d-Amphetamine interaction with glutathione in freshly isolated rat hepatocytes

4-Fluoromethamphetamine (4-FMA) induces in vitro hepatotoxicity mediated by CYP2E1, CYP2D6, and CYP3A4 metabolism

4-Fluoromethamphetamine (4-FMA) is an amphetamine-like psychoactive substance with recognized entactogenic and stimulant effects, but hitherto unclear toxicological mechanisms. Taking into consideration that the vast majority of 4-FMA users consume this substance through oral route, the liver is expected to be highly exposed. The aim of this work was to determine the hepatotoxic potential of 4-FMA using in vitro hepatocellular models: primary rat hepatocytes (PRH), human hepatoma cell lines HepaRG and HepG2, and resorting to concentrations ranging from 37 μM to 30 mM, during a 24-h exposure. EC₅₀ values, estimated from the MTT viability assay data, were 2.21 mM, 5.59 mM and 9.57 mM, for each model, respectively. The most sensitive model, PRH, was then co-exposed to 4-FMA and cytochrome P450 (CYP) inhibitors to investigate the influence of metabolism on the toxicity of 4-FMA. Results show that CYP2E1, CYP3A4 and CYP2D6 have major roles in 4-FMA cytotoxicity. Inhibition of CYP2D6 and CYP3A4 led to left-geared shifts in the concentration-response curves of 4-FMA, hinting at a role of these metabolic enzymes for detoxifying 4-FMA, while CYP2E1 inhibition pointed towards a toxifying role of this enzyme in 4-FMA metabolism at physiologically-relevant concentrations. The drug also destabilised mitochondrial membrane potential and decreased ATP levels, increased the production of reactive oxygen and nitrogen species and compromised thiol antioxidant defences. 4-FMA further affected PRH integrity by interfering with the machinery of apoptosis and necrosis, increasing the activity of initiator and effector caspases, and causing loss of cell membrane integrity. Potential for autophagy was also observed. This research contributes to the growing body of evidence regarding the toxicity of new psychoactive substances, in particular regarding their hepatotoxic effects; the apparent influence of metabolism over the resulting cytotoxicity of 4-FMA shows that there is a substantial degree of unpredictability of the consequences for users that could be independent of the dose.

From street to lab: in vitro hepatotoxicity of buphedrone, butylone and 3,4-DMMC

Synthetic cathinones are among the most popular new psychoactive substances, being abused for their stimulant properties, which are similar to those of amphetamine and 3,4-methylenedioxymethamphetamine (MDMA). Considering that the liver is a likely target for cathinones-induced toxicity, and for their metabolic activation/detoxification, we aimed to determine the hepatotoxicity of three commonly abused synthetic cathinones: butylone, α-methylamino-butyrophenone (buphedrone) and 3,4-dimethylmethcathinone (3,4-DMMC). We characterized their cytotoxic profile in primary rat hepatocytes (PRH) and in the HepaRG and HepG2 cell lines. PRH was the most sensitive cell model, showing the lowest EC₅₀ values for all three substances (0.158 mM for 3,4-DMMC; 1.21 mM for butylone; 1.57 mM for buphedrone). Co-exposure of PRH to the synthetic cathinones and CYP450 inhibitors (selective and non-selective) proved that hepatic metabolism reduced the toxicity of buphedrone but increased that of butylone and 3,4-DMMC. All compounds were able to increase oxidative stress, disrupting mitochondrial homeostasis and inducing apoptotic and necrotic features, while also increasing the occurrence of acidic vesicular organelles in PRH, compatible with autophagic activation. In conclusion, butylone, buphedrone and 3,4-DMMC have hepatotoxic potential, and their toxicity lies in the interference with a number of homeostatic processes, while being influenced by their metabolic fate.

Glutathione and Glutathione-Like Sequences of Opioid and Aminergic Receptors Bind Ascorbic Acid, Adrenergic and Opioid Drugs Mediating Antioxidant Function: Relevance for Anesthesia and Abuse

Opioids and their antagonists alter vitamin C metabolism. Morphine binds to glutathione (l-γ-glutamyl-l-cysteinyl-glycine), an intracellular ascorbic acid recycling molecule with a wide range of additional activities. The morphine metabolite morphinone reacts with glutathione to form a covalent adduct that is then excreted in urine. Morphine also binds to adrenergic and histaminergic receptors in their extracellular loop regions, enhancing aminergic agonist activity. The first and second extracellular loops of adrenergic and histaminergic receptors are, like glutathione, characterized by the presence of cysteines and/or methionines, and recycle ascorbic acid with similar efficiency. Conversely, adrenergic drugs bind to extracellular loops of opioid receptors, enhancing their activity. These observations suggest functional interactions among opioids and amines, their receptors, and glutathione. We therefore explored the relative binding affinities of ascorbic acid, dehydroascorbic acid, opioid and adrenergic compounds, as well as various control compounds, to glutathione and glutathione-like peptides derived from the extracellular loop regions of the human beta 2-adrenergic, dopamine D1, histamine H1, and mu opioid receptors, as well as controls. Some cysteine-containing peptides derived from these receptors do bind ascorbic acid and/or dehydroascorbic acid and the same peptides generally bind opioid compounds. Glutathione binds not only morphine but also naloxone, methadone, and methionine enkephalin. Some adrenergic drugs also bind to glutathione and glutathione-like receptor regions. These sets of interactions provide a novel basis for understanding some ways that adrenergic, opioid and antioxidant systems interact during anesthesia and drug abuse and may have utility for understanding drug interactions.

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.

The new psychoactive substance 3-methylmethcathinone (3-MMC or metaphedrone) induces oxidative stress, apoptosis, and autophagy in primary rat hepatocytes at human-relevant concentrations

3-Methylmethcathinone (3-MMC or metaphedrone) has become one of the most popular recreational drugs worldwide after the ban of mephedrone, and was recently deemed responsible for several intoxications and deaths. This study aimed at assessing the hepatotoxicity of 3-MMC. For this purpose, Wistar rat hepatocytes were isolated by collagenase perfusion, cultured and exposed for 24 h at a concentration range varying from 31 nM to 10 mM 3-MMC. The modulatory effects of cytochrome P450 (CYP) inhibitors on 3-MMC hepatotoxicity were evaluated. 3-MMC-induced toxicity was perceived at the lysosome at lower concentrations (NOEC 312.5 µM), compared to mitochondria (NOEC 379.5 µM) and cytoplasmic membrane (NOEC 1.04 mM). Inhibition of CYP2D6 and CYP2E1 diminished 3-MMC cytotoxicity, yet for CYP2E1 inhibition this effect was only observed for concentrations up to 1.3 mM. A significant concentration-dependent increase of intracellular reactive species was observed from 10 μM 3-MMC on; a concentration-dependent decrease in antioxidant glutathione defences was also observed. At 10 μM, caspase-3, caspase-8, and caspase-9 activities were significantly elevated, corroborating the activation of both intrinsic and extrinsic apoptosis pathways. Nuclear morphology and formation of cytoplasmic acidic vacuoles suggest prevalence of necrosis and autophagy at concentrations higher than 10 μM. No significant alterations were observed in the mitochondrial membrane potential, but intracellular ATP significantly decreased at 100 μM. Our data point to a role of metabolism in the hepatotoxicity of 3-MMC, which seems to be triggered both by autophagic and apoptotic/necrotic mechanisms. This work is the first approach to better understand 3-MMC toxicology.

Targeting redox regulation to treat substance use disorder using N‐acetylcysteine

Substance use disorder (SUD) is a chronic relapsing disorder characterized by transitioning from acute drug reward to compulsive drug use. Despite the heavy personal and societal burden of SUDs, current treatments are limited and unsatisfactory. For this reason, a deeper understanding of the mechanisms underlying addiction is required. Altered redox status, primarily due to drug-induced increases in dopamine metabolism, is a unifying feature of abused substances. In recent years, knowledge of the effects of oxidative stress in the nervous system has evolved from strictly neurotoxic to include a more nuanced role in redox-sensitive signaling. More specifically, S-glutathionylation, a redox-sensitive post-translational modification, has been suggested to influence the response to drugs of abuse. In this review we will examine the evidence for redox-mediating drugs as therapeutic tools focusing on N-acetylcysteine as a treatment for cocaine addiction. We will conclude by suggesting future research directions that may further advance this field.

Amphetamine exposure imbalanced antioxidant activity in the bivalve Dreissena polymorpha causing oxidative and genetic damage

Illicit drugs have been recognized as emerging aquatic pollutants due to their presence in aquatic ecosystems up to µg/L level. Among these, the synthetic psycho-stimulant drug amphetamine (AMPH) is commonly found in both surface and wastewaters worldwide. Even though the environmental occurrence of AMPH is well-known, the information on its toxicity towards non-target freshwater organisms is completely lacking. This study investigated the imbalance of the oxidative status and both oxidative and genetic damage induced by a 14-day exposure to two concentrations (500 ng/L and 5000 ng/L) of AMPH on the freshwater bivalve Dreissena polymorpha by the application of a biomarker suite. We investigated the activity of antioxidant enzymes (SOD, CAT and GPx), the phase II detoxifying enzyme GST, the lipid peroxidation level (LPO) and protein carbonyl content (PCC), as well as primary (Single Cell Gel Electrophoresis assay) and fixed (DNA diffusion assay and Micronucleus test) genetic damage. Our results showed that a current realistic AMPH concentration (500 ng/L) did neither cause notable imbalances in enzymatic activities, nor oxidative and genetic damage to cellular macromolecules. In contrast, the bell-shaped trend of antioxidants showed at the highest tested concentration (5000 ng/L) suggested an overproduction of reactive oxygen species, leading to oxidative damage, as confirmed by the significant increase of protein carbonylation and DNA fragmentation.

Hepatotoxicity of piperazine designer drugs: Comparison of different in vitro models

Piperazine derived drugs emerged on the drug market in the last decade. The aim of this study was to investigate in vitro the potential hepatotoxicity of the designer drugs N-benzylpiperazine (BZP), 1-(3-trifluoromethylphenyl)piperazine (TFMPP), 1-(4-methoxyphenyl)piperazine (MeOPP) and 1-(3,4-methylenedioxybenzyl)piperazine (MDBP) in two human hepatic cell lines (HepaRG and HepG2) and in primary rat hepatocytes. Cell death was evaluated by the MTT assay, after 24 h-incubations. Among the tested drugs, TFMPP was the most cytotoxic. HepaRG cells and primary hepatocytes revealed to be the most and the least resistant cellular models, respectively. To ascertain whether the CYP450 metabolism could explain their higher susceptibility, primary hepatocytes were co-incubated with the piperazines and the CYP450 inhibitors metyrapone and quinidine, showing that CYP450-mediated metabolism contributes to the detoxification of these drugs. Additionally, the intracellular contents of reactive species, ATP, reduced (GSH) and oxidized (GSSG) glutathione, changes in mitochondrial membrane potential (Δψm) and caspase-3 activation were further evaluated in primary cells. Overall, an increase in reactive species formation, followed by intracellular GSH and ATP depletion, loss of Δψm and caspase-3 activation was observed for all piperazines, in a concentration-dependent manner. In conclusion, piperazine designer drugs produce hepatic detrimental effects that can vary in magnitude among the different analogues.

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.

d-Amphetamine-induced cytotoxicity and oxidative stress in isolated rat hepatocytes

Amphetamines (AMP) are potent psychostimulants and commonly used drugs of abuse. Its chronic administration creates tolerance and addiction and also associated with neurotoxicity and hepatocellular damage through oxidative stress. The present study was designed to evaluate the cytotoxic effects as well as the oxidative stress induced by d-amphetamines in isolated rat hepatocytes. Hepatocytes were isolated by collagenase perfusion technique and were exposed to different concentrations of AMP (0.2, 0.4, 0.8 and 1.6mM) in a time-course experiment for up to 2h. AMP exposure induced a significant decrease in cell viability and a significant increase in the leakage of hepatic enzymes {lactate dehydrogenase (LDH), alanine aminotransferase (ALT) and asparate aminotransferase (AST)} in a concentration and time-related manner. In the same experiment, GSH content and thiobarbituric acid reactive substances (TBARS) generation were determined as indices of oxidative stress and lipid peroxidation respectively. AMP exposure results in a significant decrease in cellular GSH content as well as a significant enhancement of TBARS accumulation in a concentration and time-related manners. The obtained results suggested that 2-h exposure of hepatocytes to AMP (0.8mM) was accompanied by submaximal responses. Therefore, a subsequent dose-response experiment was designed to evaluate the role of GSH modulation and oxidative stress in AMP toxicity in hepatocytes at 2h. LDH release and TBARS generation were used as indicators in this experiment. Pretreatment with the GSH-depleting agents, chlorodinitrobenzene (CDNB), buthionine sulfoximine (BSO), or bis(chloroethyl)-nitrosurea (BCNU) enhanced the cytotoxicity of AMP. Conversely, pretreatment with GSH or sulfhydryl compounds such as methionine (MT), cysteine (CYS) or dithiothreitol (DTT) attenuated AMP toxicity. Similarly, co-incubation with enzymatic antioxidants, superoxide dismutase (SOD) or catalase (CAT) or iron chelator, desferroxiamine (DFO) or the hydroxyl radical scavengers, dimethylsulfoxide (DMSO) exhibited significant protection against AMP cytotoxicity. The present results indicate that AMP has a potential cytotoxic effect in isolated rat hepatocytes. AMP cytotoxicity is concentration-dependent. GSH depletion and oxidative stress play an important role in enhancing hepatotoxic potential of AMP in isolated rat hepatocyte. Thiol group-donors, antioxidants, free radical scavengers and iron chelators can play a critical role against AMP-induced cellular damage.

D-Amphetamine Toxicity in Freshly Isolated Rat Hepatocytes: A Possible Role of CYP3A

The aim of this study was to trace D-amphetamine toxicity in isolated rat hepatocytes and to elucidate a possible involvement of CYP3A in the mechanisms of its toxicity. To this end, male Wistar rats were treated with nifedipine (5 mg kg-1i.p., 5 days), a substrate and inducer of CYP3A. Hepatocytes isolated from nifedipine-treated and control rats were incubated with D-amphetamine at a concentration of 100 μmol L-1, which was determined to be an average toxic concentration (TC50) for the compound. To evaluate the possible toxic effects of D-amphetamine on freshly isolated rat hepatocytes, we assessed the following parameters: cell viability, lactate dehydrogenase (LDH) activity, and glutathione (GSH).

The results showed that nifedipine potentiated amphetamine cytotoxicity in vitro, as follows: cell viability dropped by 65% (p>0.001), GSH by 80% (p>0.001), and LDH activity increased by 190% (p>0.001). To clarify the role of nifedipine in amphetamine cytotoxicity, we used amiodarone, a substrate and an inhibitor of CYP3A. Pre-incubation of nifedipine-treated hepatocytes with amiodarone (14 μmol L-1) significantly lowered amphetamine cytotoxicity.

Our results confirmed the toxicity of D-amphetamine in isolated rat hepatocytes and the involvement of CYP3A in its metabolism and hepatotoxicity.

Evaluation of GSH adducts of adrenaline in biological samples

The sustained high release of catecholamines to circulation is a deleterious condition that may induce toxicity, which seems to be partially related to the products formed by oxidation of catecholamines that can be further conjugated with glutathione (GSH). The aim of the present study was to develop a method for the determination of GSH adducts of adrenaline in biological samples. Two position isomers of the glutathion-S-yl-adrenaline were synthesized and characterized by HPLC using diode array, coulometric and mass detectors. A method for the extraction of these adducts from human plasma was also developed, based on adsorption to activated alumina, which showed adequate recoveries and proved to be crucial in removing interferences from plasma. The selectivity, precision and linearity of the method were all within the accepted values for these parameters. Furthermore, the sensitivity of this method allows the detection of adduct amounts that are within the range of the expected concentrations for these adducts under certain pathophysiological conditions and/or drug treatments. In conclusion, the development of this method allows the direct analysis of GSH adducts of adrenaline in human plasma, providing a valuable tool for the study of the catecholamine oxidation process and its related toxicity.

Factors associated with fulminant liver failure during an outbreak among injection drug users with acute hepatitis B

Death related to acute hepatitis B occurs in approximately 1% of patients. We investigated an outbreak of hepatitis B virus (HBV) infections among injection drug users (IDUs) resulting in several deaths. We conducted a case-control study of fulminant (case patients) and nonfulminant (control patients) HBV infections. We directly sequenced the entire HBV genome from fulminant and nonfulminant cases. From October 1998 to July 2000, 21 acute HBV infections, including 10 fulminant hepatitis B cases, were identified. The median age was 30 (range, 18-49) years, 12 (57%) were female, 20 (95%) were American Indians, and 20 (95%) reported injecting illicit drugs. All patients with fulminant hepatitis B died (case-fatality rate = 47.6%). Case patients (n = 5) and control patients (n = 9) were similar with respect to age, sex, race, and hepatitis C virus serostatus. All case patients used acetaminophen during their illness compared with 44% of control patients (P =.08). Compared with control patients, case patients lost more weight in the 6 months before illness (P =.04); during their illness, they used more alcohol (P =.03) and methamphetamine (P =.04). All 9 isolates sequenced were genotype D, shared 99.7% homology, and included mutations previously described in association with fulminant hepatitis B. In conclusion, a high prevalence of exposure to factors potentiating hepatic damage with acute hepatitis B contributed to the outbreak's high mortality rate; mutations present in the outbreak strain might also have been a factor. Improved vaccination coverage among IDUs has the potential to prevent similar outbreaks in the future.

Toxicokinetics of amphetamines: metabolism and toxicokinetic data of designer drugs, amphetamine, methamphetamine, and their N-alkyl derivatives

This paper reviews the toxicokinetics of amphetamines. The designer drugs MDA (methylenedioxy-amphetamine, R,S-1-(3;,4;-methylenedioxyphenyl)2-propanamine), MDMA (R,S-methylenedioxymethamphetamine), and MDE (R,S-methylenedioxyethylamphetamine), as well as BDB (benzodioxolylbutanamine; R,S-1-(1;,3;-benzodioxol-5;-yl)-2-butanamine or R,S-1-(3;,4;-methylenedioxyphenyl)-2-butanamine) and MBDB (R,S-N-methyl-benzodioxolylbutanamine), were taken into consideration, as were the following N-alkylated amphetamine derivatives: amphetaminil, benzphetamine, clobenzorex, dimethylamphetamine, ethylamphetamine, famprofazone, fencamine, fenethylline, fenproporex, furfenorex, mefenorex, mesocarb, methamphetamine, prenylamine, and selegiline. English-language publications from 1995 to 2000 were reviewed. Papers describing identification of metabolites or cytochrome P450 isoenzyme-dependent metabolism and papers containing pharmacokinetic/toxicokinetic data were considered and summarized. The implications of toxicokinetics for toxicologic assessment or for interpretation in forensic cases are discussed.

Determination of amphetamine and its metabolite p-hydroxyamphetamine in rat urine by reversed-phase high-performance liquid chromatography after dabsyl derivatization

The consumption of amphetamine is illicit and controlled due to both the elicited behavioural deviations and the toxicity effects reported in abusers. Thus, amphetamine levels in biological samples must be monitored in several clinical and forensic circumstances. In spite of the interspecies differences in the preferred route of biotransformation, benzylmethylketone, benzoic acid and 4-hydroxyamphetamine are the principal metabolites of amphetamine. However, the clinical and forensic studies are focused in the parent compound and in 4-hydroxyamphetamine since benzylmethylketone is a minor metabolite in human and benzoic acid is also an endogenous compound. In the present study amphetamine and its metabolite, 4-hydroxyamphetamine, are quantified in urine by HPLC after derivatization with 4-dimethylaminoazobenzene-4'-sulfonyl chloride (dabsyl chloride). This derivatization procedure transforms amphetamine and its hydroxylated metabolite in compounds with similar lipofilicity, enabling their quantitative and simultaneous extraction with an organic solvent. The precision of the HPLC technique was 7.3 and 10.0% for amphetamine and 4-hydroxyamphetamine derivatives, respectively. For the overall procedure, including enzymatic hydrolysis, derivatization and extraction of the derivatives, the obtained values were 9.3 and 6.2%. Recoveries obtained from spiked urines for amphetamine and 4-hydroxyamphetamine were better than 97% and 94% (mean value), respectively. The detection limits of the method was 10 ng for both compounds. The principal advantages of the present proposed method are the stability of the dabsyl derivatives at room temperature and the detection carried out in the visible region, reducing the interferences detected.

Adaptative response of antioxidant enzymes in different areas of rat brain after repeated d-amphetamine administration

d-Amphetamine has been shown to be a potential brain neurotoxic agent, particularly to dopaminergic neurones. Reactive oxygen species indirectly generated by this drug have been indicated as an important factor in the appearance of neuronal damage but little is known about the adaptations of brain antioxidant systems to its chronic administration. In this study, the activities of several antioxidant enzymes in different areas of rat brain were measured after repeated administration of d-amphetamine sulphate (sc, 20 mg/kg/day, for 14 days), namely glutathione-S-transferase (GST), glutathione peroxidase (GPx), glutathione reductase (GRed), catalase, and superoxide dismutase (SOD). When compared to a pair-fed control group, d-amphetamine treatment enhanced the activity of GST in hypothalamus to 167%, GPx in striatum to 127%, in nucleus accumbens to 192%, and in medial prefrontal cortex to 139%, GRed in hypothalamus to 139%, as well as catalase in medial prefrontal cortex to 153%. However, the same comparison revealed a decrease in the activity of GRed in medial pre-frontal cortex by 35%. Food restriction itself reduced GRed activity by 49% and enhanced catalase activity to 271% in nucleus accumbens. The modifications observed for the measured antioxidant enzymes reveal that oxidative stress probably plays a role in the deleterious effects of this drug in CNS and that, in general, the brain areas studied underwent adaptations which provided protection against the continuous administration of the drug.

Simultaneous determination of reduced and oxidized glutathione in freshly isolated rat hepatocytes and cardiomyocytes by HPLC with electrochemical detection

Glutathione and glutathione disulphide constitute an essential thiol redox system present in the cell. The balance in favour of the latter is an indication of oxidative stress. Glutathione and glutathione disulphide quantification in isolated cells may therefore be essential for the evaluation of mechanistic and comparative studies of toxic xenobiotics. In this study, a rapid and sensitive isocratic reverse-phase high-performance liquid chromatographic method using coulometric detection was implemented for the simultaneous detection of glutathione and glutathione disulphide, in freshly isolated hepatocytes and cardiomyocytes of the rat. The method implemented proved to be effective for the measurement of glutathione and glutathione disulphide in control conditions and for the detection of variations in this redox system, induced by tert-butylhydroperoxide. tert-Butylhydroperoxide is an organic peroxide, which has been used as a model molecule for inducing oxidative stress in isolated cells. A comparative study with a previously published HPLC-electrochemical detection method was performed.

Implication of Bcl-2 family genes in basal and D-amphetamine-induced apoptosis in preneoplastic and neoplastic rat liver lesions

Molecular mechanisms of basal and D-amphetamine (AMPH)-induced apoptosis were studied in rat liver nodules, 12 (N12) and 30 (N30) weeks after initiation, and in hepatocellular carcinoma (HCC) induced by diethylnitrosamine in rats subjected to resistant hepatocyte model. Basal apoptosis in hematoxylin/eosin- and propidium iodide-stained sections was higher in nodules and HCC than in normal livers. It sharply increased in all tissues 4 hours after AMPH treatment (10 mg/kg), and declined to basal levels at 8 to 12 hours in liver and N12, but remained high up to 18 hours in N30 and HCC. c-myc, Tgf-alpha, p53, and Bcl-X(S) messenger RNA (mRNA) levels were higher, and Bcl-2 mRNA was lower in N12 and/or N30 and HCC than in normal liver. Four hours after AMPH injection, increase in c-myc and decreases in Bcl-2 and Bcl-X(L) mRNAs occurred in all tissues, whereas p53, Bax, and Bcl-X(S) mRNAs increased in N30 and HCC. These changes disappeared in liver and N12 at 18 hours, but persisted in N30 and HCC. c-Myc, P53, Bcl-2, and Bax proteins in normal liver and HCC +/- AMPH showed similar patterns. Tgf-beta1, Tgf-beta-RIII, CD95, and CD95L mRNA levels underwent slight or no changes in any tissue +/- AMPH. Basal Hsp27 expression was high in nodules and HCC, and was stimulated by AMPH in liver and N12, but not in N30 and HCC. These data suggest a role of dysregulation of Bcl-2 family genes and, at least in atypical lesions, of p53 overexpression, in basal and AMPH-induced apoptosis in nodules and HCCs. Hsp27 does not appear to sufficiently protect atypical lesions against apoptosis.

Toxicokinetics and analytical toxicology of amphetamine-derived designer drugs ('Ecstasy')

The phase I and II metabolites of the designer drugs methylenedioxyamphetamine (MDA), R,S-methylenedioxymethamphetamine (MDMA), R,S-methylenedioxyethylamphetamine (MDE), R, S-benzodioxazolylbutanamine (BDB) and R, S-N-methyl-benzodioxazolylbutanamine (MBDB) were identified by gas chromatography-mass spectrometry (GC-MS) or liquid chromotography-mass spectrometry (LC-MS) in urine and liver microsomes of humans and rats. Two overlapping pathways could be postulated: (1) demethylenation followed by catechol-O-methyl-transferase (COMT) catalyzed methylation and/or glucuronidation/sulfatation; (2) N-dealkylation, deamination and only for MDA, MDMA, MDE oxidation to the corresponding benzoic acid derivatives conjugated with glycine. Demethylenation was mainly catalyzed by CYP2D1/6 or CYP3A2/4, but also by CYP independent mechanisms. In humans, MDMA and MBDB could also be demethylenated by CYP1A2. N-demethylation was mainly catalyzed by CYP1A2, N-deethylation by CYP3A2/4. Based on these studies, GC-MS procedures were developed for the toxicological analysis in urine and plasma. Finally, toxicokinetic parameters are reviewed.

3,4-Methylenedioxymethamphetamine (ecstasy)-induced hepatotoxicity: effect on cytosolic calcium signals in isolated hepatocytes

AIMS/BACKGROUND

Hepatocellular damage has been reported as a consequence of 3,4-methylenedioxymethamphetamine (MDMA) intake. However, little is known about the cellular mechanisms involved. The present study was undertaken to evaluate the effects of MDMA on cell viability as well as free calcium levels ([Ca2+]i) in short-term cultured hepatocytes. Reduced glutathione (GSH), adenosine-5'-triphosphate (ATP) and lipid peroxidation were investigated to evaluate the toxic effect of MDMA, in vitro, using freshly isolated rat hepatocytes.

METHODS

In order to measure cytosolic free Ca2+ concentrations ([Ca2+]i), rat hepatocytes were loaded with the Ca2+ indicator fura-2-acetoxymethylester (fura-2-AM).

RESULTS

A sustained rise of ([Ca2+]i) after incubation with MDMA was the most noteworthy finding. In Ca2+-free medium, MDMA caused a reduced increase of ([Ca2+]i). On the other hand, MDMA (0.1-5 mM) induced a concentration-dependent and time exposure-dependent GSH and ATP depletion. Although it did not reach statistical significance, GSH deficits were accompanied by a tendency to increase lipid peroxidation 3 h after MDMA incubation.

CONCLUSIONS

The above data suggest that the marked rise of ([Ca2+]i) and subsequent ATP and GSH depletion can lead to a rapid decrease in cell viability.

Review article: mechanisms and management of hepatotoxicity in ecstasy (MDMA) and amphetamine intoxications

The social use of ecstasy (methylenedioxymethampheta-mine, MDMA) and amphetamines is widespread in the UK and Europe, and they are popularly considered as 'safe'. However, deaths have occurred and hepatotoxicity has featured in many cases of intoxication with amphetamine or its methylenedioxy analogues such as ecstasy. Recreational use of these drugs presents an important but often concealed cause of hepatitis or acute liver failure, particularly in young people. The patterns of liver damage and multiple putative mechanisms of injury are discussed. Recognition of the aetiological agent requires a high index of suspicion. Optimum management of the resultant liver damage, including the controversial role of liver transplantation for fulminant hepatic failure, is also discussed.