Glutamatergic neurometabolites during early abstinence from chronic methamphetamine abuse

Brain Glutamate Dynamics Predict Positive Agency in Healthy Women: Insights from Combined Application of Pharmacological Challenge, Comprehensive Affective Assessment, and Magnetic Resonance Spectroscopy

Contributions of brain glutamate (Glu) to conscious emotion are not well understood. Here, we evaluate the relationship of experimentally induced change in neocortical Glu (ΔGlu) and subjective states in well individuals, using combined application of pharmacological challenge, magnetic resonance spectroscopy (MRS), and comprehensive affective assessment. Drug challenge with d-amphetamine (AMP) (20 mg oral), methamphetamine (MA) (Desoxyn, 20 mg oral), and placebo (PBO) was conducted on three separate test days in a within-subjects double blind design. Proton MRS quantified neurometabolites in the right dorsal anterior cingulate cortex 140-150 min post-drug and PBO. Subjective states were assessed at half hour intervals over 5.5 h on each session, yielding 3792 responses per participant (91,008 responses overall, N = 24 participants), with self-reports reduced by principal components analysis (PCA). PCA produced a primary factor score of AMP- and MA-induced positive agency (ΔPA). MRS indicated drug-induced ΔGlu related positively to ΔPA (ΔGluMA r = +0.44, p < 0.05, N = 21), with large effects in females (ΔGluMA r = +0.52, p < 0.05; ΔGluAMP r = +0.61, p < 0.05, N = 11). Subjective states related to ΔGlu included rise in subjective stimulation, vigor, friendliness, elation, positive mood, positive affect (r's = +0.51 to +0.74, p < 0.05), and alleviation of anxiety in females (r = -0.61, p < 0.05, N = 11). These self-reports correlated with ΔGlu to the extent they loaded on ΔPA (r = 0.95 AMP, p = 5 × 10-10; r = 0.63 MA, p = 0.0015, N = 11), indicating the coherence of ΔGlu effects on emotional states. Timing data indicated Glu shaped positive emotion both concurrently and prospectively, with no relationship with pre-MRS emotion (ΔGluAMP r = +0.59 to +0.65, p's < 0.05; ΔGluMA r = +0.53, p < 0.05, N = 11). Together these findings indicate substantive, mechanistic contributions of neocortical Glu to positive agentic states in healthy individuals, which are most readily observed in women. The findings illustrate the promise of combined application of pharmacological challenge, comprehensive affective assessment, and MRS neuroimaging techniques in basic and clinical studies.

Brain Glutamate Dynamics Predict Positive Agency in Healthy Women

Contributions of brain glutamate to conscious emotion are not well understood. Here we evaluate the relationship of experimentally-induced change in neocortical glutamate (ΔGlu) and subjective states in well individuals. Drug challenge with d-amphetamine (AMP; 20 mg oral), methamphetamine (MA; Desoxyn®, 20 mg oral), and placebo (PBO) was conducted on three separate test days in a within-subjects double blind design. Proton magnetic resonance spectroscopy (MRS) quantified neurometabolites in the right dorsal anterior cingulate cortex (dACC) 140-150 m post-drug and PBO. Subjective states were assessed at half hour intervals over 5.5-hours on each session, yielding 3,792 responses per participant (91,008 responses overall, N=24 participants). Self-reports were reduced by principal components analysis to a single factor score of AMP- and MA-induced Positive Agency (ΔPA) in each participant. We found drug-induced ΔGlu related positively with ΔPA (ΔGluMA r=+.44, p<.05, N=21), with large effects in females (ΔGluMA r=+.52, p<.05; ΔGluAMP r=+.61, p<.05, N=11). States related to ΔGlu in females included rise in subjective stimulation, vigor, friendliness, elation, positive mood, positive affect (r's=+.51 to +.74, p<.05), and alleviation of anxiety (r=-.61, p<.05, N=11). Self-reports correlated with DGlu to the extent they loaded on ΔPA (r=.95 AMP, p=5×10-10; r=.63 MA, p=.0015, N=11), indicating coherence of ΔGlu effects. Timing data indicated Glu shaped emotion both concurrently and prospectively, with no relationship to pre-MRS emotion (ΔGluAMP r=+.59 to +.65, p's<.05; ΔGluMA r=+.53, p<.05, N=11). Together these findings indicate substantive, mechanistic contributions of neocortical Glu to positive agentic states in healthy individuals, most readily observed in women.

Lower dACC glutamate in cannabis users during early phase abstinence

Glutamate plays an important role in continued use of and relapse to abused substances. However, its involvement in cannabis withdrawal is still unclear. We hypothesize that regional glutamate is associated with the cannabis withdrawal syndrome and recently examined possible association of glutamate with cannabis withdrawal, using magnetic resonance spectroscopy (MRS), in non-treatment-seeking cannabis users. We recruited 26 frequent cannabis users and 11 age-matched non-using controls. Of the 37, 20 users (8f/12m) and 10 controls (5f/5m) completed a verified 21-day abstinence protocol. Dorsal anterior cingulate cortex (dACC) glutamate and γ-amino butyric acid (GABA) were measured with proton MRS at baseline and on abstinent days 7 and 21 in conjunction with measures of cannabis withdrawal and craving (MCQ), sleep difficulties (PSQI) and mood state. We used ANOVA to examine group differences in glutamate and GABA from baseline through day 21 and used linear regression to evaluate correlations between intra-individual glutamate and withdrawal symptoms. We found that self-reported anxiety severity (HAMA) was correlated with urinary THC/Cr ratios at baseline (r = 0.768, p = 0.000076) and abstinent day 7 (r = 0.5636, p = 0.0097), dACC glutamate was significantly lower in the users compared with the controls from baseline through day 21 (F = 5.90, p = 0.022), changes in glutamate between baseline and abstinent day 21 had a significantly negative correlation with corresponding changes in craving (r = -0.72, p = 0.005) after adjusting for age, consumption of alcohol/cigarettes, sleep difficulties, and urinary THC levels. These findings provide preliminary evidence that dACC glutamate is associated with the cannabis withdrawal syndrome.

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.

ERK-Directed Phosphorylation of mGlu5 Gates Methamphetamine Reward and Reinforcement in Mouse

Methamphetamine (MA) is a highly addictive psychomotor stimulant drug. In recent years, MA use has increased exponentially on a global scale, with the number of MA-involved deaths reaching epidemic proportions. There is no approved pharmacotherapy for treating MA use disorder, and we know relatively little regarding the neurobiological determinants of vulnerability to this disease. Extracellular signal-regulated kinase (ERK) is an important signaling molecule implicated in the long-lasting neuroadaptations purported to underlie the development of substance use disorders, but the role for this kinase in the propensity to develop addiction, particularly MA use disorder, is uncharacterized. In a previous MA-induced place-conditioning study of C57BL/6J mice, we characterized mice as MA-preferring, -neutral, or -avoiding and collected tissue from the medial prefrontal cortex (mPFC). Using immunoblotting, we determined that elevated phosphorylated ERK expression within the medial prefrontal cortex (mPFC) is a biochemical correlate of the affective valence of MA in a population of C57BL/6J mice. We confirmed the functional relevance for mPFC ERK activation for MA-induced place-preference via site-directed infusion of the MEK inhibitor U0126. By contrast, ERK inhibition did not have any effect upon MA-induced locomotion or its sensitization upon repeated MA treatment. Through studies of transgenic mice with alanine point mutations on T1123/S1126 of mGlu5 that disrupt ERK-dependent phosphorylation of the receptor, we discovered that ERK-dependent mGlu5 phosphorylation normally suppresses MA-induced conditioned place-preference (MA-CPP), but is necessary for this drug’s reinforcing properties. If relevant to humans, the present results implicate individual differences in the capacity of MA-associated cues/contexts to hyper-activate ERK signaling within mPFC in MA Use Disorder vulnerability and pose mGlu5 as one ERK-directed target contributing to the propensity to seek out and take MA.

A novel brief treatment for methamphetamine use disorders in South Africa: a randomised feasibility trial

Background

Effective brief treatments for methamphetamine use disorders (MAUD) are urgently needed to complement longer more intensive treatments in low and middle income countries, including South Africa. To address this gap, the purpose of this randomised feasibility trial was to determine the feasibility of delivering a six-session blended imaginal desensitisation, plus motivational interviewing (IDMI) intervention for adults with a MAUD.

Methods

We enrolled 60 adults with a MAUD and randomly assigned them 1:1 to the IDMI intervention delivered by clinical psychologists and a control group who we referred to usual care. Feasibility measures, such as rates of recruitment, consent to participate in the trial and retention, were calculated. Follow-up interviews were conducted at 6 weeks and 3 months post-enrollment.

Results

Over 9 months, 278 potential particiants initiated contact. Following initial screening 78 (28%) met inclusion criteria, and 60 (77%) were randomised. Thirteen of the 30 participants assigned to the treatment group completed the intervention. Both psychologists were highly adherent to the intervention, obtaining a fidelity rating of 91%. In total, 39 (65%) participants completed the 6-week follow-up and 40 (67%) completed the 3-month follow-up. The intervention shows potential effectiveness in the intention-to-treat analysis where frequency of methamphetamine use was significantly lower in the treatment than in the control group at both the 6 week and 3-month endpoints. No adverse outcomes were reported.

Conclusions

This feasibility trial suggests that the locally adapted IDMI intervention is an acceptable and safe intervention as a brief treatment for MAUD in South Africa. Modifications to the study design should be considered in a fully powered, definitive controlled trial to assess this potentially effective intervention.

Trial registration The trial is registered with the Pan African Clinical Trials Registry (Trial ID: PACTR201310000589295)

1H MRS spectroscopy in preclinical autosomal dominant Alzheimer disease

¹H magnetic resonance spectroscopy (MRS) can reveal changes in brain biochemistry in vivo in humans and has been applied to late onset Alzheimer disease (AD). Carriers of mutations for autosomal dominant Alzheimer disease (ADAD) may show changes in levels of metabolites prior to the onset of clinical symptoms. Proton MR spectra were acquired at 1.5 T for 16 cognitively asymptomatic or mildly symptomatic mutation carriers (CDR < 1) and 11 non-carriers as part of a comprehensive cross-sectional study of preclinical ADAD. Levels of N-acetyl-aspartate+N-acetyl-aspartyl-glutamate (NAA), glutamate/glutamine (Glx), creatine/phosphocreate (Cr), choline (Cho), and myo-inositol (mI) in the left and right anterior cingulate and midline posterior cingulate and precuneus were compared between mutation carriers (MCs) and non-carriers (NCs) using multivariate analysis of variance with age as a covariate. Among MCs, correlations between metabolite levels and time until expected age of dementia diagnosis were calculated. MCs had significantly lower levels of NAA and Glx in the left pregenual anterior cingulate cortex, and lower levels of NAA and higher levels of mI and Cho in the precuneus compared to NCs. Increased levels of mI were seen in these regions in association with increased proximity to expected age of dementia onset. MRS shows effects of ADAD similar to those seen in late onset AD even during the preclinical period including lower levels of NAA and higher levels of mI. These indices of neuronal and glial dysfunction might serve as surrogate outcome measures in prevention studies of putative disease-modifying agents.

Metabolomics profiling of methamphetamine addicted human serum and three rat brain areas

Methamphetamine (METH) has already been a serious problem all over the world. The identification of related biomarkers and pathways is helpful to evaluate the degree of METH addiction, develop appropriate treatment during abstinence, and explore the mechanism. Here, it is the first time to perform metabolomics profiling of METH addicted human serum and three regions of METH-induced conditioned place preference (CPP) rat brain by using UHPLC-MS/MS and matrix-assisted laser desorption/ionization-mass spectrometry imaging (MALDI-MSI), respectively. Untargeted metabolomics analysis demonstrated clear differences between METH abusers and the healthy control by finding 35 distinct expressed metabolites in serum, including 5 TCA intermediates, 17 amino acids and 13 other biomolecules, 15 of which were newly identified following METH exposure. By using MALDI-MSI, the relative quantification and distribution of 14 metabolites were investigated in the nucleus accumbens (NAc), dorsal hippocampus (dHPC) and ventral hippocampus (vHPC) of CPP rat brain. Taken together, METH addiction could influence energy metabolism, amino acids metabolism, and phospholipids metabolism. A multi-parameter model consisting of these related metabolites can be established as a METH addiction biomarker in the future. The mapping of phospholipids provided new insights into the mechanism of METH addiction. Notably, the trend of metabolite changes in NAc and dHPC was almost the same, while it was opposite between dHPC and vHPC. It seems that NAc and dHPC were the two regions more susceptible to METH administration in the brain. And dHPC and vHPC play different roles in METH addiction proved by metabolites mapping.

To explore the mechanism of METH addiction, the metabolomics profiling of METH addicted human serum and rat brain were performed using UHPLC-MS/MS and MALDI-MSI, respectively. 35 differentially expressed metabolites were identified in the serum.

Metabolites Alterations in the Medial Prefrontal Cortex of Methamphetamine Users in Abstinence: A 1H MRS Study

Background: The medial prefrontal cortex (mPFC) contains various neurotransmitter systems and plays an important role in drug use. Broad body of literature on how methamphetamine (MA) affects the structure and metabolism in the animal's mPFC is emerging, while the effects on metabolites of mPFC among human is still unclear. In this study, proton magnetic resonance spectroscopy (1H MRS) was used to measure metabolites of mPFC in methamphetamine dependent subjects. Methods: Sixty-one subjects with a history of MA dependence (fulfiled the Diagnostic and Statistical Manual of Mental Disorders, fourth edition criteria) and 65 drug-naïve control subjects (age19-45) completed 1H MRS scans using 3.0T Siemens MRI scanner. Single voxel spectra were acquired from the mPFC bilaterally using a point resolved spectroscopy sequence (PRESS). The 1H MRS data were automatically fit with linear combination model for quantification of metabolite levels of n-acetyl-aspartate (NAA), myo-inositol (mI), glycerophosphocholine plus phosphocholine(GPC+PC), phosphocreatine plus creatine (PCr+Cr), and glutamate (Glu). Metabolite levels were reported as ratios to PCr+Cr. Results: The MA group showed a significant reduction in NAA/PCr+Cr ratio and elevation in Glu/PCr+Cr ratio and mI/PCr+Cr ratio, compared with healthy control. No significant correlation was found between metabolite ratios and MA use variables. Conclusions: MA use is associated with a significant increased Glu/PCr+Cr ratio, mI/PCr+Cr ratio and reduced NAA/PCr+Cr ratio in the mPFC of MA dependence subjects. These findings suggest that Glu may play a key role in MA induced neurotoxicity.

Gray matter volume showed dynamic alterations in methamphetamine users at 6 and 12months abstinence: A longitudinal voxel-based morphometry study

BACKGROUND

Previous studies have demonstrated brain gray matter reduction in methamphetamine (MA) users; however, little is known about longitudinal brain structural alternations during abstinence.

METHOD

Brain volumes were compared among 30 MA-dependent patients (average 6.3years of drug use) at 6months' abstinence and 27 drug-naïve controls by voxel-based morphometry. A longitudinal analysis of MA subjects was performed from 6 to 12months' abstinence, and multiple regression analyses were performed between drug use patterns and gray matter volumes (GMV) at 6months' abstinence.

RESULTS

Compared with drug-naïve subjects, subjects with 6months' abstinent of MA showed significantly lower GMV in the precentral gyrus, caudate head, fusiform gyrus, and cerebellum. Compared to 6months' abstinence, GMV was greater in the cerebellum and lower in the cingulate gyrus at 12months' abstinence. Accumulated years of MA use negatively correlated with GMV in the right superior frontal gyrus, the right superior temporal cortex, and the right caudate nucleus (significant at the whole brain level, p<0.001; FWE cluster-corrected p<0.05).

CONCLUSION

The present study suggested that heavy MA users' GMV could show dynamic alterations in different brain regions at different time lengths of abstinence.

Modeling human methamphetamine use patterns in mice: chronic and binge methamphetamine exposure, reward function and neurochemistry

Different methamphetamine use patterns in human subjects may contribute to inconsistent findings regarding the effects of methamphetamine abuse on brain and behavior. The present study investigated whether human-derived chronic and binge methamphetamine use patterns have differential effects on reward and neurochemistry in mice. Brain reward function in mice was evaluated during acute/prolonged withdrawal, and in response to methamphetamine challenge using the intracranial self-stimulation procedure. Brain dopaminergic, serotonergic and glutamatergic neurochemistry was determined with high-performance liquid chromatography. Chronic and binge regimens induced withdrawal-related decreases in reward function that were more severe during the binge regimen during cycles 1-2. Despite large differences in methamphetamine dose, both regimens induced similar reward deficits during cycles 3-4. Neither methamphetamine regimen led to persistent alterations in the sensitivity to the reward-enhancing effects of acute methamphetamine challenge. The binge regimen severely depleted striatal dopamine levels and increased brain glutamine levels. The chronic regimen had milder effects on striatal dopamine levels and altered cortical dopamine and serotonin levels. This work highlights that the magnitude of acute/prolonged withdrawal may not reflect amount or frequency of methamphetamine intake. In contrast, the array of underlying neurochemical alterations was methamphetamine regimen dependent. Thus, stratifying methamphetamine-dependent individuals based on use pattern may help to cater therapeutic interventions more appropriately by targeting use pattern-specific neurotransmitter systems.

Molecular, Behavioral, and Physiological Consequences of Methamphetamine Neurotoxicity: Implications for Treatment

Understanding the relationship between the molecular mechanisms underlying neurotoxicity of high-dose methamphetamine (METH) and related clinical manifestations is imperative for providing more effective treatments for human METH users. This article provides an overview of clinical manifestations of METH neurotoxicity to the central nervous system and neurobiology underlying the consequences of administration of neurotoxic METH doses, and discusses implications of METH neurotoxicity for treatment of human abusers of the drug.

Methamphetamine Induces Anhedonic-Like Behavior and Impairs Frontal Cortical Energetics in Mice

INTRODUCTION

We recently showed that a single high dose of methamphetamine (METH) induces a persistent frontal cortical monoamine depletion that is accompanied by helpless-like behavior in mice. However, brain metabolic alterations underlying both neurochemical and mood alterations remain unknown.

AIMS

Herein, we aimed at characterizing frontal cortical metabolic alterations associated with early negative mood behavior triggered by METH. Adult C57BL/6 mice were injected with METH (30 mg/kg, i.p.), and their frontal cortical metabolic status was characterized after probing their mood and anxiety-related phenotypes 3 days postinjection.

RESULTS

Methamphetamine induced depressive-like behavior, as indicated by the decreased grooming time in the splash test and by a transient decrease in sucrose preference. At this time, METH did not alter anxiety-like behavior or motor functions. Depolarization-induced glucose uptake was reduced in frontocortical slices from METH-treated mice compared to controls. Consistently, astrocytic glucose transporter (GluT1) density was lower in the METH group. A proton high rotation magic angle spinning (HRMAS) spectroscopic approach revealed that METH induced a significant decrease in N-acetyl aspartate (NAA) and glutamate levels, suggesting that METH decreased neuronal glutamatergic function in frontal cortex.

CONCLUSIONS

We report, for the first time, that a single METH injection triggers early self-care and hedonic deficits and impairs frontal cortical energetics in mice.

Neuroimaging markers of glutamatergic and GABAergic systems in drug addiction: Relationships to resting-state functional connectivity

Drug addiction is characterized by widespread abnormalities in brain function and neurochemistry, including drug-associated effects on concentrations of the excitatory and inhibitory neurotransmitters glutamate and gamma-aminobutyric acid (GABA), respectively. In healthy individuals, these neurotransmitters drive the resting state, a default condition of brain function also disrupted in addiction. Here, our primary goal was to review in vivo magnetic resonance spectroscopy and positron emission tomography studies that examined markers of glutamate and GABA abnormalities in human drug addiction. Addicted individuals tended to show decreases in these markers compared with healthy controls, but findings also varied by individual characteristics (e.g., abstinence length). Interestingly, select corticolimbic brain regions showing glutamatergic and/or GABAergic abnormalities have been similarly implicated in resting-state functional connectivity deficits in drug addiction. Thus, our secondary goals were to provide a brief review of this resting-state literature, and an initial rationale for the hypothesis that abnormalities in glutamatergic and/or GABAergic neurotransmission may underlie resting-state functional deficits in drug addiction. In doing so, we suggest future research directions and possible treatment implications.

Proton Magnetic Resonance Spectroscopy: Relevance of Glutamate and GABA to Neuropsychology

Proton Magnetic Resonance Spectroscopy (MRS) has been widely used to study the healthy and diseased brain in vivo. The availability of whole body MR scanners with a field strength of 3 Tesla and above permit the quantification of many metabolites including the neurotransmitters glutamate (Glu) and γ-aminobutyric acid (GABA). The potential link between neurometabolites identified by MRS and cognition and behavior has been explored in numerous studies both in healthy subjects and in patient populations. Preliminary findings suggest direct or opposite associations between GABA or Glu with impulsivity, anxiety, and dexterity. This chapter is intended to provide an overview of basic principles of MRS and the literature reporting correlations between GABA or Glu and results of neuropsychological assessments.

The Utility of Magnetic Resonance Spectroscopy for Understanding Substance Use Disorders: A Systematic Review of the Literature

The aim of this article is to present a systematic review of magnetic resonance spectroscopy (MRS) studies of substance use disorders. As a noninvasive and nonionizing imaging technique, MRS is being widely used in substance abuse research to evaluate the effects substances of abuse have on brain chemistry. Nearly 40 peer-reviewed research articles that focused on the utility of MRS in alcohol, methamphetamine, 3,4-methylenedioxymethamphetamine, cocaine, opiates, opioids, marijuana, and nicotine use disorders were reviewed. Findings indicate inconsistencies with respect to alterations in brain chemistry within each substance of abuse, and the most consistent finding across substances was decreased N-acetylaspartate and choline levels with chronic alcohol, methamphetamine, and nicotine use. Variation in the brain regions studied, imaging technique, as well as small sample sizes might explain the discrepancies in findings within each substance. Future well-designed MRS studies offer promise in examining novel treatment approaches in substance use disorders.