MDMA Induces Caspase-3 Activation in the Limbic System but not in Striatum

Of mice and men on MDMA: A translational comparison of the neuropsychobiological effects of 3,4-methylenedioxymethamphetamine ('Ecstasy')

MDMA (3,4-methylendioxymethamphetamine), also known as Ecstasy, is a stimulant drug recreationally used by young adults usually in dance clubs and raves. Acute MDMA administration increases serotonin, dopamine and noradrenaline by reversing the action of the monoamine transporters. In this work, we review the studies carried out over the last 30 years on the neuropsychobiological effects of MDMA in humans and mice and summarise the current knowledge. The two species differ with respect to the neurochemical consequences of chronic MDMA, since it preferentially induces serotonergic dysfunction in humans and dopaminergic neurotoxicity in mice. However, MDMA alters brain structure and function and induces hormonal, psychomotor, neurocognitive, psychosocial and psychiatric outcomes in both species, as well as physically damaging and teratogen effects. Pharmacological and genetic studies in mice have increased our knowledge of the neurochemical substrate of the multiple effects of MDMA. Future work in this area may contribute to developing pharmacological treatments for MDMA-related disorders.

The Mediating Role of A2A Adenosine Receptors in the Mitochondrial Pathway of Apoptotic Hippocampal Cell Death, Following the Administration of MDMA in Rat

Introduction:

The 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) is a popular recreational drug and a major source of substance abuse, which ultimately leads to sensations of well-being, elation and euphoria, moderate derealization/depersonalization, and cognitive disruptions, as well as intense sensory awareness. The mechanisms involved in memory impairment induced by MDMA are not completely understood.

Methods:

The current study used 40 Sprague-Dawley rats, weighted 200 to 250 g. Experiments were performed in four groups, each containing 10 rats. The first group of rats was used as the control, treated with dimethyl sulfoxide (DMSO). The second group was treated with MDMA. The third group was treated with MDMA and CGS (the adenosine A_2A receptor agonist, 2-[p-(2-carboxyethyl) phenethylamino]-5′-N-ethylcarboxamidoadenosine) (CGS 21680) and the fourth group was treated with MDMA and SCH (the A_2A receptor antagonist [7-(2-phenylethyl)-5-amino-2-(2-furyl-) pyrazolo-[4, 3-e]-1, 2, 4 triazolo [1,5-] pyrimidine]) (SCH 58261). The drugs in all groups were administrated intraperitoneally (i.p.) once a day for 7 days. In 5 rats of each group, following perfusion, samples were taken from hippocampi to investigate apoptosis. Accordingly, the samples were stained using the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay kit, and studied by light microscopy. In other rats, fresh tissue was also removed to study the expression of bax and bcl-2 by Western blotting technique.

Results:

It was observed that the coadministration of MDMA with CGS reduced bax expression and prevented apoptosis of hippocampal cells. The coadministration of MDMA and SCH increased bax expression, and also increased the frequency of hippocampal cell apoptosis.

Conclusion:

The results of the current study showed that administration of CGS with MDMA decreased the common side effects associated with MDMA.

Effects of dextromethorphan on MDMA-induced serotonergic aberration in the brains of non-human primates using [123I]-ADAM/SPECT

3,4-Methylenedioxymethamphetamine (MDMA), a common recreational drug, is known to cause serotonergic neurotoxicity in the brain. Dextromethorphan (DM) is a widely used antitussive reported to exert anti-inflammatory effect in vivo. In this study, we examined the long-term effect of MDMA on the primate serotonergic system and the protective property of DM against MDMA-induced serotonergic abnormality using single photon emission computed tomography (SPECT). Nine monkeys (Macaca cyclopis) were divided into three groups, namely control, MDMA and co-treatment (MDMA/DM). [¹²³I]-ADAM was used as the radioligand for serotonin transporters (SERT) in SPECT scans. SERT levels of the brain were evaluated and presented as the uptake ratios (URs) of [¹²³I]-ADAM in several regions of interest of the brain including midbrain, thalamus and striatum. We found that the URs of [¹²³I]-ADAM were significantly lower in the brains of MDMA than control group, indicating lower brain SERT levels in the MDMA-treated monkeys. This MDMA-induced decrease in brain SERT levels could persist for over four years. However, the loss of brain SERT levels was not observed in co-treatment group. These results suggest that DM may exert a protective effect against MDMA-induced serotonergic toxicity in the brains of the non-human primate.

MDMA decreases glutamic acid decarboxylase (GAD) 67-immunoreactive neurons in the hippocampus and increases seizure susceptibility: Role for glutamate

3,4-Methylenedioxy-methamphetamine (MDMA) is a unique psychostimulant that continues to be a popular drug of abuse. It has been well documented that MDMA reduces markers of 5-HT axon terminals in rodents, as well as humans. A loss of parvalbumin-immunoreactive (IR) interneurons in the hippocampus following MDMA treatment has only been documented recently. In the present study, we tested the hypothesis that MDMA reduces glutamic acid decarboxylase (GAD) 67-IR, another biochemical marker of GABA neurons, in the hippocampus and that this reduction in GAD67-IR neurons and an accompanying increase in seizure susceptibility involve glutamate receptor activation. Repeated exposure to MDMA (3×10mg/kg, ip) resulted in a reduction of 37-58% of GAD67-IR cells in the dentate gyrus (DG), CA1, and CA3 regions, as well as an increased susceptibility to kainic acid-induced seizures, both of which persisted for at least 30days following MDMA treatment. Administration of the NMDA antagonist MK-801 or the glutamate transporter type 1 (GLT-1) inducer ceftriaxone prevented both the MDMA-induced loss of GAD67-IR neurons and the increased vulnerability to kainic acid-induced seizures. The MDMA-induced increase in the extracellular concentration of glutamate in the hippocampus was significantly diminished in rats treated with ceftriaxone, thereby implicating a glutamatergic mechanism in the neuroprotective effects of ceftriaxone. In summary, the present findings support a role for increased extracellular glutamate and NMDA receptor activation in the MDMA-induced loss of hippocampal GAD67-IR neurons and the subsequent increased susceptibility to evoked seizures.

MDMA-induced loss of parvalbumin interneurons within the dentate gyrus is mediated by 5HT2A and NMDA receptors

MDMA is a widely abused psychostimulant which causes a rapid and robust release of the monoaminergic neurotransmitters dopamine and serotonin. Recently, it was shown that MDMA increases extracellular glutamate concentrations in the dorsal hippocampus, which is dependent on serotonin release and 5HT2A/2C receptor activation. The increased extracellular glutamate concentration coincides with a loss of parvalbumin-immunoreactive (PV-IR) interneurons of the dentate gyrus region. Given the known susceptibility of PV interneurons to excitotoxicity, we examined whether MDMA-induced increases in extracellular glutamate in the dentate gyrus are necessary for the loss of PV cells in rats. Extracellular glutamate concentrations increased in the dentate gyrus during systemic and local administration of MDMA. Administration of the NMDA receptor antagonist, MK-801, during systemic injections of MDMA, prevented the loss of PV-IR interneurons seen 10 days after MDMA exposure. Local administration of MDL100907, a selective 5HT2A receptor antagonist, prevented the increases in glutamate caused by reverse dialysis of MDMA directly into the dentate gyrus and prevented the reduction of PV-IR. These findings provide evidence that MDMA causes decreases in PV within the dentate gyrus through a 5HT2A receptor-mediated increase in glutamate and subsequent NMDA receptor activation.

Mitochondria: key players in the neurotoxic effects of amphetamines

Amphetamines are a class of psychotropic drugs with high abuse potential, as a result of their stimulant, euphoric, emphathogenic, entactogenic, and hallucinogenic properties. Although most amphetamines are synthetic drugs, of which methamphetamine, amphetamine, and 3,4-methylenedioxymethamphetamine ("ecstasy") represent well-recognized examples, the use of natural related compounds, namely cathinone and ephedrine, has been part of the history of humankind for thousands of years. Resulting from their amphiphilic nature, these drugs can easily cross the blood-brain barrier and elicit their well-known psychotropic effects. In the field of amphetamines' research, there is a general consensus that mitochondrial-dependent pathways can provide a major understanding concerning pathological processes underlying the neurotoxicity of these drugs. These events include alterations on tricarboxylic acid cycle's enzymes functioning, inhibition of mitochondrial electron transport chain's complexes, perturbations of mitochondrial clearance mechanisms, interference with mitochondrial dynamics, as well as oxidative modifications in mitochondrial macromolecules. Additionally, other studies indicate that amphetamines-induced neuronal toxicity is closely regulated by B cell lymphoma 2 superfamily of proteins with consequent activation of caspase-mediated downstream cell death pathway. Understanding the molecular mechanisms at mitochondrial level involved in amphetamines' neurotoxicity can help in defining target pathways or molecules mediating these effects, as well as in developing putative therapeutic approaches to prevent or treat the acute- or long-lasting neuropsychiatric complications seen in human abusers.

Neurotoxicity of methamphetamine and 3,4-methylenedioxymethamphetamine

Amphetamines are a class of psychostimulant drugs that are widely abused for their stimulant, euphoric, empathogenic and hallucinogenic properties. Many of these effects result from acute increases in dopamine and serotonin neurotransmission. Subsequent to these acute effects, methamphetamine and 3,4 methylenedioxymethamphetamine (MDMA) produce persistent damage to dopamine and serotonin nerve terminals. This review summarizes the numerous interdependent mechanisms including excitotoxicity, mitochondrial damage and oxidative stress that have been demonstrated to contribute to this damage. Emerging non-neuronal mechanisms by which the drugs may contribute to monoaminergic terminal damage, as well as the neuropsychiatric consequences of this terminal damage are also presented. Methamphetamine and 3,4-methylenedioxymethamphetamine (MDMA) have similar chemical structures and pharmacologic properties compared to other abused substances including cathinone (khat), as well as a relatively new class of novel synthetic amphetamines known as 'bath salts' that have gained popularity among drug abusers.

The neurotoxicity of hallucinogenic amphetamines in primary cultures of hippocampal neurons

3,4-Methylenedioxymethamphetamine (MDMA or "Ecstasy") and 2,5-dimethoxy-4-iodoamphetamine hydrochloride (DOI) are hallucinogenic amphetamines with addictive properties. The hippocampus is involved in learning and memory and seems particularly vulnerable to amphetamine's neurotoxicity. We evaluated the neurotoxicity of DOI and MDMA in primary neuronal cultures of hippocampus obtained from Wistar rat embryos (E-17 to E-19). Mature neurons after 10 days in culture were exposed for 24 or 48 h either to MDMA (100-800 μM) or DOI (10-100 μM). Both the lactate dehydrogenase (LDH) release and the tetrazolium-based (MTT) assays revealed a concentration- and time-dependent neuronal death and mitochondrial dysfunction after exposure to both drugs. Both drugs promoted a significant increase in caspase-8 and caspase-3 activities. At concentrations that produced similar levels of neuronal death, DOI promoted a higher increase in the activity of both caspases than MDMA. In the mitochondrial fraction of neurons exposed 24h to DOI or MDMA, we found a significant increase in the 67 kDa band of apoptosis inducing factor (AIF) by Western blot. Moreover, 24h exposure to DOI promoted an increase in cytochrome c in the cytoplasmatic fraction of neurons. Pre-treatment with an antibody raised against the 5-HT(2A)-receptor (an irreversible antagonist) greatly attenuated neuronal death promoted by 48 h exposure to DOI or MDMA. In conclusion, hallucinogenic amphetamines promoted programmed neuronal death involving both the mitochondria machinery and the extrinsic cell death key regulators. Death was dependent, at least in part, on the stimulation of the 5-HT(2A)-receptors.

Effects of 3,4-methylenedioxymethamphetamine administration on retinal physiology in the rat

3,4-Methylenedioxymethamphetamine (MDMA; ecstasy) is known to produce euphoric states, but may also cause adverse consequences in humans, such as hyperthermia and neurocognitive deficits. Although MDMA consumption has been associated with visual problems, the effects of this recreational drug in retinal physiology have not been addressed hitherto. In this work, we evaluated the effect of a single MDMA administration in the rat electroretinogram (ERG). Wistar rats were administered MDMA (15 mg/kg) or saline and ERGs were recorded before (Baseline ERG), and 3 h, 24 h, and 7 days after treatment. A high temperature (HT) saline-treated control group was also included. Overall, significantly augmented and shorter latency ERG responses were found in MDMA and HT groups 3 h after treatment when compared to Baseline. Twenty-four hours after treatment some of the alterations found at 3 h, mainly characterized by shorter latency, tended to return to Baseline values. However, MDMA-treated animals still presented increased scotopic a-wave and b-wave amplitudes compared to Baseline ERGs, which were independent of temperature elevation though the latter might underlie the acute ERG alterations observed 3 h after MDMA administration. Seven days after MDMA administration recovery from these effects had occurred. The effects seem to stem from specific changes observed at the a-wave level, which indicates that MDMA affects subacutely (at 24 h) retinal physiology at the outer retinal (photoreceptor/bipolar) layers. In conclusion, we have found direct evidence that MDMA causes subacute enhancement of the outer retinal responses (most prominent in the a-wave), though ERG alterations resume within one week. These changes in photoreceptor/bipolar cell physiology may have implications for the understanding of the subacute visual manifestations induced by MDMA in humans.

DNA fragmentation and oxidative stress in the hippocampal formation: a bridge between 3,4-methylenedioxymethamphetamine (ecstasy) intake and long-lasting behavioral alterations

Intake of 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) in humans leads to marked behavioral alterations. In a recent paper, we demonstrated that chronic MDMA intake produces a latent hippocampal hyperexcitability that parallels a reduced threshold for limbic seizures and a slowing of electroencephalographic activity. These phenomena suggest an alteration in hippocampal function. So far, only a few studies have focused on the hippocampal formation as a potential target for the effects induced by MDMA. In this study we sought to evaluate whether the intrinsic cells of the hippocampus might be modified chronically by ecstasy intake. In particular, we examined whether administration of MDMA, at doses producing hippocampal hyperexcitability also produces rearrangements of DNA strands measured by the comet assay. We found that MDMA, at very low doses, comparable with those self-administered by humans, produces acute oxidative stress and DNA single and double-strand breaks, which persist together with long-lasting metabolic changes in the hippocampal formation. These persisting effects are accompanied by behavioral sensitization, reduced seizure threshold and long-lasting slowing of electroencephalographic activity, and hyperexcitability of the hippocampus, without affecting the basal ganglia. The present data indicate that the intake of very low doses of MDMA, comparable to those consumed by humans, produces selective hippocampal alterations which may underlie cognitive impairment and seizure susceptibility.

Calpain and caspase proteolytic markers co-localize with rat cortical neurons after exposure to methamphetamine and MDMA

Abuse of the club drugs Methamphetamine (Meth) and Ecstasy (MDMA) is an international problem. The seriousness of this problem is the result of what appears to be programmed cell death (PCD) occurring within the brain following their use. This follow up study focused on determining which cell types, neurons and/or glial cells, were affected in the brains of drug-injected rats. Two proteolytic enzyme families involved in PCD, calpains and caspases, were previously shown to be activated and to degrade the brain cytoskeletal associated protein alphaII-spectrin. Using methods employed and confirmed in traumatic brain injury (TBI) studies, rat brain tissues were examined, 24 and 48 h after Meth and MDMA exposure, for the activation of calpain-1 and caspase-3, and their subsequent alphaII-spectrin cleavage breakdown products (SBDPs), SBDP145, and SBDP120, respectively. Based upon our previous studies we know that activated calpain-1 and caspase-3 were up-regulated after drug use as were the levels of their cleaved SBDPs, SBDP145, and SBDP120, respectively, which is indicative of PCD. Here we show that activated calpain-1 and caspase-3 increases could be localized to neurons in the cortex where the products of their cleaved targets were found to be concentrated, particularly, to the axonal regions. These findings support the hypothesis that calpains and caspases mediate PCD in cortical neurons following club drug abuse and, more importantly, appear to contribute to the neuropathology suffered by abusers.