans and other vertebrate models. Accordingly we expose D. magna juveniles to pharmacological and environmental relevant concentrations. The study was complemented with the measurement of the main neurotransmitters involved in the known mechanisms of action of these drugs in mammals and physiological relevant amino acids. Behavioural cognitive patters clearly differentiate the 3 psychostimulant drugs (methamphetamine, cocaine, MDMA) from the dissociative one ketamine. Psychostimulant drugs at pharmacological doses (10-200 μM), increased basal locomotion activities and responses to light, and decreased habituation to it. Ketamine only increased habituation to light. The four drugs enhanced the production of reactive oxygen species in a concentration related manner, and at moderate concentrations (10-60 μM) increased heartbeats, diminishing them at high doses (200 μM). In chronic exposures to environmental low concentrations (10-1000 ng/L) the four drugs did not affect any of the behavioural responses measured but methamphetamine and cocaine inhibited reproduction at 10 ng/L. Observed effects on neurotransmitters and related metabolites were in concern with reported responses in mammalian and other vertebrate models: cocaine and MDMA enhanced dopamine and serotonin levels, respectively, methamphetamine and MDMA decreased dopamine and octopamine, and all but MDMA decreased 3 MT levels. Drug effects on the concentration of up to 10 amino acids evidence disruptive effects on neurotransmitter synthesis, the urea cycle, lipid metabolism and cardiac function.

Determination of Methamphetamine by High-Performance Liquid Chromatography in Odor-Adsorbent Material Used for Training Drug-Detection Animals

The objective of the present report was to develop and validate a simple, sensitive, and selective analytical method for the determination of methamphetamine in an odor-adsorbent material (gauze) which was used to improve and standardize the training method used for drug-detection animals. High-performance liquid chromatography (HPLC) was performed using a Spherisorb ODS2 C18 column (200 mm × 4.6 mm, 5 μm), with a mobile phase consisting of a 0.25% methanol/triethylamine aqueous solution (V:V = 20:80), the pH of which was adjusted to 3.1 using glacial acetic acid, at a flow rate of 1.0 mL/min. The column temperature was 25 °C, and the detection of the analytes was performed at a wavelength of 260 nm. Methamphetamine showed good linearity (R2 = 0.9999) in the range of 4.2~83.2 mg/mL. The stability of the test material was good over 24 h. The precision of the method was good, with an average spiked recovery of 86.2% and an RSD of 2.9%. The methamphetamine content in the gauze sample was determined to be 7.8 ± 2.2 μg/sample. A high-performance liquid chromatography (HPLC) method was optimized and validated for the determination of methamphetamine in adsorbent materials (gauze). Validation data in terms of specificity, linearity, the limit of detection and the limit of quantification, reproducibility, precision, stability, and recovery indicated that the method is suitable for the routine analysis of methamphetamine in adsorbent materials (gauze) and provided a basis for training drug-detection animals.

The Role of Non-coding RNAs in Methamphetamine-Induced Neurotoxicity

Methamphetamine (METH) is an amphetamine-type stimulant that is highly toxic to the central nervous system (CNS). Repeated intake of METH can lead to addiction, which has become a globalized problem, resulting in multiple public health and safety problems. Recently, the non-coding RNA (ncRNA) has been certified to play an essential role in METH addiction through various mechanisms. Herein, we mainly focused on three kinds of ncRNAs including long non-coding RNAs (lncRNAs), microRNAs (miRNAs), and circular RNAs (circRNAs), which are involved in neurotoxicity effects such as cognitive impairment, behavioral abnormalities, and psychiatric disorders due to METH abuse. In addition, differential expression (DE) ncRNAs also suggest that specific responses and sensitivity to METH neurotoxicity exist in different brain regions and cells. We summarized the relationships between the ncRNAs and METH-induced neurotoxicity and psychiatric disturbances, respectively, hoping to provide new perspectives and strategies for the prevention and treatment of METH abuse. Schematic diagram of the non-coding RNAs (ncRNAs) was involved in methamphetamine (METH)-induced neurotoxicity. The ncRNAs were involved in METH-induced blood-brain barrier disruption, neuronal, astrocyte, and microglial damage, and synaptic neurotransmission impairment. The study of ncRNAs is a hot spot in the future to further understand the neurotoxicity of METH and provide more favorable scientific support for clinical diagnosis and innovation of related treatments.

Circadian disruption and psychostimulants dysregulates plasma acute-phase proteins and circulating cell-free mitochondrial DNA

Background

Previous studies have indicated a close link between the inflammatory response, exacerbated by circadian disruption and psychostimulants such as cocaine and methamphetamine (METH). Indicators of this inflammation include cortisol and acute-phase proteins (APPs) like C-reactive protein (CRP), complement C3 (C3), and serum amyloid A (SAA). The connection between these inflammation markers and circulating mitochondrial DNA (mtDNA) has been gaining attention. However, the specific influence of cocaine and METH on APP, cortisol, and mtDNA levels in mice with disturbed circadian rhythm has yet to be explored, which is the main aim of this research.

Methods

In our study, we employed 10-12-week-old male C57BL/6J mice, which underwent an imposed 6-h phase advance every six days for a total of eight cycles. This process led to the formation of mice with disrupted circadian rhythm and sleep disorders (CRSD). We administered 11 dosages of cocaine and METH 15 mg/kg and 20 mg/kg, respectively to these CRSD mice over the course of 22 days. Quantitative assessments of CRP, C3, SAA, cortisol, and cell-free circulating mtDNA were conducted using enzyme-linked immunosorbent assay (ELISA), Western Blot, and quantitative real-time polymerase chain reaction (qRT-PCR) techniques.

Results

The experiment revealed that disruption in circadian rhythm alone or cocaine or METH on their own increased CRP, C3, SAA, and cortisol levels in comparison with the control group. CRSD mice, exposed to cocaine and METH, showed a significant rise in CRP, C3, and SAA, while those without exposure remained stable. We also found a reduction in circulating cell-free mtDNA in all CRSD mice, regardless of cocaine and METH exposure.

Conclusions

The findings of our study affirm that the levels of CRP, C3, SAA, and cortisol, which reflect inflammation, are enhanced by circadian disruption, cocaine, and METH, and these levels show a strong correlation with the content of circulating cell-free mtDNA. Furthermore, it also shows the potential link between the disruption of the circadian clock and the inflammatory response triggered by cocaine and METH.

Effect of methamphetamine on ultraweak photon emission and level of reactive oxygen species in male rat brain

All living cells, including neurons, generate ultra-weak photon emission (UPE) during biological activity, and in particular, in the brain, it has been shown that UPE is correlated with neuronal activity and associated metabolic processes. Various intracellular factors, as well as external factors, can reduce or increase the intensity of UPE. In this study, we have used Methamphetamine (METH) as one potentially effective external factor, which is a substance that has the property of stimulating the central nervous system. METH can impair mitochondrial function by causing toxicity via various pathways, including an increase in the number of mitochondria, hyperthermia, the increased metabolic activity of the brain, and the production of glutamate and excess calcium. In addition to mitochondrial dysfunction, METH alters cellular homeostasis, leading to cell damage and the production of excess ROS. The aim of this study is to measure and compare the UPE intensity and reactive oxygen species (ROS) levels of the prefrontal, motor, and visual cortex before and after METH administration. Twenty male rats were randomly assigned to two groups, the control, and METH groups. In the control group, 2 h after injection of normal saline and without any intervention, and in the experimental group 2 h after IP injection of 20 mg/kg METH, sections were prepared from three areas: prefrontal, motor, and V1-V2 cortex, which were used to evaluate the emission of UPE using a photomultiplier tube (PMT) device and to evaluate the amount of ROS. The results showed that the amount of ROS and UPE in the experimental group in all three areas significantly increased compared to the control group. So, METH increases UPE and ROS in the prefrontal, motor, and visual regions, and there is a direct relationship between UPE intensity and ROS production. Therefore, UPE may be used as a dynamic reading tool to monitor oxidative metabolism in physiological processes related to ROS and METH research. Also, the results of this experiment may create a new avenue to test the hypothesis that the excess in UPE generation may lead to the phenomenon of phosphene and visual hallucinations.

Exploring psilocybin-assisted psychotherapy in the treatment of methamphetamine use disorder

Methamphetamine use disorder is a chronic relapsing condition associated with substantial mental, physical, and social harms and increasing rates of mortality. Contingency management and psychotherapy interventions are the mainstays of treatment but are modestly effective with high relapse rates, while pharmacological treatments have shown little to no efficacy. Psilocybin-assisted psychotherapy is emerging as a promising treatment for a range of difficult-to-treat conditions, including substance use disorders; however, no studies have yet been published looking at psilocybin-assisted psychotherapy in the treatment of methamphetamine use disorder. Here we review the rationale for psilocybin-assisted psychotherapy as a potential treatment for this indication, and describe practical considerations based on our early experience designing and implementing four separate clinical trials of psilocybin-assisted psychotherapy for methamphetamine use disorder.

2-Phenethylamines in Medicinal Chemistry: A Review

A concise review covering updated presence and role of 2-phenethylamines in medicinal chemistry is presented. Open-chain, flexible alicyclic amine derivatives of this motif are enumerated in key therapeutic targets, listing medicinal chemistry hits and appealing screening compounds. Latest reports in discovering new bioactive 2-phenethylamines by research groups are covered too.

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.

Noninvasive Vagus Nerve Stimulation in the Treatment of Methamphetamine Use Disorder: A Review Article

: Methamphetamine (MA) use and the mortality it causes are increasing worldwide. The neurobiological mechanisms underlying the destructive effects of MA use are complex; however, there is much evidence that MA induces the dysfunction of monoaminergic transmission and causes oxidative stress, neuroinflammation, gliosis, and apoptosis. These toxic effects are associated with cardiotoxicity and neurotoxicity and with an imbalance in the autonomic nervous system, which altogether manifest themselves in clinical symptoms, such as neuropsychiatric disorders and cardiovascular diseases. There is no approved treatment for methamphetamine use disorder (MUD) despite all efforts made to date. The behavioral and pharmacological approaches currently used for the treatment of MUD are not completely effective. In this study, it is hypothesized that the stimulation of the vagus nerve and biological pathways underlying the processes of this stimulation might be effective as adjunctive therapy. Despite the potential effects of vagus nerve stimulation (VNS) to improve MUD, no study has yet examined the clinical potential effects of VNS in patients with the disorder. Therefore, further studies, including experimental and clinical trials, are needed to examine the effects of VNS on MUD.

A Review of Methods Used to Detect Methamphetamine from Indoor Air and Textiles in Confined Spaces

Methamphetamine manufacture, use, and the resulting contamination is a significant issue that affects public health, the environment, and the economy. Third-hand exposure to methamphetamine can result in adverse health risks for individuals and first responders. Such exposures can result from the inhalation of airborne residues or from contact with contaminated objects. This review was conducted to determine the current methods used for methamphetamine extraction from indoor air and porous fabric materials. Dynamic solid phase microextraction (SPME) and sorbent sampling tubes have been applied to extract airborne methamphetamine residues from contaminated properties. SPME and solvent extraction have been applied to sample clothing and textiles for methamphetamine detection. This review demonstrates that there is limited literature on the detection of methamphetamine from indoor air and clothing. Supplementary and consistent methods to detect methamphetamine from air and porous surfaces should be developed and published to allow better assessment of the environmental risk to public health caused by third-hand exposure to methamphetamine.

Increased Lipid Peroxidation and Lowered Antioxidant Defenses Predict Methamphetamine Induced Psychosis

BACKGROUND

a significant percentage of methamphetamine (MA) dependent patients develop psychosis. The associations between oxidative pathways and MA-induced psychosis (MIP) are not well delineated.

OBJECTIVE

the aim of this study is to delineate whether acute MA intoxication in MA dependent patients is accompanied by increased nitro-oxidative stress and whether the latter is associated with MIP.

METHOD

we recruited 30 healthy younger males and 60 acutely intoxicated males with MA dependence and assessed severity of MA use and dependence and psychotic symptoms during intoxication, and serum oxidative toxicity (OSTOX) biomarkers including oxidized high (oxHDL) and low (oxLDL)-density lipoprotein, myeloperoxidase (MPO), malondialdehyde (MDA), and nitric oxide (NO), and antioxidant defenses (ANTIOX) including HDL-cholesterol, zinc, glutathione peroxidase (GPx), total antioxidant capacity (TAC), and catalase-1.

RESULTS

a large part (50%, n = 30) of patients with MA dependence could be allocated to a cluster characterized by high psychosis ratings including delusions, suspiciousness, conceptual disorganization and difficulties abstract thinking and an increased OSTOX/ANTIOX ratio. Partial Least Squares analysis showed that 29.9% of the variance in MIP severity (a first factor extracted from psychosis, hostility, excitation, mannerism, and formal thought disorder scores) was explained by HDL, TAC and zinc (all inversely) and oxLDL (positively). MA dependence and dosing explained together 44.7% of the variance in the OSTOX/ANTIOX ratio.

CONCLUSIONS

MA dependence and intoxication are associated with increased oxidative stress and lowered antioxidant defenses, both of which increase risk of MIP during acute intoxication. MA dependence is accompanied by increased atherogenicity due to lowered HDL and increased oxLDL and oxHDL.

Neural signaling of methamphetamine craving and seeking intensified by bupropion in the ventral tegmental area-cortico-accumbens circuitry in mice

Previously, bupropion (BUP), a norepinephrine (NE)/dopamine (DA) transporter blocker and nicotinic acetylcholine receptors (nAChRs) antagonist, was found to intensify methamphetamine (METH) craving behaviours in mice. Intense craving causes relapse in drug dependence. This study characterized local field potential (LFP) patterns in the brain regions associated with METH-conditioned place preference (CPP) enhanced by BUP. Male Swiss albino ICR mice were implanted with LFP electrodes to the ventral tegmental area (VTA), medial prefrontal cortex (mPFC) and the nucleus accumbens core (NAcc). Animals received sessions to learn the association between injection effects (1 mg/kg METH and normal saline) with contextual environments (METH- and saline-paired compartments) during the conditioning phase. A total of 20 mg/kg BUP was given to animals before LFP, and behaviour recording in the CPP apparatus during the post-conditioning phase. The results showed that increased CPP scores and % number of entries to the METH-paired zone, as well as changes in VTA, mPFC and NAcc spectral powers and coherence among these areas, were associated with METH-CPP. Treatment with BUP increased VTA delta and gamma I, decreased mPFC alpha, increased NAcc gamma I and decreased gamma II powers. Coherence analyses revealed that BUP decreased gamma II VTA-mPFC and increased beta and gamma I VTA-NAcc connectivity. Altogether, BUP produced additional effects to that of METH-CPP alone. These findings demonstrated changes in neural circuit activities associated with METH-CPP intensified by BUP. Moreover, modulation of NE/DA systems and/or nAChRs actions in the VTA-cortico-accumbens loop might underlie METH craving and dependence.

Methamphetamine Induces Systemic Inflammation and Anxiety: The Role of the Gut–Immune–Brain Axis

Methamphetamine (METH) is a highly addictive drug abused by millions of users worldwide, thus becoming a global health concern with limited management options. The inefficiency of existing treatment methods has driven research into understanding the mechanisms underlying METH-induced disorders and finding effective treatments. This study aims to understand the complex interactions of the gastrointestinal–immune–nervous systems following an acute METH dose administration as one of the potential underlying molecular mechanisms concentrating on the impact of METH abuse on gut permeability. Findings showed a decreased expression of tight junction proteins ZO-1 and EpCAm in intestinal tissue and the presence of FABP-1 in sera of METH treated mice suggests intestinal wall disruption. The increased presence of CD45+ immune cells in the intestinal wall further confirms gut wall inflammation/disruption. In the brain, the expression of inflammatory markers Ccl2, Cxcl1, IL-1β, TMEM119, and the presence of albumin were higher in METH mice compared to shams, suggesting METH-induced blood–brain barrier disruption. In the spleen, cellular and gene changes are also noted. In addition, mice treated with an acute dose of METH showed anxious behavior in dark and light, open field, and elevated maze tests compared to sham controls. The findings on METH-induced inflammation and anxiety may provide opportunities to develop effective treatments for METH addiction in the future.

Molecular mechanisms of programmed cell death in methamphetamine-induced neuronal damage

Methamphetamine, commonly referred to as METH, is a highly addictive psychostimulant and one of the most commonly misused drugs on the planet. Using METH continuously can increase your risk for drug addiction, along with other health complications like attention deficit disorder, memory loss, and cognitive decline. Neurotoxicity caused by METH is thought to play a significant role in the onset of these neurological complications. The molecular mechanisms responsible for METH-caused neuronal damage are discussed in this review. According to our analysis, METH is closely associated with programmed cell death (PCD) in the process that causes neuronal impairment, such as apoptosis, autophagy, necroptosis, pyroptosis, and ferroptosis. In reviewing this article, some insights are gained into how METH addiction is accompanied by cell death and may help to identify potential therapeutic targets for the neurological impairment caused by METH abuse.

Drugs and Bugs: The Gut-Brain Axis and Substance Use Disorders

Substance use disorders (SUDs) represent a significant public health crisis. Worldwide, 5.4% of the global disease burden is attributed to SUDs and alcohol use, and many more use psychoactive substances recreationally. Often associated with comorbidities, SUDs result in changes to both brain function and physiological responses. Mounting evidence calls for a precision approach for the treatment and diagnosis of SUDs, and the gut microbiome is emerging as a contributor to such disorders. Over the last few centuries, modern lifestyles, diets, and medical care have altered the health of the microbes that live in and on our bodies; as we develop, our diets and lifestyle dictate which microbes flourish and which microbes vanish. An increase in antibiotic treatments, with many antibiotic interventions occurring early in life during the microbiome's normal development, transforms developing microbial communities. Links have been made between the microbiome and SUDs, and the microbiome and conditions that are often comorbid with SUDs such as anxiety, depression, pain, and stress. A better understanding of the mechanisms influencing behavioral changes and drug use is critical in developing novel treatments for SUDSs. Targeting the microbiome as a therapeutic and diagnostic tool is a promising avenue of exploration. This review will provide an overview of the role of the gut-brain axis in a wide range of SUDs, discuss host and microbe pathways that mediate changes in the brain's response to drugs, and the microbes and related metabolites that impact behavior and health within the gut-brain axis.

A review of basic to clinical studies of the association between hyperammonemia, methamphetamine

Methamphetamine (METH), an addictive psychostimulant drug, is the second most widely used type of drug all around the world. METH abusers are more likely to develop a psycho-neurological complication. Hyperammonemia (HAM) causes neuropsychiatric illnesses such as mental state changes and episodes of acute encephalopathy. Recently, there are some shreds of evidence about the relationship between METH complication and HAM. Both METH intoxication and HAM could induce psychosis, agitation, memory impairment, and psycho-neuronal disorders. They also have similar mechanisms of neuronal damages, such as excitotoxicity, oxidative stress, mitochondrial impairments, and inflammation responses, which can subsequently increase the glutamate level of the brain. Hence, the basic to clinical studies of the association between HAM and METH are reviewed by monitoring six case studies and a good body of animal studies literature. All instances of METH-associated HAM had changes in mental state and some level of confusion that were improved when the ammonia serum level returned to the normal level. Furthermore, most of them had typical vital signs. Several studies suggested some sources for METH-associated HAM, including METH-induced liver and renal damages, muscular hyperactivity, gut bacterial overgrowth, co-abuse of other substances, and using some forms of NH3 in METH cooking. In conclusion, it seems that mental status changes in METH abusers may be related to ammonia intoxication or HAM; therefore, it is important to assess the serum level of ammonia in METH intoxicated patients and resolve it.

MicroRNAs in Methamphetamine-Induced Neurotoxicity and Addiction

Methamphetamine (METH) abuse remains a significant public health concern globally owing to its strong addictive properties. Prolonged abuse of the drug causes irreversible damage to the central nervous system. To date, no efficient pharmacological interventions are available, primarily due to the unclear mechanisms underlying METH action in the brain. Recently, microRNAs (miRNAs) have been identified to play critical roles in various cellular processes. The expression levels of some miRNAs are altered after METH administration, which may influence the transcription of target genes to regulate METH toxicity or addiction. This review summarizes the miRNAs in the context of METH use, discussing their role in the reward effect and neurotoxic sequelae. Better understanding of the molecular mechanisms involved in METH would be helpful for the development of new therapeutic strategies in reducing the harm of the drug.

Dopamine D1 receptors mediate methamphetamine-induced dopaminergic damage: involvement of autophagy regulation via the AMPK/FOXO3A pathway

RATIONALE

Clinical studies have revealed that methamphetamine abuse increases risk for developing Parkinson's diseases. It is thus important to elucidate the mechanisms by which methamphetamine damages dopaminergic neurons.

OBJECTIVES

The present study was designed to elucidate the role of the dopamine D1 receptor in methamphetamine-mediated dopaminergic neuronal damage and its underlying mechanisms.

METHODS

Mice were treated for 4 days with vehicle, methamphetamine, or the D1 agonist SKF38393 and then assessed for locomotion and performance in the pole and rotarod tests. Cellular indices of autophagy, LC3, P62, and Beclin-1, tyrosine hydroxylase, and the AMPK/FOXO3A pathway were analyzed in striatal tissue from treated mice, in PC12 cells, and in D1 receptor mutant mice.

RESULTS

Repeated treatment with a relatively high dose of methamphetamine for 4 days induced both loss of dopaminergic neurons and activation of autophagy in the striatum as evidenced by increased expression of LC3 and P62. However, such treatment did not induce either loss of dopaminergic neurons or activation of autophagy in D1 receptor knockout mice. D1 receptor-mediated activation of autophagy was also confirmed in vitro using dopaminergic neuronal PC12 cells. Further studies demonstrated that the AMPK/FOXO3A signaling pathway is responsible for D1 receptor-mediated activation of autophagy.

CONCLUSIONS

The present data indicate a novel mechanism for methamphetamine-induced dopaminergic neuronal damage and reveal an important role for D1 receptors in the neurotoxicity of this drug.

Macula and optic disk features in methamphetamine and crystal methamphetamine addicts using optical coherence tomography

PURPOSE

Methamphetamine and crystal methamphetamine abusers were compared with healthy subjects using optical coherence tomography to assess their retinal nerve fiber layer, macula, and optic disk characteristics.

METHODS

Forty-one methamphetamine and crystal methamphetamine abusers and 42 healthy subjects (mean ± SD of age: 35.82 ± 8.6 and 37.76 ± 9.1 years, respectively) were incorporated in this cross-sectional study. The drug abusers had a history of at least five years of substance use through smoking. Fourier-domain optical coherence tomography was used to image and assess the characteristics of retinal nerve fiber layer, macular thickness, and optic disk in the study groups.

RESULTS

The retinal nerve fiber layer thickness was significantly lower in the superior and temporal retinal quadrants of drug abusers than healthy subjects (P = 0.008 and P = 0.028, respectively). This study did not find a significant difference between drug abusers and healthy controls regarding optic to disk ratio, rim area, and disk area (P > 0.05). The comparison between the study groups showed that the reductions in perifovea and the superior quadrant of parafoveal thickness were statistically significant (P < 0.001 and P = 0.029, respectively).

CONCLUSION

Fourier-domain optical coherence tomography measurements showed that the retinal nerve fiber layer and macular thickness were different between methamphetamine and crystal methamphetamine abusers and healthy subjects, which should be considered in clinical practice. It seems that these drug abuses can cause alterations in retinal morphology.

Disruption of regional homogeneity in the brains of chronic methamphetamine users

Previous studies have reported evidence supporting structural and functional alterations in the brains of methamphetamine (MA) users. The aim of the present study was to extend current knowledge regarding brain function(s) in MA users by examining regional homogeneity (ReHo). Chronic MA users (51 male, 46 female), who were undergoing supervised abstinence for 12 to 621 days, and 79 healthy controls (43 male, 36 female) underwent resting-state functional brain magnetic resonance imaging. Voxel-wise whole-brain scale group differences in ReHo were examined. The mean ReHo values of significant clusters were extracted, and linear regression was used to identify factors that contributed to these mean ReHo values. MA users exhibited lower ReHo values in the left orbital part of the inferior frontal gyrus extending to the left insula and left temporal pole, left amygdala, and left fusiform gyrus. MA users also exhibited greater ReHo values in the bilateral pre- and postcentral gyri and right cerebellum. Characteristics of MA use, including duration, duration of abstinence from MA, and age at onset of MA use, demonstrated no reliable contribution to ReHo of the significant clusters. Findings of the present study demonstrated that chronic MA use was associated with regional specific disruption of ReHo, which is relatively independent of structural and functional alterations and, apparently, does not recover after relatively long-term abstinence. This disruption may underlie overall neurocognitive deficits in MA users, which is difficult to recover.

Methamphetamine Downregulates the Sperm-Specific Calcium Channels Involved in Sperm Motility in Rats

Calcium channels play essential roles in sperm motility. A family of sperm-specific cation channels including CatSper1-4 has been identified as voltage-dependent ion channels that act as sperm motility regulators. Methamphetamine is known to cause apoptosis in seminiferous tubules and affect sperm quality. This research was conducted to investigate the effects of methamphetamine on expression of the CatSper family and Mvh genes. Thirty-six adult Wistar rats were divided into four groups of nine rats each: the control and experimental groups 1, 2, and 3. The control group received no solvents or drugs, but experimental groups 1, 2, and 3 were daily given 0.2 mL of a solution by gavage that contained 0.5, 1, and 2 mg of methamphetamine, respectively, for 45 days. The rats were then anesthetized, and one testis removed from each rat was used in a reverse transcription-polymerase chain reaction (RT-PCR). Analysis of variance (ANOVA) and Tukey's posthoc test were used to analyze the data at the P < 0.05 significance level. Treatment with methamphetamine resulted in decreased testis and epididymis weights compared to the control rats. The results showed that the mRNA fold expression level of the CatSper family and Mvh genes decreased significantly in experimental groups compared to that in the control (P < 0.05). Methamphetamine decreased the expression levels of the CatSper and Mvh genes, and thus, it seemed that it can increase the probability of infertility through sperm motility reduction by lowering the expression levels of these genes.

Natural Products in Modulating Methamphetamine-Induced Neuronal Apoptosis

Methamphetamine (METH), an amphetamine-type psychostimulant, is highly abused worldwide. Chronic abuse of METH causes neurodegenerative changes in central dopaminergic neurons with numerous neuropsychiatric consequences. Neuronal apoptosis plays a critical role in METH-induced neurotoxicity and may provide promising pharmacological targets for preventing and treating METH addiction. In recent years, accumulating evidence has revealed that natural products may possess significant potentials to inhibit METH-evoked neuronal apoptosis. In this review, we summarized and analyzed the improvement effect of natural products on METH-induced neuronal apoptosis and their potential molecular mechanisms on modulating dopamine release, oxidative stress, mitochondrial-dependent apoptotic pathway, endoplasmic reticulum stress-mediated apoptotic pathway, and neuroinflammation. Hopefully, this review may highlight the potential value of natural products in modulating METH-caused neuronal apoptosis and provide useful information for future research and developments of novel and efficacious pharmacotherapies in this field.

Neuron–Microglia Contact-Dependent Mechanisms Attenuate Methamphetamine-Induced Microglia Reactivity and Enhance Neuronal Plasticity

Exposure to methamphetamine (Meth) has been classically associated with damage to neuronal terminals. However, it is now becoming clear that addiction may also result from the interplay between glial cells and neurons. Recently, we demonstrated that binge Meth administration promotes microgliosis and microglia pro-inflammation via astrocytic glutamate release in a TNF/IP₃R2-Ca²⁺-dependent manner. Here, we investigated the contribution of neuronal cells to this process. As the crosstalk between microglia and neurons may occur by contact-dependent and/or contact-independent mechanisms, we developed co-cultures of primary neurons and microglia in microfluidic devices to investigate how their interaction affects Meth-induced microglia activation. Our results show that neurons exposed to Meth do not activate microglia in a cell-autonomous way but require astrocyte mediation. Importantly, we found that neurons can partially prevent Meth-induced microglia activation via astrocytes, which seems to be achieved by increasing arginase 1 expression and strengthening the CD200/CD200r pathway. We also observed an increase in synaptic individual area, as determined by co-localization of pre- and post-synaptic markers. The present study provides evidence that contact-dependent mechanisms between neurons and microglia can attenuate pro-inflammatory events such as Meth-induced microglia activation.

Coenzyme Q10 reduces expression of apoptotic markers in adult rat nucleus accumbens dopaminergic neurons treated with methamphetamine

BACKGROUND

Abuse of addictive drugs such as methamphetamine (METH) has become a global problem, leading to many social, economic, and health disturbances, including neurological and cognitive disorders. Neuronal damage is reported in chronic METH abusers. The neuroprotective role of CoQ10 has been shown in many studies. In the present study, we aimed to assess the pre and post-efficacy of CoQ10 on the dopaminergic neurons of the Nucleus Accumbens (de Miranda et al. in Food Res Int 121:641-647, 2019) in the male adult rats treated with METH.

METHODS

80 rats were randomly divided into eight groups (n = 10), including: negative control (intact), positive control (received 5 mg/kg/day METH/IP), three post-treatment groups (METH + 5, 10, 20 mg/kg CoQ10) and three pre-treatment groups (received 5, 10, 20 mg/kg CoQ10 as pre-treatment for 14 days before METH injection). The expression of Bax, Bcl-2, Bax/Bcl-2 ratio, P53, Caspase-3 and tyrosine hydroxylase in NAc studied using western blotting. Nissl staining was used to study the neuronal density of NAc.

RESULTS

Our results showed that the different doses of CoQ10 in METH-treated animals significantly changed pro-apoptotic proteins' expression in the benefit of neuronal survival of NAc (P < 0.05). Neuronal density in NAc were significantly lower in the METH group compared to the control and CoQ10 treated groups. Pre- and post-treatment with different doses of CoQ10 restored the neuronal damage in NAc.

CONCLUSIONS

CoQ10 could decrease the activation of pro-apoptotic proteins and reduce the neurodegenerative effects induced by METH. From a clinical point of view, it seems that certain antioxidants such as CoQ10 should receive more attention in clinical trial research. We believe that antioxidants could be the promising for drug abuse treatment in the future.

A Zebrafish Model of Neurotoxicity by Binge-Like Methamphetamine Exposure

Hyperthermia is a common confounding factor for assessing the neurotoxic effects of methamphetamine (METH) in mammalian models. The development of new models of methamphetamine neurotoxicity using vertebrate poikilothermic animals should allow to overcome this problem. The aim of the present study was to develop a zebrafish model of neurotoxicity by binge-like methamphetamine exposure. After an initial testing at 20 and 40 mg/L for 48 h, the later METH concentration was selected for developing the model and the effects on the brain monoaminergic profile, locomotor, anxiety-like and social behaviors as well as on the expression of key genes of the catecholaminergic system were determined. A concentration- and time-dependent decrease in the brain levels of dopamine (DA), norepinephrine (NE) and serotonin (5-HT) was found in METH-exposed fish. A significant hyperactivity was found during the first hour of exposure, followed 3 h after by a positive geotaxis and negative scototaxis in the novel tank and in the light/dark paradigm, respectively. Moreover, the behavioral phenotype in the treated fish was consistent with social isolation. At transcriptional level, th1 and slc18a2 (vmat2) exhibited a significant increase after 3 h of exposure, whereas the expression of gfap, a marker of astroglial response to neuronal injury, was strongly increased after 48 h exposure. However, no evidences of oxidative stress were found in the brain of the treated fish. Altogether, this study demonstrates the suitability of the adult zebrafish as a model of METH-induced neurotoxicity and provides more information about the biochemical and behavioral consequences of METH abuse.

Krill Oil Alleviated Methamphetamine-Induced Memory Impairment via the MAPK Signaling Pathway and Dopaminergic Synapse Pathway

Methamphetamine (METH) abuse exerts severe harmful effects in multiple organs, especially the brain, and can induce cognitive dysfunction and memory deficits in humans. Krill oil is rich in polyunsaturated fatty acids, while its effect on METH-induced cognitive impairment and mental disorders, and the underlying mechanism remain unknown. The aim of the present study was to investigate the protective effect of krill oil on METH-induced memory deficits and to explore the molecular mechanisms by using an integrated strategy of bioinformatics analysis and experimental verification. METH-exposed mice were treated with or without krill oil. Learning and memory functions were evaluated by the Morris water maze. The drug–component–target network was constructed in combination with network pharmacology. The predicted hub genes and pathways were validated by the Western blot technique. With krill oil treatment, memory impairment induced by METH was significantly improved. 210 predicted targets constituted the drug–compound–target network by network pharmacology analysis. 20 hub genes such as DRD2, MAPK3, CREB, BDNF, and caspase-3 were filtered out as the underlying mechanisms of krill oil on improving memory deficits induced by METH. The KEGG pathway and GO enrichment analyses showed that the MAPK signaling pathway, cAMP signaling pathway, and dopaminergic synapse pathway were involved in the neuroprotective effects of krill oil. In the hippocampus, DRD2, cleaved caspase-3, and γ-H2AX expression levels were significantly increased in the METH group but decreased in the krill oil–treated group. Meanwhile, krill oil enhanced the expressions of p-PKA, p-ERK1/2, and p-CREB. Our findings suggested that krill oil improved METH-induced memory deficits, and this effect may occur via the MAPK signaling pathway and dopaminergic synapse pathways. The combination of network pharmacology approaches with experimental validation may offer a useful tool to characterize the molecular mechanism of multicomponent complexes.

Mass spectrometry-based metabolomics in hair from current and former patients with methamphetamine use disorder

Drug use disorder, a chronic and relapsing mental disorder, is primarily diagnosed via self-reports of drug-seeking behavioral and psychological conditions, accompanied by psychiatric assessment. Therefore, the identification of peripheral biomarkers that reflect pathological changes caused by such disorders is essential for improving treatment monitoring. Hair possesses great potential as a metabolomic sample for monitoring chronic diseases. This study aimed to investigate metabolic alterations in hair to elucidate a suitable treatment modality for methamphetamine (MA) use disorder. Consequently, both targeted and untargeted metabolomics analyses were performed via mass spectrometry on hair samples obtained from current and former patients with MA use disorder. Healthy subjects (HS), current (CP), and former (FP) patients with this disorder were selected based on psychiatric diagnosis and screening the concentrations of MA in hair. The drug abuse screening questionnaire scores did not differentiate between CP and FP. Moreover, according to both targeted and untargeted metabolomics, clustering was not observed among all three groups. Nevertheless, a model of partial least squares-discriminant analysis was established between HS and CP based on seven metabolites derived from the targeted metabolomics results. Thus, this study demonstrates the promising potential of hair metabolomes for monitoring recovery from drug use disorders in clinical practice.

Functional and structural alternations in the choroid plexus upon methamphetamine exposure

Choroid plexus (CP) is the principal source of cerebrospinal fluid. CP can produce and release a wide range of materials including growth factors, neurotrophic factors, etc. all of which play an important role in the maintenance and proper functioning of the brain. Methamphetamine (METH) is a CNS neurostimulant that causes brain dysfunction. Herein, we investigated the potential effects of METH exposure on CP structure and function. Stereological analysis revealed a significant alteration in CP volume, epithelial cells and capillary number upon METH treatment. Electron microscopy exhibited changes in ultrastructure. Moreover, the upregulation of neurotrophic factors such as BDNF and VEGF as well as autophagy and apoptosis gene following METH administration were observed. We also identified several signaling cascades related to autophagy. In conclusion, gene expression changes coupled with structural alterations of the CP in response to METH suggested METH-induced autophagy in CP.

Inhibition of Methamphetamine-Induced Cytotoxicity in the U87-Cell Line by Atorvastatin-Conjugated Carbon Nanotubes

In biological systems, carbon nanotubes can enhance the biological effects of drugs and reduce their side effects. Methamphetamine (METH) is a stimulant drug that induces cell death in various cell types, primarily neural cells. On the other hand, specific doses of atorvastatin (ATO) can stimulate cell growth and inhibit cell death in different cell lines. This study aimed to investigate the improvement effect of ATO@single-walled carbon nanotube (SWCNT) on METH-induced cell cytotoxicity in the U87 glioblastoma cell line. In this study, cells were cultured in 10 mM of METH during the cell treatment with 0-10 nM of ATO and ATO@SWCNT. The conjugated drugs to SWCNT as Van der Waals were detected using field emission scanning electron microscopy, Fourier transform-infrared spectroscopy, and other analyses. Then, the in vitro proliferating of ATO@SWCNT was explored against glioblastoma cells compared to pure ATO. This examine was performed using methyl thiazole tetrazolium approach, terminal deoxynucleotidyl transferase deoxy uridine-triphosphate nick end labeling assay, caspase-3 method, lactate dehydrogenase assay, and RH-123 assay with 10 mM METH. The results obtained from transmission electron microscopy analysis showed the average size of 50 nm for ATO@SWCNT. This study indicated that U87 cells, which were exposed to METH and suffered cell death, were severely reduced in the presence of ATO, especially ATO@SWCNT (for its anti-apoptotic effect), but they survived. This study suggests that ATO, which was primarily used to reduce blood lipids, can significantly reduce brain cell death. The findings of this study indicate that by using SWCNT, more drugs can reach the target cells. This method reduces the total amount of required medication and shows a more beneficial therapeutic effect.

Neurotoxicity of methamphetamine: Main effects and mechanisms

Methamphetamine (METH) is an illicit psychostimulant that is abused throughout the world. METH addiction is also a major public health concern and the abuse of large doses of the drug is often associated with serious neuropsychiatric consequences that may include agitation, anxiety, hallucinations, paranoia, and psychosis. Some human methamphetamine users can also suffer from attention, memory, and executive deficits. METH-associated neurological and psychiatric complications might be related, in part, to METH-induced neurotoxic effects. Those include altered dopaminergic and serotonergic functions, neuronal apoptosis, astrocytosis, and microgliosis. Here we have endeavored to discuss some of the main effects of the drug and have presented the evidence supporting certain of the molecular and cellular bases of METH neurotoxicity. The accumulated evidence suggests the involvement of transcription factors, activation of dealth pathways that emanate from mitochondria and endoplasmic reticulum (ER), and a role for neuroinflammatory mechanisms. Understanding the molecular processes involved in METH induced neurotoxicity should help in developing better therapeutic approaches that might also serve to attenuate or block the biological consequences of use of large doses of the drug by some humans who meet criteria for METH use disorder.

Synergistic Impairment of the Neurovascular Unit by HIV-1 Infection and Methamphetamine Use: Implications for HIV-1-Associated Neurocognitive Disorders

The neurovascular units (NVU) are the minimal functional units of the blood-brain barrier (BBB), composed of endothelial cells, pericytes, astrocytes, microglia, neurons, and the basement membrane. The BBB serves as an important interface for immune communication between the brain and peripheral circulation. Disruption of the NVU by the human immunodeficiency virus-1 (HIV-1) induces dysfunction of the BBB and triggers inflammatory responses, which can lead to the development of neurocognitive impairments collectively known as HIV-1-associated neurocognitive disorders (HAND). Methamphetamine (METH) use disorder is a frequent comorbidity among individuals infected with HIV-1. METH use may be associated not only with rapid HIV-1 disease progression but also with accelerated onset and increased severity of HAND. However, the molecular mechanisms of METH-induced neuronal injury and cognitive impairment in the context of HIV-1 infection are poorly understood. In this review, we summarize recent progress in the signaling pathways mediating synergistic impairment of the BBB and neuronal injury induced by METH and HIV-1, potentially accelerating the onset or severity of HAND in HIV-1-positive METH abusers. We also discuss potential therapies to limit neuroinflammation and NVU damage in HIV-1-infected METH abusers.

Tetrahydropalmatine Regulates BDNF through TrkB/CAM Interaction to Alleviate the Neurotoxicity Induced by Methamphetamine

Tetrahydropalmatine (THP) has analgesic, hypnotic, sedative, and other pharmacological effects. Brain-derived neurotrophic factor (BDNF) plays an important role in neuronal plasticity, growth, and development. However, their mechanism of action in methamphetamine (MA)-induced neurotoxicity remains unclear. This study aims to explore the important role of BDNF in MA neurotoxicity and whether THP can regulate BDNF through the interaction between tyrosine kinase receptor B (TrkB)/calmodulin (CAM) to alleviate the neurotoxicity induced by MA. SD rats were randomly divided into control, MA, and MA + THP groups. Stereotyped behavior test, captive rejection test, open field test (OFT), and Morris water maze (MWM) were used to evaluate the anxiety, aggression, cognition, learning, and memory. Extracted hippocampus and mesencephalon tissue were detected by Western blot, HE staining, and immunohistochemistry. TUNEL staining was used to detect apoptosis. MOE was used for bioinformatics prediction, and coimmunoprecipitation was used to confirm protein interactions. Long-term abuse of MA resulted in lower weight gain ratio and nerve cell damage and caused various neurotoxicity-related behavioral abnormalities: anxiety, aggression, cognitive motor disorders, and learning and memory disorders. MA-induced neurotoxicity is related to the down-regulation of BDNF and apoptosis. THP attenuated the MA-induced neurotoxicity by decreasing CAM, increasing TrkB, phosphorylating Akt, up-regulating NF-κB and BDNF, and inhibiting cell apoptosis. MA can induce neurotoxicity in rats. BDNF may play a vital role in MA-induced neurotoxicity. THP regulates BDNF through TrkB/CAM interaction to alleviate the neurotoxicity induced by MA. THP may be a potential therapeutic drug for the neurotoxic and neurodegenerative diseases related to MA.

Cerebral dopamine neurotrophic factor transfection in dopamine neurons using neurotensin-polyplex nanoparticles reverses 6-hydroxydopamine-induced nigrostriatal neurodegeneration

Overexpression of neurotrophic factors in nigral dopamine neurons is a promising approach to reverse neurodegeneration of the nigrostriatal dopamine system, a hallmark in Parkinson's disease. The human cerebral dopamine neurotrophic factor (hCDNF) has recently emerged as a strong candidate for Parkinson's disease therapy. This study shows that hCDNF expression in dopamine neurons using the neurotensin-polyplex nanoparticle system reverses 6-hydroxydopamine-induced morphological, biochemical, and behavioral alterations. Three independent electron microscopy techniques showed that the neurotensin-polyplex nanoparticles containing the hCDNF gene, ranging in size from 20 to 150 nm, enabled the expression of a secretable hCDNF in vitro. Their injection in the substantia nigra compacta on day 21 after the 6-hydroxydopamine lesion resulted in detectable hCDNF in dopamine neurons, whose levels remained constant throughout the study in the substantia nigra compacta and striatum. Compared with the lesioned group, tyrosine hydroxylase-positive (TH⁺) nigral cell population and TH⁺ fiber density rose in the substantia nigra compacta and striatum after hCDNF transfection. An increase in βIII-tubulin and growth-associated protein 43 phospho-S41 (GAP43p) followed TH⁺ cell recovery, as well as dopamine and its catabolite levels. Partial reversal (80%) of drug-activated circling behavior and full recovery of spontaneous motor and non-motor behavior were achieved. Brain-derived neurotrophic factor recovery in dopamine neurons that also occurred suggests its participation in the neurotrophic effects. These findings support the potential of nanoparticle-mediated hCDNF gene delivery to develop a disease-modifying treatment against Parkinson's disease. The Institutional Animal Care and Use Committee of Centro de Investigación y de Estudios Avanzados approved our experimental procedures for animal use (authorization No. 162-15) on June 9, 2019.

Thymoquinone abrogates methamphetamine-induced striatal neurotoxicity and hyperlocomotor activity in mice

Background and purpose:

Methamphetamine (METH) abuse has devastating consequences on the nervous system. There are limited therapy choices in METH abuse with reduced effectiveness and elevated recurrence rates. Thymoquinone (TQ), the most bioactive constituent of Nigella sativa seeds exerts neuroprotective effects mainly via antioxidant properties. This study aimed to evaluate the effect of TQ against METH-induced striatal neurotoxicity and hyperlocomotor activity in mice.

Experimental approach:

Our groups of animals received METH (10 mg/kg) four times a day with 2 h intervals. Normal saline or TQ (5, 10, or 20 mg/kg) was injected intraperitoneally 30 min before METH administration. Control and sham groups received vehicle or TQ, respectively. The rectal temperature and behavioral tests including the open field for locomotor activity and rotarod for motor coordination were evaluated. The level of superoxide dismutase (SOD), as well as pathological changes, were also assessed in the striatum region.

Findings/Results:

No significant differences in rectal temperatures were observed among treated groups. Administration of METH increased locomotor activity and did not change motor coordination. TQ co-administration with METH significantly reduced the central and total locomotion and the mean latency to fall off the rotarod in a dose-dependent manner compared with the METH group. TQ also alleviated the METH-induced decrease in the activity of SOD.TQ, especially at the high dose, reduced the METH-induced reactive gliosis level.

Conclusion and implications:

In conclusion, TQ prevents the enhanced locomotor activity, antioxidant impairment, and morphological striatal damage caused by METH in mice. TQ may be a potential candidate for the treatment of specific METH-induced brain disorders or neurological diseases.

Mystery of methamphetamine-induced autophagosome accumulation in hippocampal neurons: loss of syntaxin 17 in defects of dynein-dynactin driving and autophagosome-late endosome/lysosome fusion

Methamphetamine (METH), a psychoactive-stimulant facilitates massive accumulation of autophagosomes and causes autophagy-associated neuronal death. However, the underlying mechanisms involving METH-induced auto-phagosome accumulation remain poorly understood. In the current study, autophagic flux was tracked by mRFP-GFP-LC3 adenovirus, 900 μM METH treatment was found to significantly disrupt autophagic flux, which was further validated by remarkable increase of co-localized of LC3 and SQSTM1/p62, enhancement of LC3-II and SQSTM1/p62 protein levels, and massive autophagosome puncta aggregation. With the cycloheximide (CHX) treatment, METH treatment was displayed a significant inhibition of SQSTM1/p62 degradation. Therefore, the mRNAs associated with vesicle degradation were screened, and syntaxin 17 (Stx17) and dynein-dynactin mRNA levels significantly decreased, an effect was proved in protein level as well. Intriguingly, METH induced autophagosome accumulation and autophagic flux disturbance was incredibly retarded by overexpression of Stx17, which was validated by the restoration of the fusion autophagosome-late endosome/lysosome fusion. Moreover, Stx17 overexpression obviously impeded the METH-induced decrease of co-localization of the retrograded motor protein dynein/dynactin and autophagosome-late endosome, though the dynein/dynactin proteins were not involved in autophagosome-late endosome/lysosome fusion. Collectively, our findings unravel the mechanism of METH-induced autophagosome accumulation involving autophagosome-late endosome/lysosome fusion deficiency and that autophagy-enhancing mechanisms such as the overexpression of Stx17 may be therapeutic strategies for the treatment of METH-induced neuronal damage.

Methamphetamine in Orthopaedics: Considerations of an At-Risk Population

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Methamphetamine use by orthopaedic trauma patients has risen to epidemic proportions.

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Perioperative methamphetamine use by orthopaedic trauma patients requires physicians to consider both medical and psychosocial factors during treatment.

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Behavioral and psychosocial effects of methamphetamine use present barriers to care.

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Patients who use methamphetamine face elevated rates of complications.

We Have a Lot to Do: Lack of Sexual Protection and Information-Results of the German-Language Online Survey "Let's Talk About Chemsex"

Background: The prevalence of chemsex and sexualized substance use is increasing in several European countries, particularly among men who have sex with men. In this subgroup, illegal substance use is associated with increased sexual risk behavior, which can result in severe physical and psychological impairments. The present study examined the incidence and prevalence of chemsex in German-speaking countries. Methods: To further describe the high-risk group of Chemsex users, participants (N = 429) were asked about their psychotropic substance use, sexual and health-related behavior, health status, and socio-demographic information by using an online questionnaire. Whether Chemsex has negative effects on well-being was measured with the WHO well-being index. Of additional interest was how informed Chemsex users are about the topic and what needs are placed on the practitioners. The online questionnaire consisted of 105 items, and data was collected from March to May 2019. Thousand forty seven datasets were saved with a dropout rate of 59%, 123 completed questionnaires fulfilled the criteria for chemsex users (n =123). Results: There were no significant differences in well-being between chemsex users and non-users. All participants protected themselves against sexually transmitted diseases irregularly or not at all. The majority of chemsex users reported intermittently using illegal substances (ketamine, methamphetamine, mephedrone, γ-butyrolactone/γ-hydroxy butyric acid). They viewed their sexual and substance use behavior as problematic, but few showed motivation for behavior change. Chemsex users clearly expressed a need for more information and advice centers. Conclusion: The results provide information on chemsex users that can be used for the future development of a therapy manual and thus contribute to improving health care for this group. The prevalence of chemsex is increasing and urgently needs more research to protect clients from health impairments and stigmatization.

The Relationship Between Brain Metabolites Alterations and Neuropsychological Deficits in Patients with Methamphetamine Use Disorder: A Proton Magnetic Resonance Spectroscopy Study

INTRODUCTION

Chronic use of methamphetamine induces neuropsychological deficits and neurochemical changes in frontostriatal regions. This study aimed to examine the relationship between brain metabolites alterations in frontostriatal regions and neuropsychological deficits in patients with methamphetamine use disorder.

METHOD

A total of 30 methamphetamine users and 20 control participants were selected and a battery of standardized executive function, attention, and memory tasks, including the Wisconsin Card Sorting Test, Stroop Test, and Wechsler Memory Scale, was administered to them. Proton-Magnetic resonance spectroscopy (H-MRS) of N-Acetylaspartate/Creatine (NAA/Cr), Choline/Creatine (Cho/Cr), and glutamate + glutamine/creatine (Glx/Cr) in dorsolateral prefrontal cortex (DLPFC), anterior cingulate cortex (ACC), and basal ganglia (BG) were also undertaken.

RESULTS

Current findings indicated that there were significant differences between two groups in metabolite ratios including NAA/Cr, Cho/Cr, and Glx/Cr in three areas, except for Glx/Cr in BG. Moreover, compared to healthy controls, methamphetamine users showed poorer performance in all neuropsychological tests. Finally, a significant relationship was found between regional metabolites alterations, particularly in the ACC, and neuropsychological deficits in methamphetamine users.

CONCLUSIONS

In addition to neurochemical changes and neuropsychological deficits in patients with methamphetamine use disorder, current results highlighted the relationship between these changes in DLPFC, ACC, and BG with cognitive deficits in methamphetamine users.

Understanding the genetics and neurobiological pathways behind addiction (Review)

The hypothesis issued by modern medicine states that many diseases known to humans are genetically determined, influenced or not by environmental factors, which is applicable to most psychiatric disorders as well. This article focuses on two pending questions regarding addiction: Why do some individuals become addicted while others do not? along with Is it a learned behavior or is it genetically predefined? Recent data suggest that addiction is more than repeated exposure, it is the synchronicity between intrinsic factors (genotype, sex, age, preexisting addictive disorder, or other mental illness), extrinsic factors (childhood, level of education, socioeconomic status, social support, entourage, drug availability) and the nature of the addictive agent (pharmacokinetics, path of administration, psychoactive properties). The dopamine-mesolimbic motivation-reward-reinforcement cycle remains the most coherent physiological theory in addiction. While the common property of addictive substances is that they are dopamine-agonists, each class has individual mechanisms, pharmacokinetics and psychoactive potentials.

The Role of α-Synuclein in Methamphetamine-Induced Neurotoxicity

Methamphetamine (METH), a highly addictive psychostimulant, is the second most widely used illicit drug. METH produces damage dopamine neurons and apoptosis via multiple inter-regulating mechanisms, including dopamine overload, hyperthermia, oxidative stress, mitochondria dysfunction, endoplasmic reticulum stress, protein degradation system dysfunction, and neuroinflammation. Increasing evidence suggests that chronic METH abuse is associated with neurodegenerative changes in the human brain and an increased risk of Parkinson's disease (PD). METH use and PD may share some common steps in causing neurotoxicity. Accumulation of α-synuclein, a presynaptic protein, is the pathological hallmark of PD. Intriguingly, α-synuclein upregulation and aggregation are also found in dopaminergic neurons in the substantia nigra in chronic METH users. This suggests α-synuclein may play a role in METH-induced neurotoxicity. The mechanism of α-synuclein cytotoxicity in PD has attracted considerable attention; however, how α-synuclein affects METH-induced neurotoxicity has not been reviewed. In this review, we summarize the relationship between METH use and PD, interdependent mechanisms that are involved in METH-induced neurotoxicity and the significance of α-synuclein upregulation in response to METH use. The identification of α-synuclein overexpression and aggregation as a contributor to METH-induced neurotoxicity may provide a novel therapeutic target for the treatment of the deleterious effect of this drug and drug addiction.

Methamphetamine Inhibits Long-Term Memory Acquisition and Synaptic Plasticity by Evoking Endoplasmic Reticulum Stress

Methamphetamine (MA), an illicit drug abused worldwide, leads to cognitive impairment and memory loss. However, the detailed mechanisms of MA-induced neurologic impairment are still unclear. The present study aimed to investigate the mechanisms of MA-induced inhibition of memory acquisition from the perspective of endoplasmic reticulum (ER) stress. ER stress, caused by the accumulation of wrongly folded proteins in the ER, is important for new protein synthesis, which further influence the formation of long-term memory. A subacute MA poisoning model of mice was established and several behavioral experiments were performed, including elevated plus maze, Morris water maze, electro-stimulus Y-maze, and novel object recognition tasks. The present results suggested that 4 days exposure to MA induced significant memory loss. Whereas, this damage to memory formation could be protected when mice were pre-treated with ER stress inhibitor, tauroursodeoxycholic acid (TUDCA). The results of Western blotting showed that subacute exposure to MA increased the expression levels of ER stress marker proteins, such as binding immunoglobulin protein, phosphorylated eukaryotic translation initiation factor 2α, cyclic AMP-dependent transcription factor (ATF)-4, ATF-6, and CCAAT-enhancer binding protein homologous protein. Meanwhile, the enhanced expression levels of these proteins were reversed by TUDCA, indicating that MA administration induced memory loss by evoking ER stress in the hippocampus. We also found that MA inhibited the induction of long-term potentiation (LTP) in the hippocampus. Nevertheless, LTP could be induced when mice were pre-treated with TUDCA. In conclusion, MA inhibited long-term memory acquisition and synaptic plasticity via ER stress.