Regional distribution of methamphetamine in autopsied brain of chronic human methamphetamine users

Challenges and insights: Methamphetamine analysis in post-mortem putrefied human tissues in a hot climate

Background

The production and distribution of methamphetamine (meth) is often associated with illegal and clandestine laboratories, posing significant challenges for law enforcement and public health efforts. Global concern is growing over meth-related fatalities, as its high potential for abuse and detrimental impact on health make it an important issue in the realm of substance abuse and addiction. This concern has notably increased in Saudi Arabia, where the hot climate adds complexity to the analysis due to challenges posed by putrefaction. There is still an urgent need to enhance the screening capabilities of many toxicology laboratories to determine the cause of death, whether it be due to drug use or natural causes.

Aim

This research aimed to investigate meth concentrations in post-mortem putrefied human solid tissues in a hot climate and comparing meth metabolite concentrations in cases where signs of putrefaction were observed versus those with no signs of putrefaction. The objective is to assist criminal investigations by analyzing meth and its metabolite concentrations.

Methods

This retrospective cohort study involved postmortem samples from human subjects during autopsies conducted between 2016 and 2022. It focused on analyzing meth and its metabolite concentrations using LC-MS/MS analysis. Data on demographics, medical history, age, location, putrefaction, and other drug use were retrieved from medical records.

Results

Out of the 27 reported samples of meth and its metabolite amphetamine in both putrefied and non-putrefied biological fluids and tissues, only 8 (30%) exhibited signs of putrefaction between 2016 and 2022. Despite decomposition, detectable concentrations of meth and amphetamine were sufficient to determine the cause of death and the source of amphetamines.

Conclusion

This study found no significant difference in concentrations between putrefied and non-putrefied cases, underscoring the importance of multiple sample testing during autopsy for accurate interpretation. Each case is unique and must be considered individually.

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.

Methamphetamine facilitates HIV infection of primary human monocytes through inhibiting cellular viral restriction factors

Background

Methamphetamine (METH), a potent addictive psychostimulant, is highly prevalent in HIV-infected individuals. Clinically, METH use is implicated in alteration of immune system and increase of HIV spread/replication. Therefore, it is of importance to examine whether METH has direct effect on HIV infection of monocytes, the major target and reservoir cells for the virus.

Results

METH-treated monocytes were more susceptible to HIV infection as evidenced by increased levels of viral proteins (p24 and Pr55Gag) and expression of viral GAG gene. In addition, using HIV Bal with luciferase reporter gene (HIV Bal-eLuc), we showed that METH-treated cells expressed higher luciferase activities than untreated monocytes. Mechanistically, METH inhibited the expression of IFN-λ1, IRF7, STAT1, and the antiviral IFN-stimulated genes (ISGs: OAS2, GBP5, ISG56, Viperin and ISG15). In addition, METH down-regulated the expression of the HIV restriction microRNAs (miR-28, miR-29a, miR-125b, miR-146a, miR-155, miR-223, and miR-382).

Conclusions

METH compromises the intracellular anti-HIV immunity and facilitates HIV replication in primary human monocytes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13578-021-00703-4.

Methamphetamine deaths: Changing trends and diagnostic issues

The term 'amphetamine' refers to a class of synthetic drugs which includes methamphetamine. The latter is a globally popular drug of abuse which induces euphoria, affecting cognitive/psychomotor performance and sleep. It also provokes risk taking and violent behaviour. The central effects of methamphetamine are due to the overproduction of neurotransmitters, resulting in high levels of dopamine. In recent years, there have been significant increases in cases of methamphetamine abuse in North and South America, Australia and Asia due to its ready availability and low cost. The following review examines changing trends in methamphetamine use and problems that arise diagnostically in medico-legal cases in determining the significance of post-mortem blood levels, the relationship of these to ante-mortem levels, the possible effects on physical and psychological behaviours and the possible contribution of the drug to a lethal episode.

Methamphetamine-related postmortem cases in Jeddah, Saudi Arabia

A more than 500% increase in the number of deaths involving methamphetamine occurred between 2016 and 2018 in Jeddah, Saudi Arabia. As such, this report employed a validated liquid chromatography tandem mass spectrometry method to quantify methamphetamine and its metabolites in bodily fluids from 47 postmortem cases in which methamphetamine was involved. The mean age of the deceased was 33 years old (median: 30, range: 16-63), and 94% were male. Methamphetamine was co-ingested with another drug in 32 of the cases (68%); however, the deaths were only due to the combined toxicity of methamphetamine and another drug in 15 of the cases (32%). Of note, 13 of these deaths (28% of all deaths) involved heroin. When methamphetamine was the sole cause of death (32% of the studied cases), the median concentrations of methamphetamine and amphetamine were 527 and 128 ng/mL. When methamphetamine was combined toxicity with another drug, the median concentrations of methamphetamine and amphetamine decreased to 161 and 53 ng/mL. When deaths were unrelated to methamphetamine, the median concentrations of methamphetamine and amphetamine were 130 and 44 ng/mL, respectively. The highest median methamphetamine concentration was found in urine (5281 ng/mL), followed by stomach contents (878 ng/mL), bile (762 ng/mL), vitreous humor (3 ng/mL), and blood (208 ng/mL). Almost 40% of the studied cases involved violence, 61% were accidental, 21% were suicides, 17% were homicides, and 2% were natural deaths. Methamphetamine is highly addictive. Increases in deaths have been seen in various countries. More awareness, education and treatment programs are required to reduce the likelihood of addiction, crimes, suicide, and other fatalities resulting from methamphetamine abuse.

Activation of proline biosynthesis is critical to maintain glutamate homeostasis during acute methamphetamine exposure

Methamphetamine (METH) is a highly addictive psychostimulant that causes long-lasting effects in the brain and increases the risk of developing neurodegenerative diseases. The cellular and molecular effects of METH in the brain are functionally linked to alterations in glutamate levels. Despite the well-documented effects of METH on glutamate neurotransmission, the underlying mechanism by which METH alters glutamate levels is not clearly understood. In this study, we report an essential role of proline biosynthesis in maintaining METH-induced glutamate homeostasis. We observed that acute METH exposure resulted in the induction of proline biosynthetic enzymes in both undifferentiated and differentiated neuronal cells. Proline level was also increased in these cells after METH exposure. Surprisingly, METH treatment did not increase glutamate levels nor caused neuronal excitotoxicity. However, METH exposure resulted in a significant upregulation of pyrroline-5-carboxylate synthase (P5CS), the key enzyme that catalyzes synthesis of proline from glutamate. Interestingly, depletion of P5CS by CRISPR/Cas9 resulted in a significant increase in glutamate levels upon METH exposure. METH exposure also increased glutamate levels in P5CS-deficient proline-auxotropic cells. Conversely, restoration of P5CS expression in P5CS-deficient cells abrogated the effect of METH on glutamate levels. Consistent with these findings, P5CS expression was significantly enhanced in the cortical brain region of mice administered with METH and in the slices of cortical brain tissues treated with METH. Collectively, these results uncover a key role of P5CS for the molecular effects of METH and highlight that excess glutamate can be sequestered for proline biosynthesis as a protective mechanism to maintain glutamate homeostasis during drug exposure.

Cerebral vasculitis associated with drug abuse

PURPOSE OF REVIEW

To review understand the epidemiology, background, neuropharmacology, and histopathology of literature verified cases, and likely etiopathogenic mechanisms.

RECENT FINDINGS

There are only a handful of histologically confirmed patients in the literature with cerebral vasculitis because of drug abuse.

SUMMARY

There is little justification for invasive laboratory investigation given the ready availability of highly accurate vascular neuroimaging techniques to dictate management, which usually rests upon avoidance of further exposure and minimizing the secondary neurotoxic effects of the abused substances and polypharmacy use.

The emergence of cardiac changes following the self-administration of methamphetamine

BACKGROUND

Clinical observations suggest an association between methamphetamine (METH) use and cardiovascular disease, but preclinical studies are lacking. The purpose of the current study was to explore changes in left ventricular function as a potential precursor to cardiovascular disease in a rodent model of METH use.

METHODS

Male rats were allowed to self-administer either METH or saline for 9 d. On the day following the 4th and 9th self-administration sessions, an echocardiogram was performed to assess left-ventricular parameters under basal conditions and following a low-dose of METH (1 mg/kg).

RESULTS

A low challenge dose of METH resulted in subtle but statistically significant changes in cardiac function during the echocardiogram in both the METH and saline self-administering groups. Further, differences in left-ventricular parameters such as stroke volume and heart rate were observed between METH and saline groups following the 9th self-administration session. Finally, supervised machine learning correctly predicted the self-administration group assignment (saline or METH) using cardiac parameters following the 9th self-administration session.

CONCLUSIONS

The findings of the current study suggest the heart, specifically the left ventricle, is sensitive to METH. Overall, these findings and emerging clinical observations highlight the need for research to investigate the effects of METH use on the heart.

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.

Exercise protects against methamphetamine-induced aberrant neurogenesis

While no effective therapy is available for the treatment of methamphetamine (METH)-induced neurotoxicity, aerobic exercise is being proposed to improve depressive symptoms and substance abuse outcomes. The present study focuses on the effect of exercise on METH-induced aberrant neurogenesis in the hippocampal dentate gyrus in the context of the blood-brain barrier (BBB) pathology. Mice were administered with METH or saline by i.p. injections for 5 days with an escalating dose regimen. One set of mice was sacrificed 24 h post last injection of METH, and the remaining animals were either subjected to voluntary wheel running (exercised mice) or remained in sedentary housing (sedentary mice). METH administration decreased expression of tight junction (TJ) proteins and increased BBB permeability in the hippocampus. These changes were preserved post METH administration in sedentary mice and were associated with the development of significant aberrations of neural differentiation. Exercise protected against these effects by enhancing the protein expression of TJ proteins, stabilizing the BBB integrity, and enhancing the neural differentiation. In addition, exercise protected against METH-induced systemic increase in inflammatory cytokine levels. These results suggest that exercise can attenuate METH-induced neurotoxicity by protecting against the BBB disruption and related microenvironmental changes in the hippocampus.

Effects of HIV and Methamphetamine on Brain and Behavior: Evidence from Human Studies and Animal Models

Methamphetamine (Meth) use is frequent among HIV-infected persons. Combined HIV and Meth insults may exacerbate neural injury in vulnerable neuroanatomic structures or circuitries in the brain, leading to increased behavioral disturbance and cognitive impairment. While acute and chronic effects of Meth in humans and animal models have been studied for decades, the neurobehavioral effects of Meth in the context of HIV infection are much less explored. In-depth understanding of the scope of neurobehavioral phenotypes and mechanisms in HIV/Meth intersection is needed. The present report summarizes published research findings, as well as unpublished data, in humans and animal models with regard to neurobehavioral disturbance, neuroimaging, and neuropathology, and in vitro experimental systems, with an emphasis on findings emerging from the National Institute on Drug Abuse (NIDA) funded Translational Methamphetamine AIDS Research Center (TMARC). Results from human studies and animal (primarily HIV-1 gp120 transgenic mouse) models thus far suggest that combined HIV and Meth insults increase the likelihood of neural injury in the brain. The neurobehavioral effects include cognitive impairment and increased tendencies toward impaired behavioral inhibition and social cognition. These impairments are relevant to behaviors that affect personal and social risks, e.g. worse medication adherence, riskier behaviors, and greater likelihood of HIV transmission. The underlying mechanisms may include electrochemical changes in neuronal circuitries, injury to white matter microstructures, synaptodendritic damage, and selective neuronal loss. Utilization of research methodologies that are valid across species is instrumental in generating new knowledge with clinical translational value.

Lifetime methamphetamine dependence is associated with cerebral microgliosis in HIV-1-infected adults

Methamphetamine (Meth) use is common among HIV-infected persons. It remains unclear whether Meth dependence is associated with long-lasting degenerative changes in the brain parenchyma and microvasculature of HIV-infected individuals. We examined the postmortem brains of 78 HIV-infected adults, twenty of whom were diagnosed with lifetime Meth dependence (18 past and two current at the final follow-up visit). Using logistic regression models, we analyzed associations of Meth with cerebral gliosis (immunohistochemistry for ionized calcium-binding adapter molecule-1 (Iba1) and glial fibrillary acidic protein (GFAP) in frontal, temporo-parietal, and putamen-internal capsule regions), synaptodendritic loss (confocal microscopy for synaptophysin (SYP) and microtubule-associated protein-2 (MAP2) in frontal cortex), β-amyloid plaque deposition (immunohistochemistry in frontal and temporo-parietal cortex and putamen), and arteriolosclerosis (histopathology in forebrain white matter). We found that Meth was associated with marked Iba1 gliosis in the temporo-parietal region (odds ratio, 4.42 (95 % confidence interval, 1.36, 14.39), p = 0.014, n = 62), which remained statistically significant after adjusting for HIV encephalitis, white matter lesions, and opportunistic diseases (n = 61); hepatitis C virus seropositivity (n = 54); and lifetime dependence on alcohol, opiates, and cannabis (n = 62). There was no significant association of Meth with GFAP gliosis, SYP or MAP2 loss, β-amyloid plaque deposition, or arteriolosclerosis. In conclusion, we found lifetime Meth dependence to be associated with focal cerebral microgliosis among HIV-infected adults, but not with other brain degenerative changes examined. Some of the changes in select brain regions might be reversible following extended Meth abstinence or, alternatively, might have not been induced by Meth initially.

Galectin-1 suppresses methamphetamine induced neuroinflammation in human brain microvascular endothelial cells: Neuroprotective role in maintaining blood brain barrier integrity

Methamphetamine (Meth) abuse can lead to the breakdown of the blood-brain barrier (BBB) integrity leading to compromised CNS function. The role of Galectins in the angiogenesis process in tumor-associated endothelial cells (EC) is well established; however no data are available on the expression of Galectins in normal human brain microvascular endothelial cells and their potential role in maintaining BBB integrity. We evaluated the basal gene/protein expression levels of Galectin-1, -3 and -9 in normal primary human brain microvascular endothelial cells (BMVEC) that constitute the BBB and examined whether Meth altered Galectin expression in these cells, and if Galectin-1 treatment impacted the integrity of an in-vitro BBB. Our results showed that BMVEC expressed significantly higher levels of Galectin-1 as compared to Galectin-3 and -9. Meth treatment increased Galectin-1 expression in BMVEC. Meth induced decrease in TJ proteins ZO-1, Claudin-3 and adhesion molecule ICAM-1 was reversed by Galectin-1. Our data suggests that Galectin-1 is involved in BBB remodeling and can increase levels of TJ proteins ZO-1 and Claudin-3 and adhesion molecule ICAM-1 which helps maintain BBB tightness thus playing a neuroprotective role. Galectin-1 is thus an important regulator of immune balance from neurodegeneration to neuroprotection, which makes it an important therapeutic agent/target in the treatment of drug addiction and other neurological conditions.

Is brain gliosis a characteristic of chronic methamphetamine use in the human?

Animal data show that high doses of the stimulant drug methamphetamine can damage brain dopamine neurones; however, it is still uncertain whether methamphetamine, at any dose, is neurotoxic to human brain. Since gliosis is typically associated with brain damage and is observed in animal models of methamphetamine exposure, we measured protein levels (intact protein and fragments, if any) of markers of microgliosis (glucose transporter-5, human leukocyte antigens HLA-DRα [TAL.1B5] and HLA-DR/DQ/DPβ [CR3/43]) and astrogliosis (glial fibrillary acidic protein, vimentin, and heat shock protein-27) in homogenates of autopsied brain of chronic methamphetamine users (n=20) and matched controls (n=23). Intact protein levels of all markers were, as expected, elevated (+28%-1270%, P<0.05) in putamen of patients with the neurodegenerative disorder multiple system atrophy (as a positive control) as were concentrations of fragments of glial fibrillary acidic protein, vimentin and heat shock protein-27 (+170%-4700%, P<0.005). In contrast, intact protein concentrations of the markers were normal in dopamine-rich striatum (caudate, putamen) and in the frontal cortex of the drug users. However, striatal levels of cleaved vimentin and heat shock protein-27 were increased (by 98%-211%, P<0.05), with positive correlations (r=0.41-0.60) observed between concentrations of truncated heat shock protein-27 and extent of dopamine loss (P=0.006) and levels of lipid peroxidation products 4-hydroxynonenal (P=0.046) and malondialdehyde (P=0.11). Our failure to detect increased intact protein levels of commonly used markers of microgliosis and astrogliosis could be explained by exposure to methamphetamine insufficient to cause a toxic process associated with overt gliosis; however, about half of the subjects had died of drug intoxication suggesting that "high" drug doses might have been used. Alternatively, drug tolerance to toxic effects might have occurred in the subjects, who were all chronic methamphetamine users. Nevertheless, the finding of above-normal levels of striatal vimentin and heat shock protein-27 fragments (which constituted 10-28% of the intact protein), for which changes in the latter correlated with those of several markers possibly suggestive of damage, does suggest that some astrocytic "disturbance" had occurred, which might in principle be related to methamphetamine neurotoxicity or to a neuroplastic remodeling process. Taken together, our neurochemical findings do not provide strong evidence for either marked microgliosis or astrogliosis in at least a subgroup of human recreational methamphetamine users who used the drug chronically and shortly before death. However, a logistically more difficult quantitative histopathological study is needed to confirm whether glial changes occur or do not occur in brain of human methamphetamine (and amphetamine) users.

Modulation of intracellular restriction factors contributes to methamphetamine-mediated enhancement of acquired immune deficiency syndrome virus infection of macrophages

Epidemiological studies have demonstrated that the use of methamphetamine (METH), a sympathomimetic stimulant, is particularly common among patients infected with HIV. In vitro studies have determined that METH enhances HIV infection of CD4+ T cells, monocyte-derived dendritic cells, and macrophages. In addition, animal studies have also showed that METH treatment increases brain viral load of SIV-infected monkeys and promotes HIV replication and viremia in HIV/hu-CycT1 transgenic mice. However, the mechanisms (s) of METH actions on HIV remain to be determined. In this study, we investigated the impact of METH on intracellular restriction factors against HIV and SIV. We demonstrated that METH treatment of human blood mononuclear phagocytes significantly affected the expression of anti-HIV microRNAs and several key elements (RIG-I, IRF-3/5, SOCS-2, 3 and PIAS-1, 3, X, Y) in the type I IFN pathway. The suppression of these innate restriction factors was associated with a reduced production of type I IFNs and the enhancement of HIV or SIV infection of macrophages. These findings indicate that METH use impairs intracellular innate antiviral mechanism(s) in macrophages, contributing to cell susceptibility to the acquired immune deficiency syndrome (AIDS) virus infection.

Prior methamphetamine self-administration attenuates serotonergic deficits induced by subsequent high-dose methamphetamine administrations

BACKGROUND

Pre-clinical studies indicate that high-dose, non-contingent methamphetamine (METH) administration both rapidly and persistently decreases serotonergic neuronal function. Despite research indicating the hippocampus plays an important role in METH abuse and is affected by METH use, effects of METH self-administration on hippocampal serotonergic neurons are not well understood, and were thus an important focus of the current study. Because humans often administer METH in a binge-like pattern, effects of prior METH self-administration on a subsequent "binge-like" METH treatment were also examined.

METHODS

Rats were treated as described above, and sacrificed 1 or 8d after self-administration or 1h or 7d after the final binge METH or saline exposure. Hippocampal serotonin (5-hydroxytryptamine; 5HT) content and transporter (SERT) function were assessed.

RESULTS

METH self-administration per se had no persistent effect on hippocampal 5HT content or SERT function. However, this treatment attenuated the persistent, but not acute, hippocampal serotonergic deficits caused by a subsequent repeated, high-dose, non-continent METH treatment administered 1 d the last self-administration session. No attenuation in persistent deficits were seen when the high-dose administration of METH occurred 15d after the last self-administration session.

CONCLUSIONS

The present findings demonstrate that METH self-administration alters serotonergic neurons so as to engender "tolerance" to the persistent serotonergic deficits caused by a subsequent METH exposure. However, this "tolerance" does not persist. These data provide a foundation to investigate complex questions including how the response of serotonergic neurons to METH may contribute to contingent-related disorders such as dependence and relapse.

Nanoparticle based galectin-1 gene silencing, implications in methamphetamine regulation of HIV-1 infection in monocyte derived macrophages

Galectin-1, an adhesion molecule, is expressed in macrophages and implicated in human immunodeficiency virus (HIV-1) viral adsorption. In this study, we investigated the effects of methamphetamine on galectin-1 production in human monocyte derived macrophages (MDM) and the role of galectin-1 in methamphetamine potentiation of HIV-1 infection. Herein we show that levels of galectin-1 gene and protein expression are significantly increased by methamphetamine. Furthermore, concomitant incubation of MDM with galectin-1 and methamphetamine facilitates HIV-1 infection compared to galectin-1 alone or methamphetamine alone. We utilized a nanotechnology approach that uses gold nanorod (GNR)-galectin-1 siRNA complexes (nanoplexes) to inhibit gene expression for galectin-1. Nanoplexes significantly silenced gene expression for galectin-1 and reversed the effects of methamphetamine on galectin-1 gene expression. Moreover, the effects of methamphetamine on HIV-1 infection were attenuated in the presence of the nanoplex in MDM.

Methamphetamine and inflammatory cytokines increase neuronal Na+/K+-ATPase isoform 3: relevance for HIV associated neurocognitive disorders

Methamphetamine (METH) abuse in conjunction with human immunodeficiency virus (HIV) exacerbates neuropathogenesis and accelerates neurocognitive impairments in the central nervous system (CNS), collectively termed HIV Associated Neurocognitive Disorders (HAND). Since both HIV and METH have been implicated in altering the synaptic architecture, this study focused on investigating alterations in synaptic proteins. Employing a quantitative proteomics approach on synaptosomes isolated from the caudate nucleus from two groups of rhesus monkeys chronically infected with simian immunodeficiency virus (SIV) differing by one regimen, METH treatment, we identified the neuron specific Na(+)/K(+)-ATPase alpha 1 isoform 3 (ATP1A3) to be up regulated after METH treatment, and validated its up regulation by METH in vitro. Further studies on signaling mechanisms revealed that the activation of ATP1A3 involves the extracellular regulated kinase (ERK) pathway. Given its function in maintaining ionic gradients and emerging role as a signaling molecule, changes in ATP1A3 yields insights into the mechanisms associated with HAND and interactions with drugs of abuse.

Methamphetamine self-administration causes persistent striatal dopaminergic alterations and mitigates the deficits caused by a subsequent methamphetamine exposure

Preclinical studies have demonstrated that repeated methamphetamine (METH) injections (referred to herein as a "binge" treatment) cause persistent dopaminergic deficits. A few studies have also examined the persistent neurochemical impact of METH self-administration in rats, but with variable results. These latter studies are important because: 1) they have relevance to the study of METH abuse; and 2) the effects of noncontingent METH treatment do not necessarily predict effects of contingent exposure. Accordingly, the present study investigated the impact of METH self-administration on dopaminergic neuronal function. Results revealed that self-administration of METH, given according to a regimen that produces brain METH levels comparable with those reported postmortem in human METH abusers (0.06 mg/infusion; 8-h sessions for 7 days), decreased striatal dopamine transporter (DAT) uptake and/or immunoreactivity as assessed 8 or 30 days after the last self-administration session. Increasing the METH dose per infusion did not exacerbate these deficits. These deficits were similar in magnitude to decreases in DAT densities reported in imaging studies of abstinent METH abusers. It is noteworthy that METH self-administration mitigated the persistent deficits in dopaminergic neuronal function, as well as the increases in glial fibrillary acidic protein immunoreactivity, caused by a subsequent binge METH exposure. This protection was independent of alterations in METH pharmacokinetics, but may have been attributable (at least in part) to a pretreatment-induced attenuation of binge-induced hyperthermia. Taken together, these results may provide insight into the neurochemical deficits reported in human METH abusers.

Methamphetamine exerts toxic effects on subventricular zone stem/progenitor cells and inhibits neuronal differentiation

Methamphetamine (METH) is a potent and widely consumed psychostimulant drug that causes brain functional and structural abnormalities. However, there is little information regarding METH impact on adult neurogenic niches and, indeed, nothing is known about its consequences on the subventricular zone (SVZ). Thus, this work aims to clarify the effect of METH on SVZ stem/progenitor cells dynamics and neurogenesis. For that purpose, SVZ neurospheres were obtained from early postnatal mice and treated with increasing concentrations of METH (1  μM to 500  μM). Exposure to 100, 250, or 500  μM METH for 24  h triggered cell death both by necrosis and apoptosis, as assessed by propidium iodide uptake, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining, and quantification of the proapoptotic caspase-3 activity. Furthermore, we showed that METH inhibited SVZ progenitor cells proliferation as it decreased BrdU incorporation. Interestingly, at non-toxic concentrations (1 and 10  μM), METH decreased neuronal differentiation and maturation, which were evaluated by quantification of the number of neuronal nuclei-positive neurons and measurements of phospho-c-Jun-NH(2)-terminal kinase signal in growing axons, respectively. Altogether, our data demonstrate that METH has a negative impact on SVZ stem/progenitor cells, inducing cell death and inhibiting neurogenesis, effects that in vivo may challenge the cell replacement capacities displayed by endogenous populations of brain stem/progenitor cells.

Methamphetamine causes mitrochondrial oxidative damage in human T lymphocytes leading to functional impairment

Methamphetamine (METH) abuse is known to be associated with an inordinate rate of infections. Although many studies have described the association of METH exposure and immunosuppression, so far the underlying mechanism still remains elusive. In this study, we present evidence that METH exposure resulted in mitochondrial oxidative damage and caused dysfunction of primary human T cells. METH treatment of T lymphocytes led to a rise in intracellular calcium levels that enhanced the generation of reactive oxygen species. TCR-CD28 linked calcium mobilization and subsequent uptake by mitochondria in METH-treated T cells correlated with an increase in mitochondrion-derived superoxide. Exposure to METH-induced mitochondrial dysfunction in the form of marked decrease in mitochondrial membrane potential, increased mitochondrial mass, enhanced protein nitrosylation and diminished protein levels of complexes I, III, and IV of the electron transport chain. These changes paralleled reduced IL-2 secretion and T cell proliferative responses after TCR-CD28 stimulation indicating impaired T cell function. Furthermore, antioxidants attenuated METH-induced mitochondrial damage by preserving the protein levels of mitochondrial complexes I, III, and IV. Altogether, our data indicate that METH can cause T cell dysfunction via induction of oxidative stress and mitochondrial injury as underlying mechanism of immune impairment secondary to METH abuse.

Proteomic analyses of the effects of drugs of abuse on monocyte-derived mature dendritic cells

Drug abuse has become a global health concern. Understanding how drug abuse modulates the immune system and how the immune system responds to pathogens associated with drug abuse, such hepatitis C virus (HCV) and human immunodeficiency virus (HIV-1), can be assessed by an integrated approach comparing proteomic analyses and quantitation of gene expression. Two-dimensional (2D) difference gel electrophoresis was used to determine the molecular mechanisms underlying the proteomic changes that alter normal biological processes when monocyte-derived mature dendritic cells were treated with cocaine or methamphetamine. Both drugs differentially regulated the expression of several functional classes of proteins including those that modulate apoptosis, protein folding, protein kinase activity, and metabolism and proteins that function as intracellular signal transduction molecules. Proteomic data were validated using a combination of quantitative, real-time PCR and Western blot analyses. These studies will help to identify the molecular mechanisms, including the expression of several functionally important classes of proteins that have emerged as potential mediators of pathogenesis. These proteins may predispose immunocompetent cells, including dendritic cells, to infection with viruses such as HCV and HIV-1, which are associated with drug abuse.

Human methamphetamine pharmacokinetics simulated in the rat: behavioral and neurochemical effects of a 72-h binge

Bingeing is one pattern of high-dose methamphetamine (METH) abuse, which involves continuous drug taking over several days and can result in psychotic behaviors for which the brain pathology remains poorly defined. A corresponding animal model of this type of METH exposure may provide novel insights into the neurochemical and behavioral sequelae associated with this condition. Accordingly, to simulate the pharmacokinetic profile of a human METH binge exposure in rats, we used a computer-controlled, intravenous METH procedure (dynamic infusion, DI) to overcome species differences in METH pharmacokinetics and to replicate the human 12-h plasma METH half-life. Animals were treated over 13 weeks with escalating METH doses, using DI, and then exposed to a binge in which drug was administered every 3 h for 72 h. Throughout the binge, behavioral effects included unabated intense oral stereotypies in the absence of locomotion and in the absence of sleep. Decrements in regional brain dopamine, norepinephrine, and serotonin levels, measured at 1 and 10 h after the last injection of the binge, had, with the exception of caudate-putamen dopamine and frontal cortex serotonin, recovered by 48 h. At 10 h after the last injection of the binge, [(3)H]ligand binding to dopamine and vesicular monoamine transporters in caudate-putamen were reduced by 35 and 13%, respectively. In a separate METH binge-treated cohort, post-binge behavioral alterations were apparent in an attenuated locomotor response to a METH challenge infusion at 24 h after the last injection of the binge. Collectively, the changes we characterized during and after a METH binge suggest that for human beings under similar exposure conditions, multiple time-dependent neurochemical deficits contribute to their behavioral profiles.

Modulation of the proteome of peripheral blood mononuclear cells from HIV-1-infected patients by drugs of abuse

INTRODUCTION

We used proteomic analyses to assess how drug abuse modulates immunologic responses to infections with the human immunodeficiency virus type 1 (HIV-1).

METHODS

Two-dimensional difference gel electrophoresis was utilized to determine changes in the proteome of peripheral blood mononuclear cells (PBMC) isolated from HIV-1-positive donors that occurred after treatment with cocaine or methamphetamine. Both drugs differentially regulated the expression of several functional classes of proteins. We further isolated specific subpopulations of PBMC to determine which subpopulations were selectively affected by treatment with drugs of abuse. Monocytes, B cells, and T cells were positively or negatively selected from PBMC isolated from HIV-1-positive donors.

RESULTS

Our results demonstrate that cocaine and methamphetamine modulate gene expression primarily in monocytes and T cells, the primary targets of HIV-1 infection. Proteomic data were validated with quantitative, real-time polymerase chain reaction. These studies elucidate the molecular mechanisms underlying the effects of drugs of abuse on HIV-1 infections. Several functionally relevant classes of proteins were identified as potential mediators of HIV-1 pathogenesis and disease progression associated with drug abuse.

Brain serotonin transporter in human methamphetamine users

RATIONALE

Research on methamphetamine (MA) toxicity primarily focuses on the possibility that some of the behavioural problems in human MA users might be caused by damage to brain dopamine neurones. However, animal data also indicate that MA can damage brain serotonin neurones, and it has been suggested that cognitive problems and aggression in MA users might be explained by serotonergic damage. As information on the brain serotonin system in human MA users is fragmentary, our objective was to determine whether protein levels of serotonin transporter (SERT), a key marker of serotonin neurones, are decreased in brain of chronic MA users.

METHODS

SERT immunoreactivity was measured using an immunoblotting procedure in autopsied brain of 16 chronic MA users testing positive for the drug in blood and brain and matched controls.

RESULTS

SERT levels were non-significantly decreased (-14% to -33%) in caudate, putamen and thalamus (normal in hippocampus), and, unlike the robust striatal dopamine reduction, there was marked overlap between control and MA user ranges. Concentrations of SERT were significantly decreased (-23% to -39%) in orbitofrontal and occipital cortices (normal in frontopolar and temporal cortices).

CONCLUSIONS

Our data suggest that MA might modestly damage brain serotonin neurones and/or inhibit SERT protein expression, with cerebral cortex being more affected than sub-cortical regions. The SERT reduction in orbitofrontal cortex complements other data suggesting involvement of this area in MA-related behaviour. Decreased brain SERT could also be related to the clinical finding that treatment with a selective serotonin re-uptake inhibitor might increase relapse to MA.

Increased vesicular monoamine transporter binding during early abstinence in human methamphetamine users: Is VMAT2 a stable dopamine neuron biomarker?

Animal data indicate that methamphetamine can damage striatal dopamine terminals. Efforts to document dopamine neuron damage in living brain of methamphetamine users have focused on the binding of [(11)C]dihydrotetrabenazine (DTBZ), a vesicular monoamine transporter (VMAT2) positron emission tomography (PET) radioligand, as a stable dopamine neuron biomarker. Previous PET data report a slight decrease in striatal [(11)C]DTBZ binding in human methamphetamine users after prolonged (mean, 3 years) abstinence, suggesting that the reduction would likely be substantial in early abstinence. We measured striatal VMAT2 binding in 16 recently withdrawn (mean, 19 d; range, 1-90 d) methamphetamine users and in 14 healthy matched-control subjects during a PET scan with (+)[(11)C]DTBZ. Unexpectedly, striatal (+)[(11)C]DTBZ binding was increased in methamphetamine users relative to controls (+22%, caudate; +12%, putamen; +11%, ventral striatum). Increased (+)[(11)C]DTBZ binding in caudate was most marked in methamphetamine users abstinent for 1-3 d (+41%), relative to the 7-21 d (+15%) and >21 d (+9%) groups. Above-normal VMAT2 binding in some drug users suggests that any toxic effect of methamphetamine on dopamine neurons might be masked by an increased (+)[(11)C]DTBZ binding and that VMAT2 radioligand binding might not be, as is generally assumed, a "stable" index of dopamine neuron integrity in vivo. One potential explanation for increased (+)[(11)C]DTBZ binding is that VMAT2 binding is sensitive to changes in vesicular dopamine storage levels, presumably low in drug users. If correct, (+)[(11)C]DTBZ might be a useful imaging probe to correlate changes in brain dopamine stores and behavior in users of methamphetamine.

Fast uptake and long-lasting binding of methamphetamine in the human brain: comparison with cocaine

Methamphetamine is one of the most addictive and neurotoxic drugs of abuse. It produces large elevations in extracellular dopamine in the striatum through vesicular release and inhibition of the dopamine transporter. In the U.S. abuse prevalence varies by ethnicity with very low abuse among African Americans relative to Caucasians, differentiating it from cocaine where abuse rates are similar for the two groups. Here we report the first comparison of methamphetamine and cocaine pharmacokinetics in brain between Caucasians and African Americans along with the measurement of dopamine transporter availability in striatum. Methamphetamine's uptake in brain was fast (peak uptake at 9 min) with accumulation in cortical and subcortical brain regions and in white matter. Its clearance from brain was slow (except for white matter which did not clear over the 90 min) and there was no difference in pharmacokinetics between Caucasians and African Americans. In contrast cocaine's brain uptake and clearance were both fast, distribution was predominantly in striatum and uptake was higher in African Americans. Among individuals, those with the highest striatal (but not cerebellar) methamphetamine accumulation also had the highest dopamine transporter availability suggesting a relationship between METH exposure and DAT availability. Methamphetamine's fast brain uptake is consistent with its highly reinforcing effects, its slow clearance with its long-lasting behavioral effects and its widespread distribution with its neurotoxic effects that affect not only striatal but also cortical and white matter regions. The absence of significant differences between Caucasians and African Americans suggests that variables other than methamphetamine pharmacokinetics and bioavailability account for the lower abuse prevalence in African Americans.

Impairments in timing, temporal memory, and reversal learning linked to neurotoxic regimens of methamphetamine intoxication

Methamphetamine intoxication has long-term consequences on dopaminergic function and corticostriatal-mediated behaviors in humans and other animals. In order to determine the potential impact on timing and temporal memory, we examined methamphetamine dose regimens that have been linked to neurotoxicity in adult (8 months) male rats. Rats that were given repetitive, high-dose methamphetamine (3.0 mg/kg ip x 4 injections/2 h) or saline injections were trained on a 2-s vs 8-s bisection procedure using auditory and visual signal durations. Following the high-dose regimen, baseline timing performance was reestablished prior to the rats' receiving reversal training in which the spatial/temporal mapping of the anchor durations (2 s and 8 s) to response options (left or right lever) was reversed. Low-dose methamphetamine (0.5 mg/kg ip) or saline injections were subsequently used to evaluate the effectiveness of the neurotoxic doses in terms of modifying the horizontal leftward shifts associated with increases in clock speed. Overall, the results indicate that MAP intoxication leads to reduced auditory/visual differences in clock speed, deficits in reversal learning, distortions in temporal memory, and lowered dopaminergic regulation of clock speed consistent with damage to prefrontal cortex and corticostriatal circuitry.

Brain levels of neuropeptides in human chronic methamphetamine users

Animal data show that neuropeptide systems in the dopamine-rich brain areas of the striatum (caudate, putamen, and nucleus accumbens) are influenced by exposure to psychostimulants, suggesting that neuropeptides are involved in mediating aspects of behavioral responses to drugs of abuse. To establish in an exploratory study whether levels of neuropeptides are altered in brain of human methamphetamine users, we measured tissue concentrations of dynorphin, metenkephalin, neuropeptide Y, neurotensin, and substance P in autopsied brains of 16 chronic methamphetamine users and 17 matched control subjects. As expected, levels of most neuropeptides were enriched in dopamine-linked brain regions such as the nucleus accumbens and striatum of normal human brain. In contrast to animal findings of increased neuropeptide levels following short-term methamphetamine exposure, striatal neuropeptide concentrations were either normal or moderately decreased in the methamphetamine users. In other examined dopamine-poor cortical and subcortical brain areas, neuropeptide levels were generally either normal or variably reduced. Although the neuropeptide differences might be explained by methamphetamine-induced damage to neuropeptide-containing neurons, our human data are consistent with the possibility that, at least in the human striatum, long-term methamphetamine exposure leads to an adaptive process that is distinct from that which increases neuropeptide levels after acute methamphetamine exposure.

Proteomic analyses of methamphetamine (METH)-induced differential protein expression by immature dendritic cells (IDC)

In the US, the increase in methamphetamine (METH) use has been associated with increased human immunodeficiency virus (HIV-1) infection. Dendritic cells (DC) are the first line of defense against HIV-1. DC play a critical role in harboring HIV-1 and facilitate the infection of neighboring T cells. However, the role of METH on HIV-1 infectivity and the expression of the proteome of immature dendritic cells (IDC) has not been elucidated. We hypothesize that METH modulates the expression of a number of proteins by IDC that foster the immunopathogenesis of HIV-1 infection. We utilized LTR amplification, p24 antigen assay and the proteomic method of difference gel electrophoresis (DIGE) combined with protein identification through high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) to analyze the effects of METH on HIV-1 infectivity (HIV-1 IIIB; CXCR4-tropic, X4 strain) and the proteomic profile of IDC. Our results demonstrate that METH potentiates HIV-1 replication in IDC. Furthermore, METH significantly differentially regulates the expression of several proteins including CXCR3, protein disulfide isomerase, procathepsin B, peroxiredoxin and galectin-1. Identification of unique, METH-induced proteins may help to develop novel markers for diagnostic, preventive and therapeutic targeting in METH using subjects.

Methamphetamine downregulates peroxiredoxins in rat pheochromocytoma cells

Methamphetamine (METH) is an abusive psychostimulant that induces neuronal cell death/degeneration in experimental animals and humans. METH-induced apoptosis in rat pheochromocytoma cells was utilized to study the neurotoxic mechanism. During METH intoxication, we found that peroxiredoxins and thioredoxins/thioredoxin reductases (peroxiredoxin reducing systems) which are known to prevent oxidative stress and apoptosis were differentially downregulated and upregulated, respectively. We also found not only the free radicals but also the oxidative forms of peroxiredoxin and thioredoxin were increased, indicating the dysfunction of these enzymes. Thus, METH-induced differential regulation and oxidation of peroxiredoxins and thioredoxin may be an important mechanism for apoptosis.

Levels of 4-Hydroxynonenal and Malondialdehyde Are Increased in Brain of Human Chronic Users of Methamphetamine

Animal studies suggest that the widely used psychostimulant drug methamphetamine (MA) can harm brain dopamine neurones, possibly by causing oxidative damage. However, evidence of oxidative damage in brain of human MA users is lacking. We tested the hypothesis that levels of two "gold standard" products generated from lipid peroxidation, 4-hydroxynonenal (one of the most reactive lipid peroxidation aldehyde products) and malondialdehyde, would be elevated in post mortem brain of 16 dopamine-deficient chronic MA users compared with those in 21 matched control subjects. Derivatized aldehyde concentrations were determined by gas chromatography-mass spectrometry. In the MA group, we found significantly increased levels of 4-hydroxynonenal and malondialdehyde in the dopamine-rich caudate nucleus (by 67 and 75%, respectively) and to a lesser extent in frontal cortex (48 and 36%, respectively) but not in the cerebellar cortex. Approximately half of the MA users had levels of 4-hydroxynonenal falling above the upper limit of the control range in caudate and frontal cortex. A subgroup of MA users with high brain drug levels had higher concentrations of the aldehydes. Our data suggest that MA exposure in human causes, as in experimental animals, above-normal formation of potentially toxic lipid peroxidation products in brain. This provides evidence for involvement of oxygen-based free radicals in the action of MA in both dopamine-rich (caudate) and -poor (cerebral cortex) areas of human brain.

Involvement of sigma (sigma) receptors in the acute actions of methamphetamine: receptor binding and behavioral studies

Methamphetamine interacts with sigma (sigma) receptors, suggesting that the drug produces some of its physiological and behavioral effects through these sites. Therefore, in the present report, receptor binding and pharmacological studies were performed to characterize the interaction between methamphetamine and sigma receptors. Of the two major sigma receptor subtypes, sigma1 and sigma2, competition binding studies showed that methamphetamine has a 22-fold preferential affinity for the sigma1 subtype. Saturation binding studies using the sigma1 selective radioligand [3H]+-pentazocine showed that in the presence of methamphetamine, there was a significant change in Kd, but not Bmax, suggesting competitive interactions. In behavioral studies, pretreatment of Swiss Webster mice with the sigma1 receptor antagonists, BD1063 or BD1047, significantly attenuated the locomotor stimulatory effects of methamphetamine. Mice that were administered an antisense oligodeoxynucleotide to down-regulate brain sigma1 receptors also exhibited a reduced locomotor stimulatory response to methamphetamine, as compared to control mice receiving mismatch oligonucleotides. Together, the data suggest that sigma1 receptors are involved in the acute actions of methamphetamine and that antagonism of this subtype is sufficient to prevent the locomotor stimulatory effects of methamphetamine.

Prolonged exposure of rats to intravenous methamphetamine: behavioral and neurochemical characterization

The translational value of preclinical models of methamphetamine abuse depends in large part on the degree to which the drug regimens used in animals produce methamphetamine exposure patterns similar to those experienced by human methamphetamine abusers. To approximate one common form of methamphetamine abuse, we studied the effects of a schedule of intravenous methamphetamine administration in rats which included 2 weeks of progressively more frequent drug injections (0.125 mg/kg/injection) followed by 40 maintenance days during which animals received 40 daily injections (at 15-min intervals), with the dose gradually increasing (0.125-0.25 mg/kg per injection) every 5-10 days. This treatment produced an emerging behavioral profile characterized by gradually more continuous periods of activation consisting of progressively more intense, focused stereotypy interrupted by episodic bursts of locomotion. We also assessed markers of dopamine neurotransmission (dopamine transporter, vesicular monoamine transporter, and dopamine D1 and D2 receptors) at 15 min and (including dopamine levels) at 6 and 30 days following cessation of methamphetamine treatment. All dopamine components measured in caudate-putamen were significantly reduced at 15 min and 6 days after the final methamphetamine injection. Dopamine D1 and D2 receptors fully recovered after 30 days of drug abstinence, whereas dopamine and the dopamine transporter exhibited significant but incomplete recovery by this time point. In contrast, only the vesicular monoamine transporter exhibited no evidence of recovery over the 30-day withdrawal period. These data are discussed in terms of damage to dopamine terminals and compensatory adjustments in mechanisms maintaining functional dopaminergic transmission.

Postmortem toxicology of drugs of abuse

Conducting toxicology on post-mortem specimens provides a number of very significant challenges to the scientist. The range of additional specimens include tissues such as decomposing blood and other tissues, hair, muscle, fat, lung, and even larvae feeding on the host require special techniques to isolate a foreign substance and allow detection without interference from the matrix. A number of drugs of abuse are unstable in the post-mortem environment that requires careful consideration when trying to interpret their significance. Heroin, morphine glucuronides, cocaine and the benzodiazepines are particularly prone to degradation. Moreover, redistributive process can significantly alter the concentration of drugs, particularly those with a higher tissue concentration than the surrounding blood. The designer amphetamines, methadone and other potent opioids will increase their concentration in blood post-mortem. These processes together with the development of tolerance means that no concentration of a drug of abuse can be interpreted in isolation without a thorough examination of the relevant circumstances and after the conduct of a post-mortem to eliminate or corroborate relevant factors that could impact on the drug concentration and the possible effect of a substance on the body. This article reviews particular toxicological issues associated with the more common drugs of abuse such as the amphetamines, cannabinoids, cocaine, opioids and the benzodiazepines.

Why is parkinsonism not a feature of human methamphetamine users?

For more than 50 years, methamphetamine has been a widely used stimulant drug taken to maintain wakefulness and performance and, in high doses, to cause intense euphoria. Animal studies show that methamphetamine can cause short-term and even persistent depletion of brain levels of the neurotransmitter dopamine. However, the clinical features of Parkinson's disease, a dopamine deficiency disorder of the brain, do not appear to be characteristic of human methamphetamine users. We compared dopamine levels in autopsied brain tissue of chronic methamphetamine users with those in patients with Parkinson's disease and in a control group. Mean dopamine levels in the methamphetamine users were reduced more in the caudate (-61%) than in the putamen (-50%), a pattern opposite to that of Parkinson's disease. Some methamphetamine users had severely decreased dopamine levels, within the parkinsonian range, in the caudate (up to 97% dopamine loss) but not in the putamen. As the putamen and caudate subserve aspects of motor and cognitive function, respectively, our data suggest that methamphetamine users are not parkinsonian because dopamine levels are not sufficiently decreased in the motor component of the striatum. However, the near-total reduction in the caudate could explain reports of cognitive disturbances, sometimes disabling, in some drug users, and suggests that treatment with dopamine substitution medication (e.g. levodopa) during drug rehabilitation might be helpful.

Brain vesicular acetylcholine transporter in human users of drugs of abuse

Limited animal data suggest that the dopaminergic neurotoxin methamphetamine is not toxic to brain (striatal) cholinergic neurons. However, we previously reported that activity of choline acetyltransferase (ChAT), the cholinergic marker synthetic enzyme, can be very low in brain of some human high-dose methamphetamine users. We measured, by quantitative immunoblotting, concentrations of a second cholinergic marker, the vesicular acetylcholine transporter (VAChT), considered to be a "stable" marker of cholinergic neurons, in autopsied brain (caudate, hippocampus) of chronic users of methamphetamine and, for comparison, in brain of users of cocaine, heroin, and matched controls. Western blot analyses showed normal levels of VAChT immunoreactivity in hippocampus of all drug user groups, whereas in the dopamine-rich caudate VAChT levels were selectively elevated (+48%) in the methamphetamine group, including the three high-dose methamphetamine users who had severely reduced ChAT activity. To the extent that cholinergic neuron integrity can be inferred from VAChT concentration, our data suggest that methamphetamine does not cause loss of striatal cholinergic neurons, but might damage/downregulate brain ChAT in some high-dose users. However, the finding of increased VAChT levels suggests that brain VAChT concentration might be subject to up- and downregulation as part of a compensatory process to maintain homeostasis of neuronal cholinergic activity. This possibility should be taken into account when utilizing VAChT as a neuroimaging outcome marker for cholinergic neuron number in human studies.

Analysis of methamphetamine and its metabolites in hair

Methamphetamine (MA) is a sympathomimetic amine whose abuse has become a serious problem in Japan, Korea, Taiwan and other Southeast Asian countries. The use of hair for the determination of MA use has become more commonplace. The maximum period in which MA and its main metabolites (amphetamine and p-hydroxymethamphetamine) can be detected in urine is about 10 days after its use. However, proof of MA use is possible in hair even several years after its use if the part of the hair that grew in the period of its use is available. In addition, segmental analysis of hair is capable of clarifying the history of MA abuse. This paper reviews the clean-up, extraction, analytical method and distribution of MA and its metabolites in hair from reports published in the last 20 years.