Glucocorticoids and 3,4-methylenedioxymethamphetamine (MDMA)-induced neurotoxicity

The present study was carried out in order to explore the role of glucocorticoids in 3,4-methylenedio-xymethamphetamine (MDMA)-induced neurotoxicity of the central serotonergic system. The activity of tryptophan hydroxylase (TPH) was used as an index of this drug-induced neuronal degeneration. One week after a single high dose of MDMA (20 mg/kg), a significant decrease in the enzyme activity was measured in both the frontal cortex and hippocampus. Adrenalectomy (ADX) attenuated or blocked this decrease in TPH activity in the hippocampus but not in the frontal cortex. This protective effect of ADX on hippocampal serotonergic neurons disappeared with concurrent administration of corticosterone (CORT) and MDMA administration. The long-term MDMA-induced decreases in hippocampal serotonin (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) concentrations were similarly affected by CORT replacement. However, ADX did not alter the short-term decline in hippocampal TPH activity and 5-HT concentrations measured 3 h after a single dose of MDMA (10 mg/kg s.c.). This study suggests that CORT play a role in the development of neurotoxicity induced by MDMA in the hippocampal serotonergic system, but may be less important in other brain structures.     

Thermoregulatory effects of 3,4-methylenedioxymethamphetamine (MDMA) in humans

Rationale Although 3,4-methylenedioxymethamphetamine (MDMA; Ecstasy) has been reported to cause fatal hyperthermia, few studies of the effects of MDMA on core body temperature in humans have been conducted demonstrating increased body temperature. In rats, MDMA causes hyperthermia at warm ambient temperatures but hypothermia at cold ones.Objectives In this study, the physiological and subjective effects of MDMA in humans were determined at cold (18°C) and warm (30°C) ambient temperatures in a temperature and humidity-controlled laboratory.Methods Ten healthy volunteers who were recreational users of MDMA were recruited. Four laboratory sessions were conducted in a 2×2 design [i.e., two sessions at 30°C and two at 18°C, two during MDMA (2 mg/kg, p.o.) and two during placebo, in double-blind fashion]. Core body temperature (ingested radiotelemetry pill), skin temperature (four weighted sites), heart rate, blood pressure, metabolic rate (indirect calorimetry), shivering (electromyogram levels), and sweat rate (capacitance hygrometry) were measured as well as subjective effects for several time periods following capsule ingestion.Results MDMA produced significant elevations in core body temperature and metabolic rate in both warm and cold conditions. MDMA also produced significant elevations in blood pressure and heart rate and significantly increased several ratings of subjective effects similar to those previously reported. There were no differences related to ambient temperature for any of the subjective effects, except that ratings of cold and warm were appropriate to the ambient temperature and were not influenced by MDMA.Conclusions Unlike findings in rats, MDMA increased core body temperature regardless of ambient temperature in humans. These increases appeared related to increases in metabolic rate, which were substantial. These findings warrant further investigations on the role of MDMA and other stimulants in altering metabolism and thermogenesis.     

Effects of (+-)3,4-methylenedioxymethamphetamine (MDMA) on brain dopaminergic activity in rats

Acute treatment with (+-)3,4-methylenedioxymethamphetamine (MDMA) at high doses (10 and 30 mg/kg, IP), but not lower doses increased locomotor activity in male rats. MDMA did not consistently produce any other stereotyped behaviors at any dose. Dopamine (DA) turnover rate as estimated by the ratio of brain tissue levels of 3,4-dihydroxyphenylacetic acid (DOPAC) over DA was decreased in the striatum for up to two hours after acute treatment with 10 mg/kg of MDMA. DA turnover rate was inconsistently decreased in the olfactory tubercle and medial basal hypothalamus, and was unchanged in the medial prefrontal cortex and the substantia nigra/ventral tegmental area. Two hours after a 30 mg/kg injection of MDMA, DA turnover rate was decreased in all brain areas tested. MDMA and d-amphetamine partially reversed a haloperidol-induced elevation of striatal DOPAC levels. In contrast, the nonamphetamine stimulant, amfonelic acid, enhanced haloperidol's effect. In chloral hydrate-anesthesized rats, MDMA injected IV partially inhibited spontaneous firing rate of DA neurons in the substantia nigra (34% decrease at 4 mg/kg of MDMA). Seventeen days after subchronic MDMA treatment (10 or 20 mg/kg, IP, twice per day for four days), DA and DOPAC levels were unchanged in all brain areas tested as compared to levels in control rats. It is concluded that acute treatment with high but not low doses of MDMA has a weak amphetamine-like effect on nigrostriatal as well as mesolimbic/mesocortical and tuberoinfundibular DA neurons in rats. Repeated treatment with MDMA does not appear to be toxic to mesotelencephalic or tuberoinfundibular DA neurons.     

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.     

The effects of 3,4-methylenedioxymethamphetamine (MDMA) and 3,4-methylenedioxyamphetamine (MDA) on monoaminergic systems in the rat brain

The effects of two amphetamine-like designer drugs, 3,4-methylenedioxyamphetamine (MDA) and 3,4-methylenedioxymethamphetamine (MDMA), on dopaminergic and serotonergic systems in the rat brain were investigated and compared to those of methamphetamine (METH). Like METH, single or multiple 10 mg/kg doses of either drug caused marked reductions in both tryptophan hydroxylase (TPH) activity and concentrations of 5-hydroxytryptamine (5-HT) and 5-hydroxyindoleacetic acid, in several serotonergic nerve terminal regions. In all regions examined, the reduction in 5-HT content corresponded to the depression of TPH activity. Unlike multiple METH administrations, which induced pronounced deficits in dopaminergic neuronal markers, repeated doses of MDA or MDMA did not alter striatal tyrosine hydroxylase (TH) activities or reduce striatal dopamine concentrations. A single dose of MDA or MDMA significantly elevated striatal dopamine content; however, after repeated drug administrations dopamine concentrations were comparable to control values. At this time, striatal levels of homovanillic acid were significantly elevated suggesting that both drugs influence dopamine turnover. The effects of MDA or MDMA administration in the rat brain are reminiscent of those elicited by p-chloroamphetamine, a presumed serotonergic neurotoxin.     

The antinociceptive effects of 3,4-methylenedioxymethamphetamine (MDMA) in the rat

The antinociceptive effects of MDMA and morphine were examined in rats using the tail-flick and hot-plate analgesiometric tests. MDMA, in the dose range of 1.5-6.0 mg/kg IP, produced a dose-dependent elevation in hot-plate latency, but did not elevate tail-flick latency. In contrast, morphine (2-8 mg/kg, IP) produced analgesia on both the tail-flick and hot-plate tests in a dose-dependent manner. Neither the opiate antagonist naltrexone nor the adrenoceptor antagonist phentolamine effectively attenuated MDMA-induced analgesia. Conversely, the serotonin antagonist methysergide significantly reversed the analgesic effects of MDMA on the hot-plate test. These findings suggest that the antinociceptive effects of MDMA are serotonergically mediated. Furthermore, the results verify earlier findings describing the test-specific effects of serotonin-induced pain modulation.     

Subjective and hormonal effects of 3,4-methylenedioxymethamphetamine (MDMA) in humans

RATIONALE: 3,4-Methylenedioxymethamphetamine (MDMA) is a widely used phenethylamine. Reports have described the effects of MDMA in a controlled laboratory setting, but the full range of effects of MDMA in humans is still not completely characterized. OBJECTIVES: To describe the physiological, subjective, and hormonal changes after single doses of MDMA in a laboratory setting and examine relationships between these effects. METHODS: Eight MDMA-experienced volunteers each received placebo, 0.5 mg/kg, and 1.5 mg/kg oral doses of MDMA in a double-blind crossover study. RESULTS: The 1.5 mg/kg dose (comparable to that typically used by most participants) produced significant subjective effects, peaking at about 2 h after dosing, including some effects commonly associated with stimulant drugs, hallucinogens, and entactogens. MDMA significantly increased plasma cortisol, prolactin, and dehydroepiandrosterone (DHEA) levels. Increase in plasma cortisol after the 1.5 mg/kg dose correlated with increased heart rate, rate-pressure product, and drug liking. Rise in DHEA correlated with euphoria. CONCLUSIONS: A typically used dose of MDMA produced effects commonly associated with stimulants and hallucinogens. Subjects liked MDMA. Correlations between cortisol and DHEA levels and some physiological and psychological effects are consistent with animal data suggesting that hormones modulate some responses to drugs of abuse.     

Amphetamine analogs methamphetamine and 3,4-methylenedioxymethamphetamine (MDMA) differentially affect speech

Rationale  

Kappa agonists can attenuate reinstatement of cocaine-seeking behavior induced by cocaine priming. The mechanisms underlying this effect have not been characterized fully but may have a serotonergic component as kappa agonists also increase the release of serotonin (5-hydroxytryptamine, 5-HT).     

3H]3,4-methylenedioxymethamphetamine (MDMA) interactions with brain membranes and glass fiber filter paper

The binding of [3H]3,4-methylenedioxymethamphetamine [( 3H]MDMA) to both rat brain membrane preparations and glass fiber filter papers was analyzed in the present study. Saturation studies indicate that [3H]MDMA binding is saturable and monophasic in both the presence and absence of rat brain membranes. This apparent 'specific' binding of [3H]MDMA in both the presence and absence of brain homogenates was totally eliminated by pretreating glass fiber filter papers with polyethylenimine. Drug competition studies demonstrated that [3H]MDMA binding displays a distinct 'pharmacological' profile in the absence of brain tissue. These data indicate that apparent [3H]MDMA binding to rat brain homogenates results from artifactual of [3H]MDMA to glass fiber filter paper. In addition, uptake of [3H]MDMA into rat brain synaptosomes could not be detected. We conclude the [3H]MDMA has limited usefulness in radioligand binding studies.     

3,4-methylenedioxymethamphetamine (MDMA, ecstasy)-induced egr-1 mRNA in rat brain: pharmacological manipulation

Using in situ hybridization and immunohistochemical techniques, we examined the expression pattern of egr-1 mRNA and Egr-1 protein in several brain regions following administration of 3, 4-methylenedioxymethamphetamine (MDMA). Furthermore, we also studied the role of N-methyl-D-aspartate (NMDA) receptor, dopamine D(1) receptor, 5-hydroxytryptamine (5-HT) transporter or 5-HT(2A) receptor in the induction of egr-1 mRNA by MDMA. Basal constitutive levels of egr-1 mRNA were detected in control rat brains. A single administration of MDMA (10 mg/kg) caused marked induction of egr-1 mRNA in the prefrontal cortex, striatum and hippocampal dentate gyrus. However, no changes in the egr-1 mRNA levels were detected in the CA1 region of hippocampus and occipital cortex after administration of MDMA (10 mg/kg). Furthermore, the expression of egr-1 mRNA in the prefrontal cortex, striatum and hippocampal dentate gyrus after administration of MDMA (10 mg/kg) was blocked significantly by pretreatment with NMDA receptor antagonist (5R, 10S)-(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,b]-cyclohepten-5, 10-imine ((+)-MK801; 1 mg/kg), dopamine D(1) receptor antagonist SCH 23390 (1 mg/kg) or 5-HT uptake inhibitor paroxetine (5 mg/kg), but not by 5-HT(2A) receptor antagonist SR46349B (5 mg/kg). However, high basal levels of Egr-1 immunoreactivity in the rat brain were not altered by administration of MDMA (10 mg/kg). These results suggest that MDMA alters the expression of egr-1 mRNA in several regions of rat brain, and that the expression of egr-1 mRNA by MDMA in the prefrontal cortex, striatum and hippocampal dentate gyrus appears to be mediated, at least in part, by NMDA receptor, dopamine D(1) receptor and 5-HT transporter.     

3,4-Dihydroxymethamphetamine (HHMA). A major in vivo 3,4-methylenedioxymethamphetamine (MDMA) metabolite in humans

There is evidence that some heavy users of 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) show signs of neurotoxicity (a cognitive dysfunction, a larger incidence of psychopathology). It has been postulated that the catechol intermediates of methylenedioxyamphetamines such as 3,4-dihydroxymethamphetamine (HHMA), a metabolite of MDMA, may play a role in their neurotoxicity by formation of thioether adducts. This study describes the first validated method for HHMA determination in plasma and urine by strong cation-exchange solid-phase extraction high-performance liquid chromatography/electrochemical detection (HPLC/ED) analysis. The method has been applied for the determination of HHMA in plasma and urine samples from a clinical study in healthy volunteers of MDMA and provides preliminary kinetic data on this metabolite. HHMA appeared to be a major MDMA metabolite with plasma concentrations as high as the parent compound. Thus, HHMA C(max) (154.5 microg/L) and AUC(0-24h)(1990.9 microg/L h) were similar to those obtained in previously published reports for MDMA (181.6 microg/L and 1465.9 microg/L h, respectively). The 24-h urinary recovery of HHMA accounted for 17.7% of the MDMA dose administered and increases the total 24 h recovery of MDMA and metabolites to 58% of the 100 mg dose administered. The determination of HHMA in plasma and urine samples is of interest in order to establish its relevance in MDMA metabolism and its possible contribution to MDMA neurotoxicity in humans. Its validation showed appropriate accuracy and precision for its use in pharmacokinetic studies.     

3,4-methylenedioxymethamphetamine (MDMA) intoxication in an infant chronically exposed to cocaine

Accidental ingestion of 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) was detected in an infant admitted at the Pediatric Emergency Department by drug testing in urine. Concentrations of MDMA and its principal metabolite 4-hydroxy-3-methoxymethamphetamine (HMMA) in the infant's hydrolyzed urine were 11.7 mg/L and 34.4 mg/L, respectively. Apparent febrile convulsions and cardiovascular side effects resolved within 1 day after treatment with benzodiazepines. Chronic exposure to cocaine was evidenced by segmental hair analysis. Continuous maternal denial of the presence of any drug in the household made diagnosis of accidental ingestion of MDMA and chronic exposure to cocaine problematic. Periodic clinical and laboratory follow-ups were requested to check eventual long-term effects of exposure to illicit drugs and discontinuation of the child from exposure to dangerous environments.     

Serotonergic-dopaminergic mediation of 3,4-methylenedioxymethamphetamine (MDMA, "ecstasy")

A series of three experiments were conducted to investigate the possible serotonergic and dopaminergic mediation of the discriminative stimulus properties of the "designer" drug MDMA. In Experiment 1, rats trained to discriminate 1.5 mg/kg (+/-)-MDMA from its vehicle at 20 min postadministration were shown to generalize to another drug of abuse, N-ethyl-3,4-methylenedioxyamphetamine (MDE) and to the serotonergically-active agents norfenfluramine and TFMPP. In contrast, testing of various dopaminergically-active agonists did not result in MDMA-like responding. In Experiment 2, dopaminergic and serotonergic antagonist were employed to observe their effect upon MDMA discrimination at 20 min postinjection. The serotonin antagonist pirenperone significantly decreased MDMA discrimination, whereas the dopamine decreasing drugs CGS 10746B and haloperidol had no effect. In Experiment 3, another group of rats were trained to discriminate MDMA at 105 min postadministration to investigate if, at this (later) time, the dopaminergic properties of MDMA may be more salient. Indeed, the dopaminergically-active drugs had a heightened effect upon MDMA at this later time, although the serotonergic component of the MDMA discriminative stimulus was predominant. The results suggest that the effects of MDMA at 20 min postadministration are solely serotonergic in nature. At 105 min postinjection there appears to be the presence of a weak dopaminergic component. This biphasic serotonergic-then-dopaminergic action of MDMA may explain the reported human experience with the drug, as well as the often controversial results in the literature.     

Acute effects of 3,4-methylenedioxymethamphetamine (MDMA) on monoamines in rat caudate.

Extracellular levels of dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), 5-hydroxyindoleacetic acid (5-HIAA) and serotonin (5-HT) were assayed in the caudate of freely moving rats using microdialysis and high performance liquid chromatography with electrochemical detection (HPLC-EC) to detect changes in their release. Dialysates were assayed at 20-minute intervals for four hours after an intraperitoneal (IP) injection of MDMA (10 mg/kg). In a separate study to determine MDMA effects on total caudate levels of the above neurochemicals, animals were injected IP with MDMA (10 mg/kg) and then sacrificed at 20, 60, 120 and 180 minutes after treatment. Brains were quickly removed, and caudate nuclei were dissected for neurochemical analysis using HPLC-EC. MDMA elicited an amphetamine-like increase in DA release, followed by an increase in DA content. DOPAC and HVA were both reduced in homogenate. 5-HT release was also increased, followed by a drop in caudate homogenate levels by three hours. DA extracellular content was 686% of control at 80 minutes; caudate homogenate levels were 122% at 120 minutes. 5-HT extracellular release was 123% at 20 minutes, then decreased thereafter. It is concluded that the acute effect of MDMA on caudate is at least as great on the DA as it is on the 5-HT system.     

MDMA (3,4-methylenedioxymethamphetamine) inhibits the firing of dorsal raphe neurons in brain slices via release of serotonin

The effects of MDMA (3,4-methylenedioxymethamphetamine) on the activity of serotonin (5-HT)-containing dorsal raphe neurons were characterized using extracellular single-unit recording and microdialysis techniques in the in vitro midbrain slice preparation. Addition of (+)-MDMA, (-)-MDMA or p-chloroamphetamine (PCA) to the superfusate (final concentration 3-100 microM) produced a concentration-dependent inhibition of 5-HT cell firing which was reversible and reproducible. Based upon IC50 values, (+)-MDMA was 2- to 3-fold more potent than (-)-MDMA. Pretreatment with the selective 5-HT uptake inhibitor fluoxetine, at a concentration which had no effect on baseline firing (20 microM), blocked the inhibitory effect of (+)-MDMA and PCA on dorsal raphe neurons. The selective norepinephrine uptake inhibitor desipramine (20 microM) was ineffective. In a parallel series of experiments, microdialysis probes resting on the brain slice surface provided a means to estimate 5-HT release from the dorsal raphe nucleus. (+)-MDMA (100 microM) caused the release of measureable quantities of 5-HT with a time course which corresponded to the change in dorsal raphe cell firing rate. Taken together, these data suggest that MDMA acts indirectly to inhibit dorsal raphe neurons through release of endogenous 5-HT.     

Self-injection of d,1-3,4-methylenedioxymethamphetamine (MDMA) in the baboon

MDMA (d,1-3,4-Methylenedioxymethamphetamine HCl; ecstasy) self-injection (0.1–3.2 mg/kg/injection) was examined in baboons under conditions in which baseline responding was maintained by intravenous injections of cocaine HCl (0.32 mg/kg/injection). Drug was available under a FR 160-response schedule of intravenous injection. Each drug injection was followed by a 3-h time out allowing a maximum of eight injections per day. MDMA or MDMA vehicle (saline) was substituted for cocaine for a period of 14 or more days followed by a return to the cocaine baseline. MDMA (0.32–3.2 mg/kg/inj) maintained more injections and higher responses rates than were maintained by saline. The maximal number of injections maintained by MDMA and the maximal response rate maintained by MDMA were less than those maintained under baseline conditions with cocaine. The highest dose of MDMA tested maintained a cyclic pattern of self-injection, i.e., days of high numbers of injections intermixed with days of low numbers of injections. At the highest dose of MDMA tested, concurrent food maintained behavior was suppressed to an extent that food intake was also decreased.