Learning and memory effects of neonatal methamphetamine exposure in rats: Role of reactive oxygen species and age at assessment

In utero methamphetamine (MA) exposure leads to a range of adverse effects, such as decreased attention, reduced working‐memory capability, behavioral dysregulation, and spatial memory impairments in exposed children. In the current experiment, preweaning Sprague‐Dawley rats—as a model of third trimester human exposure—were administered the spin trapping agent, N‐tert‐butyl‐α‐phenylnitrone (PBN), daily prior to MA. Rats were given 0 (SAL) or 40 mg/kg PBN prior to each MA dose (10 mg/kg, 4× per day) from postnatal day (P) 6–15. Littermates underwent Cincinnati water maze, Morris water maze, and radial water maze assessment beginning on P30 (males) or P60 (females). Males were also tested for conditioned contextual and cued freezing, while females were trained in passive avoidance. Findings show that, regardless of age/sex, neonatal MA induced deficits in all tests, except passive avoidance. PBN did not ameliorate these effects, but had a few minor effects. Taken together, MA induced learning deficits emerge early and persist, but the mechanism remains unknown.     

RIP3/MLKL-mediated neuronal necroptosis induced by methamphetamine at 39℃

Methamphetamine is one of the most prevalent drugs abused in the world.Methamphetamine abusers usually present with hyperpyrexia (39℃),hallucination and other psychiatric symptoms.However,the detailed mechanism underlying its neurotoxic action remains elusive.This study investigated the effects of methamphetamine + 39℃ on primary cortical neurons from the cortex of embryonic Sprague-Dawley rats.Primary cortex neurons were exposed to 1 mM methamphetamine + 39℃.Propidium iodide staining and lactate dehydrogenase release detection showed that methamphetamine + 39℃ triggered obvious necrosis-like death in cultured primary cortical neurons,which could be partially inhibited by receptor-interacting protein-1 (RIP1) inhibitor Necrostatin-1 partially.Western blot assay results showed that there were increases in the expressions of receptor-interacting protein-3 (RIP3) and mixed lineage kinase domain-like protein (MLKL) in the primary cortical neurons treated with 1 mM methamphetamine + 39℃ for 3 hours.After pre-treatment with RIP3 inhibitor GSK’872,propidium iodide staining and lactate dehydrogenase release detection showed that neuronal necrosis rate was significantly decreased;RIP3 and MLKL protein expression significantly decreased.Immunohistochemistry staining results also showed that the expressions of RIP3 and MLKL were up-regulated in brain specimens from humans who had died of methamphetamine abuse.Taken together,the above results suggest that methamphetamine + 39℃ can induce RIP3/MLKL regulated necroptosis,thereby resulting in neurotoxicity.The study protocol was approved by the Medical Ethics Committee of the Third Xiangya Hospital of Central South University,China (approval numbers: 2017-S026 and 2017-S033) on March 7,2017.     

Breast abscess after intravenous methamphetamine injection into the breast

Intravenous drug use is a problem plaguing our society. We present a case of a young female who injected methamphetamine into her mammary vein, resulting in the formation of a breast abscess. This case demonstrates a rare but dangerous complication of intravenous drug use and a possible differential diagnosis in a patient presenting with a breast abscess.     

The spatial epidemiology of cocaine, methamphetamine and 3,4-methylenedioxymethamphetamine (MDMA) use: a demonstration using a population measure of community drug load derived from municipal wastewater

Aims   To determine the utility of community-wide drug testing with wastewater samples as a population measure of community drug use and to test the hypothesis that the association with urbanicity would vary for three different stimulant drugs of abuse.
Design and participants   Single-day samples were obtained from a convenience sample of 96 municipalities representing 65% of the population of the State of Oregon.
Measurements   Chemical analysis of 24-hour composite influent samples for benzoylecgonine (BZE, a cocaine metabolite), methamphetamine and 3,4-methylenedioxymethamphetamine (MDMA). The distribution of community index drug loads accounting for total wastewater flow (i.e. dilution) and population are reported.
Findings   The distribution of wastewater-derived drug index loads was found to correspond with expected epidemiological drug patterns. Index loads of BZE were significantly higher in urban areas and below detection in many rural areas. Conversely, methamphetamine was present in all municipalities, with no significant differences in index loads by urbanicity. MDMA was at quantifiable levels in fewer than half the communities, with a significant trend towards higher index loads in more urban areas.
Conclusion   This demonstration provides the first evidence of the utility of wastewater-derived community drug loads for spatial analyses. Such data have the potential to improve dramatically the measurement of the true level and distribution of a range of drugs. Drug index load data provide information for all people in a community and are potentially applicable to a much larger proportion of the total population than existing measures.     

Reduced (+/-)-3,4-methylenedioxymethamphetamine ("Ecstasy") metabolism with cytochrome P450 2D6 inhibitors and pharmacogenetic variants in vitro

"Ecstasy" [(+/-)-3,4-methylenedioxymethamphetamine or MDMA] is a CNS stimulant, whose use is increasing despite evidence of long-term neurotoxicity. In vitro, the majority of MDMA is demethylenated to (+/-)-3,4-dihydroxymethamphetamine (DHMA) by the polymorphic cytochrome P450 2D6 (CYP2D6). We investigated the demethylenation of MDMA and dextromethorphan (DEX), as a comparison drug, in reconstituted microsomes expressing the variant CYP2D6 alleles (*)2, (*)10, and (*)17, all of which have been linked to decreased enzyme activity. With MDMA, intrinsic clearances (V(max)/K(m)) in CYP2D6.2, CYP2D6.17, and CYP2D6.10 were reduced 15-, 13-, and 135-fold, respectively, compared with wild-type CYP2D6.1. With DEX, intrinsic clearances were reduced by 37-, 51-, and 164-fold, respectively. It was evident that CYP2D6.17 displayed substrate-specific changes in drug affinity (K(m)). Compounds potentially used with MDMA [fluoxetine, paroxetine, (-)-cocaine] demonstrated significant inhibition of MDMA metabolism in both human liver and CYP2D6.1-expressing microsomes. These data demonstrate that individuals possessing the CYP2D6(*)2, (*)17, and, particularly, (*)10 alleles may show significantly reduced MDMA metabolism. These individuals, and those taking CYP2D6 inhibitors, may demonstrate altered acute and/or long-term MDMA-related toxicity.     

Drugs of Abuse, Immune Modulation, and AIDS

Illicit drugs such as amphetamines, cocaine, marijuana, and opiates alter immune function and decrease host resistance to microbes in vitro and in experimental animal models. Effects on the immune system may be mediated indirectly as a result of drug interactions in the central nervous system (CNS) or directly through activation of cognate receptors on various immune cell types. For marijuana and opioids, seven-transmembranal G protein-coupled receptors have been identified in the CNS and in the immune system that may play a functionally relevant role in immune modulation. There is accumulating evidence that sigma₁ receptors play a comparable role in cocaine-mediated alteration of immune responses. A mode by which these exogenously introduced substances affects immunity and host resistance may be by perturbing the balance of Th₁ proinflammatory versus Th₂ anti-inflammatory cytokines and lipid bioeffectors. However, while illicit drugs have been documented to alter immune functions in vitro and in animal models, there is a paucity of controlled longitudinal epidemiological studies that definitively correlate immunosuppressive effects with increased incidence of infections or immune disorders in humans, including infection with the human immunodeficiency virus (HIV) or disease progression to AIDS.     

Substance initiation sequences among Taiwanese adolescents using methamphetamine

The aim of this study was to examine substance initiation sequences in Taiwanese adolescent methamphetamine (MAMP) users. Three hundred adolescent MAMP users were questioned about their use of cigarettes, alcohol, areca quid, benzodiazepine, glue, marijuana, MAMP and heroin. The sequences of substance use before MAMP use were determined in every subject according to their age at substance initiation. The sequences of substance initiation were compared between genders and between early-onset and late-onset MAMP users. The results revealed that the adolescents had used cigarettes, alcohol and areca quid before MAMP, and very few (4%) adolescents had started using MAMP before using other substances. Female MAMP users were more likely to use MAMP as their first substance and were less likely to use areca quid than males. Male early-onset MAMP users were more likely to drink alcohol and chew areca quid before MAMP use than were late-onset users. This study found that the sequences of substance initiation were different between genders and between the early-onset and late-onset MAMP users. There are several findings that are different from those in Western studies on the sequence of substance initiation in the adolescent population.     

Brain vesicular acetylcholine transporter in human users of drugs of abuse

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

Focused motor stereotypies do not require enhanced activation of neurons in striosomes

Stereotypic motor behavior is a widespread phenomenon of many neurologic and psychiatric disorders. Studies on the mechanisms controlling motor stereotypies have focused on the role of dopamine in modulating the activity of basal ganglia neuronal circuits, and recent results demonstrated that stereotypic motor responses characteristic of psychomotor stimulant sensitization correlate with an enhanced activation of neurons located in striatal striosomes that substantially exceeds that of the surrounding matrix. The present study tested whether predominant striosomal activation is a general predictor for stereotypy. Wild-type and dopamine D(2) and D(3) receptor knockout mice were treated either three times with methamphetamine (METH; 3 x 5 mg/kg every 2 hours) or once with a full D(1) agonist. Depending on the genotype, both treatments elicit the same focused stereotypy (taffy pulling). Repeated METH-treatment elicits intense stereotypy in wild-type and D(3) mutants but not in D(2) single and D(2)/D(3) double mutants. The stereotypic response of wild-type and D(3) mutants correlates with a predominant activation of neurons located in striosomes. No striosomal predominance is detected in METH-treated D(2) single and D(2)/D(3) double mutants. In contrast, D(2) single and D(2)/D(3) double mutants exhibited the most severe stereotypic response to D(1)-agonist treatment. However, this treatment did not result in enhanced striosomal activation. Thus, whereas the expression of stereotypy in response to repeated METH treatment requires D(2) receptor expression, D(2) receptor expression diminishes stereotypic responses to an acute dose of a D(1) agonist. Enhanced striosomal activation, however, is a reliable indicator of D(1)- and D(2)-receptor coactivation but not a predictor for repetitive motor behavior in general.