Subchronic Methamphetamine Research Articles

The Effects of Subchronic Methamphetamine Administration on the NLRP3 Inflammasome, Memory Function, and Hippocampal Morphology

Background: While it is established that addictive doses of methamphetamine correlate with inflammation-mediated neurotoxic pathways, the extent of toxicity resulting from subchronic administration at lower doses remains uncertain. Objectives: This study aimed to investigate the subtle effects of daily subchronic methamphetamine (MA) administration on neuroinflammatory processes, cognitive dimensions, gene expression, and hippocampal morphology. Methods: The experimental study employed a longitudinal design with three groups (G1B, G2B, G3B) receiving methamphetamine (5 mg/kg, intraperitoneally, once daily) for 1, 2, or 3 weeks, respectively. Corresponding control groups (G1A, G2A, G3A) received 0.2 mL of normal saline. Spatial learning, novel object recognition, and passive avoidance tests were conducted to assess spatial, recognition, and fear avoidance memories. Hippocampal morphology was evaluated using Nissl staining, and the expressions of NLRP3, ASC, and caspase-1 genes were measured as markers of neuroinflammation. Results: Statistical analyses, including one-way and two-way ANOVA, showed that subchronic low-dose administration of MA led to significant activation of the inflammasome (NLRP3, ASC, and caspase-1), which may have resulted in pyramidal cell death in the hippocampus. The hippocampal structure in the CA1 region was completely disrupted. Spatial memory and passive avoidance learning were impaired in the MA groups, while recognition memory remained unaffected. Conclusions: The findings suggest that prolonged administration of 5 mg/kg of methamphetamine may be associated with significant inflammasome activation, pyramidal cell death, and mild cognitive decline. Contrary to previous evidence, even lower doses of methamphetamine taken over an extended period could be neurotoxic.

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

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

Melatonin recovers cognitive impairments caused by sub-chronic methamphetamine administration in adult mice

Melatonin recovers cognitive impairments caused by sub-chronic methamphetamine administration in adult mice

Modafinil improves methamphetamine-induced object recognition deficits and restores prefrontal cortex ERK signaling in mice

Chronic use of methamphetamine (METH) leads to long-lasting cognitive dysfunction in humans and in animal models. Modafinil is a wake-promoting compound approved for the treatment of sleeping disorders. It is also prescribed off label to treat METH dependence. In the present study, we investigated whether modafinil could improve cognitive deficits induced by sub-chronic METH treatment in mice by measuring visual retention in a Novel Object Recognition (NOR) task. After sub-chronic METH treatment (1 mg/kg, once a day for 7 days), mice performed the NOR task, which consisted of habituation to the object recognition arena (5 min a day, 3 consecutive days), training session (2 equal objects, 10 min, day 4), and a retention session (1 novel object, 5 min, day 5). One hour before the training session, mice were given a single dose of modafinil (30 or 90 mg/kg). METH-treated mice showed impairments in visual memory retention, evidenced by equal preference of familiar and novel objects during the retention session. The lower dose of modafinil (30 mg/kg) had no effect on visual retention scores in METH-treated mice, while the higher dose (90 mg/kg) rescued visual memory retention to control values. We also measured extracellular signal-regulated kinase (ERK) phosphorylation in medial prefrontal cortex (mPFC), hippocampus, and nucleus accumbens (NAc) of METH- and vehicle-treated mice that received modafinil 1 h before exposure to novel objects in the training session, compared to mice placed in the arena without objects. Elevated ERK phosphorylation was found in the mPFC of vehicle-treated mice, but not in METH-treated mice, exposed to objects. The lower dose of modafinil had no effect on ERK phosphorylation in METH-treated mice, while 90 mg/kg modafinil treatment restored the ERK phosphorylation induced by novelty in METH-treated mice to values comparable to controls. We found neither a novelty nor treatment effect on ERK phosphorylation in hippocampus or NAc of vehicle- and METH-treated mice receiving acute 90 mg/kg modafinil treatment. Our results showed a palliative role of modafinil against METH-induced visual cognitive impairments, possibly by normalizing ERK signaling pathways in mPFC. Modafinil may be a valuable pharmacological tool for the treatment of cognitive deficits observed in human METH abusers as well as in other neuropsychiatric conditions.This article is part of the Special Issue entitled ‘CNS Stimulants’.

Methamphetamine alters expression of DNA methyltransferase 1 mRNA in rat brain

Methamphetamine, a potent and indirect dopaminergic agonist, also increases glucocorticoid hormone secretion. Glucocorticoid hormones facilitate behavioral effects of methamphetamine in rodents. Several reports suggest that glucocorticoid hormones modulate expression of DNA (cytosine-5-)-methyltransferase 1 (Dnmt1). Dnmt1 was originally recognized as being involved in DNA replication, but a recent study found high levels of Dnmt1 in rodent brains, suggesting a neuron-specific unknown function of Dnmt1. In the present study, we found subchronic methamphetamine treatment (4 mg/kg, i.p., once daily for 21 days) to induce different patterns of Dnmt1 mRNA expression in the nucleus caudatus and nucleus accumbens of two inbred rat strains, Fischer 344/N (increased Dnmt1) and Lewis/N (decreased Dnmt1). These patterns paralleled methamphetamine-induced striatal glucocorticoid receptor mRNA in these two rat strains in our previous study. Because Fischer rats have a hyperresponsive negative feedback in their hypothalamic–pituitary–adrenocortical (HPA) axis and thus a shorter duration corticosterone response to subchronic methamphetamine treatment, they were resistant to sensitizing effects of methamphetamine and their glucocorticoid receptor mRNA levels were upregulated. Lewis rats which have a hyporesponsive feedback in their HPA axis and a longer duration of corticosterone secretion with subchronic methamphetamine were prone to methamphetamine sensitization and their striatal glucocorticoid receptor mRNA levels were downregulated. Our present data suggest that methamphetamine results in differential DNA methylation as well as gene expression in the nucleus caudatus and nucleus accumbens of F344 and Lewis rats. Methamphetamine-induced differences in gene expression might be related to the contrasting susceptibilities of these rats to behavioral and neurochemical effects of methamphetamine.

Effects of subchronic methamphetamine exposure on basal dopamine and stress-induced dopamine release in the nucleus accumbens shell of rats

Subchronic administration of stimulants reduces basal dopamine (DA) concentrations and blocks stress-induced DA release in the nucleus accumbens (NA) of rats during withdrawal. However, no studies have attempted to relate early withdrawal from chronic drug exposure to stress reactivity and changes in DA transmission. The effects of subchronic low-dose methamphetamine (METH) administration on regional changes in dopamine transporter (DAT) and norepinephrine transporter (NET) immunoreactivity and function during early withdrawal were examined. The effects of subchronic METH on stress responsivity measured by DA release in the nucleus accumbens shell (NA SHELL) and core (NA CORE) during acute restraint stress were also examined. Male rats received single injections of METH (2.0 mg/kg i.p.) or saline (SAL) for 10 days and then were killed 24 h after the last injection. DAT and NET protein in NA, striatum (STR), medial prefrontal cortex (mPFC), and hippocampus were assayed by Western blot analysis. Experiment 2 measured basal extracellular DA concentrations and restraint-stress-induced DA release in vivo in the NA SHELL and CORE of SAL- and METH-pretreated rats after 24-h withdrawal. Experiment 3 examined the in vivo regulation of extracellular DA in the NA SHELL and/or CORE after local administration of GBR12909 (50 microM) or nisoxetine (100 microM; NA SHELL). Subchronic METH increased DAT but not NET immunoreactivity in the NA compared to the STR and mPFC. METH reduced basal extracellular DA and blocked restraint-stress-induced DA release in the NA SHELL. DA uptake blockade increased extracellular DA more in the NA SHELL of METH rats, whereas NE uptake blockade increased basal DA concentrations to a similar extent in METH and SAL rats. These results suggest that subchronic METH exposure selectively increases NA DAT and consequently reduces basal and stress-induced DA release in the NA SHELL during early withdrawal.

Changes in Expression of the Mouse Homologues of KIAA Genes after Subchronic Methamphetamine Treatment

Amphetamine abuse may be associated with adaptive changes in gene expression in the brain. In the present study, a newly developed cDNA array system comprising mouse KIAA (mKIAA) cDNA clones was used to examine the gene expression affected by chronic methamphetamine treatment. Approximately 800 mKIAA clones were blotted onto a nylon membrane and hybridized with 33P-labeled cDNA derived from mRNAs isolated from the whole brains of mice that had been treated daily with saline or methamphetamine (2 mg/kg, i.p.) for 2 weeks. The arrays displayed robust hybridization for almost all transcripts. The results obtained from five experiments were averaged, each performed with triplicate samples. Several clones were chosen as positive candidates for methamphetamine-induced changes; however, only Per2 and mKIAA0099 genes showed a significantly increased expression (P < .05). Subsequently, with the focus on the period-related proteins, the expression of these proteins in various parts of the rat brain were assessed by immunoblot analysis. Chronic administration of methamphetamine (8 mg/kg, i.p., for 10 days) caused increased Per2 protein expression in the hippocampus. Interestingly, chronic methamphetamine treatment at a lower dose (4 mg/kg, i.p., for 10 days) induced an increase in SCN circadian oscillatory protein (SCOP) expression, also in the hippocampus. These data suggest that long-lasting alterations of the period-related gene expressions in the hippocampus might play an important role in methamphetamine addiction.

Methamphetamine induces cytosolic Ca2+ oscillations in the VTA dopamine neurons.

Methamphetamine (METH) induces a schizophrenia-like psychosis. The dopamine neurons in the ventral tegmental area (VTA) have been implicated in schizophrenia and drug abuse. The present study investigated direct effects of METH on VTA dopamine neurons. We treated adult SD rats with METH (5 mg/kg/day) or saline for 7 days, isolated single VTA neurons, and monitored neuronal activities by measuring cytosolic Ca2+ concentration ([Ca2+]i) in immunocytochemically identified dopamine neurons. Acutely administered METH increased [Ca2+]i in dopamine neurons from METH- and saline-treated rats and induced oscillations of [Ca2+]i in dopamine neurons only from METH-treated rats. The METH-induced [Ca2+]i oscillations were inhibited by Ca(2+)-free conditions and Ca2+ channel blockers. The results indicate that acute METH increases [Ca2+]i in VTA dopamine neurons and that subchronic METH treatment sensitizes them to this drug, resulting in induction of [Ca2+]i oscillations. The activation of VTA dopamine neurons may be related to psycho-stimulant effects of METH.

The absence of impairment of cliff avoidance reaction induced by subchronic methamphetamine treatment in inbred strains of mice.

Cliff avoidance reaction (CAR), an index of behavioral teratology in rodents, can be impaired by motor, arousal, or cognitive dysfunction. We formerly reported subchronic administration of methamphetamine (MAP) induced the CAR impairment, which might reflect MAP-induced cognitive dysfunction, in three strains of rats. In this study, the effects of subchronic MAP treatment on the behavioral sensitization in stereotypy (stereotypy sensitization) and CAR were examined in two inbred strains of male mice; C57BL/6J(C57) and DBA/2J(DBA). The animals received 4 mg/kg/day MAP intraperitoneally for 28 days. There were apparent strain differences in the development of stereotypy sensitization induced by chronic MAP; DBA mice developed stereotypy sensitization quickly, but C57 did not. Unlike rats, neither strains of mice showed the CAR impairment. These results suggest that chronic MAP (4 mg/kg) administration did not introduce any cognitive dysfunction measured by CAR in the two inbred mice, DBA and C57. The discrepancy between rats and mice is still unclear. It might relate to the species-selective effect of MAP on the CAR impairment. Further studies should to be required.

Impairment of cliff avoidance reaction induced by subchronic methamphetamine administration and restraint stress: comparison between two inbred strains of rats

1. 1. The effects of subchronic methamphetamine (MAP) treatment and restraint stress on the behavioral sensitization in stereotypy (stereotypy sensitization) and cliff avoidance reaction (CAR) were examined in two inbred strains of male rats; Fischer 344/N (F344), and Lewis/N (LEW). 2. 2. In experiment 1, the animals received 4 mg/kg/day MAP for 30 days. LEW rats developed stereotypy sensitization earlier than F344 rats. However, both strains plateaued at the same stereotypy rating score. Furthermore, F344 rats were susceptible to CAR impairment as a result of MAP treatment, whereas LEW rats were not. 3. 3. In experiment 2, the animals were exposed to daily restraint stress of 2hr for 4 weeks. MAP was administered (4mg/kg) 7 days after the last treatment day. Repeated restraint stress induced almost the same degree of stereotypy sensitization in both strains. F344 rats were susceptible to CAR impairment induced by repeated stress, whereas LEW rats were not. 4. 4. The effects of psychostimulant and Stressors appear to be similar not only with respect to stereotypy sensitization but also CAR impairment. Differences in MAP- or stress-induced CAR impairment between the two inbred strains may be genetically linked and may be involved in the development of psychotic behavior.

Methamphetamine-induced behavioral sensitization and its implications for relapse of schizophrenia

Vulnerability to relapse is a central issue in the biology of schizophrenia. The common neural mechanisms underlying such vulnerability can be studied using the experimental model of behavioral sensitization induced by repeated administration of low doses of methamphetamine (MAP) to rodents. This review summarizes a series of behavioral and neurochemical studies on MAP-induced behavioral sensitization from the viewpoint that the mechanisms involved in initiation (or development) of psychotic symptoms and their expression differ. The initiation of behavioral sensitization to MAP in rats requires stimulation of dopaminergic neurons, and can be blocked by SCH 23390 (a dopamine D1-receptor antagonist) and BMY 14802 (a sigma-receptor antagonist). The expression of behavioral sensitization induced by subchronic MAP pretreatment takes several forms. First, dopamine release from the cerebral dopaminergic neuron terminal containing areas in response to either to rechallenge with MAP or cocaine, or evoked by intrastriatal ouabain infusion is enhanced. Second, the behavioral responses to dopamine D2- and sigma-receptor agonists are augmented. A third form involves changes indicative of transsynaptic neural circuits, such as increased numbers of D1 receptors in the substantia nigra pars reticulata, enhanced electrophysiological responses to D1 receptor activation, the putative role of excitatory amino acid receptors and interchangeability of MAP and stress. Although MAP-induced behavioral sensitization in rodents serves as a useful animal model, the elucidation of the mechanisms involved in the vulnerability of patients with schizophrenia to relapse of psychotic episodes requires further study.

Subchronic methamphetamine treatment enchances ouabain-induced striatal dopamine efflux in vivo

The effect of manipulation of the Na + gradient between the intracellular and extracellular media on striatal dopamine (DA) efflux under steady-state conditions after subchronic methamphetamine (MAP) treatment was investigated. Rats were injected with 4 mg/kg MAP or saline (i.p.), once daily for 14 days. Seven days after the last injection, ouabain (10 −4 M), a selective inhibitor of the Na +,K +-ATPase, was infused locally through a semi-permeable probe in the striatum. Ouabain induced a significantly greater ( P < 0.01) increase of the DA concentrations in the striatal perfusate in the subchronic MAP than the control group. The levels of 3,4-dihydroxyphenylacetic acid (DOPAC) ( P < 0.05) and 5-hydroxyindoleacetic acid (5-HIAA) ( P < 0.05) were significantly higher in the subchronic MAP than in the control group. Reserpine pretreatment (5 mg/kg, i.p.) did not affect the enhanced ouabain-induced DA efflux ( P < 0.01) in the subchronic MAP group, and the levels of DOPAC ( P < 0.01), 5-HIAA ( P < 0.01) and HVA ( P < 0.01) were also significantly higher in the subchronic MAP than in the control group. In contrast, α-methyl- p-tyrosine (250 mg/kg, i.p.) pretreatment abolished the ouabain-induced efflux of DA, DOPAC and HVA, but not 5-HIAA, in both groups. Specific striatal [ 3H]ouabain binding and striatal Na +,K +-ATPase activity in the subchronic MAP and control groups did not differ significantly. These results suggest that subchronic MAP treatment facilitates the efflux of newly synthesized DA, which is induced by the ouabain-induced decrease of the Na + gradient between intracellular and extracellular media. The Na + gradient may, therefore, play an important role in the efflux of DA after subchronic MAP treatment.

Lasting increase in D 1 dopamine receptors in the lateral part of the substantia nigra pars reticulata after subchronic methamphetamine administration

To examine the possible involvement of D 1 dopamine receptors in behavioral sensitization induced by subchronic methamphetamine (MAP) administration, regional D 1 receptors labeled with [ 3H]SCH 23390 were examined using binding assay and quantitative autoradiography. Rats received 4 mg/kg/day MAP (i.p.) for 14 days, and were decapitated after an abstinence period of 24 h, 7 days or 21 days. In MAP-treated rats, a significant decrease in K d in the mesolimbic area was observed 24 h but not 7 days after the last injection. Neither K d nor B max changed in the striatum or medial prefrontal cortex of MAP-treated rats after any period of abstinence. Autoradiography revealed a significant increase in specific [ 3H]SCH 22390 binding in the lateral part of the substantia nigra pars reticulata (SNr) of MAP-treated rats. Since this increase lasted up to 21 days after cessation of subchronic MAP administration, it is suggested that lasting increase in the nigral D 1 receptors may be associated with the biological changes underlying MAP-induced behavioral sensitization.

覚醒剤後遺症の慢性化に関する神経化学的検討

覚醒剤後遺症の慢性化に関する神経化学的検討

Methamphetamine投与による脳内substance P系, TRH系の変化におよぼす選択的D-1, D-2遮断薬の効果

The effects of pretreatment with either SCH 23390, a selective D-1 antagonist or YM-09151-2, a selective D-2 antagonist, on methamphetamine (MAP)-induced changes in the substance P and TRH system were investigated. A single dose of 4 mg/kg of MAP reduced the striatal level of substance P 30 min after injection. This reduction was reversed by pretreatment with YM-09151-2 but not with SCH 23390. Repeated administration of 4 mg/kg of MAP for 14 days reduced specific substance P and TRH binding in the striatum at 1 h, but not at 48 h, after the last injection. The reduction of striatal substance P receptor binding was prevented by pretreatment YM-09151-2 but not SCH 23390 prior to each MAP administration. The reduction of striatal TRH receptor binding was prevented by pretreatment with either antagonist. These results indicate that changes in striatal substance P level and substance P receptor binding induced by subchronic MAP treatment are mediated via activation of D-2 but not D-1 receptors by MAP-released dopamine, while changes in striatal TRH receptor binding are mediated via both D-1 and D-2 receptors.

Subchronic methamphetamine treatment enhances methamphetamine- or cocaine-induced dopamine efflux in vivo

Intracerebral dialysis was used to study the mechanism underlying behavioral sensitization. Rats were divided into two groups: a control group that received intraperitoneal injections of saline and an experimental group that was given methamphetamine (MAP) (4 mg/kg) once a day for 14 days. Seven days after the last injection, dopamine (DA) and its metabolites were measured in striatal dialy sates obtained from awake freely moving rats. A challenge injection of MAP (4 mg/kg) caused a marked increase in the extracellular concentrations of DA, and the extent of the increase was significantly greater in MAP-pretreated rats than in the saline-pretreated controls. A challenge injection of cocaine (20 mg/kg) also caused a significantly greater increase in extracellular DA levels in MAP-pretreated rats than in saline-pretreated rats. These results suggest that an enhancement in striatal DA efflux may play an important role in MAP-induced behavioral sensitization and cross-sensitization to cocaine.

Effect of Subchronic Treatment with Methamphetamine on Apomorphine-lnduced Changes in Locomotor Activity in Mice

Subchronic treatment with methamphetamine (3 mg/kg, s.c., twice daily for 14 days) attenuated hypomotility produced by a low dose of apomorphine (0.1 mg/kg, s.c.) and enhanced hypermotility induced by a high dose of apomorphine (3 mg/kg, s.c.) in mice. The treatment did not affect apomorphine-induced decrease in striatal DOPA accumulation following γ-butyrolactone plus m-hydroxybenzylhydrazine, an L-amino acid decarboxylase inhibitor, administration. These results suggest that drug sensitivity of presynaptic dopamine receptors in the striatum may not be altered after subchronic methamphetamine treatment.

Subchronic methamphetamine treatment selectively attenuates apomorphine-induced decrease in 3,4-dihydroxyphenylacetic acid level in mesolimbic dopaminergic regions

To investigate mechanisms of behavioral enhancement produced by repeated doses of amphetamines, the effects of apomorphine on 3,4-dihydroxyphenylacetic acid (DOPAC) and dopamine (DA) levels were examined in various brain regions of the rat on the 4th day of withdrawal after repeated administration of saline or methamphetamine (3 mg/kg, s.c.) twice daily for 14 days. Apomorphine (0.1 and 1.0 mg/kg, i.p.) produced a dose-dependent decrease in DOPAC levels and no effect on DA levels in the olfactory tubercle, nucleus accumbens, striatum, frontal and cingulate cortices of saline-treated animals. A decrease in DOPAC levels produced by a low dose of apomorphine was attenuated selectively in the olfactory tubercle and nucleus accumbens of methamphetamine-treated animals. A high dose of apomorphine produced a significant decrease in DOPAC levels in both regions. No such attenuation was obtained in the striatum and the frontal and cingulate cortices. These results suggest that subchronic methamphetamine may induce development of hyposensitivity of presynaptic DA receptors in the mesolimbic regions, which contribute to the behavioral enhancement produced by the drug.