MDMA ('ecstasy') enhances basal acetylcholine release in brain slices of the rat striatum

Contribution of analog signaling to neurotransmitter interactions and behavior: Role of transporter-mediated nonquantal dopamine release

Neuronal networks cause changes in behaviorally important information processing through the vesicular release of neurotransmitters governed by the rate and timing of action potentials (APs). Herein, we provide evidence that dopamine (DA), nonquantally released from the cytoplasm, may exert similar effects in vivo. In mouse slice preparations, (+/-)-3,4-methylenedioxy-methamphetamine (MDMA, or ecstasy) and β-phenylethylamine (β-PEA)-induced DA release in the striatum and nucleus accumbens (NAc), two regions of the brain involved in reward-driven and social behavior and inhibited the axonal stimulation-induced release of tritiated acetylcholine ([3 H]ACh) in the striatum. The DA transporter (DAT) inhibitor (GBR-12909) prevented MDMA and β-PEA from causing DA release. GBR-12909 could also restore some of the stimulated acetylcholine release reduced by MDMA or β-PEA in the striatum confirming the fundamental role of DAT. In addition, hypothermia could prevent the β-PEA-induced release in the striatum and in the NAc. Sulpiride, a D2 receptor antagonist, also prevented the inhibitory effects of MDMA or β-PEA on stimulated ACh release, suggesting they act indirectly via binding of DA. Reflecting the neurochemical interactions in brain slices at higher system level, MDMA altered the social behavior of rats by preferentially enhancing passive social behavior. Similar to the in vitro effects, GBR-12909 treatment reversed specific elements of the MDMA-induced changes in behavior, such as passive social behavior, while left others including social play unchanged. The changes in behavior by the high level of extracellular DA-- a significant amount originating from cytoplasmic release--suggest that in addition to digital computation through synapses, the brain also uses analog communication, such as DA signaling, to mediate some elements of complex behaviors, but in a much longer time scale.

The effects of MDMA on socio-emotional processing: Does MDMA differ from other stimulants?

±3,4-Methylenedioxymethamphetamine (MDMA) is a popular recreational drug that enhances sociability and feelings of closeness with others. These "prosocial" effects appear to motivate the recreational use of MDMA and may also form the basis of its potential as an adjunct to psychotherapy. However, the extent to which MDMA differs from prototypic stimulant drugs, such as dextroamphetamine, methamphetamine, and methylphenidate, in either its behavioral effects or mechanisms of action, is not fully known. The purpose of this review is to evaluate human laboratory findings of the social effects of MDMA compared to other stimulants, ranging from simple subjective ratings of sociability to more complex elements of social processing and behavior. We also review the neurochemical mechanisms by which these drugs may impact sociability. Together, the findings reviewed here lay the groundwork for better understanding the socially enhancing effects of MDMA that distinguish it from other stimulant drugs, especially as these effects relate to the reinforcing and potentially therapeutic effects of the drug.

Evaluation of acetylcholinesterase in an animal model of mania induced by D-amphetamine

The present study aims to investigate the effects of mood stabilizers, lithium (Li) and valproate (VPA), on acetylcholinesterase (AChE) activity in the brains of rats subjected to an animal model of mania induced by D-amphetamine (D-AMPH). In the reversal treatment, Wistar rats were first given D-AMPH or saline (Sal) for 14 days. Between days 8 and 14, the rats were treated with Li, VPA, or Sal. In the prevention treatment, rats were pretreated with Li, VPA, or Sal. AChE activity was measured in the brain structures (prefrontal cortex, hippocampus, and striatum). Li, alone in reversion and prevention treatments, increased AChE activity in the brains of rats. VPA, alone in prevention treatment, increased AChE activity in all brain regions evaluated; in the reversion, only in the prefrontal. However, D-AMPH decreased activity of AChE in the striatum of rats in both the reversion and prevention treatments. VPA was able to revert and prevent this AChE activity alteration in the rat striatum. Our findings further support the notion that the mechanisms of mood stabilizers also involve changes in AChE activity, thus reinforcing the need for more studies to better characterize the role of acetylcholine in bipolar disorder.

3,4-methylenedioxyamphetamine upregulates p75 neurotrophin receptor protein expression in the rat brain

The p75 neurotrophin receptor, which is a member of the tumor necrosis factor receptor superfamily, facilitates apoptosis during development and following central nervous system injury. Previous studies have shown that programmed cell death is likely involved in the neurotoxic effects of 3, 4-methylenedioxy-N-methylamphetamine (MDMA), because MDMA induces apoptosis of immortalized neurons through regulation of proteins belonging to the Bcl-2 family. In the present study, intraperitoneal injection of different doses of MDMA (20, 50, and 100 mg/kg) induced significant behavioral changes, such as increased excitability, increased activity, and irritability in rats. Moreover, changes exhibited dose-dependent adaptation. Following MDMA injection in rat brain tissue, the number of apoptotic cells dose-dependently increased and p75 neurotrophin receptor expression significantly increased in the prefrontal cortex, cerebellum, and hippocampus. These findings confirmed that MDMA induced neuronal apoptosis, and results suggested that this effect was related by upregulated protein expression of the p75 neurotrophin receptor.

A role for adenosine A(1) receptor blockade in the ability of caffeine to promote MDMA "Ecstasy"-induced striatal dopamine release

Co-administration of caffeine profoundly enhances the acute toxicity of 3,4 methylenedioxymethamphetamine (MDMA) in rats. The aim of this study was to determine the ability of caffeine to impact upon MDMA-induced dopamine release in superfused brain tissue slices as a contributing factor to this drug interaction. MDMA (100 and 300μM) induced a dose-dependent increase in dopamine release in striatal and hypothalamic tissue slices preloaded with [(3)H] dopamine (1μM). Caffeine (100μM) also induced dopamine release in the striatum and hypothalamus, albeit to a much lesser extent than MDMA. When striatal tissue slices were superfused with MDMA (30μM) in combination with caffeine (30μM), caffeine enhanced MDMA-induced dopamine release, provoking a greater response than that obtained following either caffeine or MDMA applications alone. The synergistic effects in the striatum were not observed in hypothalamic slices. As adenosine A(1) receptors are, one of the main pharmacological targets of caffeine, which are known to play an important role in the regulation of dopamine release, their role in the modulation of MDMA-induced dopamine release was investigated. 1μM 8-cyclopentyl-1,3-dipropylxanthine (DPCPX), a specific A(1) antagonist, like caffeine, enhanced MDMA-induced dopamine release from striatal slices while 1μM 2,chloro-N(6)-cyclopentyladenosine (CCPA), a selective adenosine A(1) receptor agonist, attenuated this. Treatment with either SCH 58261, a selective A(2A) receptor antagonist, or rolipram, a selective PDE-4 inhibitor, failed to reproduce a caffeine-like effect on MDMA-induced dopamine release. These results suggest that caffeine regulates MDMA-induced dopamine release in striatal tissue slices, via inhibition of adenosine A(1) receptors.

Role of serotonin and/or norepinephrine in the MDMA-induced increase in extracellular glucose and glycogenolysis in the rat brain

The acute administration of MDMA has been shown to promote glycogenolysis and increase the extracellular concentration of glucose in the striatum. In the present study the role of serotonergic and/or noradrenergic mechanisms in the MDMA-induced increase in extracellular glucose and glycogenolysis was assessed. The relationship of these responses to the hyperthermia produced by MDMA also was examined. The administration of MDMA (10mg/kg, i.p.) resulted in a significant and sustained increase of 65-100% in the extracellular concentration of glucose in the striatum, as well as in the prefrontal cortex and hippocampus, and a 35% decrease in brain glycogen content. Peripheral blood glucose was modestly increased by 32% after MDMA treatment. Treatment of rats with fluoxetine (10mg/kg, i.p.) significantly attenuated the MDMA-induced increase in extracellular glucose in the striatum but had no effect on MDMA-induced glycogenolysis or hyperthermia. Treatment with prazosin (1mg/kg, i.p.) did not alter the glucose or glycogen responses to MDMA but completely suppressed MDMA-induced hyperthermia. Finally, propranolol (3mg/kg, i.p.) significantly attenuated the MDMA-induced increase in extracellular glucose and glycogenolysis but did not alter MDMA-induced hyperthermia. The present results suggest that MDMA increases extracellular glucose in multiple brain regions, and that this response involves both serotonergic and noradrenergic mechanisms. Furthermore, beta-adrenergic and alpha-adrenergic receptors appear to contribute to MDMA-induced glycogenolysis and hyperthermia, respectively. Finally, hyperthermia, glycogenolysis and elevated extracellular glucose appear to be independent, unrelated responses to acute MDMA administration.

Effects of ethanol and 3,4-methylenedioxymethamphetamine (MDMA) alone or in combination on spontaneous and evoked overflow of dopamine, serotonin and acetylcholine in striatal slices of the rat brain

Ethanol (EtOH) potentiates the locomotor effects of 3,4-methylenedioxymetamphetamine (MDMA) in rats. This potentiation might involve pharmacokinetic and/or pharmacodynamic mechanisms. We explored whether the latter could be local. Using a slice superfusion approach, we assessed the effects of MDMA (0.3, 3microm) and/or EtOH (2mm) on the spontaneous outflow and electrically evoked release of serotonin (5-HT), dopamine (DA) and acetylcholine (ACh) in the striatum, and for comparison, on 5-HT release in hippocampal and neocortical tissue. MDMA and less effectively EtOH, augmented the outflow of 5-HT in all regions. The electrically evoked 5-HT release was increased by MDMA at 3microm in striatal slices only. With nomifensine throughout, EtOH significantly potentiated the 0.3microm MDMA-induced outflow of 5-HT, but only in striatal slices. EtOH or MDMA also enhanced the spontaneous outflow of DA, but MDMA reduced the electrically evoked DA release. With fluvoxamine throughout superfusion, EtOH potentiated the effect of MDMA on the spontaneous outflow of DA. Finally, 3microm MDMA diminished the electrically evoked release of ACh, an effect involving several receptors (D2, 5-HT2, NMDA, nicotinic, NK1), with some interactions with EtOH. Among other results, we show for the first time a local synergistic interaction of EtOH and MDMA on the spontaneous outflow of striatal DA and 5-HT, which could be relevant to the EtOH-induced potentiation of hyperlocomotion in MDMA-treated rats. These data do not preclude the contribution of other pharmacodynamic and/or pharmacokinetic mechanisms in vivo but support the hypothesis that EtOH may affect the abuse liability of MDMA.

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.

The recreational drug ecstasy disrupts the hypothalamic-pituitary-gonadal reproductive axis in adult male rats

Reproductive function involves an interaction of three regulatory levels: hypothalamus, pituitary, and gonad. The primary drive upon this system comes from hypothalamic gonadotropin-releasing hormone (GnRH) neurosecretory cells, which receive afferent inputs from other neurotransmitter systems in the central nervous system to result in the proper coordination of reproduction and the environment. Here, we hypothesized that the recreational drug (+/-)-3,4-methylenedioxymethamphetamine (MDMA; 'ecstasy'), which acts through several of the neurotransmitter systems that affect GnRH neurons, suppresses the hypothalamic-pituitary-gonadal reproductive axis of male rats. Adult male Sprague-Dawley rats self-administered saline or MDMA either once (acute) or for 20 days (chronic) and were euthanized 7 days following the last administration. We quantified hypothalamic GnRH mRNA, serum luteinizing hormone concentrations, and serum testosterone levels as indices of hypothalamic, pituitary, and gonadal functions, respectively. The results indicate that the hypothalamic and gonadal levels of the hypothalamic-pituitary-gonadal axis are significantly altered by MDMA, with GnRH mRNA and serum testosterone levels suppressed in rats administered MDMA compared to saline. Furthermore, our finding that hypothalamic GnRH mRNA levels are suppressed in the context of low testosterone concentrations suggests that the central GnRH neurosecretory system may be a primary target of inhibitory regulation by MDMA usage.

Actions of 3,4-methylenedioxymethamphetamine (MDMA) on cerebral dopaminergic, serotonergic and cholinergic neurons

3,4-Methylenedioxymethamphetamine (MDMA) is an amphetamine derivative and a popular drug of abuse that exhibits mild hallucinogenic and rewarding properties and engenders feelings of connectedness and openness. The unique psychopharmacological profile of this drug of abuse most likely is derived from the property of MDMA to promote the release of dopamine and serotonin (5-HT) in multiple brain regions. The present review highlights primarily data from studies employing in vivo microdialysis that detail the actions of MDMA on the release of these neurotransmitters. Data from in vivo microdialysis experiments indicate that MDMA, like most amphetamine derivatives, increases the release of dopamine in the striatum, n. accumbens and prefrontal cortex. However, the release of dopamine evoked by MDMA in each of these brain regions appears to be modulated by concomitantly released 5-HT and the subsequent activation of 5-HT2A/C or 5-HT2B/C receptors. In addition to its stimulatory effect on the release of monoamines, MDMA also enhances the release of acetylcholine in the striatum, hippocampus and prefrontal cortex, and this cholinergic response appears to be secondary to the activation of histaminergic, dopaminergic and/or serotonergic receptors. Beyond the acute stimulatory effect of MDMA on neurotransmitter release, MDMA also increases the extracellular concentration of energy substrates, e.g., glucose and lactate in the brain. In contrast to the acute stimulatory actions of MDMA on the release of monoamines and acetylcholine, the repeated administration of high doses of MDMA is thought to result in a selective neurotoxicity to 5-HT axon terminals in the rat. Additional studies are reviewed that focus on the alterations in neurotransmitter responses to pharmacological and physiological stimuli that accompany MDMA-induced 5-HT neurotoxicity.

Rewarding effects of 3,4-methylenedioxymethamphetamine ("Ecstasy") in dominant and subordinate OF-1 mice in the place preference conditioning paradigm

We tested the ability of 3,4-methylenedioxymethamphetamine (MDMA) to induce conditioned place preference (CPP) in dominant and subordinate OF-1 mice subjected to cohabitation and repeated sessions of agonistic confrontation, as well as in non-confronted mice. We selected doses of MDMA (2, 6, 10 mg/kg) previously reported to induce CPP in mice and we measured expression of c-Fos evoked by the treatments in non-confronted mice. MDMA induced c-Fos protein in several corticolimbic regions involved in drug-induced reward. Mice were exposed to brief sessions of agonistic confrontation on 5 consecutive days. Determinations of circulating hormones and drug conditioning tests were carried out on completion of the encounters. The results of hormone assays indicated that dominant mice had higher serum concentrations of testosterone, but lower levels of corticosterone, than submissive mice. Post-conditioning tests after drug conditioning (4 injections of MDMA or saline on alternate days) showed that MDMA significantly produced CPP at doses of 2 and 6 mg/kg, but not at 10 mg/kg, an inverted U-shaped pattern of conditioning that was invariable in non-confronted, dominant and subordinate mice. These results demonstrate that the endocrine and behavioural correlates linked to social status and social stress in mice are not paralleled by significant changes in the rewarding efficacy of MDMA in the CPP paradigm under the specific conditions tested.

Effect of a serotonin depleting regimen of 3,4-methylenedioxymethamphetamine (MDMA) on the subsequent stimulation of acetylcholine release in the rat prefrontal cortex

The amphetamine analog 3,4-methylenedioxymethamphetamine (MDMA) is considered to be selectively neurotoxic to serotonergic nerve terminals. Although the long term effects of MDMA on serotonin (5-HT) terminals have been well studied, other potential neurochemical consequences associated with MDMA-induced 5-HT depletion have been less well investigated. In view of the cognitive impairments in human MDMA abusers and the role of acetylcholine (ACh) in learning and memory, it was of interest to determine the influence of a 5-HT depleting regimen of MDMA on subsequent stimulation of ACh release in the prefrontal cortex (PFC). Male rats received vehicle or MDMA (10 mg/kg, i.p. every 2 h for four injections) and underwent in vivo microdialysis 7 days later to assess the subsequent drug- (e.g., MDMA, 5-HT1A agonist) or stress- (e.g., tail pinch, presence of an intruder rat) induced stimulation of ACh release. The increase in the extracellular concentration of ACh in the PFC produced by MDMA (10 mg/kg, i.p.) was significantly less in rats previously exposed to the neurotoxic regimen of MDMA than that in control animals. In contrast, there was no difference in the magnitude of the stimulation of cortical ACh release elicited by the 5-HT1A agonist, 8-hydroxy-2-(di-n-propyl-amino)tetralin (8-OH-DPAT, 0.3mg/kg, s.c.), tail pinch (30 min) or the presence of an intruder rat (40 min) between control animals and animals previously exposed to a neurotoxic regimen of MDMA. These results suggest that although MDMA-induced 5-HT depletion diminishes subsequent MDMA-induced ACh release, there is little impact on cortical ACh release elicited by the stress of pain or the novelty of an environmental intruder.

3,4-Methylenedioxymethamphetamine enhances the release of acetylcholine in the prefrontal cortex and dorsal hippocampus of the rat

RATIONALE

The neurochemical effects produced by acute administration of 3,4-methylenedioxymethamphetamine (MDMA) on the monoaminergic systems in the brain are well documented; however, there has been little consideration of the potential effects of MDMA on other neurotransmitter systems.

OBJECTIVE

The present study was designed to investigate the acute effect of MDMA on cholinergic neurons by measuring acetylcholine (ACh) release in the medial prefrontal cortex (PFC) and dorsal hippocampus, terminal regions of cholinergic projection neurons originating in the basal forebrain.

METHODS

In vivo microdialysis and high-performance liquid chromatography with electrochemical detection (HPLC-ED) were used to assess the effects of MDMA on the extracellular concentration of ACh in the PFC and dorsal hippocampus of the rat.

RESULTS

The systemic administration of MDMA (3-20 mg/kg, i.p.) resulted in an increased extracellular concentration of ACh in the PFC and dorsal hippocampus. Reverse dialysis of MDMA (100 microM) into the PFC and hippocampus also increased ACh release in these brain regions. Treatment with parachlorophenylalanine and alpha-methyl-para-tyrosine, inhibitors of serotonin (5-HT) and dopamine (DA) synthesis, respectively, significantly attenuated the release of ACh stimulated by MDMA in the PFC, but not in the dorsal hippocampus.

CONCLUSIONS

MDMA exerts a stimulatory effect on the release of ACh in the PFC and dorsal hippocampus in vivo, possibly by mechanisms localized within these brain regions. In addition, these results suggest that the MDMA-induced release of ACh in the PFC involves both serotonergic and dopaminergic mechanisms.

Serotonin synthesis inhibition reveals distinct mechanisms of action for MDMA and its enantiomers in the mouse

RATIONALE

Drug challenges in "intact" and p-chlorophenylalanine (p-CPA)-treated animals can be used to distinguish agents that act as direct serotonin (5-HT) agonists from agents that function as 5-HT releasers.

OBJECTIVES

The objective of the study was to investigate the effect of p-CPA treatment on the capacity of racemic 3,4-methylenedioxymethamphetamine (MDMA) and its stereoisomers to induce the head twitch response, hyperthermia, and locomotor stimulation in mice.

METHODS

Pretreatments with either 100 mg/kg p-CPA or equivolume saline were administered for three consecutive days. The following day, mice were either euthanized (to quantify 5-HT tone), tested with various doses of racemic MDMA or one of its enantiomers in the head twitch assay, or challenged with 32 mg/kg racemic MDMA or one of its enantiomers, while temperature and locomotor activity were monitored via radiotelemetry.

RESULTS

p-CPA reduced cortical 5-HT turnover by >70% without altering dopamine turnover. Racemic MDMA did not induce a significant head twitch response in intact or p-CPA-treated mice. S(+)-MDMA and R(-)-MDMA elicited similar head twitch curves in intact mice; p-CPA treatment attenuated this response when induced by S(+)-MDMA but not when elicited by R(-)-MDMA. Neither the hyperthermic nor locomotor-stimulant effects of racemic MDMA were altered by p-CPA treatment. The hyperthermic effects, but not the locomotor-stimulant effects, of S(+)-MDMA were attenuated in mice treated with p-CPA. R(-)-MDMA did not alter core temperature or induce significant locomotor stimulation in intact or p-CPA-treated mice.

CONCLUSIONS

The effects of S(+)-MDMA on core temperature and head twitch behavior are consistent with a mechanism involving 5-HT release, whereas the effects of R(-)-MDMA on head twitch behavior are consistent with a direct agonist mechanism of action. The actions of the racemate on core temperature and locomotor activity likely involve a combination of 5-HT release and direct agonism at 5-HT receptors.

Co-administration of THC and MDMA ('ecstasy') synergistically disrupts memory in rats

3,4-Methylenedioxymethamphetamine (MDMA, 'Ecstasy') and cannabis are two of the most commonly used illicit drugs in the western world, and are often used in combination. Very little research has examined their effect on cognitive function or behavior when combined, The present study used a double Y-maze task to examine the acute effect of MDMA and delta9-tetrahydrocannabinol (THC, the principal psychoactive ingredient of cannabis) on mnemonic function in rats, at a range of doses representative of common human use. Experiment I (low doses) examined the effect of 0.25 mg/kg THC and 1.25 mg/kg MDMA alone and together. At these doses MDMA or THC given alone had no effect on working memory, but the co-administered drugs significantly disrupted working memory. Experiment 2 (medium doses) examined the effect of 0.5 mg/kg THC and 2.5 mg/kg MDMA given alone or together. At these doses THC, but not MDMA, impaired working memory. Although MDMA alone had no effect, it exacerbated the impairment due to THC when the drugs were co-administered. Experiment 3 (high doses) examined the effects of 1 mg/kg THC and 5 mg/kg MDMA alone and together. Both drugs significantly impaired memory when given alone, although the impairment due to MDMA was less than that caused by THC. When co-administered at these doses, the drugs caused a major disruption of behavior and this precluded ascribing a mnemonic cause to poor performance on the double Y-maze task Taken together, these experiments demonstrate a synergistic disruption of working memory by acute co-administration of THC and MDMA.

Effects of MDMA administration on scopolamine-induced disruptions of learning and performance in rats

Functional deficits following short-course high-dose administration of 3,4-methylenedioxymethamphetamine (MDMA) have been difficult to characterize despite evidence indicating that MDMA is neurotoxic in several species. Therefore, the present research used rats trained to respond under a complex behavioral procedure (i.e., a multiple schedule of repeated acquisition and performance of response chains), pharmacological challenge with scopolamine and neurotransmitter assays to examine the effects of MDMA neurotoxicity on learning. Prior to MDMA administration, 0.032-0.32 mg/kg of scopolamine produced dose-dependent rate-decreasing and error-increasing effects in both components of the multiple schedule. Administration of 10 mg/kg of MDMA twice per day for 4 days also produced rate-decreasing and error-increasing effects on these days, but responding returned to baseline levels several days after the final injection. In contrast to the recovery of responding, this regimen of MDMA in untrained rats significantly reduced levels of both serotonin and its major metabolite, 5-hydroxyindoleacetic acid (5-HIAA), for 13-14 days. Furthermore, the rate-decreasing and error-increasing effects of scopolamine were significantly attenuated after MDMA treatment. These results indicate that certain complex operant behaviors rapidly recover from the effects of short-course high-dose MDMA administration, despite the reduced levels of serotonin in the central nervous system (CNS), and that this MDMA-induced loss of serotonin may affect cholinergic transmission.

3,4-Methylenedioxymethamphetamine and naloxone in rat rotational behaviour and open field

It has recently been shown that 3,4-Methylenedioxymethamphetamine (MDMA) has an anti-parkinsonian effect in rodent models of Parkinson's disease. The mechanism of this anti-parkinsonian action is unknown. Opioids have been suggested to play a role in MDMA-induced behaviour. We therefore investigated MDMA and naloxone in the rat rotational behavioural model. Male Sprague-Dawley rats were lesioned unilaterally with 6-hydroxydopamine at the medial forebrain bundle. Administration of R/S-MDMA (5 mg/kg, s.c.) produced ipsilateral rotations. Naloxone (2, 5, 10 mg/kg, s.c.) did not produce rotations on its own but reduced the number of MDMA-induced ipsilateral rotations. This effect was not dose-dependent. In contrast to reports on mice, in unlesioned animals, naloxone (10 mg/kg, s.c.) did not block MDMA (5 mg/kg, s.c.)-induced hyperactivity in an open field in our experiment. It is concluded that endogenous opioids play a role in MDMA's action in the rat rotational behavioural model.

Chronic tolerance to recreational MDMA (3,4-methylenedioxymethamphetamine) or Ecstasy

This review of chronic tolerance to MDMA (3,4-methylenedioxymetamphetamine) covers the empirical data on dosage escalation, reduced subjective efficacy and bingeing in recreational Ecstasy users. Novice users generally take a single Ecstasy tablet, regular users typically take 2-3 tablets, whereas the most experienced users may take 10-25 tablets in a single session. Reduced subjective efficacy following repeated usage is typically described, with many users subjectively reporting the development of tolerance. Intensive self-administration or bingeing is often noted by experienced users. This can comprise 'stacking' on several tablets together, and 'boosting' on successive doses over an extended period. Some experienced users snort Ecstasy powder nasally, whereas a small minority inject MDMA. Chronic tolerance and bingeing are statistically linked to higher rates of drug-related psychobiological problems. In terms of underlying mechanisms, neuroadaptive processes are certainly involved, but there is a paucity of evidence on hepatic and behavioural mechanisms. Further studies specifically designed to investigate chronic tolerance, involving low intermittent dose regimens, are required. Most animal research has involved intensive MDMA dosing regimens designed to engender serotonergic neurotoxicity, and this may comprise another underlying mechanism. If distal serotonin axon terminal loss was also developing in recreational users, it may help to explain why reducing subjective efficacy, dosage escalation and increasing psychobiological problems often develop in parallel. In conclusion, there is extensive evidence for chronic pharmacodynamic tolerance to recreational Ecstasy/MDMA, but the underlying mechanisms are currently unclear. Several traditional processes are probably involved, but one of the possible causes is a novel mechanism largely unique to the ring substituted amphetamine derivatives, namely serotonergic neurotoxicity.

3,4-Methylenedioxymethamphetamine counteracts akinesia enantioselectively in rat rotational behavior and catalepsy

We have shown recently that 3,4-methylenedioxymethamphetamine (MDMA) has symptomatic antiparkinsonian activity in rodent models of Parkinson's disease. In search of its mechanism of action, we further investigated the enantiomers of MDMA in the rotational behavioral model and catalepsy test. Catalepsy testing was done in drug-naive unlesioned animals. The parkinsonian symptoms rigor and akinesia (i.e., catalepsy) were induced by intraperitoneal administration of haloperidol 0.5 mg/kg and measured repeatedly as descent latency from a horizontal bar and a vertical grid. MDMA and both its enantiomers were effective in counteracting haloperidol-induced catalepsy, but if given as racemic, the effects were more pronounced than with the enantiomers. For testing of rotational behavior, male Sprague Dawley rats were lesioned unilaterally with 6-hydroxydopamine (6-OHDA) at the medial forebrain bundle. Administration of S-MDMA (5 mg/kg) produced ipsilateral rotations. R-MDMA was far less effective in inducing ipsilateral rotations in 6-OHDA unilaterally lesioned rats, but when S-MDMA was given additionally rotations immediately increased. Regarding their overall antiparkinsonian effects, the S-enantiomer of MDMA was more effective than its R-congener. R-MDMA was able to increase the actions of S-MDMA.

3,4-Methylenedioxymethamphetamine (MDMA) enhances the release of acetylcholine by 5-HT4 and D1 receptor mechanisms in the rat prefrontal cortex

3,4-Methylenedioxymethamphetamine (MDMA), an amphetamine analog, has been shown recently to increase the release of acetylcholine (ACh) in the prefrontal cortex (PFC). The present study further characterizes the stimulatory effect of MDMA on cortical ACh release and examines the role of serotonin (5-HT) and dopamine (DA) receptors in this response. The extracellular concentration of ACh was increased dose-dependently and similarly by the (+) and (-) enantiomers of MDMA (5 and 20 mg/kg, i.p.). The systemic administration of the 5-HT(4) antagonist SDZ 205,557 (1 mg/kg, i.p.), but not the 5-HT(2A/2B/2C) antagonist LY-53,857 (3 mg/kg, i.p.), significantly decreased cortical ACh release induced by MDMA. The MDMA-induced increase in the extracellular concentration of ACh also was significantly blunted in rats treated with the D(1) receptor antagonist SCH 23390 (0.5 mg/kg, i.p.). The extent to which the coadministration of SDZ 205,557 and SCH 23390 suppressed the MDMA-induced release of ACh in the PFC was no greater than that produced by either antagonist alone. These results suggest that the 5-HT(4) and D(1) receptor subtypes contribute to the mechanism by which MDMA increases ACh release in the PFC.

Effets aigus et à long terme de l’ecstasy

Side effects in the short term Recreational use of Ecstasy (3,4-methylenedioxymethamphetamine or MDMA), a synthetic drug, has considerably increased over the last decade. Since its appearance it is associated with the rave culture, but its use has spread to other social settings. The drug produces euphoria and empathy, but can lead to side effects, notably acute, potentially lethal, toxicity (malignant hyperthermia and/or hepatitis). Neurotoxicity in the long-term Moreover, MDMA has been shown to induce long-term deleterious effects and provoke neurotoxic affecting the serotoninergic system. However, the psychopathological consequences of such neurotoxicity are still controversial, particularly since many ecstasy consumers are multi-drug users. A complex pharmacological profile The mechanism of action of MDMA involves various neurobiological systems (serotonin, dopamine, noradrenalin), that may all interact.

Nantenine: an antagonist of the behavioral and physiological effects of MDMA in mice

RATIONALE

No selective antagonists for the effects of MDMA have yet been identified. The structurally-similar, naturally-occurring plant alkaloid nantenine (9,10-methylenedioxy-1,2 dimethoxyaporphine) may represent such a compound.

OBJECTIVES

To investigate the capacity of nantenine to block and/or reverse MDMA-induced hyperthermia, lethality, locomotor stimulation, and head twitches in mice, and to compare these actions with those of the selective alpha1 antagonist prazosin and the selective 5-HT2A antagonist M100907.

METHODS

Pretreatments of either 10 mg/kg nantenine or 1 mg/kg prazosin were administered 15 min before 32 mg/kg MDMA; core temperature and locomotor stimulation were then monitored via radiotelemetry for at least 3 h. In further hyperthermia studies, 32 mg/kg MDMA was administered first and temperature was allowed to rise for 30 min; 10 mg/kg nantenine, 1 mg/kg prazosin, or 1 mg/kg M100907 was then administered in an attempt to reverse MDMA-induced hyperthermia. In lethality assays, percent lethality was quantified 2 h after MDMA injection in two distinct housing conditions, one or 12 mice per cage, with or without 15 min pretreatments of 10 mg/kg nantenine or 1 mg/kg prazosin. Drug elicited head twitches were quantified for 10 min following administration of either MDMA enantiomer, with and without pretreatments of 1 mg/kg nantenine, 0.1 mg/kg prazosin, or 0.001 mg/kg M100907.

RESULTS

Nantenine blocked and rapidly reversed MDMA-induced hyperthermia, attenuated lethality in both housing conditions, and reduced MDMA-induced locomotor stimulation and head twitches in mice. Prazosin blocked, but did not reverse, MDMA-induced hyperthermia, attenuated lethality (more effectively in singly-housed animals), and reduced MDMA-induced locomotor stimulation and head twitches. M100907 did not reverse MDMA-induced hyperthermia, but effectively blocked drug-elicited head twitches.

CONCLUSIONS

Nantenine functions as an effective antagonist against a wide range of MDMA-induced effects in mice. The antagonist actions of this compound at serotonin and adrenergic receptors may be differentially implicated across endpoints.

The pre-clinical behavioural pharmacology of 3,4-methylenedioxymethamphetamine (MDMA)

3,4-Methylenedioxymethamphetamine (MDMA) is a relatively novel drug of abuse and as such little is currently known of its behavioural pharmacology. This review aims to examine whether MDMA represents a novel class of abused drug. MDMA is known as a selective serotonergic neurotoxin in a variety of animal species but acutely it is a potent releaser and/or reuptake inhibitor of presynaptic serotonin, dopamine, noradrenaline, and acetylcholine. Interaction of these effects contributes to its behavioural pharmacology, in particular its effects on body temperature. Drug discrimination studies indicate that MDMA and related drugs produce unique interoceptive effects which have led to their classification as entactogens. This is supported by results from other behavioural paradigms although there is evidence for dose dependency of MDMA-specific effects. MDMA also produces conditioned place preference but is not a potent reinforcer in self-administration studies. These unique behavioural effects probably underlie its current popularity. MDMA is found in the street drug ecstasy but it may not be appropriate to equate the two as other drugs are routinely found in ecstasy tablets

Effects of (+/-) 3,4-methylene-dioxymethamphetamine (ecstasy) on dopamine system function in humans

Twelve (+/-) 3,4-methylenedioxymethamphetamine (MDMA) users, who did not show other drug dependencies or prolonged alcohol abuse (group A), and 12 control subjects (group B) were included in the study. Prolactin (PRL) and growth hormone (GH) responses to the dopaminergic agonist bromocriptine (BROM) and psychometric measures were evaluated 3 weeks after MDMA discontinuation. PRL decreased both in A and B subjects after BROM suppression, without any significant difference between the two groups. PRL responses to BROM in MDMA users were in the normal range. In contrast, GH responses to BROM stimulation were found significantly reduced in ecstasy users, in comparison with control subjects (P < 0.001; F = 6.26). MDMA users showed higher scores on the Novelty Seeking (NS) scale at the Three dimensional Personality Questionnaire (TPQ), on direct aggressiveness subscale at Buss Durkee Hostility Inventory (BDHI), on subscale D (depression) at Minnesota Multiphasic Personality Inventory (MMPI 2) and on Hamilton Depression Rating Scale (HDRS) than control subjects. PRL areas under the curves (AUCs) showed a significant inverse correlation with NS scores both in A and B subjects. GH AUCs directly correlated with NS scores in healthy subjects, but not in MDMA users. No other psychometric measure correlated with hormonal responses. GH AUCs were inversely correlated with the measures of MDMA exposure (r = -0.48; P < 0.01). Lower GH response to BROM in A subjects (MDMA users) could reflect reduced D2 receptor sensitivity in the hypothalamus, possibly due to increased intrasynaptic dopamine concentration. Although the hypothesis of dopaminergic changes associated with a premorbid condition cannot be completely excluded, the inverse correlation between DA receptors sensitivity and the extent of ecstasy exposure may suggest a direct pharmacological action of MDMA on brain dopamine function in humans.

Acute psychological and neurophysiological effects of MDMA in humans

Since the mid 1990s, MDMA has been increasingly used as a recreational drug called "Ecstasy" by young people in Europe and the United States. However, despite the widespread recreational use of Ecstasy, systematic data on the psychological and neurobiological effects of MDMA have been scant. To further our understanding of the mechanism of action of MDMA, the authors conducted several studies in healthy human volunteers in an effort to characterize the psychological, cognitive and behavioral effects of MDMA in healthy human volunteers. Prospective placebo-controlled within-subject study designs and standardized psychometric ratings and neuropsychological tests were used to assess the acute, short-term and prolonged effects of the drug. To elucidate the role of various neurotransmitter and receptor systems involved in the action of MDMA in humans, the blocking effects of specific receptor antagonists on MDMA-induced psychological alterations and measures of sensory information processing were studied. To identify the functional neuroanatomy involved in the action of MDMA, Positron Emission Tomography (PET) was used. The present contribution summarizes the acute effect of MDMA on psychological and cognitive measures, information processing, and regional brain activity in healthy human volunteers.

Specific neurotoxicity of chronic use of ecstasy

The use of the illicit drug ecstasy (mainly containing methylenedioxymethamphetamine, MDMA) is widespread among young people in western Nations. Animal experiments indicate that MDMA is a potent neurotoxin specifically affecting the serotonergic system. A few functional neuroimaging studies revealed central nervous alterations after the repeated use of ecstasy. We examined 94 ecstasy users in comparison to 27 control subjects by means of positron emission tomography (PET) with 2-[18F]-fluoro-2-deoxy-D-glucose (FDG). The FDG uptake rates were globally reduced in ecstasy users, most pronounced in the striatum. The uptake rates tended to be negatively correlated with the cumulative ecstasy doses. The results indicate that younger ecstasy users may be more vulnerable with regard to neurotoxicity.

Which neuroreceptors mediate the subjective effects of MDMA in humans? A summary of mechanistic studies

In preclinical studies, 3,4-methylenedioxymethamphetamine (MDMA, 'Ecstasy') has been shown to release serotonin (5-HT), dopamine and norepinephrine. However, the role of these neurotransmitters and their corresponding receptor sites in mediating the subjective effects of MDMA has not yet been studied in humans. Therefore, we investigated the effects of three different neuroreceptor pretreatments on the subjective, cardiovascular and adverse effects of MDMA (1.5 mg/kg orally) in 44 healthy human volunteers. Pretreatments were: the selective serotonin reuptake inhibitor citalopram (40 mg intravenously) in 16 subjects, the 5-HT(2) antagonist ketanserin (50 mg orally) in 14 subjects, and the D(2) antagonist haloperidol (1.4 mg intravenously) in 14 subjects. Each of these studies used a double-blind placebo-controlled within-subject design and all subjects were examined under placebo, pretreatment, MDMA and pretreatment plus MDMA conditions. Citalopram markedly reduced most of the subjective effects of MDMA, including positive mood, increased extraversion and self-confidence. Cardiovascular and adverse effects of MDMA were also attenuated by citalopram. Haloperidol selectively reduced MDMA-induced positive mood but had no effect on other subjective effects of MDMA or the cardiovascular or adverse responses to MDMA. Ketanserin selectively reduced MDMA-induced perceptual changes and emotional excitation. These results indicate that the overall psychological effects of MDMA largely depend on carrier-mediated 5-HT release, while the more stimulant-like euphoric mood effects of MDMA appear to relate, at least in part, to dopamine D(2) receptor stimulation. The mild hallucinogen-like perceptual effects of MDMA appear to be due to serotonergic 5-HT(2) receptor stimulation. Copyright 2001 John Wiley & Sons, Ltd.

Intravenous administration of ecstasy (3,4-methylendioxymethamphetamine) enhances cortical and striatal acetylcholine release in vivo

The effect of intravenous administration of 3,4-methylendioxymethamphetamine (MDMA), in a range of doses (0.32-3.2 mg/kg) that have been shown to maintain self-administration behaviour in rats, on in vivo acetylcholine release from rat prefrontal cortex and dorsal striatum was studied by means of microdialysis with vertical concentric probes. Intravenous administration of MDMA dose-dependently increased basal acetylcholine release from the prefrontal cortex to 57+/-21%, 98+/-20%, 102+/-7% and 141+/-14% above baseline, at doses of 0.32, 0.64, 1.0 and 3.2 mg/kg, respectively. MDMA also stimulated striatal acetylcholine release at the dose of 3.2 mg/kg i.v. (the maximal increase being 32+/-3% above baseline) while at the dose of 1 mg/kg i.v., MDMA failed to affect basal acetylcholine output. Administration of MDMA also dose-dependently stimulated behaviour. The results of the present study show that MDMA affects measures of central cholinergic neurotransmission in vivo and suggest that at least some of the psychomotor stimulant actions of MDMA might be positively coupled with an increase in prefrontal cortical and striatal acetylcholine release.