Sympathomimetic actions of methylenedioxymethamphetamine in rat and rabbit isolated cardiovascular tissues

Minocycline attenuates 3,4-methylenedioxymethamphetamine-induced hyperthermia in the rat brain

Hyperthermia is most dangerous clinical symptom of acute MDMA administration, and a key factor related to potentially life-threatening MDMA-induced complications. MDMA induces a consistently faster onset of brain hyperthermia when compared to a delayed and moderate hyperthermia in the body, and the most harmful effects of MDMA are related to its modulation of neural functions. The primary focus of this study was to investigate the effects of minocycline, a centrally acting tetracycline derivative on MDMA-induced brain hyperthermia at high ambient temperature. However, we also simultaneously recorded body temperature, heart rate, and locomotor activity changes, allowing us to gain a better understanding of the mechanisms underlying the MDMA-induced hyperthermic response. We also investigated the effects of MDMA at normal ambient temperature to provide further evidence as to the importance of environmental factors on the intensity of MDMA's temperature effects. At normal ambient temperature, MDMA (10 mg/kg, i.p.) induced a significant brain and body hypothermia for the first 90 min following drug administration, and significantly increased heart rate and locomotor activity compared to saline controls. At high ambient temperature however, MDMA (10 mg/kg, i.p.) induced a robust and extended brain and body hyperthermia, as well as significantly increased heart rate and locomotor activity. A 3-day minocycline (50 mg/kg, i.p.) pre-treatment significantly attenuated MDMA-induced increases in brain temperature, body temperature, heart rate, and locomotor activity. Our findings indicate that minocycline is more effective in attenuating the exacerbated MDMA-induced hyperthermic response in the brain compared to the body at high ambient temperature.

Contractile effects of 3,4-methylenedioxymethamphetamine on the human internal mammary artery

Since the late 1980s numerous reports have detailed adverse reactions to the use of 3,4-methylenedioxymethamphetamine (MDMA) associated with cardiovascular collapse and sudden death, following ventricular tachycardia and hypertension. For a better understanding of the effects of MDMA on the cardiovascular system, it is critical to determine their effects at the vasculature level, including the transporter or neurotransmitter systems that are most affected at the whole range of drug doses. With this purpose in mind, the aim of our study was to evaluate the contractile effect of MDMA in the human internal mammary artery, the contribution of SERT for this effect and the responsiveness of this artery to 5-HT in the presence of MDMA. We have also studied the possible involvement of 5-HT2 receptors on the MDMA contractile effect in this human blood vessel using ketanserin. Our results showed that MDMA contracted the studied human's internal mammary artery in a SERT-independent form, through activation of 5-HT2A receptors. Considering the high plasma concentrations achieved in heavy users or in situations of acute exposure to drugs, this effect is probably involved in the cardiovascular risk profile of this psychostimulant, especially in subjects with pre-existing cardiovascular disease.

The heat is on: Molecular mechanisms of drug-induced hyperthermia

Thermoregulation is an essential homeostatic process in which critical mechanisms of heat production and dissipation are controlled centrally in large part by the hypothalamus and peripherally by activation of the sympathetic nervous system. Drugs that disrupt the components of this highly orchestrated multi-organ process can lead to life-threatening hyperthermia. In most cases, hyperthermic agents raise body temperature by increasing the central and peripheral release of thermoregulatory neurotransmitters that ultimately lead to heat production in thermogenic effector organs skeletal muscle (SKM) and brown adipose tissue (BAT). In many cases hyperthermic drugs also decrease heat dissipation through peripheral changes in blood flow. Drug-induced heat production is driven by the stimulation of mechanisms that normally regulate the adaptive thermogenic responses including both shivering and non-shivering thermogenesis (NST) mechanisms. Modulation of the mitochondrial electrochemical proton/pH gradient by uncoupling protein 1 (UCP1) in BAT is the most well characterized mechanism of NST in response to cold, and may contribute to thermogenesis induced by sympathomimetic agents, but this is far from established. However, the UCP1 homologue, UCP3, and the ryanodine receptor (RYR1) are established mediators of toxicant-induced hyperthermia in SKM. Defining the molecular mechanisms that orchestrate drug-induced hyperthermia will be essential in developing treatment modalities for thermogenic illnesses. This review will briefly summarize mechanisms of thermoregulation and provide a survey of pharmacologic agents that can lead to hyperthermia. We will also provide an overview of the established and candidate molecular mechanisms that regulate the actual thermogenic processes in heat effector organs BAT and SKM.

Effects of 3,4-methylenedioxymethamphetamine (MDMA) and its main metabolites on cardiovascular function in conscious rats

BACKGROUND AND PURPOSE

The cardiovascular effects produced by 3,4-methylenedioxymethamphetamine (MDMA; 'Ecstasy') contribute to its acute toxicity, but the potential role of its metabolites in these cardiovascular effects is not known. Here we examined the effects of MDMA metabolites on cardiovascular function in rats.

EXPERIMENTAL APPROACH

Radiotelemetry was employed to evaluate the effects of s.c. administration of racemic MDMA and its phase I metabolites on BP, heart rate (HR) and locomotor activity in conscious male rats.

KEY RESULTS

MDMA (1-20 mg·kg(-1)) produced dose-related increases in BP, HR and activity. The peak effects on HR occurred at a lower dose than peak effects on BP or activity. The N-demethylated metabolite, 3,4-methylenedioxyamphetamine (MDA), produced effects that mimicked those of MDMA. The metabolite 3,4-dihydroxymethamphetamine (HHMA; 1-10 mg·kg(-1)) increased HR more potently and to a greater extent than MDMA, whereas 3,4-dihydroxyamphetamine (HHA) increased HR, but to a lesser extent than HHMA. Neither dihydroxy metabolite altered motor activity. The metabolites 4-hydroxy-3-methoxymethamphetamine (HMMA) and 4-hydroxy-3-methoxyamphetamine (HMA) did not affect any of the parameters measured. The tachycardia produced by MDMA and HHMA was blocked by the β-adrenoceptor antagonist propranolol.

CONCLUSIONS AND IMPLICATIONS

Our results demonstrate that HHMA may contribute significantly to the cardiovascular effects of MDMA in vivo. As such, determining the molecular mechanism of action of HHMA and the other hydroxyl metabolites of MDMA warrants further study.

Neuropathology of substance use disorders

Addictions to licit and illicit drugs are chronic relapsing brain disorders that affect circuits that regulate reward, motivation, memory, and decision-making. Drug-induced pathological changes in these brain regions are associated with characteristic enduring behaviors that continue despite adverse biopsychosocial consequences. Repeated exposure to these substances leads to egocentric behaviors that focus on obtaining the drug by any means and on taking the drug under adverse psychosocial and medical conditions. Addiction also includes craving for the substances and, in some cases, involvement in risky behaviors that can cause death. These patterns of behaviors are associated with specific cognitive disturbances and neuroimaging evidence for brain dysfunctions in a diverse population of drug addicts. Postmortem studies have also revealed significant biochemical and/or structural abnormalities in some addicted individuals. The present review provides a summary of the evidence that has accumulated over the past few years to implicate brain dysfunctions in the varied manifestations of drug addiction. We thus review data on cerebrovascular alterations, brain structural abnormalities, and postmortem studies of patients who abuse cannabis, cocaine, amphetamines, heroin, and "bath salts". We also discuss potential molecular, biochemical, and cellular bases for the varied clinical presentations of these patients. Elucidation of the biological bases of addiction will help to develop better therapeutic approaches to these patient populations.

Toxicity of amphetamines: an update

Amphetamines represent a class of psychotropic compounds, widely abused for their stimulant, euphoric, anorectic, and, in some cases, emphathogenic, entactogenic, and hallucinogenic properties. These compounds derive from the β-phenylethylamine core structure and are kinetically and dynamically characterized by easily crossing the blood-brain barrier, to resist brain biotransformation and to release monoamine neurotransmitters from nerve endings. Although amphetamines are widely acknowledged as synthetic drugs, of which amphetamine, methamphetamine, and 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) are well-known examples, humans have used natural amphetamines for several millenniums, through the consumption of amphetamines produced in plants, namely cathinone (khat), obtained from the plant Catha edulis and ephedrine, obtained from various plants in the genus Ephedra. More recently, a wave of new amphetamines has emerged in the market, mainly constituted of cathinone derivatives, including mephedrone, methylone, methedrone, and buthylone, among others. Although intoxications by amphetamines continue to be common causes of emergency department and hospital admissions, it is frequent to find the sophism that amphetamine derivatives, namely those appearing more recently, are relatively safe. However, human intoxications by these drugs are increasingly being reported, with similar patterns compared to those previously seen with classical amphetamines. That is not surprising, considering the similar structures and mechanisms of action among the different amphetamines, conferring similar toxicokinetic and toxicological profiles to these compounds. The aim of the present review is to give an insight into the pharmacokinetics, general mechanisms of biological and toxicological actions, and the main target organs for the toxicity of amphetamines. Although there is still scarce knowledge from novel amphetamines to draw mechanistic insights, the long-studied classical amphetamines-amphetamine itself, as well as methamphetamine and MDMA, provide plenty of data that may be useful to predict toxicological outcome to improvident abusers and are for that reason the main focus of this review.

The role of monoamines in the changes in body temperature induced by 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) and its derivatives

Hyperthermia is probably the most widely known acute adverse event that can follow ingestion of 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) by recreational users. The effect of MDMA on body temperature is complex because the drug has actions on all three major monoamine neurotransmitters [5-hydroxytryptamine (5-HT), dopamine and noradrenaline], both by amine release and by direct receptor activation. Hyperthermia and hypothermia can be induced in laboratory animals by MDMA, depending on the ambient temperature, and involve both central thermoregulation and peripheral changes in blood flow and thermogenesis. Acute 5-HT release is not directly responsible for hyperthermia, but 5-HT receptors are involved in modulating the hyperthermic response. Impairing 5-HT function with a neurotoxic dose of MDMA or p-chlorophenylalanine alters the subsequent MDMA-induced hyperthermic response. MDMA also releases dopamine, and evidence suggests that this transmitter is involved in both the hyperthermic and hypothermic effects of MDMA in rats. The noradrenergic system is also involved in the hyperthermic response to MDMA. MDMA activates central alpha(2A)-adrenoceptors and peripheral alpha(1)-adrenoceptors to produce cutaneous vasoconstriction to restrict heat loss, and beta(3)-adrenoceptors in brown adipose tissue to increase heat generation. The hyperthermia occurring in recreational users of MDMA can be fatal, but data reviewed here indicate that it is unlikely that any single pharmaceutical agent will be effective in reversing the hyperthermia, so careful body cooling remains the principal clinical approach. Crucially, educating recreational users about the potential dangers of hyperthermia and the control of ambient temperature should remain key approaches to prevent this potentially fatal problem.

Neural and cardiac toxicities associated with 3,4-methylenedioxymethamphetamine (MDMA)

(+/-)-3,4-Methylenedioxymethamphetamine (MDMA) is a commonly abused illicit drug which affects multiple organ systems. In animals, high-dose administration of MDMA produces deficits in serotonin (5-HT) neurons (e.g., depletion of forebrain 5-HT) that have been viewed as neurotoxicity. Recent data implicate MDMA in the development of valvular heart disease (VHD). The present paper reviews several issues related to MDMA-associated neural and cardiac toxicities. The hypothesis of MDMA neurotoxicity in rats is evaluated in terms of the effects of MDMA on monoamine neurons, the use of scaling methods to extrapolate MDMA doses across species, and functional consequences of MDMA exposure. A potential treatment regimen (l-5-hydroxytryptophan plus carbidopa) for MDMA-associated neural deficits is discussed. The pathogenesis of MDMA-associated VHD is reviewed with specific reference to the role of valvular 5-HT(2B) receptors. We conclude that pharmacological effects of MDMA occur at the same doses in rats and humans. High doses of MDMA that produce 5-HT depletions in rats are associated with tolerance and impaired 5-HT release. Doses of MDMA that fail to deplete 5-HT in rats can cause persistent behavioral dysfunction, suggesting even moderate doses may pose risks. Finally, the MDMA metabolite, 3,4-methylenedioxyamphetamine (MDA), is a potent 5-HT(2B) agonist which could contribute to the increased risk of VHD observed in heavy MDMA users.

Electrocardiographic and echocardiographic findings in street children known to be substance abusers

Substance abuse is prevalent in adolescent street children, and death is reported as secondary to aspiration, accidental trauma, asphyxia, cardiac arrhythmia, anoxia, vagal inhibition and respiratory depression. In this study, we examined electrocardiographic and echocardiographic findings from 53 street male adolescents, comparing our findings to those obtained from 61 controls in the same age group. The street children smoked cigarettes (98.1%) and had used, or were using, thinner (73.6%), glue (75.5%), hashish (79.2%), morphine or its products (24.5%), ecstasy (37.7%), anti-emetics (13.2%) and alcohol (60.4%). On examination, their blood pressures were lower than the control group. Electrocardiographically, PR, QRS, QT were found to be longer (p less than 0.05) than the values for healthy controls. Although it was not statistically significant, QTc duration was also longer than the control group. Echocardiography revealed increased diameters of the left ventricle and atrium, the aorta, and the coronary arteries as compared to the healthy children (p less than 0.05).

Vasoconstriction of porcine left anterior descending coronary artery by ecstasy and cathinone is not an indirect sympathomimetic effect

3,4-methylenedioxymethamphetamine ('Ecstasy', MDMA) and cathinone, the active constituent of khat leaves, were examined on pig isolated left anterior descending coronary arteries to determine whether they cause vasoconstriction and whether this was an indirect sympathomimetic action. Coronary artery rings were set up in Krebs solution (37 degrees C) gassed with 5% CO2 in O2. Endothelium remained intact as indicated by relaxation by bradykinin. Isometric tension was recorded and cumulative concentration-response curves (CRCs) for noradrenaline, ecstasy or cathinone plotted as a percent of the constriction to KCl (60 mM). Noradrenaline-induced contractions of the coronary artery were enhanced by propranolol (1 microM) indicating beta-adrenoceptor-mediated opposing vasodilatation. Cocaine (10 microM) further potentiated, while prazosin (1 microM) virtually abolished the contractions to noradrenaline. Cathinone and ecstasy constricted the coronary artery rings, the peak contractions being 56.5+/-4.2% (n=4) and 37.3+/-2.4% (n=4), respectively. Higher concentrations relaxed. The vasoconstriction was not affected by cocaine (10 microM), prazosin (1 microM, in the presence of cocaine) or removal of the endothelium. There was no tachyphylaxis or desensitisation on repeated administration of single doses. Ecstasy- and cathinone-induced coronary vasoconstriction is therefore via mechanisms other than indirect sympathomimetic activity or alpha1 -adrenoceptors. This activity could explain the cardiac adverse effects following their excessive use.

Effects of MDMA, MDA and MDEA on blood pressure, heart rate, locomotor activity and body temperature in the rat involve alpha-adrenoceptors

The effects of injection of 3,4-methylenedioxymethamphetamine (MDMA), 3,4-methylenedioxyamphetamine (MDA) and N-ethyl-3,4-methylenedioxyamphetamine (MDEA) (all 20 mg kg(-1)) on blood pressure, heart rate, core body temperature and locomotor activity in conscious rats were investigated using radiotelemetry. MDMA and MDA produced a prolonged increase in both systolic and diastolic pressures, with MDA causing the most marked rise. MDEA produced a transient but nonsignificant fall in diastolic pressure. The pressor response produced by MDA was accompanied by bradycardia. All three amphetamine derivatives caused an initial hypothermic response; however, MDA also produced a subsequent hyperthermia, and the speed of recovery from hypothermia was MDA>MDMA>MDEA. The alpha2A-adrenoceptor antagonist 2-((4,5-dihydro-1H-imidazol-2-yl)methyl)-2,3-dihydro-1-methyl-1H-isoindole (BRL 44408) (1 mg kg(-1)) prolonged the hypothermic response to MDMA. Only MDA induced locomotor activity when given alone, but in the presence of BRL 44408, MDMA produced increased locomotor activity. The order of potency for producing isometric contractions of rat aorta (alpha1D) and vas deferens (alpha1A) was MDA>MDMA>MDEA, with MDEA acting as an alpha1-adrenoceptor antagonist with a pK(B) of 4.79+/-0.12 (n = 4) in aorta. The order of potency for prejunctional inhibition of stimulation-evoked contractions in rat vas deferens (alpha2A-adrenoceptor mediated) was MDA>MDMA>MDEA. Blood pressure actions of the three amphetamine derivatives may be at least partly due to alpha1-adrenoceptor agonism or antagonism. The reversal of the hypothermic actions are at least partly due to alpha2A-adrenoceptor agonism since the hypothermic response was more prolonged with MDEA which exhibits low alpha2A-adrenoceptor potency, and effects of MDMA after alpha2A-adrenoceptor antagonism were similar to those of MDEA.

MDMA (Ecstasy) and human dopamine, norepinephrine, and serotonin transporters: implications for MDMA-induced neurotoxicity and treatment

RATIONALE

3,4-Methylenedioxymethamphetamine (MDMA, designated as "Ecstasy" if illicitly marketed in tablet form) induces significant decrements in neuronal serotonin (5-HT) markers in humans, nonhuman primates, and rats as a function of dosing and dosing regimen. In rats, MDMA-mediated effects are attributed, in part, to selective high-affinity transport of MDMA into 5-HT neurons by the 5-HT transporter (SERT), followed by extensive 5-HT release.

OBJECTIVES

To clarify whether SERT-selective effects of MDMA at human monoamine transporters can account for the reported MDMA-induced selective toxicity of serotonin neurons in primate brain.

METHODS

We investigated the interaction of [(3)H](+/-, RS)- (+, S)- and (-, R)-MDMA with the human SERT, dopamine (DA) transporter (DAT), and norepinephrine (NE) transporter (NET) in stably transfected human embryo kidney (HEK)-293 cells.

RESULTS

The human DAT, NET, and SERT actively transported [(3)H]RS(+/-)-MDMA saturably, stereoselectively, and in a temperature-, concentration-, and transporter-dependent manner. MDMA exhibited the highest affinity for the NET>>SERT>or=DAT, the same rank order for MDMA inhibition of [(3)H]DA, [(3)H]NE, and [(3)H]5-HT transport and stimulated release of the [(3)H]monoamines, which differed from reports derived from rodent monoamine transporters. The extent of MDMA-induced release of 5-HT was higher compared with release of DA or NE.

CONCLUSIONS

The affinity of MDMA for the human SERT in transfected cells does not clarify the apparent selective toxicity of MDMA for serotonin neurons, although conceivably, its higher efficacy for stimulating 5-HT release may be a distinguishing factor. The findings highlight the need to investigate MDMA effects in DAT-, SERT-, and NET-expressing neurons in the primate brain and the therapeutic potential of NET or DAT inhibitors, in addition to SERT-selective inhibitors, for alleviating the pharmacological effects of MDMA.

3,4-Methylenedioxymethamphetamine (MDMA) neurotoxicity in rats: a reappraisal of past and present findings

RATIONALE

3,4-Methylenedioxymethamphetamine (MDMA) is a widely abused illicit drug. In animals, high-dose administration of MDMA produces deficits in serotonin (5-HT) neurons (e.g., depletion of forebrain 5-HT) that have been interpreted as neurotoxicity. Whether such 5-HT deficits reflect neuronal damage is a matter of ongoing debate.

OBJECTIVE

The present paper reviews four specific issues related to the hypothesis of MDMA neurotoxicity in rats: (1) the effects of MDMA on monoamine neurons, (2) the use of "interspecies scaling" to adjust MDMA doses across species, (3) the effects of MDMA on established markers of neuronal damage, and (4) functional impairments associated with MDMA-induced 5-HT depletions.

RESULTS

MDMA is a substrate for monoamine transporters, and stimulated release of 5-HT, NE, and DA mediates effects of the drug. MDMA produces neurochemical, endocrine, and behavioral actions in rats and humans at equivalent doses (e.g., 1-2 mg/kg), suggesting that there is no reason to adjust doses between these species. Typical doses of MDMA causing long-term 5-HT depletions in rats (e.g., 10-20 mg/kg) do not reliably increase markers of neurotoxic damage such as cell death, silver staining, or reactive gliosis. MDMA-induced 5-HT depletions are accompanied by a number of functional consequences including reductions in evoked 5-HT release and changes in hormone secretion. Perhaps more importantly, administration of MDMA to rats induces persistent anxiety-like behaviors in the absence of measurable 5-HT deficits.

CONCLUSIONS

MDMA-induced 5-HT depletions are not necessarily synonymous with neurotoxic damage. However, doses of MDMA which do not cause long-term 5-HT depletions can have protracted effects on behavior, suggesting even moderate doses of the drug may pose risks.

Ecstasy: are animal data consistent between species and can they translate to humans?

The number of 3,4-methylenedioxymethamphetamine (ecstasy or MDMA) animal research articles is rapidly increasing and yet studies which place emphasis on the clinical significance are limited due to a lack of reliable human data. MDMA produces an acute, rapid release of brain serotonin and dopamine in experimental animals and in the rat this is associated with increased locomotor activity and the serotonin behavioural syndrome in rats. MDMA causes dose-dependent hyperthermia, which is potentially fatal, in humans, primates and rodents. Subsequent serotonergic neurotoxicity has been demonstrated by biochemical and histological studies and is reported to last for months in rats and years in non-human primates. Relating human data to findings in animals is complicated by reports that MDMA exposure in mice produces selective long-term dopaminergic impairment with no effect on serotonin. This review compares data obtained from animal and human studies and examines the acute physiological, behavioural and biochemical effects of MDMA as well as the long-term behavioural effects together with serotonergic and dopaminergic impairments. Consideration is also given to the role of neurotoxic metabolites and the influence of age, sex and user groups on the long-term actions of MDMA.

Methylenedioxymethamphetamine (ecstasy)-related myocardial hypertrophy: an autopsy study

BACKGROUND

Myocardial hypertrophy is a well-recognized complication of cocaine and methamphetamine abuse and is a strong, independent risk factor for sudden death, myocardial infarction, and congestive heart failure. We sought to determine if use of MDMA (methylenedioxyamphetamine or "ecstasy") is associated with myocardial hypertrophy at death.

METHODS AND RESULTS

A matched, retrospective study using medical examiner (ME) death reports. Consecutive MDMA positive (+) and MDMA negative (-) deaths identified from MEs in 10 states and a local county, respectively. Five MDMA(-) cases were matched to each MDMA(+) case for age, sex, and ethnicity. MDMA(+) cases were confirmed using GC/MS and other drugs of abuse (e.g., cocaine and methamphetamine) were absent. Matched MDMA(-) cases were trauma fatalities with intact hearts and blood negative for all illicit stimulants. Cardiac weights were compared between the two groups. Twenty seven MDMA(+) deaths and 135 matched MDMA(-) deaths were enrolled. Mean age was 20 years (range 16--33 years); 44% were female. 70.4% were Caucasian, 14.8% African-American, 11.1% Asian, and 3.7% Hispanic. Mean heart weight of MDMA(+) fatalities was 315.7 and 277.2g for MDMA(-) fatalities (Diff=38.5 g; 95% CI=18.3--8.7). Multivariate analysis revealed that MDMA(+) fatalities were more likely to have an enlarged heart (OR=18.3; 95% CI=3.6--1.6).

CONCLUSION

The findings of this study suggest that MDMA users might also be at risk for myocardial hypertrophy and possible cardiac toxicity, similar to other stimulants.

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.

The pharmacology and clinical pharmacology of 3,4-methylenedioxymethamphetamine (MDMA, "ecstasy")

The amphetamine derivative (+/-)-3,4-methylenedioxymethamphetamine (MDMA, ecstasy) is a popular recreational drug among young people, particularly those involved in the dance culture. MDMA produces an acute, rapid enhancement in the release of both serotonin (5-HT) and dopamine from nerve endings in the brains of experimental animals. It produces increased locomotor activity and the serotonin behavioral syndrome in rats. Crucially, it produces dose-dependent hyperthermia that is potentially fatal in rodents, primates, and humans. Some recovery of 5-HT stores can be seen within 24 h of MDMA administration. However, cerebral 5-HT concentrations then decline due to specific neurotoxic damage to 5-HT nerve endings in the forebrain. This neurodegeneration, which has been demonstrated both biochemically and histologically, lasts for months in rats and years in primates. In general, other neurotransmitters appear unaffected. In contrast, MDMA produces a selective long-term loss of dopamine nerve endings in mice. Studies on the mechanisms involved in the neurotoxicity in both rats and mice implicate the formation of tissue-damaging free radicals. Increased free radical formation may result from the further breakdown of MDMA metabolic products. Evidence for the occurrence of MDMA-induced neurotoxic damage in human users remains equivocal, although some biochemical and functional data suggest that damage may occur in the brains of heavy users. There is also some evidence for long-term physiological and psychological changes occurring in human recreational users. However, such evidence is complicated by the lack of knowledge of doses ingested and the fact that many subjects studied are or have been poly-drug users.

Actions of amphetamine derivatives and cathinone at the noradrenaline transporter

We have recently shown that methylenedioxymethamphetamine (MDMA), methylenedioxyamphetamine (MDA), cathinone and methylenedioxyethylamphetamine (MDEA) have a cocaine-like action to potentiate the contractile actions of noradrenaline but not isoprenaline in the 1-Hz paced rat right ventricle. The purpose of this study was to directly test the actions of these compounds at the noradrenaline transporter. In rat left ventricular slices, potency (-log IC50) values at inhibiting uptake of [3H]noradrenaline were: cocaine 6.16+/-0.15, cathinone 6.03+/-0.16, MDMA 6.05+/-0.07, MDA 5.68+/-0.06 and MDEA 5.56+/-0.08. MDEA and MDA were significantly less potent. In rat cerebral cortex membranes, MDMA was significantly less potent at displacing [3H]nisoxetine binding; -log EC50 values: cocaine 5.04+/-0.08, cathinone 5.40+/-0.14, MDA 4.66+/-0.11, MDEA 4.99+/-0.15, MDMA 4.22+/-0.07. The noradrenaline uptake studies showed that MDEA was least potent: MDEA was also least potent functionally in the paced rat right ventricle. The [3H]nisoxetine displacement studies did not compare with the functional studies.

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

Altered states: the clinical effects of Ecstasy

Ecstasy is the second most widely abused illegal drug in Europe. Ecstasy is the colloquial name for 3,4-methylenedioxymethamphetamine (MDMA), but not all Ecstasy tablets contain MDMA. When taken in hot, crowded environments, Ecstasy/MDMA users have developed acute complications that have had fatal consequences. Epidemiological evidence indicates that adverse reactions to Ecstasy/MDMA intoxication are rare and idiosyncratic. Potential mechanisms of action are reviewed. In animal studies, MDMA damages serotonergic fibres and reduces the number of serotonin transporter sites within the CNS. Demonstration of neurotoxicity in human users of Ecstasy is hampered by a number of confounds that the majority of published studies have failed to address. These confounds are reviewed and their impact is discussed.

Changes in cardiovascular responsiveness and cardiotoxicity elicited during binge administration of Ecstasy

The recreational use of 3,4-methylenedioxymethamphetamine (MDMA; Ecstasy) is often characterized by a repeated pattern of frequent drug administrations (binge) followed by a period of abstinence. Radiotelemetry was used to characterize the cardiovascular responses elicited during three MDMA binges (3 or 9 mg/kg b.i.d. for 4 days), each of which was separated by a 10-day MDMA-free period. The heart rate and mean arterial pressure (MAP) responses elicited by 3-mg/kg doses of MDMA were consistent within and between the three binges. In the first binge the 9-mg/kg doses of MDMA increased MAP and produced a biphasic (decrease/increase) heart rate response. The bradycardia elicited by MDMA in the first binge (-75 bpm) was enhanced in the second and third binges (-186 and -287 bpm, respectively). Significant hypotension accompanied the increased bradycardic responses. Atropine abolished the hypotension and significantly attenuated the bradycardic responses. The MAP and heart rate responses elicited by sodium nitroprusside, acetylcholine, phenylephrine, and serotonin (5-HT) were evaluated before each binge and 10 days after the last binge. The hypotension, but not the tachycardia elicited by sodium nitroprusside was attenuated by the repeated administration of MDMA. The responses to phenylephrine, acetylcholine, and 5-HT were unaltered after MDMA. The hearts of treated rats contained foci of inflammatory infiltrates (lymphocytes and macrophages), some of which contained necrotic cells and/or disrupted cytoarchitecture. MDMA produced cardiac arrhythmias in some rats. These results indicate that the binge administration of MDMA can significantly alter cardiovascular and cardiovascular reflex function and produce cardiac toxicity.

Effects of amphetamine derivatives and cathinone on noradrenaline-evoked contractions of rat right ventricle

We have compared the effects of methylenedioxymethamphetamine (MDMA), methylenedioxyethylamphetamine (MDEA), methylenedioxyamphetamine (MDA) and cathinone on contractions to noradrenaline and isoprenaline in 1 Hz paced rat right ventricular strips. Noradrenaline increased the force of contraction of 1 Hz paced ventricular strips with a pD(2) (-log EC(50)) of 5.64 +/- 0.07 (n = 49). Cocaine (10 microM), MDMA (10 microM), MDA (10 microM) and cathinone (3 and 10 microM) significantly increased the potency of noradrenaline to 6.25 +/- 0.11, 6.48 +/- 0.13, 6.17 +/- 0.05, 6.15 +/- 0.07 and 6.27 +/- 0.10, respectively (n = 5-10 each) as compared with the effects of vehicle (5.42 +/- 0.08, n = 15). However, MDEA (10 microM) failed to affect the potency of noradrenaline, although MDEA (100 microM) significantly increased noradrenaline potency (5.98 +/- 0.12). The potency of the agonist isoprenaline, which is not a substrate for the noradrenaline transporter, was not increased by cocaine, MDMA, cathinone, MDA or MDEA. Hence, MDMA, cathinone, MDA and MDEA share with cocaine an ability to potentiate the actions of noradrenaline, an action which may involve competitive blockade of the noradrenaline transporter rather than simply displacement of noradrenaline. Since cocaine is linked to an increased incidence of myocardial infarction, these results may have implications in terms of cardiac morbidity of amphetamine derivatives and cathinone.

Fetal exposure to (+/-)-methylenedioxymethamphetamine in utero enhances the development and metabolism of serotonergic neurons in three-dimensional reaggregate tissue culture

Methylenedioxymethamphetamine (MDMA, Ecstasy) is a potent psychomotor stimulant with neurotoxic potential which is widely abused by females of childbearing age raising serious public health concerns in terms of exposure of the fetus to the drug. The current study was conducted using the three-dimensional reaggregate tissue culture system as an approach to the assessment of risk to fetal brain cells following exposure to MDMA during early to mid-gestation. In this culture system, the serotonergic and dopaminergic mesencephalic-striatal projections are reconstructed and develop with a time course similar to that observed in vivo. Pregnant C57Bl/6J mice were injected twice daily with 40 mg/kg MDMA or saline from gestational day 6 to 13. On gestational day 14, mesencephalic and striatal cells from MDMA- and saline-exposed embryos were used to prepare reaggregate cultures. Levels of neurotransmitters and their metabolites in the reaggregates and culture medium were assessed at 22 and 36 days of culture. There was a long-term enhancement of serotonergic development and metabolism by fetal exposure to MDMA as evidenced by increased reaggregate serotonin levels as well as the elevated production and release of 5-hydroxyindoleacetic acid in cultures prepared from MDMA-exposed embryos which persisted for up to 36 days of culture. Dopaminergic neurons in such cultures also exhibited increased metabolism as indicated by elevated levels of dihydroxyphenylacetic acid in reaggregate tissue and culture medium. The data obtained suggest that exposure to MDMA in utero during early to mid-gestation may result in more active serotonergic and dopaminergic neurons.

In vitro neuronal and vascular responses to 5-HT in rats chronically exposed to MDMA

1. This study examined the effects of chronic exposure of rats to 3,4-methylenedioxymethamphetamine (MDMA) on [(3)H]5-hydroxytryptamine ([(3)H]5-HT) re-uptake into purified rat brain synaptosomes, 5-HT-induced isometric contraction of aortic rings and [(3)H]5-HT re-uptake into rat aorta. 2. Rats were administered MDMA (20 mg kg(-1) i.p.) twice daily over 4 days. One, 7, 14 or 21 days post treatment, whole brain synaptosomes and descending thoracic aortic rings were prepared for investigation. 3. Chronic MDMA treatment significantly reduced the maximum rate (V(max)) of specific high-affinity [(3)H]5-HT re-uptake 1 day after treatment and for up to 21 days post-final administration of MDMA. Direct application of MDMA (100 microM) abolished synaptosomal re-uptake of [(3)H]5-HT in vitro. 4. Chronic MDMA administration significantly reduced the maximum contraction (E(max)) to 5-HT at 1 and 7 days after treatment, but not at 14 or 21 days. 5. Chronic MDMA administration had no effect on sodium-dependent [(3)H]5-HT re-uptake into aorta 1 day after treatment, nor did 100 microM MDMA have any direct effect on [(3)H]5-HT uptake into aortic rings in vitro. 6. These results show, for the first time, an altered responsiveness of vascular tissue to MDMA after chronic administration. In addition, they demonstrate a difference in the sensitivity of central and peripheral 5-HT uptake systems to chronic MDMA exposure, and suggest that the action of MDMA in the cardiovascular system does not arise from a direct effect of MDMA on peripheral 5-HT transport.

Vascular actions of MDMA involve alpha1 and alpha2-adrenoceptors in the anaesthetized rat

We have investigated the effects of methylenedioxymethamphetamine (MDMA, 'ecstasy'), i.v., on diastolic blood pressure (DBP) in pithed and pentobarbitone anaesthetized rats. In pithed rats, the non-selective 5-HT receptor antagonist methiothepin (0.1 mg kg(-1)) and the alpha2-adrenoceptor antagonists methoxyidazoxan and yohimbine (1 mg kg(-1)) showed significant alpha1-adrenoceptor antagonist potency, but methiothepin did not show alpha2-adrenoceptor antagonist potency. MDMA (1 and 5 mg kg(-1)) produced pressor responses which were significantly reduced by the alpha(1)-adrenoceptor antagonist prazosin (0.1 mg kg(-1)), yohimbine (1 mg kg(-1)) or methiothepin (0.1 mg kg(-1)), but not by the 5-HT2 receptor antagonist ritanserin (1 mg kg(-1)). In anaesthetized rats, antagonists revealed two phases with three components to the effects of MDMA (5 mg kg(-1)) on DBP: an initial pressor response, a later pressor component at 1 min, the sustained depressor response. Methoxyidazoxan, methiothepin or the combination ritanserin/prazosin significantly reduced the initial pressor response, although neither of the latter compounds alone had any effect. The pressor response to MDMA (5 mg kg(-1)) at 1 min was converted to a depressor response by prazosin and to a lesser extent methiothepin and methoxyidazoxan. The depressor response to MDMA (5 mg kg(-1)) was significantly reduced by methoxyidazoxan (0.1 mg kg(-1)), and by the noradrenaline re-uptake blocker cocaine 10 mg kg(-1) but not 1 mg kg(-1). However, the most marked reduction in the depressor response was produced by the combination of methoxyidazoxan and cocaine. It is concluded that the initial pressor response to MDMA (5 mg kg(-1)) in anaesthetized rats involves alpha2- and possibly alpha1-adrenoceptors and 5-HT2 receptors, the pressor component at 1 min is largely alpha1-adrenoceptor mediated, and the sustained depressor response involves alpha2-adrenoceptors.

Effects of methylenedioxymethamphetamine on noradrenaline-evoked contractions of rat right ventricle and small mesenteric artery

We have compared the effects of methylenedioxymethamphetamine (MDMA) and cocaine on contractions to noradrenaline in 1 Hz paced rat right ventricular strips, and in rat small mesenteric artery and aorta. Noradrenaline increased the force of contraction of 1 Hz paced ventricular strips with a pD(2) (-log EC(50)) of 5.64+/-0.07. Both cocaine (10 microM) and MDMA (10 microM) significantly increased the potency of noradrenaline to 6.31+/-0.11 and 6.42+/-0.13, respectively. However, in the presence of cocaine (10 microM) which increased the potency of noradrenaline to 6.78+/-0.15, MDMA (10 microM) no longer increased the potency of noradrenaline (pD(2) of 6.78+/-0.32). Likewise, following chemical sympathectomy, MDMA failed to increase the potency of noradrenaline. The potency of the agonist isoprenaline, which is not a substrate for the noradrenaline transporter, was not increased by either cocaine or MDMA. In rat small mesenteric artery, but not aorta, MDMA and cocaine significantly increased the potency of noradrenaline, but in the presence of cocaine, MDMA had no further effect. Hence, MDMA shares with cocaine an ability to potentiate the actions of noradrenaline, an action in the case of MDMA which may involve competitive blockade of the noradrenaline transporter, rather than simply displacement of noradrenaline. Since cocaine is linked to an increased incidence of myocardial infarction, these results may have implications in terms of cardiac morbidity of MDMA.

Cardiovascular and sympathetic responses and reflex changes elicited by MDMA

The recreational use of 3,4-methylenedioxymethamphetamine (MDMA) has increased as have the number of clinical reports linking MDMA use with cardiovascular toxicity. Nonetheless, the cardiovascular and sympathetic nerve responses elicited by MDMA have not been well characterized. The purpose of this study was to characterize the mean arterial pressure (MAP), heart rate (HR), and renal sympathetic nerve responses elicited by the acute administration of MDMA and to determine whether neurotoxic doses of MDMA change cardiovascular and/or cardiovascular reflex function. In conscious rats, MDMA or d-amphetamine elicited similar dose-dependent increases in MAP. MDMA elicited significant bradycardia at doses above 1.0 mg/kg. Pretreatment with phentolamine significantly reduced the duration but not the magnitude of the pressor response elicited by MDMA. In pentobarbital-anesthetized rats, MDMA (0.1 mg/kg) increased renal sympathetic nerve activity (RSNA; 33 +/- 10%), while larger doses significantly decreased RSNA (-91 +/- 3%, max). Neurotoxic doses of MDMA (20 mg/kg, s.c., b.i.d. for 4 days) significantly enhanced the bradycardic component of the Bezold-Jarisch reflex elicited by i.v. serotonin when tested either 2 days or 2 weeks after the last neurotoxic treatment. However, neurotoxic treatment did not significantly affect baroreceptor reflex function. These results indicate that the acute administration of MDMA and d-amphetamine produce similar cardiovascular and sympathetic responses. Neurotoxic doses of MDMA can also significantly alter cardiovascular reflex function. These findings raise the possibility that MDMA may have the potential to produce cardiovascular and/or cardiac toxicity similar to that elicited by other amphetamine analogs.

Cardiotoxic effects of fenfluramine hydrochloride on isolated cardiac preparations and ventricular myocytes of guinea-pigs

The cardiotoxic effects of fenfluramine hydrochloride on mechanical and electrical activity were studied in papillary muscles, Purkinje fibres, left atria and ventricular myocytes of guinea-pigs. Force of contraction (f(c)) was measured isometrically, action potentials and maximum rate of rise of the action potential (V(max)) were recorded by means of the intracellular microelectrode technique and the sodium current (I(Na)) with patch-clamp technique in the cell-attached mode. For kinetic analysis (S)-DPI-201-106-modified Na(+) channels from isolated guinea-pig ventricular heart cells were used. Fenfluramine (1 - 300 microM) produced negative chronotropic and inotropic effects; additional extracellular Ca(2+) competitively antagonized the negative inotropic effect. Fenfluramine concentration-dependently reduced V(max) and showed tonic blockade of sodium channels, shortened the action potential duration in papillary muscles and Purkinje fibres. In cell-attached patches, fenfluramine decreased I(Na) concentration-dependently (10 - 100 microM), frequency-independently (0.1 - 3 Hz; 30 microM). The h(infinity) curve was shifted towards hyperpolarizing direction. At 30 microM, fenfluramine blocked the sodium channel at all test potentials to the same degree, and neither changed the threshold and reversal potentials nor the peak of the curve. No effect on single channel availability, but a significant decrease in mean open times and increase in mean closed times was observed. Mean duration of the bursts decreased and number of openings per record increased with increasing drug concentration. It is concluded that the effect on I(Na) plays an important role in the cardiotoxicity of fenfluramine in addition to primary pulmonary hypertension and valvular disorders.

Investigation of the prejunctional alpha2-adrenoceptor mediated actions of MDMA in rat atrium and vas deferens

1. We have investigated the effects of methylenedioxymethamphetamine (MDMA, 'ecstasy') on peripheral noradrenergic neurotransmission in the rat. 2. In rat atrial slices pre-incubated with [3H]-noradrenaline and in the presence of desipramine (1 micronM) to prevent effects of MDMA on basal outflow of tritium, MDMA (10 micronM) significantly inhibited the release of tritium evoked by short trains of six pulses at 100 Hz every 10 s for 3 min. This effect did not occur in the presence of the alpha2-adrenoceptor antagonist yohimbine (1 micronM). 3. In epididymal portions of rat vas deferens in the presence of nifedipine (10 micronM), MDMA produced a concentration-dependent inhibition of single pulse nerve stimulation-evoked contractions with a pD2 of 5.88+/-0.16 (n=4). Inhibitory effects of MDMA were antagonized by the alpha2-adrenoceptor antagonist yohimbine (0.3 micronM), but not by the 5-hydroxytryptamine receptor antagonist cyanopindolol in a concentration (1 micronM) which markedly antagonized the inhibitory actions of the 5-HT-1 receptor agonist 5-carboxamidotryptamine. 4. In prostatic portions of rat vas deferens in the presence of cocaine (3 micronM), MDMA produced a concentration-dependent inhibition of single pulse nerve stimulation-evoked contractions with a pD2 of 5. 12+/-0.21 (n=4). In the absence of cocaine, only the highest concentration of MDMA (30 micronM) produced an inhibition, but the alpha2-adrenoceptor antagonist yohimbine (0.3 micronM) converted the response to MDMA from inhibition to potentiation of the stimulation-evoked contraction. 5. In radioligand binding studies, MDMA showed similar affinities for alpha2B, alpha2C and alpha2D-adrenoceptor sites, with pKi values of 5.14+/-0.16, 5.11+/-0. 05 and 5.31+/-0.14, respectively. 6 It is concluded that MDMA has significant alpha2-adrenoceptor agonist actions.