Current Pharmaceutical Biotechnology - Volume 11, Issue 5, 2010

This special issue of Current Pharmaceutical Biotechnology contains in depth reviews on latest and most important research developments about 3,4-Methylenedioxy-N-methylamphetamine (MDMA), a semisynthetic entactogen of the phenethylamine family. MDMA is considered a recreational drug and has long had a strong association with the rave culture. The use of ecstasy became widespread among young people, finally providing clear evidence that the drug is not harmless. MDMA is listed by the US Drug Enforcement Administration as a highly addictive and therapeutically risky drug. The increasing recreational use of MDMA led to a number of cases of intoxication, but these were still insufficient (partly due to the superficiality of case reports) to draw a clear picture of the pathological effects. Studying the problem is difficult because different experimental animals respond differently both from other models and from humans. In general, the acute effects of MDMA seem to be more or less the same in most animal models, but the models diverge widely when it comes to their ability to produce the changes induced by chronic exposure. Taken together, these studies show a close relationship between MDMA abuse and multiple organs' injury both in humans and in animals. Turillazzi and co-workers focus about the evidence that MDMA produces acute and long-lasting toxic effects in animals and humans. The conditions under which ecstasy is taken play a role in determining the pathological effects it provokes. This review of existing evidences on MDMA - related pathological findings both in humans and animals may aid in understanding the effects of MDMA on different organs. Together, the use of advanced animal models, in particular genetically modified mice, has significantly contributed to our understanding of the mechanisms underlying the (toxic) effects of MDMA. Stove and collaborators stress the role of these models, together with models under development; advanced animal models, in particular genetically modified mice may help to answer remaining questions and may assist in the development of therapies, aimed at ameliorating potential neuronal damage and cognitive impairment following abuse of MDMA and related substances. The aim of the review introduced by Byoung-Joon Song and his research group, is to present an update of the mechanistic studies on MDMA-mediated organ damage partly caused by increased oxidative/nitrosative stress. They briefly describe a method to systematically identify oxidatively-modified mitochondrial proteins in control and MDMA-exposed rats by using biotin-N-maleimide (biotin-NM) as a sensitive probe for oxidized proteins. Furthermore, some of the potential targets (including Bcl-2 family proteins involved in apoptosis) of these stress-activated protein kinases need to be experimentally demonstrated in the future. Again, results in an increase in both ROS and RNS that produces oxidative stress, mitochondrial dysfunction, and inflammatory responses in various tissue of the body are described by Cerretani & Fiaschi. Whatever is need to considerate that the oxidative stress is one of the possible mechanisms of MDMA-induced toxicity and most of reports in literature concern “in vitro” experiments and “in vivo” animal models that presents it own limitations that make extrapolation from animals to human difficult, particularly when the process being studied incorporate many components. De Letter and co-workers review the current knowledge of possible interference by the post-mortem phenomena when interpreting a post-mortem 3,4-methylenedioxymethamphetamine (MDMA) blood level. Post-mortem distribution and redistribution of MDMA is of major interest, in order to evaluate which fluid and/or tissue sample after death most closely represents the ante-mortem concentration. To that aim, animal experimental and human data were closely considered and compared. The molecular mechanisms involved in the genesis of the neurotoxic effects are not yet fully clarified, but the oxidative stress, exitotoxicity, and mitochondrial dysfunction appear to be causal events that converge to mediate MDMA-induced neurotoxicity, as measured by loss of various markers of dopaminergic and serotonergic terminals. Sarkar & Schmued cover the following topics: pharmacological mechanisms, metabolic pathways and acute effects in laboratory animals, as well as in humans, with special attention on the mechanism of MDMA induced neurotoxicity. Although the studies on MDMA induced neurotoxicity started over two decades ago, the underlying mechanism of neurotoxicity has not yet been fully elucidated. In this review, they give an overview of the factors and mechanisms that might explain MDMA induced neurotoxicity....

Indirect effects of 3,4-Methylenedioxy-N-methylamphetamine (MDMA) and metabolites on the cardiac cells are well-known, the mechanism(s) underlying direct MDMA-induced cardiotoxicity remaining to be clarified. To better understand the immuno-inflammatory phenomena accompanying the cardiac alterations during MDMA administration, we conducted a study in an in vivo animal model to evaluate the cellular morphological alterations related to the biological response between MDMA administration and inflammatory cytokines (tumor necrosis factor-alpha, IL-1β, IL-6, 8, 10, and monocyte chemotactic protein-1). A total of 25 male rats were used. The effects were evaluated at 6, 16 and 24hours after a single dose MDMA administered (20 mg/kg i.p.). We found high levels of the cardioinhibitory cytokines in rat heart after 3 and 6hs from MDMA administration. Strongest reaction was observed at 24hs for TNF-α, IL-1β, IL-6, 8, 10 and for MCP-1. Furthermore, we still determined the presence of MDMA and MDA in the plasma of rats treated with MDMA intra-peritoneal single injection; it was present as early at 6hs and still present 24hs after treatment. Western blot analysis in cardiac samples demonstrated the IL-1β and IL-6 reactions in rats died spontaneously at fourth hour. The rise of the selective cardioinhibitory cytokines may be interpreted as the adaptive response of jeopardized myocardium to the cardiac dysfunction resulting from MDMA injection.

The party drug 3,4-methylenedioxymethamphetamine -better known as MDMA or ecstasy- has numerous effects on the human body, characterized by a rush of energy, euphoria and empathy. However, also a multitude of toxic/neurotoxic effects have been ascribed to MDMA, based upon case reports and studies in animals. Given the intrinsic difficulties associated with controlled studies in human beings, most of our insights into the biology of MDMA have been gained through animal studies. The vast majority of these studies utilizes a pharmacological approach to elucidate the mechanisms by which MDMA exerts its effects. Advances in genetics during the last decade have led to the development of several mouse models (transgenic or knockout) that have greatly contributed to our understanding of MDMA biology. This review provides an overview of these genetically modified animal models, in the light of some characteristic effects of MDMA, e.g. hyperlocomotion, neurotoxicity, hyperthermia, behaviour or rewarding. Without a shadow of a doubt, the next decade will bring many more advanced animal models, such as mice with site-specific deletion or rescue of genes and more genetically modified rat models. These models will further improve our knowledge on the pharmacology and toxicity of MDMA and, possibly, may assist in developing therapies coping with potential damage in abusers of MDMA and other drugs, as well as in patients suffering from specific neuronal pathologies.

Despite numerous reports about the acute and sub-chronic toxicities caused by MDMA (3,4- methylenedioxymethamphetamine, ecstasy), the underlying mechanism of organ damage is poorly understood. The aim of this review is to present an update of the mechanistic studies on MDMA-mediated organ damage partly caused by increased oxidative/nitrosative stress. Because of the extensive reviews on MDMA-mediated oxidative stress and tissue damage, we specifically focus on the mechanisms and consequences of oxidative-modifications of mitochondrial proteins, leading to mitochondrial dysfunction. We briefly describe a method to systematically identify oxidatively-modified mitochondrial proteins in control and MDMA-exposed rats by using biotin-N-maleimide (biotin-NM) as a sensitive probe for oxidized proteins. We also describe various applications and advantages of this Cys-targeted proteomics method and alternative approaches to overcome potential limitations of this method in studying oxidized proteins from MDMA-exposed tissues. Finally we discuss the mechanism of synergistic drug-interaction between MDMA and other abused substances including alcohol (ethanol) as well as application of this redox-based proteomics method in translational studies for developing effective preventive and therapeutic agents against MDMA-induced organ damage.

3,4-methylenedioxymethamphetamine (MDMA, Ecstasy) is a substituted amphetamine with potent central nervous stimulant effects. Increasing evidence suggests that one way of MDMA-induced toxicity involves the production of reactive oxygen and reactive nitrogen species and a subsequent production of oxidative/nitrosative stress. The free radicals can originate from several molecular pathways (oxidative deamination of monoamine, metabolic pathways, cathecolamines autoxidation, and hyperthermia) and their harmful effect causing potential biological damage such as lipoperoxidation and cellular death. The role of oxidative stress in mediating MDMA toxicity is illustrated by decreases in the activity of the endogenous enzymatic and non enzymatic antioxidants observed in cells in vitro and in animals model. This review examines the available evidence for the involvement of oxidative stress in the mechanisms of MDMA-induced cellular damage with the aim to contribute to the understanding of the cellular and molecular mechanisms involved in MDMA toxicity.

In this paper, the distribution and redistribution of the amphetamine derivative, 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) is brought into focus. Animal experimental data were compared with internationally reported MDMA-related human fatalities: in general, these turned out to be parallel with each other. Due to its inherent properties (e.g. significant volume of distribution), MDMA is liable to postmortem redistribution. Indeed, very high concentrations have been found in cardiac blood and tissues located centrally in the body (blood-rich organs such as lungs and liver in particular). This confirms that post-mortem redistribution due to diffusion from higher to lower concentration can easily take place, mainly at longer post-mortem intervals and when putrefaction occurs. Therefore, we can conclude that for post-mortem quantitation of amphetamine and derivatives, and MDMA in particular, peripheral blood sampling (e.g. femoral vein) remains compulsory. However, if the latter is impossible, MDMA quantification in a few alternative matrices such as vitreous humour and iliopsoas muscle may provide additional information to come to a reliable conclusion. Furthermore, it should be stressed that - at present - it is impossible to estimate the individual susceptibility to the various possible adverse effects of MDMA, which implies that it is impossible to provide a “safe” or “therapeutic” blood MDMA level. Therefore, in current forensic practice, the post-mortem pathological and toxicological findings should form an entity in order to draw a well-grounded conclusion.

“Ecstasy” (MDMA) is a powerful hallucinogenic drug which has raised concern worldwide because of its high abuse liability. A plethora of studies have demonstrated that MDMA has the potential to induce neurotoxicity both in human and laboratory animals. Although research on MDMA has been carried out by many different laboratories, the mechanism underlying MDMA induced toxicity has not been fully elucidated. MDMA has the ability to reduce serotonin levels in terminals of axons in the cortex of rats and mice. Recently we have shown that it also has the potential to produce degenerate neurons in discrete areas of the brain such as insular and parietal cortex, thalamus, tenia tecta and bed nucleus of stria terminalis (BST). Acute effects of MDMA can result in a constellation of changes including arrthymias, hypertension, hyperthermia, serotonin (5-HT) syndrome, liver problems, seizures and also long lasting neurocognitive impairments including mood disturbances. In human MDMA abusers, there is evidence for reduction of serotonergic biochemical markers. Several factors may contribute to the MDMA-induced neurotoxicity, especially hyperthermia. Other factors potentially influencing MDMA toxicity include monoamine oxidase metabolism of dopamine and serotonin, nitric oxide generation, glutamate excitotoxicity, serotonin 2A receptor agonism and the formation of MDMA neurotoxic metabolites. In this review we will cover the following topics: pharmacological mechanisms, metabolic pathways and acute effects in laboratory animals, as well as in humans, with special attention on the mechanism and pathology of MDMA induced neurotoxicity.

The recreational use of 3, 4 methylenedioxymethamphetamine (ecstasy or MDMA) has increased dramatically over the past thirty years due to its ability to increase stamina and produce feelings of emotional closeness and wellbeing. In spite of the popular perception that MDMA is a safe drug, there is a large literature documenting that the drug can produce significant neurotoxicity, especially in serotonergic and catecholaminergic systems. There are also experimental and clinical data which document that MDMA can alter cardiovascular function and produce cardiac toxicity, including rhythm disturbances, infarction and sudden death. This manuscript will review the literature documenting the cardiovascular responses elicited by MDMA in humans and experimental animals and will examine the underlying mechanisms mediating these responses. We will also review the available clinical, autopsy and experimental data linking MDMA with cardiac toxicity. Most available data indicate that oxidative stress plays an important role in the cardiotoxic actions of MDMA. Moreover, new data indicates that redox active metabolites of MDMA may play especially important roles in MDMA induced toxicity.

3,4-Methylenedioxymethamphetamine (MDMA or ecstasy) is a worldwide illegally used amphetamine-derived designer drug known to be hepatotoxic to humans. Jaundice, hepatomegaly, centrilobular necrosis, hepatitis and fibrosis represent some of the adverse effects caused by MDMA in the liver. Although there is irrefutable evidence of MDMA-induced hepatocellular damage, the mechanisms responsible for that toxicity remain to be thoroughly clarified. One well thought-of mechanism imply MDMA metabolism in the liver into reactive metabolites as responsible for the MDMA-elicited hepatotoxicity. However, other factors, including MDMA-induced hyperthermia, the increase in neurotransmitters efflux, the oxidation of biogenic amines, polydrug abuse pattern, and environmental features accompanying illicit MDMA use, may increase the risk for liver complications. Liver damage patterns of MDMA in animals and humans and current research on the mechanisms underlying the hepatotoxic effects of MDMA will be highlighted in this review.

Molecular and cellular mechanisms of MDMA-induced toxicity have been extensively studied in a number of experimental models. Nevertheless, only few studies investigated the involvement of HSPs (“molecular chaperones”) in MDMA organs toxicity. In the present minireview we highlight this subject analysing the results of these studies conducted especially on brain tissue. Despite of it seems obvious that HSPs overexpression is a protective reaction against MDMA treatment, the molecular mechanisms for exerting their action are far to be undiscovered. At the same time, we need of comprehensive studies concerning the whole range of Hsps/chaperones expressions in all organs after acute and chronic administration of MDMA.

Studies conducted in humans or in animals explored the presence, nature and potential causes of 3,4- methylenedioxymethamphetamine (MDMA) toxicity. According to literature, there are four principal types of such serious toxicity: hepatic, cardiovascular, cerebral and hyperpyrexic. The molecular mechanisms involved in the genesis of these toxic effects are not yet fully clarified, but the oxidative stress, excitotoxicity, and mitochondrial dysfunction appear to be causal events that converge to mediate MDMA-induced toxicity. Studies conducted on animals demonstrated that the acute administration of MDMA elicits cardiovascular responses that are similar to those elicited by d-amphetamine, and that these responses appear to involve catecholaminergic and non-catecholaminergic-dependent mechanisms. Although there is undeniable evidence of MDMA-induced cardiac toxicity, the mechanism responsible remains to be clarified. While many reports both in humans and in animals have demonstrated MDMA-induced liver damage, the underlying mechanism accounting for hepatic toxicity is poorly understood. Various mechanisms may contribute to MDMA-induced liver toxicity, including the metabolism of MDMA, the increased efflux of neurotransmitters, the oxidation of biogenic amines, and hyperthermia. The molecular mechanisms involved in the genesis of these toxic effects are not yet fully clarified, but the oxidative stress, excitotoxicity, and mitochondrial dysfunction appear to be causal events that converge to mediate MDMA-induced neurotoxicity, as measured by loss of various markers of dopaminergic and serotonergic terminals. The evidence is overwhelming that MDMA produces acute and long-lasting toxic anatomic effects in animals and humans. Anatomical and functional MDMA consequences must be better understood.

The pyruvate analog, 3-bromopyruvate, is an alkylating agent and a potent inhibitor of glycolysis. This antiglycolytic property of 3-bromopyruvate has recently been exploited to target cancer cells, as most tumors depend on glycolysis for their energy requirements. The anticancer effect of 3-bromopyruvate is achieved by depleting intracellular energy (ATP) resulting in tumor cell death. In this review, we will discuss the principal mechanism of action and primary targets of 3-bromopyruvate, and report the impressive antitumor effects of 3-bromopyruvate in multiple animal tumor models. We describe that the primary mechanism of 3-bromopyruvate is via preferential alkylation of GAPDH and that 3- bromopyruvate mediated cell death is linked to generation of free radicals. Research in our laboratory also revealed that 3- bromopyruvate induces endoplasmic reticulum stress, inhibits global protein synthesis further contributing to cancer cell death. Therefore, these and other studies reveal the tremendous potential of 3-bromopyruvate as an anticancer agent.

RNA interference (RNAi) is an evolutionary conserved mechanism by which small double-stranded RNA (dsRNA) — termed small interfering RNA (siRNA) — inhibit translation or degrade complementary mRNA sequences. Identifying features and enzymatic components of the RNAi pathway have led to the design of highly-effective siRNA molecules for laboratory and therapeutic application. RNA activation (RNAa) is a newly discovered mechanism of gene induction also triggered by dsRNAs termed small activating RNA (saRNA). It offers similar benefits as RNA interference (RNAi), while representing a new method of gene overexpression. In the present study, we identify features of RNAa and explore chemical modifications to saRNAs that improve the applicability of RNAa. We evaluate the rate of RNAa activity in order to define an optimal window of gene induction, while comparing the kinetic differences between RNAa and RNAi. We identify Ago2 as a conserved enzymatic component of both RNAa and RNAi implicating that saRNA may tolerate modification based on Ago2 function. As such, we define chemical modifications to saRNAs that manipulate RNAa activity, as well as exploit their effects to design saRNAs with enhanced medicinal properties. These findings reveal functional features of RNAa that may be utilized to augment saRNA function for mechanistic studies or the development of RNAa-based drugs.

In living cell or its nucleus, the motions of molecules are complicated due to the large crowding and expected heterogeneity of the intracellular environment. Randomness in cellular systems can be either spatial (anomalous) or temporal (heterogeneous). In order to separate both processes, we introduce anomalous random walks on fractals that represented crowded environments. We report the use of numerical simulation and experimental data of single-molecule detection by fluorescence fluctuation microscopy for detecting resolution limits of different mobile fractions in crowded environment of living cells. We simulate the time scale behavior of diffusion times τD(τ) for one component, e.g. the fast mobile fraction, and a second component, e.g. the slow mobile fraction. The less the anomalous exponent α the higher the geometric crowding of the underlying structure of motion that is quantified by the ratio of the Hausdorff dimension and the walk exponent df/dw and specific for the type of crowding generator used. The simulated diffusion time decreases for smaller values of α ≠ 1 but increases for a larger time scale τ at a given value of α ≠ 1. The effect of translational anomalous motion is substantially greater if α differs much from 1. An α value close to 1 contributes little to the time dependence of subdiffusive motions. Thus, quantitative determination of molecular weights from measured diffusion times and apparent diffusion coefficients, respectively, in temporal auto- and crosscorrelation analyses and from time-dependent fluorescence imaging data are difficult to interpret and biased in crowded environments of living cells and their cellular compartments; anomalous dynamics on different time scales τ must be coupled with the quantitative analysis of how experimental parameters change with predictions from simulated subdiffusive dynamics of molecular motions and mechanistic models. We first demonstrate that the crowding exponent α also determines the resolution of differences in diffusion times between two components in addition to photophyscial parameters well-known for normal motion in dilute solution. The resolution limit between two different kinds of single molecule species is also analyzed under translational anomalous motion with broken ergodicity. We apply our theoretical predictions of diffusion times and lower limits for the time resolution of two components to fluorescence images in human prostate cancer cells transfected with GFP-Ago2 and GFP-Ago1. In order to mimic heterogeneous behavior in crowded environments of living cells, we need to introduce so-called continuous time random walks (CTRW). CTRWs were originally performed on regular lattice. This purely stochastic molecule behavior leads to subdiffusive motion with broken ergodicity in our simulations. For the first time, we are able to quantitatively differentiate between anomalous motion without broken ergodicity and anomalous motion with broken ergodicity in time-dependent fluorescence microscopy data sets of living cells. Since the experimental conditions to measure a selfsame molecule over an extended period of time, at which biology is taken place, in living cells or even in dilute solution are very restrictive, we need to perform the time average over a subpopulation of different single molecules of the same kind. For time averages over subpopulations of single molecules, the temporal auto- and crosscorrelation functions are first found. Knowing the crowding parameter α for the cell type and cellular compartment type, respectively, the heterogeneous parameter γ can be obtained from the measurements in the presence of the interacting reaction partner, e.g. ligand, with the same α value. The product α • γ = γis not a simple fitting parameter in the temporal auto- and two-color crosscorrelation functions because it is related to the proper physical models of anomalous (spatial) and heterogeneous (temporal) randomness in cellular systems. We have already derived an analytical solution for γ in the special case of γ = 3/2 . In the case of two-color crosscorrelation or/and two-color fluorescence imaging (co-localization experiments), the second component is also a two-color species gr, for example a different molecular complex with an additional ligand. Here, we first show that plausible biological mechanisms from FCS/ FCCS and fluorescence imaging in living cells are highly questionable without proper quantitative physical models of subdiffusive motion and temporal randomness. At best, such quantitative FCS/ FCCS and fluorescence imaging data are difficult to interpret under crowding and heterogeneous conditions. It is challenging to translate proper physical models of anomalous (spatial) and heterogeneous (temporal) randomness in living cells and their cellular compartments like the nucleus into biological models of the cell biological process under study testable by single-molecule approaches. Otherwise, quantitative FCS/FCCS and fluorescence imaging measurements in living cells are not well described and cannot be interpreted in a meaningful way.