Action Of Methamphetamine Research Articles

Association study between polymorphisms in glutathione‐related genes and methamphetamine use disorder in a Japanese population

Accumulating evidence suggests that oxidative stress plays a role in the mechanisms of action of methamphetamine (METH) in the brain. In the present study, we investigated the association between the genetic polymorphisms among glutathione (GSH)-related enzymes; glutathione S-transferases (GSTs) such as GSTT1 (Non-deletion/Null), GSTT2 (Met139Ile), GSTA1 (-69C/T), and GSTO1 (Ala140Asp); glutathione peroxidase 1 (GPX1) (Pro198Leu); and glutamate-cysteine ligase modifier (GCLM) subunit and METH use disorder in a Japanese population. Two hundred eighteen METH abusers and 233 healthy controls were enrolled in the study. There was a significant difference in GSTT1 genotype frequency between patients with METH psychosis and controls (P = 0.039, odds ratio: 1.52, 95% CI 1.03-2.24). Furthermore, the frequency (66.0%) of the GSTT1 null genotype among prolonged-type METH psychotic patients with spontaneous relapse was significantly higher (P = 0.025, odds ratio: 2.43, 95% CI 1.13-5.23) than that (44.4%) of transient-type METH psychotic patients without spontaneous relapse. However, there were no associations between the polymorphisms of other genes and METH abuse. The present study suggests that the polymorphism of the GSTT1 gene might be a genetic risk factor of the development of METH psychosis in a Japanese population.

Methamphetamine-induced locomotor activity and sensitization in dopamine transporter and vesicular monoamine transporter 2 double mutant mice

The dopamine transporter (DAT) and the vesicular monoamine transporter 2 (VMAT2) play pivotal roles in the action of methamphetamine (MAP), including acute locomotor effects and behavioral sensitization. However, the relative impact of heterozygous DAT and VMAT2 knockouts (KOs) on the behavioral effects of MAP remains unknown. To evaluate the roles of DAT and VMAT2 in MAP-induced locomotor behavior, we examined locomotor activity and sensitization in heterozygous DAT KO (DAT+/-), heterozygous VMAT2 KO (VMAT2+/-), double heterozygous DAT/VMAT2 KO (DAT+/-VMAT2+/-), and wild-type (WT) mice. Acute 1 mg/kg MAP injection induced significant locomotor increases in WT and VMAT2+/- mice but not in DAT+/- and DAT+/-VMAT2+/- mice. Acute 2 mg/kg MAP significantly increased locomotor activity in all genotypes. Repeated 1 mg/kg MAP injections revealed a delayed and attenuated development of sensitization in DAT+/- and DAT+/-VMAT2+/- mice compared to WT mice and delayed development in VMAT2+/- mice. In repeated 2 mg/kg MAP injections, DAT+/- and DAT+/-VMAT2+/- mice showed delayed but not attenuated development of sensitization, while there was no difference in the onset of sensitization between VMAT2+/- and WT mice. In DAT+/-VMAT2+/- mice, all of MAP-induced behavioral responses were similar to those in DAT+/- but not VMAT2+/- mice. Heterozygous deletion of DAT attenuates the locomotor effects of MAP and may play larger role in behavioral responses to MAP compared to heterozygous deletion of VMAT2.

5-Methoxy- N, N-diisopropyltryptamine (Foxy), a selective and high affinity inhibitor of serotonin transporter

5-Methoxy- N, N-diisopropyltryptamine (5-MeO-DIPT) is a synthetic orally active hallucinogenic tryptamine derivative, known also as Foxy or Foxy methoxy. However, few studies have examined its effects in vitro. In the present study, we investigated the actions of 5-MeO-DIPT against monoamine neurotransmitter transporters, including the transporters for dopamine (DAT), norepinephrine (NET), and serotonin (SERT), using COS-7 cells heterologously expressing these transporters and rat brain synaptosomes. 5-MeO-DIPT specifically inhibited the uptake of [ 3H]serotonin (5-HT) by the SERT-expressing COS-7 cells and rat striatal synaptosomes in a high affinity manner at concentrations similar to those for cocaine. The effect was reversible and competitive. 5-MeO-DIPT failed to stimulate reverse transport of [ 3H]5-HT through SERT, while it prevented the releasing action of methamphetamine. 5-MeO-DIPT induced cell toxicity at high concentrations in COS-7 cells, and it was not influenced by the expression of SERT. These results demonstrated that 5-MeO-DIPT acts as a competitive SERT inhibitor and has an inability to cause reverse transport, underlying its serotonergic actions.

Sex differences in (+)-amphetamine- and (+)-methamphetamine-induced behavioral response in male and female Sprague–Dawley rats

(+)-Methamphetamine (METH) and (+)-amphetamine (AMP) are structurally similar drugs that are reported to induce similar pharmacological effects in rats of the same sex. Because pharmacokinetic data suggest female rats should be more affected than males, the current studies sought to test the hypothesis that the behavioral and temporal actions of METH and AMP should be greater in female Sprague–Dawley rats than in males. Using a dosing regimen designed to reduce the possibility of tolerance and sensitization, rats were administered 1.0 and 3.0 mg/kg intravenous drug doses. Distance traveled, rearing events and focal stereotypies (e.g., head weaving, sniffing) were measured. Female rats traveled significantly greater distances and displayed a greater number of rearing events than males after both doses. Analysis of stereotypy ratings after 3.0 mg/kg revealed that focal stereotypies were more pronounced and lasted longer in females. The second study compared the potencies of METH and AMP in inducing locomotor activity and focal stereotypies in each sex. No differences in potency were found when METH and AMP effects were compared within males or females. In summary, these studies showed female rats displayed greater and longer-lasting locomotor activity and more stereotypic behaviors, supporting earlier evidence of significant sexual dimorphism in pharmacokinetics.

Modification of Monoaminergic Activity by MAO Inhibitors Influences Methamphetamine Actions

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Modification of Monoaminergic Activity by MAO Inhibitors Influences Methamphetamine Actions

Modification of Monoaminergic Activity by MAO Inhibitors Influences Methamphetamine Actions

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

Methamphetamine interacts with sigma (σ) 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 σ receptors. Of the two major σ receptor subtypes, σ 1 and σ 2, competition binding studies showed that methamphetamine has a 22-fold preferential affinity for the σ 1 subtype. Saturation binding studies using the σ 1 selective radioligand [ 3H](+)-pentazocine showed that in the presence of methamphetamine, there was a significant change in K d, but not B max, suggesting competitive interactions. In behavioral studies, pretreatment of Swiss Webster mice with the σ 1 receptor antagonists, BD1063 or BD1047, significantly attenuated the locomotor stimulatory effects of methamphetamine. Mice that were administered an antisense oligodeoxynucleotide to down-regulate brain σ 1 receptors also exhibited a reduced locomotor stimulatory response to methamphetamine, as compared to control mice receiving mismatch oligonucleotides. Together, the data suggest that σ 1 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.

A functional glutathioneS‐transferase P1 gene polymorphism is associated with methamphetamine‐induced psychosis in Japanese population

Several lines of evidence suggest that oxidative stress plays a role in the mechanisms of action of methamphetamine (MAP) in the human brain. Given the role of glutathione S-transferases (GSTs) in the protection against oxidative stress, genes encoding the GSTs have been considered as candidates for association studies of MAP abuse. This study was undertaken to investigate the role of the functional polymorphism of GSTP1 gene exon 5 (Ile105Val) in the pathogenesis of MAP abuse. Genotyping for GSTP1 gene polymorphism exon 5 (Ile105Val) in 189 MAP abusers and 199 normal controls was performed by polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP). Association between GSTP1 gene polymorphism and clinical features (prognosis of psychosis (transient-type and prolonged-type), spontaneous relapse (positive and negative), and poly-substance abuse) of MAP abusers was evaluated. Significant differences in the frequency of both alleles (P = 0.026, odds ratio: 1.70, 95% confidence intervals (CI) 1.06-2.72) and genotypes (P = 0.029) between MAP abusers and controls were detected. In particular, a significant difference in both genotype frequency (P = 0.013) and allele frequency (P = 0.014, odds ratio: 1.84, 95% CI 1.13-2.97) between MAP abusers with psychosis (transient-type and prolonged-type) and controls was detected. Our findings suggest that the polymorphism (Ile105Val) on exon 5 of the GSTP1 gene may contribute to a vulnerability to psychosis associated with MAP abuse in Japanese population.

Methamphetamine and Brain Histamine: A Study Using Histamine‐Related Gene Knockout Mice

The central histamine (HA) neurons that originate from the posterior hypothalamus modulate a variety of physiological functions. In order to investigate the roles of brain histaminergic neuron system in the behavioral effects of methamphetamine (METH), we administrated METH repeatedly to L-histidine decarboxylase (HDC)-, histamine H1 receptor-, H2 receptor-gene knockout (KO) mice, H1/H2 receptor-gene double KO mice, and wild type (WT) mice corresponding to each of them, and we measured locomotor activities. We also measured the contents of monoamines and amino acids in the brain of HDC-gene KO and WT mice after a single administration of METH. METH-induced locomotor hyperactivity and the development of behavioral sensitization were facilitated more in the HDC-gene KO mice and H1/H2 gene double KO mice than the WT mice, suggesting that brain histamine has an inhibitory effect on the METH action through both H1 and H2 receptors. In addition, neurochemical study suggested the involvement of the GABAergic neuron system in the inhibitory effect of brain histamine.

Serial Analysis of Gene Expression in Methamphetamine‐ and Phencyclidine‐Treated Rodent Cerebral Cortices: Are There Common Mechanisms?

Pharmacological actions of methamphetamine (METH) and phencyclidine (PCP) are different, but both of them can induce similar psychiatric disorders including abuse, intoxication, withdrawal, and psychotic symptoms like those of schizophrenia. These mental disorders are caused not only by their direct pharmacological effects, but also by secondary brain damage containing gene expression changes. In order to broadly grasp these alterations, we used serial analysis of gene expression (SAGE), a transcriptome analysis. We analyzed three cDNA libraries from cerebral cortices of saline (1 mL/kg)-, METH (4 mg/kg)-, or PCP (10 mg/kg)-treated Wistar rats (one hour after i.p. administration). The numbers of total tags were about 50,000 in each library, and approximately 18,000 kinds of tags were identified respectively. From the comparisons of three groups, we found both METH- and PCP-reactive genes. Upregulated genes contained calmodulin 2, stromal cell-derived factor receptor 1, brain-specific angiogenesis inhibitor 1-associated protein 2, ras homologue enriched in brain, basigin and thyrotropin-releasing hormone receptor. Downregulated genes contained lipocalin 2, aldolase A, importin 13, fatty acid binding protein 3, and glycine receptor alpha2 subunit. These data suggest important clues of common molecular basis in METH- and PCP-related psychiatric disorders.

Neuroprotective action of MPEP, a selective mGluR5 antagonist, in methamphetamine-induced dopaminergic neurotoxicity is associated with a decrease in dopamine outflow and inhibition of hyperthermia in rats

The aim of this study was to examine the role of metabotropic glutamate receptor 5 (mGluR5) in the toxic action of methamphetamine on dopaminergic neurones in rats. Methamphetamine (10 mg/kg sc), administered five times, reduced the levels of dopamine and its metabolites in striatal tissue when measured 72 h after the last injection. A selective antagonist of mGluR5, 2-methyl-6-(phenylethynyl)pyridine (MPEP; 5 mg/kg ip), when administered five times immediately before each methamphetamine injection reversed the above-mentioned methamphetamine effects. A single MPEP (5 mg/kg ip) injection reduced the basal extracellular dopamine level in the striatum, as well as dopamine release stimulated either by methamphetamine (10 mg/kg sc) or by intrastriatally administered veratridine (100 μM). Moreover, it transiently diminished the methamphetamine (10 mg/kg sc)-induced hyperthermia and reduced basal body temperature. MPEP administered into the striatum at high concentrations (500 μM) increased extracellular dopamine levels, while lower concentrations (50–100 μM) were devoid of any effect. The results of this study suggest that the blockade of mGluR5 by MPEP may protect dopaminergic neurones against methamphetamine-induced toxicity. Neuroprotection rendered by MPEP may be associated with the reduction of the methamphetamine-induced dopamine efflux in the striatum due to the blockade of extrastriatal mGluR5, and with a decrease in hyperthermia.

Pharmacological comparison between the actions of methamphetamine and 1-aminoindan stereoisomers on sympathetic nervous function in rat vas deferens

The selective monoamine oxidase-B inhibitor selegiline (deprenyl) causes sympathomimetic effects and is metabolised to R(−)-methamphetamine and R(−)-amphetamine. The new monoamine oxidase-B inhibitor rasagiline is devoid of sympathomimetic effects and is metabolised to R(+)-1-aminoindan. Sympathomimetic effects of methamphetamine and 1-aminoindan enantiomers were compared in the rat vas deferens. R(−)-methamphetamine and S(+)-methamphetamine caused initial potentiation and subsequent inhibition of the field stimulation-induced twitch response of isolated rat vas deferens (0.1 Hz). EC 50 values for inhibition of twitch in prazosin-treated vas deferens were 0.36±0.13 and 1.64±0.10 μM (mean±S.E.M.) for S(+)- and R(−)-methamphetamine, respectively. There was no difference between S(+)-methamphetamine and R(−)-methamphetamine in potentiation of postsynaptic contractile response to noradrenaline. R(+)- and S(−)-1-aminoindan increased twitch response only at concentrations above 30 μM. R(−)-methamphetamine has similar potency to S(+)-methamphetamine in potentiation of noradrenaline-mediated responses and can therefore play a role in the sympathomimetic effects of selegiline.

Association study of the dopamine and serotonin transporter genetic polymorphisms and methamphetamine abuse in Chinese males

The dopamine transporter (DAT) and the serotonin transporter (5-HTT) play important roles in methamphetamine (METH) dependence because they are the target of METH action. For this study, the association between the DAT and 5-HTT polymorphisms and METH dependence were investigated for a Chinese-male sample population. The investigated polymorphisms included those of the DAT 3'-variable number tandem repeat, the 5-HTT gene promoter and a 5-HTT variable number tandem repeat polymorphisms. No significant difference was demonstrated for genotype or allele frequency, when comparing METH dependent and control cases for the DAT and the 5-HTT polymorphisms. The findings of this study suggest that these polymorphisms do not play major roles in METH dependence in the Chinese-male population.

Ibogaine signals addiction genes and methamphetamine alteration of long-term potentiation.

The mapping of the human genetic code will enable us to identify potential gene products involved in human addictions and diseases that have hereditary components. Thus, large-scale, parallel gene-expression studies, made possible by advances in microarray technologies, have shown insights into the connection between specific genes, or sets of genes, and human diseases. The compulsive use of addictive substances despite adverse consequences continues to affect society, and the science underlying these addictions in general is intensively studied. Pharmacological treatment of drug and alcohol addiction has largely been disappointing, and new therapeutic targets and hypotheses are needed. As the usefulness of the pharmacotherapy of addiction has been limited, an emerging potential, yet controversial, therapeutic agent is the natural alkaloid ibogaine. We have continued to investigate programs of gene expression and the putative signaling molecules used by psychostimulants such as amphetamine in in vivo and in vitro models. Our work and that of others reveal that complex but defined signal transduction pathways are associated with psychostimulant administration and that there is broad-spectrum regulation of these signals by ibogaine. We report that the actions of methamphetamine were similar to those of cocaine, including the propensity to alter long-term potentiation (LTP) in the hippocampus of the rat brain. This action suggests that there may be a "threshold" beyond which the excessive brain stimulation that probably occurs with compulsive psychostimulant use results in the occlusion of LTP. The influence of ibogaine on immediate early genes (IEGs) and other candidate genes possibly regulated by psychostimulants and other abused substances requires further evaluation in compulsive use, reward, relapse, tolerance, craving and withdrawal reactions. It is therefore tempting to suggest that ibogaine signals addiction gene products.

Persistent Antagonism of Methamphetamine-Induced Dopamine Release in Rats Pretreated with GBR12909 Decanoate

Methamphetamine abuse is a serious global health problem, and no effective treatments for methamphetamine dependence have been developed. In animals, the addictive properties of methamphetamine are mediated via release of dopamine (DA) from nerve terminals in mesolimbic reward circuits. At the molecular level, methamphetamine promotes DA release by a nonexocytotic diffusion-exchange process involving DA transporter (DAT) proteins. We have shown that blocking DAT activity with high-affinity DA uptake inhibitors, such as 1-[2-[bis(4-fluorophenyl)methoxy]ethyl]-4-(3-phenylpropyl) piperazine (GBR12909), can substantially reduce amphetamine-induced DA release in vivo. In the present study, we examined the ability of a long-acting depot formulation of GBR12909 decanoate (GBR-decanoate) to influence neurochemical actions of methamphetamine in the nucleus accumbens of rats. Rats received single injections of GBR-decanoate (480 mg/kg i.m.) and were subjected to in vivo microdialysis testing 1 and 2 weeks later. Pretreatment with GBR-decanoate produced modest elevations in basal extracellular levels of DA, but not 5-hydroxytryptamine (5-HT), at both time points. GBR-decanoate nearly eliminated the DA-releasing ability of methamphetamine (0.3 and 1.0 mg/kg i.v.) for 2 weeks, whereas methamphetamine-induced 5-HT release was unaffected. Autoradiographic analysis revealed that GBR-decanoate caused long-term decreases in DAT binding in the brain. Our data suggest that GBR-decanoate, or similar agents, may be useful adjuncts in treating methamphetamine dependence. This therapeutic strategy would be especially useful for noncompliant patient populations.

Studies Show How Speed Exacts Toll on Brain

Studies Show How Speed Exacts Toll on Brain

Differential involvement of 5-HT 2A receptors in the discriminative-stimulus effects of cocaine and methamphetamine

Involvement of 5-HT 2A receptors in the discriminative-stimulus effects of cocaine versus methamphetamine was studied in Sprague Dawley rats ( n=10) trained to discriminate 10 mg/kg cocaine, i.p., from saline under a fixed-ratio 10 (FR10) schedule of food presentation. The ability of (±)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI), a 5-HT 2A receptor agonist, and ketanserin, a 5-HT 2A receptor antagonist, to either substitute for or block the discriminative-stimulus effects of cocaine, or to shift the cocaine dose–response curve, was evaluated. DOI (0.18–1.0 mg/kg) partially substituted for the training dose of 10 mg/kg cocaine, but only at doses that decreased rates of responding. At the highest dose of DOI tested (1.0 mg/kg), there was about 65% cocaine-appropriate responding. Substitution of DOI for cocaine and DOI-induced decreases in rates of responding were completely reversed by ketanserin (3.0 mg/kg). Ketanserin (3.0 mg/kg) also produced a significant shift to the right of the cocaine dose–response curve and antagonized increases in rates of responding produced by lower doses of cocaine. Ketanserin (1.0–10.0 mg/kg), however, did not block the discriminative-stimulus effects of the training dose of cocaine. When DOI (0.3 mg/kg) was co-administered with different doses of cocaine, there was a slight leftward shift in the cocaine dose–response curve, which was not significant and appeared to reflect simple additive effects of DOI and cocaine. In contrast, the same dose of DOI (0.3 mg/kg) produced a marked and highly significant shift to the left of the methamphetamine (0.18–1.0 mg/kg) dose–response curve in the same subjects and the effects of DOI and methamphetamine were clearly more than additive. The present findings provide new evidence that there is some serotonergic modulation of cocaine's discriminative-stimulus actions, which appears to involve stimulation of 5-HT 2A receptors. However, involvement of 5-HT 2A receptor activity in the discriminative-stimulus actions of cocaine appears to be less pronounced than in similar actions of methamphetamine.

Patterns of Methamphetamine Abuse and Their Consequences

The abuse of methamphetamine (METH) continues to increase throughout all age groups in different regions of the United States. “Ice,” the popularized jargon for (+) methamphetamine hydrochloride, is the predominant drug form that is now consumed. “Ice” is effectively absorbed after either smoking or snorting and it is this rapid influx of drug that produces effects similar to those after intravenous administration. The intensity of METH actions in the central and peripheral nervous system shows tolerance after chronic administration, indicating that neuro-adaptations have occurred. Thus, the physiological processes and corresponding biochemical mechanisms that regulate neuronal function have been changed by METH exposure. These biological alterations contribute to the craving and dependence associated with METH abuse and the withdrawal syndrome upon abstinence. However, these changes in behavior may also result from METH-induced neurotoxicity. This article reviews aspects of METH pharmacokinetics and related molecular pharmacodynamics that represent METH pharmacology and then relates those actions to their potential to produce neurotoxicity in humans.

Parallel increases in lipid and protein oxidative markers in several mouse brain regions after methamphetamine treatment

The neurotoxic actions of methamphetamine (METH) may be mediated in part by reactive oxygen species (ROS). Methamphetamine administration leads to increases in ROS formation and lipid peroxidation in rodent brain; however, the extent to which proteins may be modified or whether affected brain regions exhibit similar elevations of lipid and protein oxidative markers have not been investigated. In this study we measured concentrations of TBARs, protein carbonyls and monoamines in various mouse brain regions at 4 h and 24 h after the last of four injections of METH (10 mg/kg/injection q 2 h). Substantial increases in TBARs and protein carbonyls were observed in the striatum and hippocampus but not the frontal cortex nor the cerebellum of METH-treated mice. Furthermore, lipid and protein oxidative markers were highly correlated within each brain region. In the hippocampus and striatum elevations in oxidative markers were significantly greater at 24 h than at 4 h. Monoamine levels were maximally reduced within 4 h (striatal dopamine [DA] by 95% and serotonin [5-HT] in striatum, cortex and hippocampus by 60-90%). These decrements persisted for 7 days after METH, indicating effects reflective of nerve terminal damage. Interestingly, NE was only transiently depleted in the brain regions investigated (hippocampus and cortex), suggesting a pharmacological and non-toxic action of METH on the noradrenergic nerve terminals. This study provides the first evidence for concurrent formation of lipid and protein markers of oxidative stress in several brain regions of mice that are severely affected by large neurotoxic doses of METH. Moreover, the differential time course for monoamine depletion and the elevations in oxidative markers indicate that the source of oxidative stress is not derived directly from DA or 5HT oxidation.

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

We measured levels of methamphetamine and those of its metabolite amphetamine in 15 autopsied brain regions of 14 human methamphetamine users. Only slight regional differences were observed in drug concentrations among the brain areas. Although, some redistribution of the drugs probably occurred postmortem, these data suggest that methamphetamine might not be preferentially retained in dopamine-rich brain areas but is heterogenously distributed in brain of chronic human users of the drug. The possible pharmacological actions of methamphetamine in both dopamine-rich and poor brain areas of chronic drug users need to be considered.