Relevance of MDMA (\ecstasy)-induced neurotoxicity to long-lasting psychomotor stimulation in mice (original) (raw)
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Behavioural analysis of the acute and chronic effects of MDMA treatment in the rat
Psychopharmacology, 1999
Rationale: A variety of animal models have shown MDMA (3,4-methylenedioxymethamphetamine) to be a selective 5-HT neurotoxin, though little is known of the long-term behavioural effects of the pathophysiology. The widespread recreational use of MDMA thus raises concerns over the long-term functional sequelae in humans. Objective: This study was designed to explore both the acute-and post-treatment consequences of a 3day neurotoxic exposure to MDMA in the rat, using a variety of behavioural paradigms. Methods: Following training to pretreatment performance criteria, animals were treated twice daily with ascending doses of MDMA (10, 15, 20 mg/kg) over 3 days. Body temperature, locomotor activity, skilled paw-reaching ability and performance of the delayed non-match to place (DNMTP) procedure was assessed daily during this period and on an intermittent schedule over the following 16 days. Finally, post mortem biochemical analyses of [ 3 H] citalopram binding and monoamine levels were performed. Results: During the MDMA treatment period, an acute 5-HT-like syndrome was observed which showed evidence of tolerance. Once drug treatment ceased the syndrome abated completely. During the post-treatment phase, a selective, delay-dependent, deficit in DNMTP performance developed. Post-mortem analysis confirmed reductions in markers of 5-HT function, in cortex, hippocampus and striatum. Conclusions: These results confirm that acutely MDMA exposure elicits a classical 5-HT syndrome. In the long-term, exposure results in 5-HT neurotoxicity and a lasting cognitive impairment. These results have significant implications for the prediction that use of MDMA in humans could have deleterious long-term neuropsychological/psychiatric consequences.
Initial deficit and recovery of function after MDMA preexposure in rats
Psychopharmacology, 2006
Rationale: 3,4-methylenedioxymethamphetamine (MDMA) exposure was reported to result in deficits in serotonergic neurotransmission with concomitant behavioral suppression and tolerance to MDMA. Some data have also suggested that the neurochemical deficits recover over time, raising the question as to whether behavioral suppression would show a similar recovery. Objectives: The possibility of recovery of behavioral deficits was examined in the present study. Rats were administered an MDMA pretreatment regimen that was shown to produce numerous serotonergic deficits and behavioral suppression 2 weeks thereafter. The full expression of MDMA-produced hyperactivity was dependent upon serotonergic integrity, therefore, the present study aimed to determine whether MDMA pretreated rats were tolerant to MDMA 2 weeks after exposure. Further, because serotonergic deficits have shown recovery over time, similar behavioral tests were conducted at a later time point to determine whether functional recovery was evident. Methods: MDMA-produced hyperactivity was measured at different withdrawal periods (2 and 12 weeks) to determine initial effects and the possibility of recovery of function. Results: In salinepretreated control rats, +/-MDMA (0.0-10.0 mg/kg) produced a dose-dependent increase in locomotor activity. Rats that had received prior exposure to MDMA (4×10 mg/ kg MDMA injections administered at 2 h intervals) demonstrated tolerance when the activity was measured 2 weeks after pretreatment. For these rats, there was a downward shift in the dose-effect curve for MDMAproduced hyperactivity. MDMA-produced hyperactivity in rats that were tested 12 weeks after pretreatment was, however, comparable to controls, suggesting recovery of function. Conclusion: These data are consistent with the idea that high dose MDMA exposure produces neuroadap-tations that exhibit recovery with extended abstinence from the drug.
Psychopharmacology, 1999
Rationale: 3,4-Methylenedioxymethamphetamine (MDMA) produces a long-term depletion of serotonin (5-HT) in the rat brain; this depletion may have some functional consequences. Objective: The aim of the present study was to evaluate the acute effects of MDMA on the extracellular concentrations of dopamine and 5-HT, body temperature and the 5-HT behavioral syndrome in rats 7 days following a neurotoxic regimen of MDMA. Methods: One week after the rats were treated with a neurotoxic regimen of MDMA (10 mg/kg, IP, every 2 h for a total of four injections), the rats were injected with a subsequent injection of MDMA. In vivo microdialysis combined with HPLC was utilized to measure the extracellular concentration of 5-HT and dopamine in the striatum. The increase in body temperature was determined by rectal temperature measurements, and the 5-HT behavioral syndrome was scored using a rating scale following the administration of MDMA.Results: The neurotoxic regimen produced a 45% reduction in brain 5-HT concentrations. The magnitude of the MDMA-induced increase in the extracellular concentration of 5-HT, but not dopamine, in the striatum produced by an acute injection of MDMA (7.5 mg/kg, IP) was reduced in rats treated previously with the neurotoxic regimen of MDMA when compared with that in control animals. In addition, the magnitude of the 5-HT behavioral syndrome, as well as the hyperthermic response, produced by MDMA was markedly diminished in rats that had previously received the neurotoxic regimen of MDMA. Conclusions: It is concluded that the long-term depletion of brain 5-HT produced by MDMA is accompanied by impairments in 5-HT function, as evidenced by the deficits in the neurochemical, thermal and behavioral responses to subsequent MDMA administration.
…, 2002
Rationale: Decreased 5-HT function has been shown to induce behaviour consistent with an "anxiolytic" effect. Administration of a single dose of 3,4-methylenedioxymethamphetamine (MDMA; "ecstasy" 12.5 mg/kg IP) to rats results in prolonged damage to central serotonergic nerve terminals. Thus we wished to assess whether an MDMA-induced lesion may have longer-term behavioural consequences. Objective: The study was designed to examine the behaviour of MDMA-pretreated and control animals in the elevated plus-maze and open field at a number of time-points, up to 80 days, after the administration of a single neurotoxic dose of MDMA (12.5 mg/kg IP). Results: MDMApretreated Dark Agouti rats demonstrated a statistically significant reduction in anxiety-related behaviour, compared to saline-pretreated control rats, in both the elevated plus-maze and open field when the rats were tested on day 73 (open field) and day 80 (plus maze) after MDMA administration. Conclusions: The behavioural consequences of a single neurotoxic dose of MDMA can be demonstrated over 2 months after administration of the compound, thereby indicating that long-term adaptive changes occur within the brain following the neurodegeneration of 5-HT neurones produced by this recreationally used drug.
Methamphetamine and MDMA (Ecstasy) Neurotoxicity: 'of Mice and Men
IUBMB Life (International Union of Biochemistry and Molecular Biology: Life), 2004
and 3,4-meythylenedioxymethamphetamine (MDMA; 'ecstasy') are currently major drugs of abuse. One of the major concerns of amphetamines abuse is their potential neurotoxic effect on dopaminergic and serotonergic neurons. Although data from human studies are somewhat limited, compelling evidence suggests that these drugs cause neurotoxicity in rodents and primates. Recent studies in transgenic and knockout mice identified the role of dopamine transporters, nitric oxide, apoptotic proteins, and inflammatory cytokines in amphetamines neurotoxicity. Further research into the mechanisms underlying the dopaminergic and serotonergic neurotoxicity and the behavioral corollaries of these neuronal insults could facilitate our understanding of the consequences of human abuse of METH and MDMA on cognition, drug-seeking behavior, extinction and relapse. IUBMB Life, 56: 249-255, 2004
Psychopharmacology, 2006
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 longterm 5-HT depletions can have protracted effects on behavior, suggesting even moderate doses of the drug may pose risks.
Neuropsychopharmacology, 2005
A large body of data indicates that (7)3,4-methylenedioxymethamphetamine (MDMA, 'ecstasy') can damage brain serotonin neurons in animals. However, the relevance of these preclinical data to humans is uncertain, because doses and routes of administration used in animals have generally differed from those used by humans. Here, we examined the pharmacokinetic profile of MDMA in squirrel monkeys after different routes of administration, and explored the relationship between acute plasma MDMA concentrations after repeated oral dosing and subsequent brain serotonin deficits. Oral MDMA administration engendered a plasma profile of MDMA in squirrel monkeys resembling that seen in humans, although the half-life of MDMA in monkeys is shorter (3 vs 6-9 h). MDMA was biotransformed into MDA, and the plasma ratio of MDA to MDMA was 3-5/100, similar to that in humans. MDMA accumulation in squirrel monkeys was nonlinear, and plasma levels were highly correlated with regional brain serotonin deficits observed 2 weeks later. The present results indicate that plasma concentrations of MDMA shown here to produce lasting serotonergic deficits in squirrel monkeys overlap those reported by other laboratories in some recreational 'ecstasy' consumers, and are two to three times higher than those found in humans administered a single 100-150 mg dose of MDMA in a controlled setting. Additional studies are needed on the relative sensitivity of brain serotonin neurons to MDMA toxicity in humans and non-human primates, the pharmacokinetic parameter(s) of MDMA most closely linked to the neurotoxic process, and metabolites other than MDA that may play a role.
Pharmacology Biochemistry and Behavior, 2008
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.
MDMA and the Brain: A Short Review on the Role of Neurotransmitters in ...
Basic and Clinical Neuroscience, 2020
N-Methyl-3, 4-methylenedioxyamphetamine (MDMA), or ecstasy is a recreational drug of abuse. It is a synthetic substance that affects the body's systems, which its mechanism of action and treatment should be more investigated. MDMA provides an immediate enjoyable feeling by stimulating the release of neurotransmitters, such as dopamine and serotonin in the brain. Unfortunately, abnormal regulation of the brain neurotransmitters, as well as the increased oxidative stress causes damage to the brain neurons after the MDMA exposure. Only a few studies have been done regarding its treatment. Thus, the treatment of MDMA complications should be further explored mainly by targeting its mechanism of action in the neurotransmitter systems. Hence, this study presents a short review regarding the recent findings on the role of neurotransmitters to cause MDMA neurotoxicity. The results will be useful for future research in elucidating the potential treatment based on the targeted mechanisms to treat the neurotoxic effects of MDMA.