Synergistic toxicity of ethanol and MDMA towards primary cultured rat hepatocytes

Combining ecstasy and ethanol: higher risk for toxicity? A review

Ecstasy use is commonly combined with ethanol consumption. While combination drug use in general is correlated with a higher risk for toxicity, the risk of the specific combination of ecstasy (3,4-methylenedioxymethamphetamine (MDMA)) and ethanol is largely unknown. Therefore, we have reviewed the literature on changes in MDMA pharmacokinetics and pharmacodynamics due to concurrent ethanol exposure in human, animal and in vitro studies. MDMA pharmacokinetics appear unaffected: the MDMA blood concentration after concurrent exposure to MDMA and ethanol was comparable to lone MDMA exposure in multiple human placebo-controlled studies. In contrast, MDMA pharmacodynamics were affected: locomotor activity increased and body temperature decreased after concurrent exposure to MDMA and ethanol compared to lone MDMA exposure. Importantly, these additional ethanol effects were consistently observed in multiple animal studies. Additional ethanol effects have also been reported on other pharmacodynamic aspects, but are inconclusive due to a low number of studies or due to inconsistent findings. These investigated pharmacodynamic aspects include monoamine brain concentrations, neurological (psychomotor function, memory, anxiety, reinforcing properties), cardiovascular, liver and endocrine effects. Although only a single or a few studies were available investigating these aspects, most studies indicated an aggravation of MDMA-induced effects upon concurrent ethanol exposure. In summary, concurrent ethanol exposure appears to increase the risk for MDMA toxicity. Increased toxicity is due to an aggravation of MDMA pharmacodynamics, while MDMA pharmacokinetics is largely unaffected. Although a significant attenuation of the MDMA-induced increase of body temperature was observed in animal studies, its relevance for human exposure remains unclear.

Exogenous Ghrelin Could Not Ameliorate 3,4-methylenedioxymethamphetamine-induced Acute Liver Injury in The Rat: Involved Mechanisms

MDMA (3,4-methylenedioxymethamphetamine, ecstasy) is often abused by youth as a recreational drug. MDMA abuse is a growing problem in different parts of the world. An important adverse consequence of the drug consumption is hepatotoxicity of different intensities. However, the underlying mechanism of this toxicity has not been completely understood. Ghrelin is a gut hormone with growth hormone stimulatory effect. It expresses in liver, albeit at a much lower level than in stomach, and exerts a hepatoprotective effect. In this study, we investigated hepatotoxicity effect of MDMA alone and its combination with ghrelin as a hepatoprotective agent. MDMA and MDMA+ ghrelin could transiently increase serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) followed by tissue necrosis. However, they could significantly decrease liver tumor necrosis factor-a (TNF-±) in both treatment groups. Unexpectedly, in MDMA treated rats, Bax, Bcl-xl, Bcl-2, Fas, Fas ligand (Fas-L), caspase 8, cytochrome c, caspase 3 gene expression, and DNA fragmentation were nearly unchanged. In addition, apoptosis in MDMA+ ghrelin group was significantly reduced when compared with MDMA treated animals. In all, MDMA could transiently increase serum transaminases and induce tissue necrosis and liver toxicity. Ghrelin, however, could not stop liver enzyme rise and MDMA hepatotoxicity. MDMA hepatotoxicity seems to be mediated via tissue necrosis than apoptotic and inflammatory pathways. Conceivably, ghrelin as an anti-inflammatory and anti-apoptotic agent may not protect hepatocytes against MDMA liver toxicity.

3,4-Methylenedioxymethamphetamine Hepatotoxicity under the Heat Stress Condition: Novel Insights from in Vitro Metabolomic Studies

Hyperthermia has been extensively reported as a life-threatening consequence of 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) abuse. In this work, we used a sensitive untargeted metabolomic approach based on gas chromatography-mass spectrometry to evaluate the impact of hyperthermia on the hepatic metabolic changes caused by MDMA. For this purpose, primary mouse hepatocytes were exposed to subtoxic (LC₀₁ and LC₁₀) and toxic (LC₃₀) concentrations of MDMA for 24 h, at 37 or 40.5 °C (simulating body temperature increase after MDMA consumption), and alterations on both intracellular metabolome and extracellular volatilome were evaluated. Multivariate analysis showed that metabolic patterns clearly discriminate MDMA treated cells from control cells, both in normothermic and hyperthermic conditions. The metabolic signature was found to be largely common to MDMA subtoxic and toxic concentrations, although with evident differences in the magnitude of response, with metabolic changes significantly more pronounced at 40.5 °C. Discriminant metabolites associated with MDMA-induced hepatotoxicity are mostly involved in the amino acid metabolism, aminoacyl tRNA biosynthesis, glutathione metabolism, tricarboxylic acid cycle, and pyruvate metabolism. Moreover, our metabolomic findings were corroborated by classical toxicity parameters, demonstrating the high sensitivity of this omic approach to assess molecular-level effects. Overall, this study indicates that MDMA triggers significant metabolic alterations on hepatic cells, even at low concentrations, that are clearly exacerbated at high temperatures. These findings provide new metabolic pieces to solve the puzzle of MDMA's hepatotoxicity mechanism and emphasize the increased risks of MDMA abuse due to the thermogenic action of the drug.

Emerging club drugs: 5-(2-aminopropyl)benzofuran (5-APB) is more toxic than its isomer 6-(2-aminopropyl)benzofuran (6-APB) in hepatocyte cellular models

New phenylethylamine derivatives are among the most commonly abused new psychoactive substances. They are synthesized and marketed in lieu of classical amphetaminic stimulants, with no previous safety testing. Our study aimed to determine the in vitro hepatotoxicity of two benzofurans [6-(2-aminopropyl)benzofuran (6-APB) and 5-(2-aminopropyl)benzofuran (5-APB)] that have been misused as 'legal highs'. Cellular viability was assessed through the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) reduction assay, following 24-h drug exposure of human hepatoma HepaRG cells (EC₅₀ 2.62 mM 5-APB; 6.02 mM 6-APB), HepG2 cells (EC₅₀ 3.79 mM 5-APB; 8.18 mM 6-APB) and primary rat hepatocytes (EC₅₀ 964 μM 5-APB; 1.94 mM 6-APB). Co-incubation of primary hepatocytes, the most sensitive in vitro model, with CYP450 inhibitors revealed a role of metabolism, in particular by CYP3A4, in the toxic effects of both benzofurans. Also, 6-APB and 5-APB concentration-dependently enhanced oxidative stress (significantly increased reactive species and oxidized glutathione, and decreased reduced glutathione levels) and unsettled mitochondrial homeostasis, with disruption of mitochondrial membrane potential and decline of intracellular ATP. Evaluation of cell death mechanisms showed increased caspase-8, -9, and -3 activation, and nuclear morphological changes consistent with apoptosis; at concentrations higher than 2 mM, however, necrosis prevailed. Concentration-dependent formation of acidic vesicular organelles typical of autophagy was also observed for both drugs. Overall, 5-APB displayed higher hepatotoxicity than its 6-isomer. Our findings provide new insights into the potential hepatotoxicity of these so-called 'safe drugs' and highlight the putative risks associated with their use as psychostimulants.

Increased iNOS and Nitrosative Stress in Dopaminergic Neurons of MDMA-Exposed Rats

Several mechanisms underlying 3,4-Methylenedioxy-N-methylamphetamine (MDMA) neurotoxicity have been proposed, including neurochemical alterations and excitotoxicity mediated by reactive oxygen species (ROS), nitric oxide (NO), and reactive nitrogen species (RNS). However, ROS, NO, and RNS sources in the brain are not fully known. We aimed to investigate possible alterations in the expression of the ROS producer NOX enzymes (NOX2, NOX1, and NOX4), NO generators (iNOS, eNOS, and nNOS), markers of oxidative (8-hydroxy-2'-deoxyguanosine, 8OHdG), and nitrosative (3-nitrotyrosine, NT) stress, as well as the colocalization between cells positive for the dopamine transporter (DT1) and cells expressing the neuronal nuclei (NeuN) marker, in the frontal cortex of rats receiving saline or MDMA, sacrificed 6 h, 16 h, or 24 h after its administration. MDMA did not affect NOX2, NOX1, and NOX4 immunoreactivity, whereas iNOS expression was enhanced. The number of NT-positive cells was increased in MDMA-exposed animals, whereas no differences were detected in 8OHdG expression among experimental groups. MDMA and NT markers colocalized with DT1 positive cells. DT1 immunostaining was found in NeuN-positive stained cells. Virtually no colocalization was observed with microglia and astrocytes. Moreover, MDMA immunostaining was not found in NOX2-positive cells. Our results suggest that iNOS-derived nitrosative stress, but not NOX enzymes, may have a crucial role in the pathogenesis of MDMA-induced neurotoxicity, highlighting the specificity of different enzymatic systems in the development of neuropathological alterations induced by the abuse of this psychoactive compound.

GC-MS metabolomics reveals disturbed metabolic pathways in primary mouse hepatocytes exposed to subtoxic levels of 3,4-methylenedioxymethamphetamine (MDMA)

3,4-Methylenedioxymethamphetamine (MDMA, ecstasy) is a well-known hepatotoxic drug. Although its toxicity has been thoroughly studied at high concentrations, there is still insufficient knowledge on possible alterations of cell function at subtoxic concentrations, which are in fact more representative concentrations of intoxication scenarios. In this study, a gas chromatography-mass spectrometry (GC-MS) metabolomics approach was used to investigate the metabolic changes in primary mouse hepatocytes (PMH) exposed to two subtoxic concentrations of MDMA (LC₀₁ and LC₁₀) for 24 h. Metabolomic profiling of both intracellular metabolites and volatile metabolites in the extracellular medium of PMH was performed. Multivariate analysis showed that the metabolic pattern of cells exposed to MDMA discriminates from the controls in a concentration-dependent manner. Exposure to LC₁₀ MDMA induces a significant increase in some intracellular metabolites, including oleic acid and palmitic acid, and a decrease in glutamate, aspartate, 5-oxoproline, fumarate, malate, phosphoric acid, α-ketoglutarate and citrate. Extracellular metabolites such as acetophenone, formaldehyde, pivalic acid, glyoxal and 2-butanone were found significantly increased after exposure to MDMA, compared to controls, whereas 4-methylheptane, 2,4-dimethyl-1-heptene, nonanal, among others, were found significantly decreased. The panel of discriminatory metabolites is mainly involved in tricarboxylic acid (TCA) cycle, fatty acid metabolism, glutamate metabolism, antioxidant defenses and possibly changes in the liver enzyme machinery. Overall, these results highlight the potential of the intra- and extracellular metabolome to study alterations triggered by subtoxic concentrations of MDMA in hepatic cell functions, which represents a more realistic appraisal of early toxicity events posed by exposure to this drug. In addition, these results also revealed some metabolites that may be used as potential biomarkers indicative of early events in the hepatotoxicity induced by MDMA.

Effects of co-exposure to atrazine and ethanol on the oxidative damage of kidney and liver in Wistar rats

Both ethanol (EtoH) and atrazine (ATZ) have hepatic and nephro-toxic effects in rats. In the present study, the toxicity of EtoH (5 g kg-1) on the kidney and liver in the absence or in the presence of different doses of ATZ (50, 100, 300 mg kg-1) was evaluated after 21 days in rats. Results showed that the mixture effects on catalase and superoxide dismutase activities were more severe in both tissues compared to EtoH alone, especially as the dose of ATZ was increased. Hepatic malondialdehyde level (an index of lipid peroxidation) was increased from 20.32% in the EtoH +50 mg kg-1 ATZ-treated rats to 34% in the EtoH +300 mg kg-1 ATZ-treated rats compared to the EtoH values. Renal malondialdehyde values remain as high as 81% in the EtoH-treated rats and the different combine exposure groups. Furthermore, as the dose of ATZ in the mixture was increased, serum uric acid level increased compared to the EtoH values. When the EtoH +300 mg kg-1 ATZ-animals were pretreated with curcumin (an antioxidant), the histopathological changes and peroxidative damages in both tissues were blocked. The exposure of EtoH-treated rats to ATZ enhanced renal and hepatic peroxidative damages in rats.

How Postmortem Redistribution of MDMA in Acute Alcohol-MDMA Combined-Use Rats Change under Effects of Alcohol

MDMA is often taken recreationally with alcohol as combined-use. The objective was to determine MDMA postmortem redistribution (PMR) and corresponding effects in combined-style under different storage conditions. Steps were 20%-mixture of alcohol-water for initial 4 weeks to Group-A&B and intragastric infusions of MDMA (150 mg/kg) to Group-A later; in the same time, drinking pure water to Group-C&D first and then MDMA-fed to Group-C. The sacrificed rats were kept under different conditions for 10-d, during which the body fluids and tissues were collected on 15 continuous time-points and then detected. The MDMA concentrations were quite different along with postmortem interval (PMI) went by; the area under concentration-PMI curve significantly increased with combined-alcohol in comparison to MDMA alone, while that significantly decreased by lowering preservation temperature, allied with corresponding humidity. Combined-alcohol could exacerbate PMR of MDMA, as concentrations of combined-use rats’ samples were quite higher than mono-MDMA ones under any conditions, while different for body fluids and tissues; meanwhile lowering storage temperature could alleviate effects of alcohol. The study implies that in case of combined-use, the changes of concentrations are probably effected by some combined component, especially when come to identification of toxic level or even death.

Is biological aging accelerated in drug addiction?

Drug-addiction may trigger early onset of age-related disease, due to drug-induced multi-system toxicity and perilous lifestyle, which remains mostly undetected and untreated. We present the literature on pathophysiological processes that may hasten aging and its relevance to addiction, including: oxidative stress and cellular aging, inflammation in periphery and brain, decline in brain volume and function, and early onset of cardiac, cerebrovascular, kidney, and liver disease. Timely detection of accelerated aging in addiction is crucial for the prevention of premature morbidity and mortality.

Development of Blood-Brain Barrier Permeable Nitrocatechol-Based Catechol O-Methyltransferase Inhibitors with Reduced Potential for Hepatotoxicity

Recent efforts have been focused on the development of centrally active COMT inhibitors, which can be valuable assets for neurological disorders such as Parkinson's disease, due to the severe hepatotoxicity risk associated with tolcapone. New nitrocatechol COMT inhibitors based on naturally occurring caffeic acid and caffeic acid phenethyl ester were developed. All nitrocatechol derivatives displayed potent inhibition of peripheral and cerebral COMT within the nanomolar range. Druglike derivatives 13, 15, and 16 were predicted to cross the blood-brain barrier in vitro and were significantly less toxic than tolcapone and entacapone when incubated at 50 μM with rat primary hepatocytes. Moreover, their unique acidity and electrochemical properties decreased the chances of formation of reactive quinone-imines and, as such, the potential for hepatotoxicity. The binding mode of 16 confirmed that the major interactions with COMT were established via the nitrocatechol ring, allowing derivatization of the side chain for future lead optimization efforts.

3,4-Methylenedioxypyrovalerone (MDPV): in vitro mechanisms of hepatotoxicity under normothermic and hyperthermic conditions

Synthetic cathinones have emerged in recreational drug markets as legal alternatives for classical amphetamines. Though currently banned in several countries, 3,4-methylenedioxypyrovalerone (MDPV) is one of the most commonly abused cathinone derivatives worldwide. We have recently reported the potential of MDPV to induce hepatocellular damage, but the underlying mechanisms responsible for such toxicity remain to be elucidated. Similar to amphetamines, a prominent toxic effect of acute intoxications by MDPV is hyperthermia. Therefore, the present in vitro study aimed to provide insights into cellular mechanisms involved in MDPV-induced hepatotoxicity and also evaluate the contribution of hyperthermia to the observed toxic effects. Primary cultures of rat hepatocytes were exposed to 0.2-1.6 mM MDPV for 48 h, at 37 or 40.5 °C, simulating the rise in body temperature that follows MDPV intake. Cell viability was measured through the MTT reduction and LDH leakage assays. Oxidative stress endpoints and cell death pathways were evaluated, namely the production of reactive oxygen and nitrogen species (ROS and RNS), intracellular levels of reduced (GSH) and oxidized (GSSG) glutathione, adenosine triphosphate (ATP) and free calcium (Ca(2+)), as well as the activities of caspases 3, 8 and 9, and nuclear morphological changes with Hoechst 33342/PI double staining. At 37 °C, MDPV induced a concentration-dependent loss of cell viability that was accompanied by GSH depletion, as one of the first signs of toxicity, observed already at low concentrations of MDPV, with negligible changes on GSSG levels, followed by accumulation of ROS and RNS, depletion of ATP contents and increases in intracellular Ca(2+) concentrations. Additionally, activation of caspases 3, 8, and 9 and apoptotic nuclear morphological changes were found in primary rat hepatocytes exposed to MDPV, indicating that this cathinone derivative activates both intrinsic and extrinsic apoptotic death pathways. The cytotoxic potential of MDPV and all the studied endpoints were markedly aggravated under hyperthermic conditions (40.5 °C). In conclusion, these data suggest that MDPV toxicity in primary rat hepatocytes is mediated by oxidative stress, subsequent to GSH depletion and increased ROS and RNS accumulation, mitochondrial dysfunction, and impairment of Ca(2+) homeostasis. Furthermore, the rise in body temperature subsequent to MDPV abuse greatly exacerbates its hepatotoxic potential.

Colchicine effect on P-glycoprotein expression and activity: in silico and in vitro studies

Colchicine is a P-glycoprotein (P-gp) substrate that induces its expression, thus increasing the risk for unexpected pharmacokinetic interactions with this drug. Because increased P-gp expression does not always correlate with increased activity of this efflux pump, we evaluated the changes in both P-gp expression and activity induced by colchicine using an in vitro model. Caco-2 cells were incubated with 0.1-100 μM colchicine up to 96 h. Cytotoxicity was evaluated by the MTT and LDH leakage assays, P-gp expression and activity were evaluated by flow cytometry and P-gp ATPase activity was measured in MDR1-Sf9 membrane vesicles. Furthermore, colchicine fitting in P-gp induction and competitive inhibition pharmacophore hypothesis, and docking studies evaluating the interaction between colchicine and P-gp drug binding pocket were tested in silico. Significant cytotoxicity was noted after 48 h. At 24 h a significant increase in P-gp expression was observed, which was not accompanied by an increase in transport activity. Moreover, colchicine significantly increased P-gp ATPase activity, demonstrating to be actively transported by the pump. New pharmacophores were constructed to predict P-gp modulatory activity. Colchicine fitted both the P-gp induction and competitive inhibition models. In silico, colchicine was predicted to bind to the P-gp drug-binding pocket suggesting a competitive mechanism of transport. These results show that colchicine induced P-gp expression in Caco-2 cells but the activity of the protein remained unchanged, highlighting the need to simultaneously evaluate P-gp expression and activity. With the newly constructed pharmacophores, new drugs can be initially screened in silico to predict such potential pharmacokinetic interactions.

An insight into the hepatocellular death induced by amphetamines, individually and in combination: the involvement of necrosis and apoptosis

The liver is a vulnerable target for amphetamine toxicity, but the mechanisms involved in the drug's hepatotoxicity remain poorly understood. The purpose of the current research was to characterize the mode of death elicited by four amphetamines and to evaluate whether their combination triggered similar mechanisms in immortalized human HepG2 cells. The obtained data revealed a time- and temperature-dependent mortality of HepG2 cells exposed to 3,4-methylenedioxymethamphetamine (MDMA, ecstasy; 1.3 mM), methamphetamine (3 mM), 4-methylthioamphetamine (0.5 mM) and D-amphetamine (1.7 mM), alone or combined (1.6 mM mixture). At physiological temperature (37 °C), 24-h exposures caused HepG2 death preferentially by apoptosis, while a rise to 40.5 °C favoured necrosis. ATP levels remained unaltered when the drugs where tested at normothermia, but incubation at 40.5 °C provoked marked ATP depletion for all treatments. Further investigations on the apoptotic mechanisms triggered by the drugs (alone or combined) showed a decline in BCL-2 and BCL- XL mRNA levels, with concurrent upregulation of BAX, BIM, PUMA and BID genes. Elevation of Bax, cleaved Bid, Puma, Bak and Bim protein levels was also seen. To the best of our knowledge, Puma, Bim and Bak have never been linked with the toxicity induced by amphetamines. Time-dependent caspase-3/-7 activation, but not mitochondrial membrane potential (∆ψm) disruption, also mediated amphetamine-induced apoptosis. The cell dismantling was confirmed by poly(ADP-ribose)polymerase proteolysis. Overall, for all evaluated parameters, no relevant differences were detected between individual amphetamines and the mixture (all tested at equieffective cytotoxic concentrations), suggesting that the mode of action of the amphetamines in combination does not deviate from the mode of action of the drugs individually, when eliciting HepG2 cell death.

Combination effects of amphetamines under hyperthermia - the role played by oxidative stress

Rise in body temperature is a life-threatening consequence of 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) abuse. We evaluated the impact of hyperthermia on the cytotoxicity of combinations of MDMA and three other amphetamines, often co-ingested. For this, Hep G2 cells were exposed to MDMA, d-amphetamine, methamphetamine and 4-methylthioamphetamine, individually or combined, at 40.5 °C. The results were compared with normothermia data (37.0 °C). Mixture additivity expectations were calculated by independent action and concentration addition (CA) models. To delineate the mechanism(s) underlying the elicited effects, a range of stress endpoints was evaluated, including quantification of reactive oxygen/nitrogen species (ROS/RNS), lipid peroxidation, reduced/oxidized glutathione (GSH/GSSG), ATP and mitochondrial membrane potential (Δψm) changes. Our data show that, in hyperthermia, amphetamines acted additively and mixture effects were accurately predicted by CA. At 40.5 °C, even slight increases in the concentrations of each drug/mixture promoted significant rises in cytotoxicity, which quickly shifted from roughly undetectable to maximal mortality. Additionally, the increase of RNS/ROS production, decrease of GSH, ATP depletion and mitochondrial impairment were exacerbated under hyperthermia. Importantly, when equieffective cytotoxic concentrations of the mixture and individual amphetamines were compared for all tested stress endpoints, mixture effects did not deviate from those elicited by individual treatments, suggesting that these amphetamines have a similar mode of action, which is not altered in combination. Concluding, our data indicate that amphetamine mixtures produce deleterious effects, even when individual drugs are combined at negligible concentrations. These effects are strongly exacerbated in hyperthermia, emphasizing the potential increased risks of ecstasy intake, especially when hyperthermia occurs concurrently with polydrug abuse.

Neurotoxicity of "ecstasy" and its metabolites in human dopaminergic differentiated SH-SY5Y cells

"Ecstasy" (3,4-methylenedioxymethamphetamine or MDMA) is a widely abused recreational drug, reported to produce neurotoxic effects, both in laboratory animals and in humans. MDMA metabolites can be major contributors for MDMA neurotoxicity. This work studied the neurotoxicity of MDMA and its catechol metabolites, α-methyldopamine (α-MeDA) and N-methyl-α-methyldopamine (N-Me-α-MeDA) in human dopaminergic SH-SY5Y cells differentiated with retinoic acid and 12-O-tetradecanoyl-phorbol-13-acetate. Differentiation led to SH-SY5Y neurons with higher ability to accumulate dopamine and higher resistance towards dopamine neurotoxicity. MDMA catechol metabolites were neurotoxic to SH-SY5Y neurons, leading to caspase 3-independent cell death in a concentration- and time-dependent manner. MDMA did not show a concentration- and time-dependent death. Pre-treatment with the antioxidant and glutathione precursor, N-acetylcysteine (NAC), resulted in strong protection against the MDMA metabolites' neurotoxicity. Neither the superoxide radical scavenger, tiron, nor the inhibitor of the dopamine (DA) transporter, GBR 12909, prevented the metabolites' toxicity. Cells exposed to α-MeDA showed an increase in intracellular glutathione (GSH) levels, which, at the 48 h time-point, was not dependent in the activity increase of γ-glutamylcysteine synthetase (γ-GCS), revealing a possible transient effect. Importantly, pre-treatment with buthionine sulfoximine (BSO), an inhibitor of γ-GCS, prevented α-MeDA induced increase in GSH levels, but did not augment this metabolite cytotoxicity. Even so, BSO pre-treatment abolished NAC protective effects against α-MeDA neurotoxicity, which were, at least partially, due to GSH de novo synthesis. Inversely, pre-treatment of cells with BSO augmented N-Me-α-MeDA-induced neurotoxicity, but only slightly affected NAC neuroprotection. In conclusion, MDMA catechol metabolites promote differential toxic effects to differentiated dopaminergic human SH-SY5Y cells.

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.

Mechanisms of MDMA (ecstasy)-induced oxidative stress, mitochondrial dysfunction, and organ damage

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.

Water extracts of Brassica oleracea var. costata potentiate paraquat toxicity to rat hepatocytes in vitro

Tronchuda cabbage extracts have been proven to have antioxidant potential against various oxidative species in cell free systems, though its antioxidant potential in cellular models remained to be demonstrated. In the present study, we used primary cultures of rat hepatocytes for the cellular assay system and paraquat PQ exposure as a pro-oxidant model agent, to test whether tronchuda cabbage hydrolysed water extracts provide protective or aggravating effects towards PQ-induced oxidative stress and cell death. For this purpose cellular parameters related to oxidative stress were measured, namely the generation of superoxide anion, glutathione oxidation, lipid peroxidation, intracellular ATP levels, activation of nuclear factor-kappaB (NF-kappaB), activity of antioxidant enzymes, and cell death. The obtained results demonstrated that the studied hydrolysed water extracts of tronchuda cabbage, especially rich in kaempferol (84%) and other polyphenols, namely hydroxycinnamic acids and traces of quercetin, can potentiate the toxicity of PQ in primary cultures of rat hepatocytes. These results highlight that prospective antioxidant effects of plant extracts, observed in vitro, using non-cellular systems, are not always confirmed in cellular models, in which the concentrations required to scavenge pro-oxidant species may be highly detrimental to the cells.