Clinical effects and management of methamphetamine abuse

Nanowired Delivery of Curcumin Attenuates Methamphetamine Neurotoxicity and Elevates Levels of Dopamine and Brain-Derived Neurotrophic Factor

Curcumin is a well-known antioxidant used as traditional medicine in China and India since ages to treat variety of inflammatory ailments as a food supplement. Curcumin has antitumor properties with neuroprotective effects in Alzheimer's disease. Curcumin elevates brain-derived neurotrophic factor (BDNF) and dopamine (DA) levels in the brain indicating its role in substance abuse. Methamphetamine (METH) is one of the most abused substances in the world that induces profound neurotoxicity by inducing breakdown of the blood-brain barrier (BBB), vasogenic edema and cellular injuries. However, influence of curcumin on METH-induced neurotoxicity is still not well investigated. In this investigation, METH neurotoxicity and neuroprotective effects of curcumin nanodelivery were examined in a rat model. METH (20 mg/kg, i.p.) neurotoxicity is evident 4 h after its administration exhibiting breakdown of BBB to Evans blue albumin in the cerebral cortex, hippocampus, cerebellum, thalamus and hypothalamus associated with vasogenic brain edema as seen measured using water content in all these regions. Nissl attaining exhibited profound neuronal injuries in the regions of BBB damage. Normal curcumin (50 mg/kg, i.v.) 30 min after METH administration was able to reduce BBB breakdown and brain edema partially in some of the above brain regions. However, TiO₂ nanowired delivery of curcumin (25 mg/kg, i.v.) significantly attenuated brain edema, neuronal injuries and the BBB leakage in all the brain areas. BDNF level showed a significant higher level in METH-treated rats as compared to saline-treated METH group. Significantly enhanced DA levels in METH-treated rats were also observed with nanowired delivery of curcumin. Normal curcumin was able to slightly elevate DA and BDNF levels in the selected brain regions. Taken together, our observations are the first to show that nanodelivery of curcumin induces superior neuroprotection in METH neurotoxicity probable by enhancing BDNF and DA levels in the brain, not reported earlier.

Evaluation of Adenosine A2A receptor gene polymorphisms as risk factors of methamphetamine use disorder susceptibility and predictors of craving degree

The adenosine A2A receptor (ADORA2A) is highly expressed in the central nervous system and plays vital roles in drug addiction. In this study, we aimed to explore the susceptibility of ADORA2A to methamphetamine use disorder (MUD) and the craving degree based on a two-stage association analysis. A total of 3,542 (1,216 patients with MUD and 2,326 controls) and 1,740 participants (580 patients with MUD and 1,160 controls) were recruited in discovery and replication stage, respectively. Significant SNPs identified in the discovery stage were genotyped in the replication samples. Serum levels of ADORA2A were measured using enzyme-linked immunosorbent assay kits. The genetic association signal of each SNP was examined using Plink. A linear model was fitted to investigate the relationship between craving scores and genotypes of significant SNPs. SNP rs5751876 was significantly associated with MUD in the discovery samples and this association signal was then further replicated in the replication samples. Significant associations were also identified between serum levels of ADORA2A and the genotypes of rs5751876 (P = 0.0002). The craving scores in patients with MUD were strongly correlated with rs5751876 genotypes. Our results suggest that polymorphisms of the ADORA2A gene could affect the susceptibility to MUD and its craving degree.

Methamphetamine-associated pulmonary arterial hypertension

PURPOSE OF REVIEW

Methamphetamine use is increasing in popularity globally, and chronic users suffer from various drug toxicities, including the development of pulmonary arterial hypertension. Although it was previously thought to be a possible cause of pulmonary arterial hypertension, as of the sixth World Symposium on Pulmonary Hypertension, methamphetamine use is now recognized as a definite cause of pulmonary arterial hypertension. This review will discuss the history of methamphetamine use, the link between methamphetamine use and pulmonary arterial hypertension, and the clinical characteristics of patients with pulmonary hypertension from methamphetamine use.

RECENT FINDINGS

The mechanism by which methamphetamine abuse leads to pulmonary hypertension is unclear. However, recent studies have suggested that reduced expression of carboxylesterase 1 may be implicated due to maladaptation to the environmental injury of methamphetamine abuse. Based on the report of two recent cohort studies, patients with methamphetamine-associated pulmonary arterial hypertension have a worse functional class, less favorable hemodynamics, impaired health-related quality of life, increased health-care utilization, and attenuated survival, as compared to those with idiopathic pulmonary arterial hypertension.

SUMMARY

Future studies are needed to better understand the mechanism by which methamphetamine use leads to pulmonary arterial hypertension. Methamphetamine-associated pulmonary arterial hypertension likely represents a more advanced disease state than idiopathic pulmonary arterial hypertension, however, it is treated less aggressively in clinical practice.

Acute psychiatric illness and drug addiction during pregnancy and the puerperium

Pregnancy and the puerperium do not protect against acute psychiatric illness. During puerperium, the chance of acute psychiatric illness, such as a psychotic episode or relapse of bipolar disorder, is greatly increased. Suicide is a leading cause of maternal death. Both psychiatric disease and ongoing drug addiction impact not only the pregnant woman's somatic and mental health but also impact short-term and long-term health of the child. Indeed, prompt recognition and expeditious treatment of acute psychiatric illness during pregnancy and the puerperium optimize health outcomes for two patients. Pregnancy and puerperium represent a stage of life of great physiologic adaptations, as well as emotional and social changes. This conjunction of changes in somatic, emotional health and social health may mitigate the occurrence, clinical presentation, and clinical course of acute psychiatric illness and call for a multidisciplinary approach, taking into account both the medical and social domains. This chapter describes acute psychiatric illnesses during pregnancy and the puerperium and illicit substance abuse, from a clinical perspective, while also describing general principles of diagnosis and clinical management during this stage of life, which is an important window of opportunity for both the pregnant woman and the child.

Gender Differences in Sleep Problems Among Drug Users

BACKGROUND

Illicit drug use has been recognized as a major problem. Clinical studies demonstrated that poor sleep quality was associated with increased frequency of drug use and relapse. However, few studies addressed the issue of sleep quality and gender differences in illicit drug dependent subjects. The present study aimed to explore the gender differences in sleep problems in drug users.

METHODS

In this cross-sectional study, a total of 2,178 illicit drug users, including 1,875 male users [884 methamphetamine (MA) users and 991 heroin or other drug users] and 303 female users (78 MA users and 225 heroin or other drug users, 13.9%), from drug rehabilitation centers in Changsha, and 2,236 non-drug-using subjects, including 1,910 males and 326 females (14.6%) completed the self-report Pittsburgh Sleep Quality Index (PSQI).

RESULTS

We found that the prevalence of suggestive sleep problems (PSQI>5) between male and female was 67.4 and 75.2% in overall illicit drug use sample (p<0.001), 52.4 and 75.6% in MA users (<0.001), 80.8 and 75.1% in heroin or other drugs users (p=0.054), 26.0 and 28.8% in healthy controls (p=0.287). For sleep quality, the mean of PSQI total score (M±SD) between male and female was 7.8±4.42 and 8.9±4.15 in overall illicit drug users (p<0.001), 6.4±4.45 and 9.1±4.00 in MA users (<0.001), 9.1±3.96 and 8.9±4.21 in heroin or other drugs users (p=0.394), 4.2±2.46 and 4.4±2.51 in healthy control sample (p=0.090). These results indicated that only MA users, rather than heroin or other drugs users and healthy controls, showed gender differences in sleep problems.

CONCLUSIONS

In this study, female users reported higher frequency of sleep problems and poorer sleep quality than male users in MA users' group, but not in heroin or other drug users group. Future studies aim at quantifying the benefits of treatment interventions should not neglect the influence of sleeping problems and its gender differences.

Clinical Characteristics and Management of Methamphetamine-Associated Cardiomyopathy: State-of-the-Art Review

Methamphetamine‐associated cardiomyopathy (MACM) is an increasingly recognized disease entity in the context of a rapidly spreading methamphetamine epidemic. MACM may afflict individuals with a wide range of ages and socioeconomic backgrounds. Presentations can vary greatly and may involve several complications unique to the disease. Given the public health significance of this disease, there is a relative dearth of consensus material to guide clinicians in understanding, diagnosing, and managing MACM. This review therefore aims to: (1) describe pathologic mechanisms of methamphetamine as they pertain to the development, progression, and prognosis of MACM, and the potential to recover cardiac function; (2) summarize existing data from epidemiologic studies and case series in an effort to improve recognition and diagnosis of the disease; (3) guide short‐ and long‐term management of MACM with special attention to expected or potential sequelae of the disease; and (4) highlight pivotal unanswered questions in need of urgent investigation from a public health perspective.

Methamphetamine Use and Sexual Risk Behaviors among Men Who Have Sex With Men in a Mexico-US Border City

BACKGROUND AND OBJECTIVES

Methamphetamine (meth) use and its related risk behaviors for HIV among men who have sex with men (MSM) are a public health concern across the Mexico-US border. This study aims to contribute to the limited literature of meth use and sexual risk behaviors among Latino MSM on the Mexico-US border.

METHODS

Data were drawn from the Meth Pilot Study (2014-2015) among men who use meth (n = 100). Descriptive statistics and bivariate analysis comparing MSM to non-MSM were conducted using Pearson's χ2 test, Fisher's exact tests, and Mann-Whitney U test; all tests were conducted using SPSS v.25.

RESULTS

Most participants obtained meth in El Paso, Texas (87.2%), used meth orally (65.2%) or smoked (78.3%), and the most common reason for initiation was curiosity. Significant differences (P < .05) in meth use behaviors and sexual risk behaviors between MSM and non-MSM who used meth included: median number of sex partners (7 vs 3), being penetrated anally by last sexual partner (31.6% vs 1.4%), and engaging in transactional sex ever (63.2% vs 9.6%) and past 12 months (52.6% vs 6.8%). Finally, rates of HIV positivity were higher among MSM than non-MSM (10.5% vs 1.4%).

DISCUSSION AND CONCLUSIONS

Among men who use meth, MSM are engaging in higher HIV risk behaviors compared with non-MSM. Understanding these risks could help identify candidates for pre-exposure prophylaxis (PrEP) and evidence-based substance use disorder treatment options.

SCIENTIFIC SIGNIFICANCE

This study reveals that Latino MSM who use meth is a high-risk group for HIV and a need for tailored interventions. (Am J Addict 2020;29:111-119).

Assessment of Executive Functions in Methamphetamine-addicted Individuals: Emphasis on Duration of Addiction and Abstinence

Introduction:

Several studies have conducted on impairments of executive functions in individuals with methamphetamine addiction; however, only a few have investigated the relationship between executive functions and duration of addiction or abstinence. This study was designed to assess the executive functions in methamphetamine-addicted individuals in relation to the duration of addiction or abstinence.

Methods:

A total of 161 subjects aged between 20 and 45 years were categorized into three subgroups: currently abusing (n=41), abstinent (n=60), and control healthy individuals (n=60). A battery of standardized executive function tasks, including Stroop test, Wisconsin Card Sorting test, and Tower of London task, were administered. Data were analyzed using Pearson correlation coefficient, analysis of variance, and post hoc Bonferroni test with SPSS16.0.

Results:

Methamphetamine-addicted and abstinent subjects performed worse than the controls. Methamphetamine-abstinent subjects performed better than the currently methamphetamine abusers in most executive functions. Duration of addiction and abstinence were correlated with executive dysfunctions.

Conclusion:

This study revealed that although executive functions may be improved by protracted abstinence, executive dysfunctions are not completely relieved, and specific attention to planning and implementation of intervention programs are necessary.

Electrophysiological Actions of Synthetic Cathinones on Monoamine Transporters

Products containing psychoactive synthetic cathinones, such as mephedrone and 3,4-methylenedioxypyrovalerone (MDPV) are prevalent in our society. Synthetic cathinones are structurally similar to methamphetamine, and numerous synthetics have biological activity at dopamine, serotonin, and norepinephrine transporters. Importantly, monoamine transporters co-transport sodium ions along with their substrate, and movement of substrates and ions through the transporter can generate measurable ionic currents. Here we review how electrophysiological information has enabled us to determine how synthetic cathinones affect transporter-mediated currents in cells that express these transporters. Specifically, drugs that act as transporter substrates induce inward depolarizing currents when cells are held near their resting membrane potential, whereas drugs that act as transporter blockers induce apparent outward currents by blocking an inherent inward leak current. We have employed the two-electrode voltage-clamp technique in Xenopus laevis oocytes overexpressing monoamine transporters to determine whether synthetic cathinones found in the so-called bath salts products behave as blockers or substrates. We also examined the structure-activity relationships for synthetic cathinone analogs related to the widely abused compound MDPV, a common constituent in "bath salts" possessing potent actions at the dopamine transporter.

Substance Use as a Risk Factor for Sleep Problems Among Adolescents Presenting to the Emergency Department

OBJECTIVES

To determine correlates of sleep problems among adolescents. Specifically, to assess the relative strength of associations between sleep problems and dating victimization, reasons for emergency department (ED) visit, depression, unhealthy alcohol use, and other drug use (marijuana, nonmedical use of prescription opioids, stimulants, and tranquilizers).

METHODS

A total of 1852 adolescents aged 14 to 20 years presenting for care to the University of Michigan Emergency Department, Ann Arbor, Michigan, during 2011-2012, self-administered a computerized health survey. Sleep problems were identified if any of the 4 items on the Sleep Problems Questionnaire were rated by a patient as greater than 3 on a 0 to 5 scale. Adolescents who were too sick to be screened in the ED were eligible to participate in the study during their inpatient stay. Exclusion criteria for baseline included insufficient cognitive orientation precluding informed consent, not having parent/guardian present if younger than 18 years, medical severity precluding participation, active suicidal/homicidal ideation, non-English-speaking, deaf/visually impaired, or already participated in this study on a prior visit.

RESULTS

23.5% of adolescents reported clinically significant sleep problems. Female gender, depression, dating victimization, tobacco use, nonmedical use of prescription medication, and an ED visit for medical reasons were each associated with sleep problems among adolescents, even while controlling for age, other types of drug use, receiving public assistance, and dropping out of school.

CONCLUSIONS

These exploratory findings indicate that ED-based screening and brief intervention approaches addressing substance use and/or dating victimization may need to account for previously undiagnosed sleep problems.

The differential effects of alprazolam and oxazepam on methamphetamine self-administration in rats

BACKGROUND

Methamphetamine is the second most commonly used illicit drug in the world, and despite recent attempts by the Drug Enforcement Administration to combat this epidemic, methamphetamine use is still on the rise. As methamphetamine use increases so does polydrug use, particularly that involving methamphetamine and benzodiazepines. The present study was designed to examine the effects of two benzodiazepines on methamphetamine self-administration.

METHODS

Five doses of methamphetamine (0.0075, 0.015, 0.03, 0.09, and 0.12mg/kg/infusion) were tested, producing an inverted U-shaped dose-response curve. Rats were then pretreated with oxazepam, alprazolam, or vehicle prior to methamphetamine self-administration. To determine if the effects of these drugs were due to the GABAA receptor and/or translocator protein (TSPO), we also pretreated rats with an antagonist for the benzodiazepine-binding site on the GABAA receptor (i.e., flumazenil) and a TSPO antagonist (i.e., PK11195) prior to alprazolam or oxazepam administration.

RESULTS

Oxazepam significantly reduced methamphetamine self-administration as demonstrated by a downward shift of the dose-response curve. In contrast, alprazolam significantly enhanced methamphetamine self-administration as evidenced by a leftward shift of the dose-response curve. Flumazenil completely blocked the effects of alprazolam on methamphetamine self-administration. When administered individually, both flumazenil and PK11195 partially reversed the effects of oxazepam on methamphetamine self-administration. However, when these two antagonists were combined, the effects of oxazepam were completely reversed.

CONCLUSIONS

The GABAA receptor is responsible for the alprazolam-induced enhancement of methamphetamine self-administration, while the activation of both the GABAA receptor and TSPO are responsible for the oxazepam-induced reduction of methamphetamine self-administration.

Adenosine 2A receptors modulate reward behaviours for methamphetamine

Addiction to methamphetamine (METH) is a global health problem for which there are no approved pharmacotherapies. The adenosine 2A (A2 A ) receptor presents a potential therapeutic target for METH abuse due to its modulatory effects on striatal dopamine and glutamate transmission. Notably, A2 A receptor signalling has been implicated in the rewarding effects of alcohol, cocaine and opiates; yet, the role of this receptor in METH consumption and seeking is essentially unknown. Therefore, the current study used A2 A knockout (KO) mice to assess the role of A2 A in behaviours relevant to METH addiction. METH conditioned place preference was absent in A2 A KO mice compared with wild-type (WT) littermates. Repeated METH treatment produced locomotor sensitization in both genotypes; however, sensitization was attenuated in A2 A KO mice in a dose-related manner. METH intravenous self-administration was intact in A2 A KO mice over a range of doses and schedules of reinforcement. However, the motivation to self-administer was reduced in A2 A KO mice. Regression analysis further supported the observation that the motivation to self-administer METH was reduced in A2 A KO mice even when self-administration was similar to WT mice. Sucrose self-administration was also reduced in A2 A KO mice but only at higher schedules of reinforcement. Collectively, these data suggest that A2 A signalling is critically required to integrate rewarding and motivational properties of both METH and natural rewards.

Effect of Abstinence on Depression, Anxiety, and Quality of Life in Chronic Methamphetamine Users in a Therapeutic Community

Background:

During withdrawal, patients experience different symptoms. These symptoms are associated with relapse. Understanding different outcomes of methamphetamine abstinence is useful for finding better treatments for dependence.

Objectives:

This study aimed to show the effects of abstinence on depression, anxiety, and quality of life in methamphetamine users.

Patients and Methods:

A prospective quasi-experimental (before and after study) method was used to show the effect of 3 weeks abstinence on depression, anxiety, and quality of life. A convenient sample of addicted people entered into the study and 34 people completed the study. Beck Depression Scale, Cattell Anxiety Inventory and Short Form Health Survey (SF-36) (for assessing quality of life), were used for outcome assessments.

Results:

The mean depression score after abstinence decreased significantly (P < 0.001). Both hidden and obvious anxiety and total anxiety had a high level at admission and after 3 weeks of abstinence, the mean level of anxiety did not change significantly (P < 0.096). However, the quality of life increased after 3 weeks of abstinence (P < 0.001).

Conclusions:

Depression and anxiety are prevalent in methamphetamine users. Short-term abstinence improves depression and quality of life but does not improve anxiety in methamphetamine abusers. During follow up of these patients, addressing depression and anxiety is important to achieve better results.

Serotonergic responses to stress are enhanced in the central amygdala and inhibited in the ventral hippocampus during amphetamine withdrawal

Withdrawal from amphetamine increases anxiety and reduces the ability to cope with stress, which are factors that are believed to contribute to drug relapse. Stress-induced serotonergic transmission in the central nucleus of the amygdala is associated with anxiety states and fear. Conversely, stress-induced increases in ventral hippocampal serotonin (5-HT) levels have been linked to coping mechanisms. The goal of this study was to investigate the neurobiological changes induced by amphetamine that contribute to stress sensitivity during withdrawal. We tested the hypothesis that limbic serotonergic responses to restraint stress would be altered in male Sprague-Dawley rats chronically pretreated with amphetamine (2.5 mg/kg, intraperitoneal) and then subjected to 2 weeks of withdrawal. Amphetamine withdrawal resulted in increased stress-induced behavioral arousal relative to control treatment, suggesting that drug withdrawal induced greater sensitivity to the stressor. When microdialysis was used to determine the effects of restraint on extracellular 5-HT, stress-induced increases in 5-HT levels were abolished in the ventral hippocampus and augmented in the central amygdala during amphetamine withdrawal. Reverse dialysis of the glucocorticoid receptor antagonist mifepristone into the ventral hippocampus blocked the stress-induced increase in 5-HT levels in saline-pretreated rats, suggesting that glucocorticoid receptors mediate stress-induced increases in 5-HT levels in the ventral hippocampus. However, mifepristone had no effect on stress-induced increases in 5-HT levels in the central amygdala, indicating that stress increases 5-HT levels in this region independently of glucocorticoid receptors. During amphetamine withdrawal, the absence of stress-induced increases in ventral hippocampal 5-HT levels combined with enhanced stress-induced serotonergic responses in the central amygdala may contribute to drug relapse by decreasing stress-coping ability and heightening stress responsiveness.

Serotonin in the ventral hippocampus modulates anxiety-like behavior during amphetamine withdrawal

Withdrawal from amphetamine is associated with increased anxiety and sensitivity to stressors which are thought to contribute to relapse. Rats undergoing amphetamine withdrawal fail to exhibit stress-induced increases in serotonin (5-HT) release in the ventral hippocampus and show heightened anxiety-like behaviors. Therefore, we tested the hypothesis that reducing 5-HT levels in the ventral hippocampus is a causal mechanism in increasing anxiety-like behaviors during amphetamine withdrawal. First, we tested whether reducing 5-HT levels in the ventral hippocampus directly increases anxiety behavior. Male rats were bilaterally infused with 5,7-dihydroxytryptamine (5,7-DHT) into the ventral hippocampus, which produced a 83% decrease in ventral hippocampus 5-HT content, and were tested on the elevated plus maze (EPM) for anxiety-like behavior. Reducing ventral hippocampus 5-HT levels decreased the time spent in the open arms of the maze, suggesting that diminished ventral hippocampus 5-HT levels increases anxiety-like behavior. Next, we tested whether increasing 5-HT levels in the ventral hippocampus reverses anxiety behavior exhibited by rats undergoing amphetamine withdrawal. Rats were treated daily with either amphetamine (2.5-mg/kg, i.p.) or saline for 2weeks, and at 2weeks withdrawal, were infused with the selective serotonin reuptake inhibitor paroxetine (0.5μM) bilaterally into the ventral hippocampus and tested for anxiety-like behavior on the EPM. Rats pre-treated with amphetamine exhibited increased anxiety-like behavior on the EPM. This effect was reversed by ventral hippocampus infusion of paroxetine. Our results suggest that 5-HT levels in the ventral hippocampus are critical for regulating anxiety behavior. Increasing 5-HT levels during withdrawal may be an effective strategy for reducing anxiety-induced drug relapse.

Central CRF2 receptor antagonism reduces anxiety states during amphetamine withdrawal

Increased depressive and anxiety-like behaviors are exhibited by rats and humans during withdrawal from psychostimulants. Anxiety-like behaviors observed during amphetamine withdrawal are mediated by increased expression and activity of corticotropin releasing factor type 2 (CRF2) receptors in the dorsal raphe nucleus (dRN). Anxiety-like behavior of rats during withdrawal can be reversed by CRF2 receptor antagonism in the dRN, but the efficacy of global central CRF2 receptor antagonism is unknown. Rats were treated with amphetamine (2.5mg/kg, ip.) or saline daily for 2 weeks, and were tested for anxiety-like behaviors during withdrawal. Rats undergoing withdrawal showed increased anxiety-like behavior, which was reduced by ventricular infusion of the CRF2 antagonist antisauvagine-30 (ASV 2 μg/2 μl). Surprisingly, ventricular ASV increased anxiety-like behavior in rats pre-treated with saline, but had an anxiolytic effect in un-treated rats. Western blots were performed to determine whether differences in CRF receptor densities could explain ASV-induced behavioral results. Saline pre-treated rats showed reduced CRF1 receptor expression in the lateral septum compared to amphetamine pre-treated and un-treated rats. Overall, these results suggest that central CRF2 antagonism reduces anxiety states during amphetamine withdrawal, and that behavioral effects may be dependent upon the balance of CRF1 and CRF2 receptor activity in anxiety-related regions.

Methamphetamine intoxication in a dog: case report

BACKGROUND

Methamphetamine abuse has undergone a dramatic worldwide increase, and represents a significant and global issue for public health. Incidents of methamphetamine intoxication and death in humans are relatively commonplace. Because of its increasing illicit availability, together with legitimate use in human medicine, accidental or intentional exposure to methamphetamine in dogs is becoming a more likely scenario.

CASE PRESENTATION

A 3-year-old, 3.7 kg intact female Miniature Poodle who had been intentionally fed an unknown amount of a crystalline-like substance developed extreme agitation, seizures, tachycardia, hyperthermia, hypertension, disseminated intravascular coagulation (DIC), bloody diarrhea, and dilated pupils. Blood work revealed leukocytosis, erythropenia, lymphocytosis, thrombocytopenia, coagulation abnormalities, but all to a mild extent, together with mild elevation in both alanine aminotranferease (ALT) and alkaline phosphatase (ALKP), and a mild decreased in glucose. Radiologic diagnosis revealed generalized, severe distension of the stomach and small intestinal tract with air. Immunochromatographic screening tests and gas chromatography mass spectrometry analysis confirmed methamphetamine intoxication and revealed concentrations of methamphetamine in blood and urine of 0.32 μg/mL and 2.35 μg/mL respectively. The dog demonstrated progressive improvement after supportive care, with the high fever resolved over the initial 24 hours of hospitalization, and agitation was successfully controlled beyond 48 hours after initial hospitalization. Hemostatic abnormalities were progressive improved after heparin therapy and supportive care. By the sixth day of hospitalization the dog was clinically well, and all laboratory data had returned to normal with the exception of a mild elevateion of ALKP.

CONCLUSION

To the authors' knowledge, this is the second case report of methamphetamine intoxication in dogs presented in veterinary practice in open literature so far. Although rare, methamphetamine intoxication should be considered as a differential diagnosis in dogs with a toxic substance ingestion history and with typical nervous and cardiovascular system symptoms. In such cases rapid diagnosis and aggressive intervention is important for prognosis. Blood methamphetamine concentration may be a helpful value for assessment of the severity of intoxication and prediction of clinical outcomes.

Psychostimulant addiction treatment

Treatment of psychostimulant addiction has been a major, and not fully met, challenge. For opioid addiction, there is strong evidence for the effectiveness of several medications. For psychostimulants, there is no corresponding form of agonist maintenance that has met criteria for regulatory approval or generally accepted use. Stimulant-use disorders remain prevalent and can result in both short-term and long-term adverse consequences. The mainstay of treatment remains behavioral interventions. In this paper, we discuss those interventions and some promising candidates in the search for pharmacological interventions. This article is part of the Special Issue entitled 'CNS Stimulants'.

SN79, a sigma receptor antagonist, attenuates methamphetamine-induced astrogliosis through a blockade of OSMR/gp130 signaling and STAT3 phosphorylation

Methamphetamine (METH) exposure results in dopaminergic neurotoxicity in striatal regions of the brain, an effect that has been linked to an increased risk of Parkinson's disease. Various aspects of neuroinflammation, including astrogliosis, are believed to be contributory factors in METH neurotoxicity. METH interacts with sigma receptors at physiologically relevant concentrations and treatment with sigma receptor antagonists has been shown to mitigate METH-induced neurotoxicity in rodent models. Whether these compounds alter the responses of glial cells within the central nervous system to METH however has yet to be determined. Therefore, the purpose of the current study was to determine whether the sigma receptor antagonist, SN79, mitigates METH-induced striatal reactive astrogliosis. Male, Swiss Webster mice treated with a neurotoxic regimen of METH exhibited time-dependent increases in striatal gfap mRNA and concomitant increases in GFAP protein, indicative of astrogliosis. This is the first report that similar to other neurotoxicants that induce astrogliosis through the activation of JAK2/STAT3 signaling by stimulating gp-130-linked cytokine signaling resulting from neuroinflammation, METH treatment also increases astrocytic oncostatin m receptor (OSMR) expression and the phosphorylation of STAT3 (Tyr-705) in vivo. Pretreatment with SN79 blocked METH-induced increases in OSMR, STAT3 phosphorylation and astrocyte activation within the striatum. Additionally, METH treatment resulted in striatal cellular degeneration as measured by Fluoro-Jade B, an effect that was mitigated by SN79. The current study provides evidence that sigma receptor antagonists attenuate METH-induced astrocyte activation through a pathway believed to be shared by various neurotoxicants.

The impact of methamphetamine ("tik") on a peri-urban community in Cape Town, South Africa

BACKGROUND

Over the last decade, South Africa's Western Cape has experienced a dramatic increase in methamphetamine ("tik") use. Our study explored local impressions of the impact of tik use in a peri-urban township community in Cape Town, South Africa.

METHODS

We conducted individual in-depth interviews with 55 women and 37 men who were regular attendees of alcohol-serving venues. Interviews were recorded and transcribed. A content analysis approach was used to identify themes related to the impact of tik use based on levels of the socio-ecological framework (individual, inter-personal and community).

RESULTS

Tik use was reported to be a greater issue among Coloureds, compared to Blacks. At an individual level, respondents reported that tik use had adverse effects on mental, physical, and economic well-being, and limited future opportunities through school drop-out and incarceration. At an inter-personal level, respondents reported that tik use contributed to physical and sexual violence as well as increased rates of sexual risk behaviour, particularly through transactional sex relationships. Respondents described how tik use led to household conflict, and had negative impacts on children, including neglect and poor birth outcomes. At a community level, respondents linked tik use to increased rates of crime, violence and corruption, which undercut community cohesion.

CONCLUSIONS

Our results highlight the negative impact that tik is having on individuals, households and the overall community in a peri-urban setting in South Africa. There is a clear need for interventions to prevent tik use in South Africa and to mitigate and address the impact of tik on multiple levels.

SN79, a sigma receptor ligand, blocks methamphetamine-induced microglial activation and cytokine upregulation

Methamphetamine (METH) abuse is associated with several negative side effects including neurotoxicity in specific brain regions such as the striatum. The precise molecular mechanisms by which METH usage results in neurotoxicity remain to be fully elucidated, with recent evidence implicating the importance of microglial activation and neuroinflammation in damaged brain regions. METH interacts with sigma receptors which are found in glial cells in addition to neurons. Moreover, sigma receptor antagonists have been shown to block METH-induced neurotoxicity in rodents although the cellular mechanisms underlying their neuroprotection remain unknown. The purpose of the current study was to determine if the prototypic sigma receptor antagonist, SN79, mitigates METH-induced microglial activation and associated increases in cytokine expression in a rodent model of METH-induced neurotoxicity. METH increased striatal mRNA and protein levels of cluster of differentiation 68 (CD68), indicative of microglial activation. METH also increased ionized calcium binding adapter molecule 1 (IBA-1) protein expression, further confirming the activation of microglia. Along with microglial activation, METH increased striatal mRNA expression levels of IL-6 family pro-inflammatory cytokines, leukemia inhibitory factor (lif), oncostatin m (osm), and interleukin-6 (il-6). Pretreatment with SN79 reduced METH-induced increases in CD68 and IBA-1 expression, demonstrating its ability to prevent microglial activation. SN79 also attenuated METH-induced mRNA increases in IL-6 pro-inflammatory cytokine family members. The ability of a sigma receptor antagonist to block METH-induced microglial activation and cytokine production provides a novel mechanism through which the neurotoxic effects of METH may be mitigated.

Influence of chronic amphetamine treatment and acute withdrawal on serotonin synthesis and clearance mechanisms in the rat ventral hippocampus

Amphetamine withdrawal in both humans and rats is associated with increased anxiety states, which are thought to contribute to drug relapse. Serotonin in the ventral hippocampus mediates affective behaviors, and reduced serotonin levels in this region are observed in rat models of high anxiety, including during withdrawal from chronic amphetamine. This goal of this study was to understand the mechanisms by which reduced ventral hippocampus serotonergic neurotransmission occurs during amphetamine withdrawal. Serotonin synthesis (assessed by accumulation of serotonin precursor as a measure of the capacity of in vivo tryptophan hydroxylase activity), expression of serotonergic transporters, and in vivo serotonergic clearance using in vivo microdialysis were assessed in the ventral hippocampus in adult male Sprague Dawley rats at 24 h withdrawal from chronic amphetamine. Overall, results showed that diminished extracellular serotonin at 24 h withdrawal from chronic amphetamine was not accompanied by a change in capacity for serotonin synthesis (in vivo tryptophan hydroxylase activity), or serotonin transporter expression or function in the ventral hippocampus, but instead was associated with increased expression and function of organic cation transporters (low-affinity, high-capacity serotonin transporters). These findings suggest that 24 h withdrawal from chronic amphetamine reduces the availability of extracellular serotonin in the ventral hippocampus by increasing organic cation transporter-mediated serotonin clearance, which may represent a future pharmacological target for reversing anxiety states during drug withdrawal.

S(+)amphetamine induces a persistent leak in the human dopamine transporter: molecular stent hypothesis

BACKGROUND AND PURPOSE

Wherever they are located, dopamine transporters (DATs) clear dopamine (DA) from the extracellular milieu to help regulate dopaminergic signalling. Exposure to amphetamine (AMPH) increases extracellular DA in the synaptic cleft, which has been ascribed to DAT reverse transport. Increased extracellular DA prolongs postsynaptic activity and reinforces abuse and hedonic behaviour.

EXPERIMENTAL APPROACH

Xenopus laevis oocytes expressing human (h) DAT were voltage-clamped and exposed to DA, R(-)AMPH, or S(+)AMPH.

KEY RESULTS

At -60mV, near neuronal resting potentials, S(+)AMPH induced a depolarizing current through hDAT, which after removing the drug, persisted for more than 30 min. This persistent leak in the absence of S(+)AMPH was in contrast to the currents induced by R(-)AMPH and DA, which returned to baseline immediately after their removal. Our data suggest that S(+)AMPH and Na(+) carry the initial S(+)AMPH-induced current, whereas Na+ and Cl(-) carry the persistent leak current. We propose that the persistent current results from the internal action of S(+)AMPH on hDAT because the temporal effect was consistent with S(+)AMPH influx, and intracellular S(+)AMPH activated the effect. The persistent current was dependent on Na(+) and was blocked by cocaine. Intracellular injection of S(+)AMPH also activated a DA-induced persistent leak current.

CONCLUSIONS AND IMPLICATIONS

We report a hitherto unknown action of S(+)AMPH on hDAT that potentially affects AMPH-induced DA release. We propose that internal S(+)AMPH acts as a molecular stent that holds the transporter open even after external S(+)AMPH is removed. Amphetamine-induced persistent leak currents are likely to influence dopaminergic signalling, DA release mechanisms, and amphetamine abuse.

Effect of methamphetamine dependence on heart rate variability

Methamphetamine (METH) is an increasing popular and highly addictive stimulant associated with autonomic nervous system (ANS) dysfunction, cardiovascular pathology and neurotoxicity. Heart rate variability (HRV) has been used to assess autonomic function and predict mortality in cardiac disorders and drug intoxication, but has not been characterized in METH use. We recorded HRV in a sample of currently abstinent individuals with a history of METH dependence compared to age- and gender-matched drug-free comparison subjects. HRV was assessed using time domain, frequency domain, and non-linear entropic analyses in 17 previously METH-dependent and 21 drug-free comparison individuals during a 5 minute rest period. The METH-dependent group demonstrated significant reduction in HRV, reduced parasympathetic activity, and diminished heartbeat complexity relative to comparison participants. More recent METH use was associated with increased sympathetic tone. Chronic METH exposure may be associated with decreased HRV, impaired vagal function, and reduction in heart rate complexity as assessed by multiple methods of analysis. We discuss and review evidence that impaired HRV may be related to the cardiotoxic or neurotoxic effects of prolonged METH use.

Synthesis and pharmacological characterization of a novel sigma receptor ligand with improved metabolic stability and antagonistic effects against methamphetamine

Methamphetamine interacts with sigma receptors at physiologically relevant concentrations suggesting a potential site for pharmacologic intervention. In the present study, a previous sigma receptor ligand, CM156, was optimized for metabolic stability, and the lead analog was evaluated against the behavioral effects of methamphetamine. Radioligand binding studies demonstrated that the lead analog, AZ66, displayed high nanomolar affinity for both sigma-1 and sigma-2 receptors (2.4 ± 0.63 and 0.51 ± 0.15, respectively). In addition, AZ66 had preferential affinity for sigma receptors compared to seven other sites and a significantly longer half-life than its predecessor, CM156, in vitro and in vivo. Pretreatment of male, Swiss Webster mice with intraperitoneal (10-20 mg/kg) or oral (20-30 mg/kg) dosing of AZ66 significantly attenuated the acute locomotor stimulatory effects of methamphetamine. Additionally, AZ66 (10-20 mg/kg, i.p.) significantly reduced the expression and development of behavioral sensitization induced by repeated methamphetamine administration. Taken together, these data indicate that sigma receptors can be targeted to mitigate the acute and subchronic behavioral effects of methamphetamine and AZ66 represents a viable lead compound in the development of novel therapeutics against methamphetamine-induced behaviors.

Stimulant abuse: pharmacology, cocaine, methamphetamine, treatment, attempts at pharmacotherapy

The high prevalence of stimulant abuse and its harmful consequences make the screening, diagnosis, and referral for treatment of persons with stimulant abuse a top concern for primary care providers. Having a working knowledge of use patterns, clinical symptomatology, end-organ effects, and advances in treatment of stimulant abuse is essential. Although cocaine and amphetamine have different use patterns, duration of action, and so forth, the consequences of use are remarkably similar. Primary care is at the forefront of screening, brief risk reduction interventions, and diagnosis of medical sequelae, with referral to addiction specialist treatment when necessary.

Effect of methamphetamine dependence on inhibitory deficits in a novel human open-field paradigm

RATIONALE

Methamphetamine (MA) is an addictive psychostimulant associated with neurocognitive impairment, including inhibitory deficits characterized by a reduced ability to control responses to stimuli. While various domains of inhibition such as exaggerated novelty seeking and perseveration have been assessed in rodents by quantifying activity in open-field tests, similar models have not been utilized in human substance abusers. We recently developed a cross-species translational human open-field paradigm, the human behavior pattern monitor (hBPM), consisting of an unfamiliar room containing novel and engaging objects. Previous work demonstrated that manic bipolar subjects exhibit a disinhibited pattern of behavior in the hBPM characterized by increased object interactions.

OBJECTIVES

In the current study, we examined the effect of MA dependence on inhibitory deficits using this paradigm. hBPM activity and object interactions were quantified in 16 abstinent MA-dependent individuals and 18 matched drug-free comparison subjects. The Wisconsin card sorting task (WCST) and the positive and negative syndrome scale (PANSS) were administered to assess executive function and psychopathology.

RESULTS

MA-dependent participants exhibited a significant increase in total object interactions, time spent with objects, and perseverative object interactions relative to comparison subjects. Greater object interaction was associated with impaired performance on the WCST, higher PANSS scores, and more frequent MA use in the past year.

CONCLUSIONS

Abstinent MA-dependent individuals exhibited impaired inhibition in the hBPM, displaying increased interaction with novel stimuli. Utilization of this measure may enable assessment of inhibitory deficits relevant to drug-seeking behavior and facilitate development of intervention methods to reduce high-risk conduct in this population.

Effect of methamphetamine dependence on everyday functional ability

BACKGROUND

Methamphetamine (METH) is an increasingly popular and highly addictive psychostimulant with a significant impact on public health. Chronic METH exposure has been associated with neurotoxic effects, profound neuropsychological deficits, and impaired quality of life, but few studies have examined the effect of the drug on the ability to carry out everyday activities. We assessed the effect of METH dependence on everyday functioning using the UCSD Performance-Based Skills Assessment (UPSA-2), a performance-based measure designed to evaluate real-life skills.

METHOD

UPSA-2 performance was quantified in 15 currently abstinent individuals with a history of METH dependence and 15 drug-free comparison subjects. The Positive and Negative Syndrome Scale (PANSS) and Wisconsin Card Sorting Task (WCST) were administered to assess psychopathology and executive function.

RESULTS

METH-dependent participants exhibited significant impairment on the UPSA-2 total score and several UPSA-2 subscales, including comprehension, finance, transportation, communication, and medication management compared to drug-free comparison subjects. Lower UPSA-2 scores were associated with impaired performance on the WCST, higher PANSS scores, and drug use at an earlier age.

CONCLUSION

METH dependence may be associated with decreased everyday functioning ability potentially mediated by frontal cortex dysfunction or the emergence of psychopathology related to chronic drug use.

Methamphetamine self-administration and the effect of contingency on monoamine and metabolite tissue levels in the rat

A number of studies have shown that exposure to high doses of methamphetamine (MA) is toxic to central dopamine (DA) and serotonin (5-HT) neurons. In most of those studies, however, high doses of MA were experimenter-administered during a short exposure time. Because contingency is a determinant for many effects of drug exposure, the present objective was to investigate the effects of self-administered MA on tissue monoamine levels following a short (24 hours) or longer (7 days) withdrawal period. As previously reported, a noncontingent "binge" high-dose treatment regimen (4 injections of 10 mg/kg MA administered every 2 hours) produced persistent depletion of cortical 5-HT and striatal DA. Effects of self-administered MA (0.1 mg/kg/infusion) were then determined following a 20-day duration where a yoked design was employed such that some rats received MA contingent on an operant lever press and others received either MA or saline dependent on the responses of the contingent rat. Self-administered MA produced a transient striatal DA depletion with a more persistent increase in DA turnover, indicating the presence of some lasting adaptations. Furthermore, the yoked design revealed that there was no effect of contingency on these parameters.

Molecular bases of methamphetamine-induced neurodegeneration

Methamphetamine (METH) is a highly addictive psychostimulant drug, whose abuse has reached epidemic proportions worldwide. The addiction to METH is a major public concern because its chronic abuse is associated with serious health complications including deficits in attention, memory, and executive functions in humans. These neuropsychiatric complications might, in part, be related to drug-induced neurotoxic effects, which include damage to dopaminergic and serotonergic terminals, neuronal apoptosis, as well as activated astroglial and microglial cells in the brain. Thus, the purpose of the present paper is to review cellular and molecular mechanisms that might be responsible for METH neurotoxicity. These include oxidative stress, activation of transcription factors, DNA damage, excitotoxicity, blood-brain barrier breakdown, microglial activation, and various apoptotic pathways. Several approaches that allow protection against METH-induced neurotoxic effects are also discussed. Better understanding of the cellular and molecular mechanisms involved in METH toxicity should help to generate modern therapeutic approaches to prevent or attenuate the long-term consequences of psychostimulant use disorders in humans.

The availability and portrayal of stimulants over the Internet

PURPOSE

To quantify the online availability and portrayal of amphetamine-class prescription stimulants with a focus on those medications commonly prescribed to and abused by adolescents.

METHOD

The Google search engine was used in searches to assess the frequency of web sites offering to sell controlled stimulants (retail sites) or web sites that directly linked to retail sites (portal sites). In addition separate searches were used to evaluate the portrayal of controlled prescription stimulants by the initial 20 web sites returned by Google. Retail and portal web site frequency was collected for each search. For searches measuring the portrayal of stimulants, web pages were categorized as pro-use, anti-misuse, neutral or other, based on set criteria.

RESULTS

Sites offering to sell stimulants without a prescription were found for nearly all search terms. Across all searches, the Schedule III stimulants indicated for the treatment of obesity returned more sites offering to sell stimulants without a prescription than Schedule II stimulants indicated for the treatment of attention-deficit hyperactivity disorder (ADHD). Internet site portrayal of each stimulant varied; however sites that contained "methamphetamine" often included anti-misuse information.

CONCLUSIONS

The apparent availability of stimulants over the Internet without a prescription indicates the potential for a significant public health problem. The extent to which teens are obtaining these drugs via the Internet remains unclear, but clinicians must be aware of the potential for abuse, concomitant prescription use issues, illicit sources, and diversion of these medications, which can be highly addictive. Education of consumers and physicians as well as further governmental interventions are needed to limit the potential scope of this problem.

Interactions of HIV and methamphetamine: cellular and molecular mechanisms of toxicity potentiation

Methamphetamine (METH) is a highly addictive psychostimulant drug, whose abuse has reached epidemic proportions worldwide. METH use is disproportionally represented among populations at high risks for developing HIV infection or who are already infected with the virus. Psychostimulant abuse has been reported to exacerbate the cognitive deficits and neurodegenerative abnormalities observed in HIV-positive patients. Thus, the purpose of the present paper is to review the clinical and basic observations that METH potentiates the adverse effects of HIV infection. An additional purpose is to provide a synthesis of the cellular and molecular mechanisms that might be responsible for the increased toxicity observed in co-morbid patients. The reviewed data indicate that METH and HIV proteins, including gp120, gp41, Tat, Vpr and Nef, converge on various caspase-dependent death pathways to cause neuronal apoptosis. The role of reactive microgliosis in METH- and in HIV-induced toxicity is also discussed.

A comparison of amphetamine- and methamphetamine-induced locomotor activity in rats: evidence for qualitative differences in behavior

RATIONALE

Methamphetamine (METH) is typically characterized as a more potent psychostimulant than amphetamine (AMPH), but few studies have directly compared the effects of these drugs at low, behaviorally activating doses that tend not to produce focused stereotypy.

OBJECTIVES

The objective of the study was to compare the effects of AMPH or METH treatment on locomotor activity in an open-field arena, focusing on their ability to produce conditioned locomotor activity, sensitization, and cross-sensitization.

MATERIALS AND METHODS

Adult male rats were given AMPH or METH (0.5 or 1.0 mg/kg) for 5 days, with half of the rats presented with discrete, salient stimuli (S+) during the postinjection period. After a 3-day withdrawal, they were given three different injections on successive days: a saline challenge to assess conditioned responding, a drug challenge to assess sensitization, and a cross-sensitization test to the same dose of the drug with which they were not pretreated.

RESULTS

Except in certain conditions, AMPH and METH were equipotent at activating locomotor activity. The exceptions included when rats were presented with S+ on acute and drug challenge days and in tests of cross-sensitization. There were no consistent differences in the magnitude of sensitization produced by AMPH or METH, and both drugs produced similar amounts of conditioned locomotion after a saline injection.

CONCLUSIONS

We have found specific conditions where METH is more potent than AMPH, but this study and others that used higher doses of these drugs are not consistent with the generalized characterization of METH as a more potent psychostimulant.

Modafinil exerts a dose-dependent antiepileptic effect mediated by adrenergic α1 and histaminergic H1 receptors in mice

Epilepsy is characterized by neuronal hyperexcitability and hypersynchronization. Disruption of electroencephalographically (EEG) synchronized epileptiform discharges may be a possible therapy for epilepsy. In the present study, to clarify the role of EEG desynchronization on epilepsy, we investigated the effect of modafinil, a potent wake-promoting substance with EEG desynchronization activity, on epilepsy in mice and clarified the receptors involved in the suppression of seizure caused by maximal electroshock (MES) and pentylenetetrazol (PTZ) kindling models. Modafinil given at 22.5, 45, and 90 mg/kg, i.p. significantly decreased the incidence of tonic hindleg extension in MES seizure models, and protected against PTZ-induced convulsive behaviors in a dose-dependent manner. In addition, modafinil at 180 mg/kg exerted an antiepileptic effect in the MES model; however, at the same dosage it increased the seizure stage in the PTZ-kindling model. The antiepileptic effect in both MES and PTZ models was antagonized by the adrenergic alpha(1) receptor antagonist terazosin, but not by the adrenergic alpha(2) receptor antagonist yohimbine or by dopaminergic receptor antagonists, SCH-23390 (for D(1) receptors) and haloperidol (for D(2) ones). Pyrilamine, a histaminergic H(1) receptor antagonist, counteracted the antiepileptic action of modafinil in the PTZ induced-kindling model, but not in the MES seizure model. Taken together, the present findings indicate that modafinil exerted its antiepileptic effect via adrenergic alpha(1) and histaminergic H(1) receptors, and might be of potential use in the treatment of epilepsy.