A developmental comparison of the neurobehavioral effects of ecstasy (MDMA)

Preventing new substance use behaviors in youth: evaluation of a two-year comprehensive program

Introduction

The Avenir Santé Association implemented a comprehensive prevention program targeting the consumption of the emerging psychoactive substances ecstasy (MDMA), cannabidiol (CBD), and nitrous oxide (N2O).

Methods

The program was evaluated through four actions: (i) training for association workers (n = 84) (ii) on-site student party interventions (n = 248), (iii) social network-based prevention (n = 186), and (iv) provision of prevention tools for party organizers (n = 148).

Results

Results showed a significant increase in understanding of emerging substances among association workers, with a pre-training score of M = 15.76 (SD = 3.65) and a post-training score of M = 18.29 (SD = 2.50). Increased awareness and reflective attitudes toward substance use were observed among young people participating in field actions, with pre- and post-intervention scores for MDMA use intentions being M = 15.89 (SD = 4.60) and M = 19.17 (SD = 3.33), respectively. Similarly, awareness of CBD effects increased from M = 14.18 (SD = 4.14) to M = 17.60 (SD = 3.31). Exposure to Instagram posts on N2O led to more negative attitudes toward N2O among young people, with a significant change in scores from M = 8.16 (SD = 1.57) to M = 8.42 (SD = 1.26). However, exposure to a website providing information about emerging substances did not produce any significant effect.

Discussion

In conclusion, this initiative underscores the usefulness of facilitator training, field interventions, and certain online information strategies for substance judgment and usage intentions. Future prevention programs can advantageously incorporate these actions.

Impact of neuroimmune activation induced by alcohol or drug abuse on adolescent brain development

Evidence obtained in recent decades has demonstrated that the brain still matures in adolescence. Changes in neural connectivity occur in different regions, including cortical and subcortical structures, which undergo modifications in white and gray matter densities. These alterations concomitantly occur in some neurotransmitter systems and hormone secretion, which markedly influence the refinement of certain brain areas and neural circuits. The immaturity of the adolescent brain makes it more vulnerable to the effects of alcohol and drug abuse, whose use can trigger long-term behavioral dysfunction. This article reviews the action of alcohol and drug abuse (cannabis, cocaine, opioids, amphetamines, anabolic androgenic steroids) in the adolescent brain, and their impact on both cognition and behavioral dysfunction, including predisposition to drug abuse in later life. It also discusses recent evidence that indicates the role of the neuroimmune system response and neuroinflammation as mechanisms that participate in many actions of ethanol and drug abuse in adolescence, including the neurotoxicity and alterations in neurocircuitry that contribute to the dysfunctional behaviors associated with addiction. The new data suggest the therapeutic potential of anti-inflammatory targets to prevent the long-term consequences of drug abuse in adolescence.

Amphetamine-related drugs neurotoxicity in humans and in experimental animals: Main mechanisms

Amphetamine-related drugs, such as 3,4-methylenedioxymethamphetamine (MDMA) and methamphetamine (METH), are popular recreational psychostimulants. Several preclinical studies have demonstrated that, besides having the potential for abuse, amphetamine-related drugs may also elicit neurotoxic and neuroinflammatory effects. The neurotoxic potentials of MDMA and METH to dopaminergic and serotonergic neurons have been clearly demonstrated in both rodents and non-human primates. This review summarizes the species-specific cellular and molecular mechanisms involved in MDMA and METH-mediated neurotoxic and neuroinflammatory effects, along with the most important behavioral changes elicited by these substances in experimental animals and humans. Emphasis is placed on the neuropsychological and neurological consequences associated with the neuronal damage. Moreover, we point out the gap in our knowledge and the need for developing appropriate therapeutic strategies to manage the neurological problems associated with amphetamine-related drug abuse.

Developmental outcomes of 3,4-methylenedioxymethamphetamine (ecstasy)-exposed infants in the UK

OBJECTIVE

This paper aims to review findings from a longitudinal study of prenatal methylenedioxymethamphetamine (MDMA, "ecstasy") on infant development.

METHODS

In a prospective, longitudinal cohort design, we followed 28 MDMA-exposed and 68 non-MDMA-exposed infants from birth to 2 years of age. Women recruited voluntarily into a study of recreational drug use during pregnancy were interviewed to obtain type, frequency, and amount of recreational drug use. Their children were followed for a 2-year period after birth. A large number of drug and environmental covariates were controlled. Infants were seen at 1, 4, 12, 18, and 24 months using standardized normative tests of mental and motor development.

RESULTS

There were no differences between MDMA-exposed and non-MDMA-exposed infants at birth except that MDMA-exposed infants were more likely to be male. Motor delays were evident in MDMA infants at each age and amount of MDMA exposure predicted motor deficits at 12 months in a dose-dependent fashion.

CONCLUSIONS

Prenatal MDMA exposure is related to fine and gross motor delays in the first 2 years of life. Follow-up studies are needed to determine long-term effects.

Adolescent MDMA exposure diminishes the physiological and neurotoxic consequences of an MDMA binge in female rats

Intermittent MDMA pretreatment blocked the reductions in serotonin transporter (SERT) binding induced by an MDMA binge in a prior study in adolescent male rats. The objective of this investigation was to determine if the physiological, behavioral, and neurochemical responses to MDMA are sexually dimorphic. Female Sprague-Dawley rats received MDMA (10 mg/kg × 2) or Saline on every fifth day from postnatal day (PD) 35-60 and an MDMA binge (5 mg/kg × 4) on PD 67. The MDMA binge induced a pronounced temperature dysregulation in MDMA-naïve, but not MDMA-pretreated, groups. Similarly, MDMA-pretreated animals were resistant to the binge-induced SERT reductions, especially in the hippocampus. Motor activity at PD 68 was not reduced by the binge, unlike the responses found in males. These results show that female rats differ from males in their responses to an MDMA binge but are similar with respect to preconditioning from prior MDMA exposure.

Sex-dependent long-term effects of adolescent exposure to THC and/or MDMA on neuroinflammation and serotoninergic and cannabinoid systems in rats

BACKGROUND AND PURPOSE

Many young people consume ecstasy as a recreational drug and often in combination with cannabis. In this study, we aimed to mimic human consumption patterns and investigated, in male and female animals, the long-term effects of Δ(9) -tetrahydrocannabinol (THC) and 3,4-methylenedioxymethamphetamine (MDMA) on diverse neuroinflammation and neurotoxic markers.

EXPERIMENTAL APPROACH

Male and female Wistar rats were chronically treated with increasing doses of THC and/or MDMA during adolescence. The effects of THC and/or MDMA on glial reactivity and on serotoninergic and cannabinoid systems were assessed by immunohistochemistry in the hippocampus and parietal cortex.

KEY RESULTS

THC increased the area staining for glial fibrilar acidic protein in both sexes. In males, both drugs, either separately or in combination, increased the proportion of reactive microglia cells [ionized calcium binding adaptor molecule 1 (Iba-1)]. In contrast, in females, each drug, administered alone, decreased of this proportion, whereas the combination of both drugs resulted in a 'normalization' to control values. In males, MDMA reduced the number of SERT positive fibres, THC induced the opposite effect and the group receiving both drugs did not significantly differ from the controls. In females, MDMA reduced the number of SERT positive fibres and the combination of both drugs counteracted this effect. THC also reduced immunostaining for CB1 receptors in females and this effect was aggravated by the combination with MDMA.

CONCLUSIONS AND IMPLICATIONS

Adolescent exposure of rats to THC and/or MDMA induced long-term, sex-dependent neurochemical and glial alterations, and revealed interactions between the two drugs.

LINKED ARTICLES

This article is part of a themed section on Cannabinoids 2013. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2014.171.issue-6.

Behavioral and neurochemical effects of repeated MDMA administration during late adolescence in the rat

Adolescents and young adults disproportionately abuse 3,4-methylenedioxymethamphetamine (MDMA; 'Ecstasy'); however, since most MDMA research has concentrated on adults, the effects of MDMA on the developing brain remain obscure. Therefore, we evaluated place conditioning to MDMA (or saline) during late adolescence and assessed anxiety-like behavior and monoamine levels during abstinence. Rats were conditioned to associate 5 or 10mg/kg MDMA or saline with contextual cues over 4 twice-daily sessions. Five days after conditioning, anxiety-like behavior was examined with the open field test and brain tissue was collected to assess serotonin (5-hydroxytryptamine, 5-HT) and its metabolite 5-hydroxyindoleacetic acid (5-HIAA) in the dorsal raphe, amygdala, and hippocampus by high-pressure liquid chromatography (HPLC). In a separate group of rats, anxiety-like and avoidant behaviors were measured using the light-dark box test under similar experimental conditions. MDMA conditioning caused a place aversion at 10, but not at 5, mg/kg, as well as increased anxiety-like behavior in the open field and avoidant behavior in light-dark box test at the same dose. Additionally, 10mg/kg MDMA decreased 5-HT in the dorsal raphe, increased 5-HT and 5-HIAA in the amygdala, and did not alter levels in the hippocampus. Overall, we show that repeated high (10mg/kg), but not low (5mg/kg), dose MDMA during late adolescence in rats increases anxiety-like and avoidant behaviors, accompanied by region-specific alterations in 5-HT levels during abstinence. These results suggest that MDMA causes a region-specific dysregulation of the serotonin system during adolescence that may contribute to maladaptive behavior.

Sex-dependent psychoneuroendocrine effects of THC and MDMA in an animal model of adolescent drug consumption

Ecstasy is a drug that is usually consumed by young people at the weekends and frequently, in combination with cannabis. In the present study we have investigated the long-term effects of administering increasing doses of delta-9-tetrahydrocannabinol [THC; 2.5, 5, 10 mg/kg; i.p.] from postnatal day (pnd) 28 to 45, alone and/or in conjunction with 3,4-methylenedioxymethamphetamine [MDMA; two daily doses of 10 mg/kg every 5 days; s.c.] from pnd 30 to 45, in both male and female Wistar rats. When tested one day after the end of the pharmacological treatment (pnd 46), MDMA administration induced a reduction in directed exploration in the holeboard test and an increase in open-arm exploration in an elevated plus maze. In the long-term, cognitive functions in the novel object test were seen to be disrupted by THC administration to female but not male rats. In the prepulse inhibition test, MDMA-treated animals showed a decrease in prepulse inhibition at the most intense prepulse studied (80 dB), whereas in combination with THC it induced a similar decrease at 75 dB. THC decreased hippocampal Arc expression in both sexes, while in the frontal cortex this reduction was only evident in females. MDMA induced a reduction in ERK1/2 immunoreactivity in the frontal cortex of male but not female animals, and THC decreased prepro-orexin mRNA levels in the hypothalamus of males, although this effect was prevented when the animals also received MDMA. The results presented indicate that adolescent exposure to THC and/or MDMA induces long-term, sex-dependent psychophysiological alterations and they reveal functional interactions between the two drugs.

Effects of a short-course MDMA binge on dopamine transporter binding and on levels of dopamine and its metabolites in adult male rats

Although the recreational drug 3,4-methylenedioxymethamphetamine (MDMA) is often described as a selective serotonergic neurotoxin, some research has challenged this view. The objective of this study was to determine the influence of MDMA on subsequent levels of two different markers of dopaminergic function, the dopamine transporter (DAT) as well as dopamine and its major metabolites. In experiment I, adult male Sprague-Dawley rats were administered either a low or moderate dose MDMA binge (2.5 or 5.0mg/kg×4 with an inter-dose interval of 1h) or saline, and were killed 1 week later. The moderate dose dramatically reduced [(3)H]WIN 35,428 binding to striatal DAT by 73.7% (P≤0.001). In experiment II, animals were binged with a higher dose of MDMA (10mg/kg×4) to determine the drug's effects on concentrations of serotonin (5-HT), dopamine, and their respective major metabolites 5-hydroxyindoleacetic acid (5-HIAA), dihydroxyphenylacetic acid (DOPAC), and homovanillic acid (HVA) in the striatum and frontal cortex 1 week later. As expected, MDMA significantly reduced 5-HT and 5-HIAA (≥50%) in these structures, while only a marginal decrease in dopamine was noted in the striatum. In contrast, levels of DOPAC (34.3%, P<0.01) and HVA (33.5%, P<0.001) were reduced by MDMA treatment, suggesting a decrease in dopamine turnover. Overall, these findings indicate that while serotonergic markers are particularly vulnerable to MDMA-induced depletion, significant dopaminergic deficits may also occur under some conditions. Importantly, DAT expression may be more vulnerable to perturbation by MDMA than dopamine itself.

Increased anxiety-related behavior in male and female adult rats following early and late adolescent exposure to 3,4-methylenedioxymethamphetamine (MDMA)

Subsequent behavioral effects in adulthood of daily exposure to MDMA during early or late adolescence were assessed in both male and female rats. From either postnatal day (PND) 35 (early adolescence) or PND45 (late adolescence), PVG/c rats of each sex were exposed via intraperitoneal injections to saline or 10mg/kg MDMA for 10 consecutive days. They were regularly weighed during treatment and again on PND90. At this age, their anxiety-related behavior was determined from frequencies of ambulation, rearing, grooming, defecation and occupancy of the center and corners of an open field, as well as entries into and time spent in the light compartment of a light-dark box. Spatial and working memories were assessed by preferences for a novel Y-maze arm, and by recognition of a novel object. MDMA-exposed rats gained less weight during treatment than saline controls but were heavier on PND90 depending on their sex or age when treated. As shown by decreased open-field ambulation (for males only) and increased defecation plus fewer entries into the light compartment of the light-dark box and entries into both arms of a Y maze, MDMA exposure increased adult anxiety-related behavior particularly for rats treated during late adolescence. There was no evidence of any effects on either spatial or working memory.

Adolescent pre-exposure to ethanol and 3,4-methylenedioxymethylamphetamine (MDMA) increases conditioned rewarding effects of MDMA and drug-induced reinstatement

Many adolescents often take ethanol (EtOH) in combination with 3,4-methylenedioxymethylamphetamine (MDMA). In the present work, we used a mouse model to study the effect of repeated pre-exposure during adolescence to EtOH (2 g/kg), MDMA (10 or 20 mg/kg) or EtOH + MDMA on the rewarding and reinstating effects of MDMA in the conditioned place preference (CPP) paradigm. Pre-exposure to EtOH, MDMA or both increased the rewarding effects of a low dose of MDMA (1.25 mg/kg). These pre-treatments did not affect the acquisition of the CPP induced by 5 mg/kg of MDMA. However, the CPP was more persistent in mice pre-exposed to both doses of MDMA or to EtOH + MDMA20. After extinction of the CPP induced by 5 mg/kg of MDMA, reinstatement was observed in all groups with a priming dose of 2.5 mg/kg of MDMA, in the groups pre-exposed to EtOH or MDMA alone with a priming dose of 1.25 mg/kg, and in the groups pre-treated with MDMA alone with a priming dose of 0.625 mg/kg. Pre-treatment during adolescence with MDMA or EtOH induced long-term changes in the level of biogenic amines [dihydroxyphenyl acetic acid, homovanillic acid, dopamine turnover, serotonin (5-hydroxytryptamine, 5-HT) and 5-hydroxyindole acetic acid (5-HIAA) in the striatum, and 5-HT and 5-HIAA in the cortex] after the first reinstatement test, although these effects depended on the dose used during conditioning. These results suggest that exposure to EtOH and MDMA during adolescence reinforces the addictive properties of MDMA.

Neurobehavioral outcomes of infants exposed to MDMA (Ecstasy) and other recreational drugs during pregnancy

3,4-methylenedioxymethamphetamine (MDMA) or "Ecstasy" is one of the most widely used illicit recreational drugs among young adults. MDMA is an indirect monoaminergic agonist and reuptake inhibitor that primarily affects the serotonin system. Preclinical studies in animals have found prenatal exposure related to neonatal tremors and long-term learning and memory impairments. To date, there are no prospective studies of the sequelae of prenatal exposure to MDMA in humans, despite concerns about its potential for harmful effects to the fetus. The present study is the first to prospectively identify MDMA-using women during pregnancy and to document patterns and correlates of use with neonatal and early infancy outcomes of offspring. All mothers and infants were prospectively recruited through the Case Western Reserve University (CWRU) and University of East London (UEL) Drugs and Infancy Study (DAISY) that focused on recreational drug use in pregnant women. Women were interviewed about substance use prior to and during pregnancy and infants were seen at 1 and 4 months using standardized, normative assessments of neonatal behavior, and cognitive and motor development, including the NICU Network Neurobehavioral Scale (NNNS), the Bayley Mental and Motor Development Scales (MDI, PDI), and the Alberta Infant Motor Scales (AIMS). The sample was primarily middle class with some university education and in stable partner relationships. The majority of women recruited had taken a number of illicit drugs prior to or during pregnancy. Group differences between those polydrug using women who had specifically used MDMA during pregnancy (n=28) and those who had not (n=68) were assessed using chi-square and t-tests. MDMA and other drug effects were assessed through multiple regression analyses controlling for confounding variables. Women who used MDMA during pregnancy had fewer prior births and more negative sequelae associated with their drug use, including more health, work, and social problems. MDMA exposed infants differed in sex ratio (more male births) and had poorer motor quality and lower milestone attainment at 4 months, with a dose-response relationship to amount of MDMA exposure. These findings suggest risk to the developing infant related to MDMA exposure and warrant continued follow-up to determine whether early motor delays persist or resolve.

During pregnancy, recreational drug-using women stop taking ecstasy (3,4-methylenedioxy-N-methylamphetamine) and reduce alcohol consumption, but continue to smoke tobacco and cannabis: initial findings from the Development and Infancy Study

While recreational drug use in UK women is prevalent, to date there is little prospective data on patterns of drug use in recreational drug-using women immediately before and during pregnancy. A total of 121 participants from a wide range of backgrounds were recruited to take part in the longitudinal Development and Infancy Study (DAISY) study of prenatal drug use and outcomes. Eighty-six of the women were interviewed prospectively while pregnant and/or soon after their infant was born. Participants reported on use immediately before and during pregnancy and on use over their lifetime. Levels of lifetime drug use of the women recruited were high, with women reporting having used at least four different illegal drugs over their lifetime. Most users of cocaine, 3,4-methylenedioxy-N-methylamphetamine (MDMA) and other stimulants stopped using these by the second trimester and levels of use were low. However, in pregnancy, 64% of the sample continued to use alcohol, 46% tobacco and 48% cannabis. While the level of alcohol use reduced substantially, average tobacco and cannabis levels tended to be sustained at pre-pregnancy levels even into the third trimester (50 cigarettes and/or 11 joints per week). In sum, while the use of 'party drugs' and alcohol seems to reduce, levels of tobacco and cannabis use are likely to be sustained throughout pregnancy. The data provide polydrug profiles that can form the basis for the development of more realistic animal models.

Repeated intermittent methylenedioxymethamphetamine exposure protects against the behavioral and neurotoxic, but not hyperthermic, effects of an MDMA binge in adult rats

We have recently shown that chronic intermittent exposure of adolescent rats to 3,4-methylenedioxymethamphetamine (MDMA or Ecstasy) completely blocks the reduction in serotonin transporter (SERT) binding and the hypoactivity seen following a subsequent MDMA binge treatment. The present study determined whether a similar neuroprotective effect also occurs in rats given the same intermittent MDMA exposure in adulthood. Adult male Sprague-Dawley rats were given either MDMA (10 mg/kg x 2) or saline, every fifth day, from postnatal day (PD) 60 to PD 85. The MDMA-induced latency until seminal plug production was reduced over the course of intermittent treatments. After a 1-week wash-out period, animals received either a low- or high-dose MDMA binge (2.5 or 5.0 mg/kg x 4). Core body temperature was measured during and after the binge to determine the effects of MDMA pretreatment on MDMA-induced hyperthermia. Spontaneous motor activity was determined the next day, and cortical and hippocampal samples were collected at 1 week postbinge to measure serotonin (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) concentrations as well as [3H]citalopram binding to SERT. Hyperthermia occurred more rapidly and seminal discharge was more common in the MDMA-pretreated group compared to the MDMA-naïve group in animals given the low-dose binge. MDMA preexposure protected animals from the reductions in cortical 5-HT levels and SERT binding produced by the high-dose binge and blocked the postbinge hypoactivity. These findings indicate that chronic, intermittent MDMA exposure in adulthood induces neuroprotective effects similar to those seen with adolescent treatment. However, there was also evidence for drug-induced sensitization in adults that was not observed in adolescents. Thus, altered drug sensitivity in chronic Ecstasy users may depend not only on the frequency and pattern of use but also on the age of the user.

Substance use in adolescence and psychosis: clarifying the relationship

Adolescence is a time of exploration of the self, and this exploration may involve the use of alcohol and drugs. Sadly, for some, adolescence also marks the first signs of a psychosis. The temporal proximity between the onset of substance use and of psychosis has been the cause of much debate. Here we review the association of alcohol, cannabis, stimulants, and other drugs with psychosis, and we conclude that the use of cannabis and the amphetamines significantly contributes to the risk of psychosis.

Involvement of mitochondrial/lysosomal toxic cross-talk in ecstasy induced liver toxicity under hyperthermic condition

The initial objectives of this study were to evaluate the extent of 3, 4-methylenedioxymethamphetamine (MDMA) induced loss of cell viability (cytotoxicity), induction of reactive oxygen species formation and damage to sub-cellular organelles (e.g. mitochondria/lysosomes) in freshly isolated rat hepatocytes under normothermic conditions (37 degrees C) and to compare the results with the effects obtained under hyperthermic conditions (41 degrees C). MDMA induced cytotoxicity, reactive oxygen species formation, mitochondrial membrane potential decline and lysosomal membrane leakiness in isolated rat hepatocytes at 37 degrees C. A rise in incubation temperature from 37 degrees C to 41 degrees C had an additive/synergic effect on the oxidative stress markers. We observed variations in mitochondrial membrane potential and lysosomal membrane stability that are significantly (P<0.05) higher than those under normothermic conditions. Antioxidants, reactive oxygen species scavengers, lysosomal inactivators, mitochondrial permeability transition (MPT) pore sealing agents, NADPH P450 reductase inhibitor, and inhibitors of reduced CYP2E1 and CYP2D6 prevented all MDMA induced hepatocyte oxidative stress cytotoxicity markers. It is therefore suggested that metabolic reductive activation of MDMA by reduced cytochrome P450s and glutathione could lead to generation of some biological reactive intermediates which could activate reactive oxygen species generation and cause mitochondrial and lysosomal oxidative stress membrane damages. We finally concluded that hyperthermia could potentiate MDMA induced liver toxicity probably through a mitochondrial/lysosomal toxic cross-talk in freshly isolated rat hepatocytes.

MDMA (ecstasy) delays pubertal development and alters sperm quality after developmental exposure in the rat

3,4-Methylenedioxymethamphetamine, MDMA or "ecstasy" is consumed mainly by young population at childbearing age. Therefore, there may be a risk of exposure of some pregnant women. The effects of the developmental exposure to MDMA on the sexual development and long-term sexual behaviour/fertility were assessed in Sprague-Dawley rats. MDMA was administered subcutaneously at 0 (control), 0.5, 5 and 10 mg/kg to female rats once a day, three consecutive days a week during 10 weeks, including gestation and lactation. The male offspring was evaluated for sexual maturation and mated with untreated sexually receptive females to evaluate the mating and pregnancy rates. Hormonal, haematological, biochemical, histological, genotoxicological and testicular and sperm parameters were also evaluated. A significant higher incidence of DNA damage in sperm and interstitial oedema in testes was found. There was also a significant and dose-related decrease in sperm count and a significant decrease in sperm motility at all doses. A significant delay in preputial separation onset in all treated groups was observed. This study reports by the first time an alteration of spermatogenesis after in utero and lactation MDMA exposure in the rat.

Atypical development of behavioural sensitization to 3,4-methylenedioxymethamphetamine (MDMA, 'Ecstasy') in adolescent rats and its expression in adulthood: role of the MDMA chirality

Despite the great popularity of 3,4-methylenedioxymethamphetamine (MDMA, Ecstasy) as a drug of abuse, not much is known about the detailed mechanisms of the acute and subchronic effects of the drug. There is especially a lack of information about the distinct behavioural effects of its optical isomers (enantiomers) R- and S-MDMA compared with the racemic RS-MDMA. For this purpose, adolescent rats were repetitively treated during two treatment stages (stage 1: days 1-10; stage 2: days 15, 17, 19) with RS-MDMA (5 or 10 mg/kg) or each of the respective enantiomers (5 mg/kg). The repeated treatment started on postnatal day (PND) 32 and locomotor activity was measured on each day by means of a photobeam-equipped activity box system. RS-MDMA or S-MDMA administration led acutely to massive hyperlocomotion and subchronically, to the development of behavioural sensitization after a short habituation period. R-MDMA was free of hyperactivating effects and even decreased locomotor behaviour upon repeated treatment. Nevertheless, co-administration of R-MDMA increased the hyperactivity of S-MDMA and made the S-MDMA induced behavioural sensitization state-dependent. The animals pre-treated with R-MDMA showed a sensitized response in adulthood when tested with RS-MDMA. Our results indicated that even in the absence of substantial neurotoxicity, both MDMA enantiomers can lead to long-term changes in brain circuitry and concomitant behavioural changes when repeatedly administered in adolescence. The sensitization development was most pronounced in the animals treated with S- and RS-MDMA; the animals with R-MDMA did not develop sensitization under repeated treatment but expressed a sensitized response when challenged with RS-MDMA.

Drugs, biogenic amine targets and the developing brain

Defects in the development of the brain have a profound impact on mature brain functions and underlying psychopathology. Classical neurotransmitters and neuromodulators, such as dopamine, serotonin, norepinephrine, acetylcholine, glutamate and GABA, have pleiotropic effects during brain development. In other words, these molecules produce multiple diverse effects to serve as regulators of distinct cellular functions at different times in neurodevelopment. These systems are impacted upon by abuse of a variety of illicit drugs, neurotherapeutics and environmental contaminants. In this review, we describe the impact of drugs and chemicals on brain formation and function in animal models and in human populations, highlighting sensitive periods and effects that may not emerge until later in life.

Transcriptomic configuration of mouse brain induced by adolescent exposure to 3,4-methylenedioxymethamphetamine

The amphetamine derivative (+/-)-3,4-methylenedioxymethamphetamine (MDMA or ecstasy) is a synthetic amphetamine analogue used recreationally to obtain an enhanced affiliative emotional response. MDMA is a potent monoaminergic neurotoxin with the potential to damage brain serotonin and/or dopamine neurons. As the majority of MDMA users are young adults, the risk that users may expose the fetus to MDMA is a concern. However, the majority of studies on MDMA have investigated the effects on adult animals. Here, we investigated whether long-term exposure to MDMA, especially in adolescence, could induce comprehensive transcriptional changes in mouse brain. Transcriptomic analysis of mouse brain regions demonstrated significant gene expression changes in the cerebral cortex. Supervised analysis identified 1028 genes that were chronically dysregulated by long-term exposure to MDMA in adolescent mice. Functional categories most represented by this MDMA characteristic signature are intracellular molecular signaling pathways of neurotoxicity, such as, the MAPK signaling pathway, the Wnt signaling pathway, neuroactive ligand-receptor interaction, long-term potentiation, and the long-term depression signaling pathway. Although these resultant large-scale molecular changes remain to be studied associated with functional brain damage caused by MDMA, our observations delineate the possible neurotoxic effects of MDMA on brain function, and have therapeutic implications concerning neuro-pathological conditions associated with MDMA abuse.

Repeated adolescent MDMA ("Ecstasy") exposure in rats increases behavioral and neuroendocrine responses to a 5-HT2A/2C agonist

MDMA (3,4-methylenedioxymethamphetamine) is a popular recreational drug among adolescents. The present study aimed to determine the effects of repeated intermittent administration of 10 mg/kg MDMA during adolescence on behavioral (Experiment 1) and neuroendocrine (Experiment 2) responses of rats to the 5-HT(2A/2C) agonist 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI) and on [(3)H]ketanserin binding to 5-HT(2A) receptors. In the first experiment, MDMA pretreatment increased the frequency of head twitches and back muscle contractions, but not wet-dog shakes, to a high-dose DOI challenge. In the second experiment, both the prolactin and corticosterone responses to DOI were potentiated in MDMA-pretreated animals. No changes were found in 5-HT(2A) receptor binding in the hypothalamus or other forebrain areas that were examined. These results indicate that intermittent adolescent MDMA exposure enhances sensitivity of 5-HT(2A/2C) receptors in the CNS, possibly through changes in downstream signaling mechanisms.

Developmental effects of 3,4-methylenedioxymethamphetamine: a review

+/-3,4-Methylenedioxymethamphetamine (MDMA) is a chemical derivative of amphetamine that has become a popular drug of abuse and has been shown to deplete serotonin in the brains of users and animals exposed to it. To date, most studies have investigated the effects of MDMA on adult animals. With a majority of users of MDMA being young adults, the chances of the users becoming pregnant and exposing the fetuses to MDMA are also a concern. Evidence to date has shown that developmental exposure to MDMA results in learning and memory impairments in the Morris water maze, a task known to be sensitive to hippocampal disruption, when the animals are tested as adults. Developmental MDMA exposure leads to hypoactivity in the offspring as adults but does not affect outcome on tests of anxiety. MDMA administration decreases pup weight, increases corticosterone and brain-derived neurotrophic factor levels during treatment while decreasing brain levels of serotonin; a decrease that initially dissipates and then reappears in adulthood. Neonatal MDMA exposure increases the sensitivity of the serotonin 1A receptor, a possible mechanism underlying the learning and memory deficits seen. Taken together, the evidence shows that MDMA exposure has adverse effects on the developing brain and behavior. The animal and human data on developmental MDMA exposure are reviewed and their public health implications discussed.

Extensive neuroadaptive changes in cortical gene-transcript expressions of the glutamate system in response to repeated intermittent MDMA administration in adolescent rats

BACKGROUND

Many studies have focused on the implication of the serotonin and dopamine systems in neuroadaptive responses to the recreational drug 3,4-methylenedioxy-metamphetamine (MDMA). Less attention has been given to the major excitatory neurotransmitter glutamate known to be implicated in schizophrenia and drug addiction. The aim of the present study was to investigate the effect of repeated intermittent MDMA administration upon gene-transcript expression of the glutamate transporters (EAAT1, EAAT2-1, EAAT2-2), the glutamate receptor subunits of AMPA (GluR1, GluR2, GluR3), the glutamate receptor subunits of NMDA (NR1, NR2A and NR2B), as well as metabotropic glutamate receptors (mGluR1, mGluR2, mGluR3, mGluR5) in six different brain regions. Adolescent male Sprague Dawley rats received MDMA at the doses of 3 x 1 and 3 x 5 mg/kg/day, or 3x vehicle 3 hours apart, every 7th day for 4 weeks. The gene-transcript levels were assessed using real-time PCR validated with a range of housekeeping genes.

RESULTS

The findings showed pronounced enhancements in gene-transcript expression of GluR2, mGluR1, mGluR5, NR1, NR2A, NR2B, EAAT1, and EAAT2-2 in the cortex at bregma +1.6. In the caudate putamen, mRNA levels of GluR3, NR2A, and NR2B receptor subunits were significantly increased. In contrast, the gene-transcript expression of GluR1 was reduced in the hippocampus. In the hypothalamus, there was a significant increase of GluR1, GluR3, mGluR1, and mGluR3 gene-transcript expressions.

CONCLUSION

Repeated intermittent MDMA administration induces neuroadaptive changes in gene-transcript expressions of glutamatergic NMDA and AMPA receptor subunits, metabotropic receptors and transporters in regions of the brain regulating reward-related associative learning, cognition, and memory and neuro-endocrine functions.