RESUMEN
3,4-Methylenedioximethamphetamine (MDMA; "ecstasy") is a psychotropic drug with well-known neurotoxic effects mediated by hitherto not fully understood mechanisms. The Na+- and K+-activated adenosine 5'-triphosphatase (Na+/K+ ATPase), by maintaining the ion gradient across the cell membrane, regulates neuronal excitability. Thus, a perturbation of its function strongly impacts cell homeostasis, ultimately leading to neuronal dysfunction and death. Nevertheless, whether MDMA affects the Na+/K+ ATPase remains unknown. In this study, we used synaptosomes obtained from whole mouse brain to test the effects of MDMA, three of its major metabolites [α-methyldopamine, N-methyl-α-methyldopamine and 5-(glutathion-S-yl)-α-methyldopamine], serotonin (5-HT), dopamine, 3,4-dihydroxy-L-phenylalanine (L-Dopa) and 3,4-dihydroxyphenylacetic acid (DOPAC) on the Na+/K+ ATPase function. A concentration-dependent increase of Na+/K+ ATPase activity was observed in synaptosomes exposed to the tested compounds (concentrations ranging from 0.0625 to 200 µM). These effects were independent of protein kinases A and C activities. Nevertheless, a rescue of the compounds' effects was observed in synaptosomes pre-incubated with the antioxidant N-acetylcysteine (1 mM), suggesting a role for reactive species-regulated pathways on the Na+/K+ ATPase effects. In agreement with this hypothesis, a similar increase in the pump activity was found in synaptosomes exposed to the chemical generator of superoxide radicals, phenazine methosulfate (1-250 µM). This study demonstrates the ability of MDMA metabolites, monoamine neurotransmitters, L-Dopa and DOPAC to alter the Na+/K+ ATPase function. This could represent a yet unknown mechanism of action of MDMA and its metabolites in the brain.
Asunto(s)
N-Metil-3,4-metilenodioxianfetamina , Animales , Ratones , N-Metil-3,4-metilenodioxianfetamina/toxicidad , Sinaptosomas/metabolismo , Serotonina/metabolismo , Ácido 3,4-Dihidroxifenilacético/metabolismo , Ácido 3,4-Dihidroxifenilacético/farmacología , Dopamina/metabolismo , Acetilcisteína/farmacología , Antioxidantes/farmacología , Levodopa/metabolismo , Levodopa/farmacología , Adenosina Trifosfatasas/metabolismo , Adenosina Trifosfatasas/farmacología , Superóxidos/metabolismo , Metosulfato de Metilfenazonio/metabolismo , Metosulfato de Metilfenazonio/farmacología , Encéfalo , Neurotransmisores/metabolismo , Neurotransmisores/farmacología , Adenosina/metabolismo , Proteínas Quinasas/metabolismoRESUMEN
Cognitive dysfunction has been one of the most reported and studied adverse effects of cancer treatment, but, for many years, it was overlooked by the medical community. Nevertheless, the medical and scientific communities have now recognized that the cognitive deficits caused by chemotherapy have a strong impact on the morbidity of cancer treated patients. In fact, chemotherapy-induced cognitive dysfunction or 'chemobrain' (also named also chemofog) is at present a well-recognized effect of chemotherapy that could affect up to 78% of treated patients. Nonetheless, its underlying neurotoxic mechanism is still not fully elucidated. Therefore, this work aimed to provide a comprehensive review using PubMed as a database to assess the studies published on the field and, therefore, highlight the clinical manifestations of chemobrain and the putative neurotoxicity mechanisms.In the last two decades, a great number of papers was published on the topic, mainly with clinical observations. Chemotherapy-treated patients showed that the cognitive domains most often impaired were verbal memory, psychomotor function, visual memory, visuospatial and verbal learning, memory function and attention. Chemotherapy alters the brain's metabolism, white and grey matter and functional connectivity of brain areas. Several mechanisms have been proposed to cause chemobrain but increase of proinflammatory cytokines with oxidative stress seem more relevant, not excluding the action on neurotransmission and cellular death or impaired hippocampal neurogenesis. The interplay between these mechanisms and susceptible factors makes the clinical management of chemobrain even more difficult. New studies, mainly referring to the underlying mechanisms of chemobrain and protective measures, are important in the future, as it is expected that chemobrain will have more clinical impact in the coming years, since the number of cancer survivors is steadily increasing.
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Antineoplásicos , Deterioro Cognitivo Relacionado con la Quimioterapia , Trastornos del Conocimiento , Disfunción Cognitiva , Neoplasias , Animales , Antineoplásicos/toxicidad , Encéfalo , Trastornos del Conocimiento/inducido químicamente , Disfunción Cognitiva/inducido químicamente , Humanos , Neoplasias/tratamiento farmacológicoRESUMEN
Mitoxantrone (MTX) is a topoisomerase II inhibitor used to treat a wide range of tumors and multiple sclerosis but associated with potential neurotoxic effects mediated by hitherto poorly understood mechanisms. In adult male CD-1 mice, the underlying neurotoxic pathways of a clinically relevant cumulative dose of 6 mg/kg MTX was evaluated after biweekly administration for 3 weeks and sacrifice 1 week after the last administration was undertaken. Oxidative stress, neuronal damage, apoptosis, and autophagy were analyzed in whole brain, while coronal brain sections were used for a closer look in the hippocampal formation (HF) and the prefrontal cortex (PFC), as these areas have been signaled out as the most affected in 'chemobrain'. In the whole brain, MTX-induced redox imbalance shown as increased endothelial nitric oxide synthase and reduced manganese superoxide dismutase expression, as well as a tendency to a decrease in glutathione levels. MTX also caused diminished ATP synthase ß expression, increased autophagic protein LC3 II and tended to decrease p62 expression. Postsynaptic density protein 95 expression decreased in the whole brain, while hyperphosphorylation of Tau was seen in PFC. A reduction in volume was observed in the dentate gyrus (DG) and CA1 region of the HF, while GFAP-ir astrocytes increased in all regions of the HF except in the DG. Apoptotic marker Bax increased in the PFC and in the CA3 region, whereas p53 decreased in all brain areas evaluated. MTX causes damage in the brain of adult CD-1 mice in a clinically relevant cumulative dose in areas involved in memory and cognition.
Asunto(s)
Deterioro Cognitivo Relacionado con la Quimioterapia , Animales , Autofagia , Masculino , Ratones , Mitoxantrona/toxicidad , Neuronas , Estrés OxidativoRESUMEN
Cathinone, the main psychoactive compound found in the plant Catha edulis Forsk. (khat), is a ß-keto analogue of amphetamine, sharing not only the phenethylamine structure, but also the amphetamine-like stimulant effects. Synthetic cathinones are derivatives of the naturally occurring cathinone that largely entered the recreational drug market at the end of 2000s. The former "legal status", impressive marketing strategies and their commercial availability, either in the so-called "smartshops" or via the Internet, prompted their large spread, contributing to their increasing popularity in the following years. As their popularity increased, the risks posed for public health became clear, with several reports of intoxications and deaths involving these substances appearing both in the social media and scientific literature. The regulatory measures introduced thereafter to halt these trending drugs of abuse have proved to be of low impact, as a continuous emergence of new non-controlled derivatives keep appearing to replace those prohibited. Users resort to synthetic cathinones due to their psychostimulant properties but are often unaware of the dangers they may incur when using these substances. Therefore, studies aimed at unveiling the pharmacological and toxicological properties of these substances are imperative, as they will provide increased expertise to the clinicians that face this problem on a daily basis. The present work provides a comprehensive review on history and legal status, chemistry, pharmacokinetics, pharmacodynamics, adverse effects and lethality in humans, as well as on the current knowledge of the neurotoxic mechanisms of synthetic cathinones.
Asunto(s)
Alcaloides/farmacología , Estimulantes del Sistema Nervioso Central/farmacología , Drogas Ilícitas/farmacología , Alcaloides/efectos adversos , Alcaloides/química , Animales , Catha/química , Estimulantes del Sistema Nervioso Central/efectos adversos , Estimulantes del Sistema Nervioso Central/química , Humanos , Drogas Ilícitas/efectos adversos , Drogas Ilícitas/química , Síndromes de Neurotoxicidad/etiologíaRESUMEN
Cathinones (ß-keto amphetamines), widely abused in recreational settings, have been shown similar or even worse toxicological profile than classical amphetamines. In the present study, the cytotoxicity of two ß-keto amphetamines [3,4-dimethylmethcathinone (3,4-DMMC) and 4-methylmethcathinone (4-MMC)], was evaluated in differentiated dopaminergic SH-SY5Y cells in comparison to methamphetamine (METH). MTT reduction and NR uptake assays revealed that both cathinones and METH induced cytotoxicity in a concentration- and time-dependent manner. Pre-treatment with trolox (antioxidant) partially prevented the cytotoxicity induced by all tested drugs, while N-acetyl-L-cysteine (NAC; antioxidant and glutathione precursor) and GBR 12909 (dopamine transporter inhibitor) partially prevented the cytotoxicity induced by cathinones, as evaluated by the MTT reduction assay. Unlike METH, cathinones induced oxidative stress evidenced by the increase on intracellular levels of reactive oxygen species (ROS), and also by the decrease of intracellular glutathione levels. Trolox prevented, partially but significantly, the ROS generation elicited by cathinones, while NAC inhibited it completely. All tested drugs induced mitochondrial dysfunction, since they led to mitochondrial membrane depolarization and to intracellular ATP depletion. Activation of caspase-3, indicative of apoptosis, was seen both for cathinones and METH, and confirmed by annexin V and propidium iodide positive staining. Autophagy was also activated by all drugs tested. Pre-incubation with bafilomycin A1, an inhibitor of the vacuolar H+-ATPase, only protected against the cytotoxicity induced by METH, which indicates dissimilar toxicological pathways for the tested drugs. In conclusion, the mitochondrial impairment and oxidative stress observed for the tested cathinones may be key factors for their neurotoxicity, but different outcome pathways seem to be involved in the adverse effects, when compared to METH.
Asunto(s)
Neuronas Dopaminérgicas/efectos de los fármacos , Metanfetamina/análogos & derivados , Neurogénesis , Propiofenonas/toxicidad , Adenosina Trifosfato/metabolismo , Apoptosis/efectos de los fármacos , Línea Celular Tumoral , Neuronas Dopaminérgicas/metabolismo , Neuronas Dopaminérgicas/patología , Relación Dosis-Respuesta a Droga , Glutatión/metabolismo , Humanos , Potencial de la Membrana Mitocondrial/efectos de los fármacos , Metanfetamina/toxicidad , Mitocondrias/efectos de los fármacos , Mitocondrias/metabolismo , Mitocondrias/patología , Estrés Oxidativo/efectos de los fármacos , Especies Reactivas de Oxígeno/metabolismo , Factores de TiempoRESUMEN
Mitoxantrone (MTX) is used to treat several types of cancers and to improve neurological disability in multiple sclerosis. Unfortunately, cardiotoxicity is a severe and common adverse effect in MTX-treated patients. Herein, we aimed to study early and late mechanisms of MTX-induced cardiotoxicity using murine HL-1 cardiomyocytes. Cells were exposed to MTX (0.1, 1 or 10 µM) during short (2, 4, 6, or 12 h) or longer incubation periods (24 or 48 h). At earlier time points, (6 and 12 h) cytotoxicity was already observed for 1 and 10 µM MTX. Proteomic analysis of total protein extracts found 14 proteins with higher expression and 26 with lower expression in the cells exposed for 12 h to MTX (pH gradients 4-7 and 6-11). Of note, the expression of the regulatory protein 14-3-3 protein epsilon was increased by a factor of two and three, after exposure to 1 and 10 µM MTX, respectively. At earlier time-points, 10 µM MTX increased intracellular ATP levels, while decreasing media lactate levels. At later stages (24 and 48 h), MTX-induced cytotoxicity was concentration and time-dependent, according to the MTT reduction and lactate dehydrogenase leakage assays, while caspase-9, -8 and -3 activities increased at 24 h. Regarding cellular redox status, total glutathione increased in 1 µM MTX (24 h), and that increase was dependent on gamma-glutamylcysteine synthetase activity. Meanwhile, for both 1 and 10 µM MTX, oxidized glutathione was significantly higher than control at 48 h. Moreover, MTX was able to significantly decrease proteasomal chymotrypsin-like activity in a concentration and time-independent manner. In summary, MTX significantly altered proteomic, energetic and oxidative stress homeostasis in cardiomyocytes at clinically relevant concentrations and our data clearly demonstrate that MTX causes early cardiotoxicity that needs further study.
Asunto(s)
Metabolismo Energético/efectos de los fármacos , Cardiopatías/inducido químicamente , Mitoxantrona/toxicidad , Miocitos Cardíacos/efectos de los fármacos , Complejo de la Endopetidasa Proteasomal/metabolismo , Proteoma , Proteómica , Animales , Proteínas Reguladoras de la Apoptosis/metabolismo , Cardiotoxicidad , Línea Celular , Relación Dosis-Respuesta a Droga , Cardiopatías/metabolismo , Ratones , Miocitos Cardíacos/metabolismo , Estrés Oxidativo/efectos de los fármacos , Carbonilación Proteica , Factores de TiempoRESUMEN
Amphetamines are a class of psychotropic drugs with high abuse potential, as a result of their stimulant, euphoric, emphathogenic, entactogenic, and hallucinogenic properties. Although most amphetamines are synthetic drugs, of which methamphetamine, amphetamine, and 3,4-methylenedioxymethamphetamine ("ecstasy") represent well-recognized examples, the use of natural related compounds, namely cathinone and ephedrine, has been part of the history of humankind for thousands of years. Resulting from their amphiphilic nature, these drugs can easily cross the blood-brain barrier and elicit their well-known psychotropic effects. In the field of amphetamines' research, there is a general consensus that mitochondrial-dependent pathways can provide a major understanding concerning pathological processes underlying the neurotoxicity of these drugs. These events include alterations on tricarboxylic acid cycle's enzymes functioning, inhibition of mitochondrial electron transport chain's complexes, perturbations of mitochondrial clearance mechanisms, interference with mitochondrial dynamics, as well as oxidative modifications in mitochondrial macromolecules. Additionally, other studies indicate that amphetamines-induced neuronal toxicity is closely regulated by B cell lymphoma 2 superfamily of proteins with consequent activation of caspase-mediated downstream cell death pathway. Understanding the molecular mechanisms at mitochondrial level involved in amphetamines' neurotoxicity can help in defining target pathways or molecules mediating these effects, as well as in developing putative therapeutic approaches to prevent or treat the acute- or long-lasting neuropsychiatric complications seen in human abusers.
Asunto(s)
Trastornos Relacionados con Anfetaminas/complicaciones , Mitocondrias/efectos de los fármacos , Síndromes de Neurotoxicidad/etiología , Anfetaminas/administración & dosificación , Anfetaminas/farmacocinética , Anfetaminas/toxicidad , Animales , Barrera Hematoencefálica/metabolismo , Estimulantes del Sistema Nervioso Central/administración & dosificación , Estimulantes del Sistema Nervioso Central/farmacocinética , Estimulantes del Sistema Nervioso Central/toxicidad , Transporte de Electrón/efectos de los fármacos , Humanos , Síndromes de Neurotoxicidad/fisiopatologíaRESUMEN
3,4-Methylenedioxymethamphetamine (MDMA; "ecstasy") is a recreational hallucinogenic drug of abuse known to elicit neurotoxic properties. Hepatic formation of neurotoxic metabolites is thought to play a major role in MDMA-related neurotoxicity, though the mechanisms involved are still unclear. Here, we studied the neurotoxicity mechanisms and stability of MDMA and 6 of its major human metabolites, namely α-methyldopamine (α-MeDA) and N-methyl-α-methyldopamine (N-Me-α-MeDA) and their correspondent glutathione (GSH) and N-acetyl-cysteine (NAC) conjugates, under normothermic (37 °C) or hyperthermic conditions (40 °C), using cultured SH-SY5Y differentiated cells. We showed that MDMA metabolites exhibited toxicity to SH-SY5Y differentiated cells, being the GSH and NAC conjugates more toxic than their catecholic precursors and MDMA. Furthermore, whereas the toxicity of the catechol metabolites was potentiated by hyperthermia, NAC-conjugated metabolites revealed higher toxicity under normothermia and GSH-conjugated metabolites-induced toxicity was temperature-independent. Moreover, a time-dependent decrease in extracellular concentration of MDMA metabolites was observed, which was potentiated by hyperthermia. The antioxidant NAC significantly protected against the neurotoxic effects of MDMA metabolites. MDMA metabolites increased intracellular glutathione levels, though depletion in thiol content was observed in MDMA-exposed cells. Finally, the neurotoxic effects induced by the MDMA metabolite N-Me-α-MeDA involved caspase 3 activation. In conclusion, this study evaluated the stability of MDMA metabolites in vitro, and demonstrated that the catechol MDMA metabolites and their GSH and NAC conjugates, rather than MDMA itself, exhibited neurotoxic actions in SH-SY5Y differentiated cells, which were differently affected by hyperthermia, thus highlighting a major role for reactive metabolites and hyperthermia in MDMA's neurotoxicity.
Asunto(s)
Diferenciación Celular/efectos de los fármacos , Fiebre/inducido químicamente , N-Metil-3,4-metilenodioxianfetamina/metabolismo , N-Metil-3,4-metilenodioxianfetamina/toxicidad , Neuronas/efectos de los fármacos , 3,4-Metilenodioxianfetamina/metabolismo , 3,4-Metilenodioxianfetamina/toxicidad , Acetilcisteína/metabolismo , Acetilcisteína/farmacología , Caspasa 3/metabolismo , Muerte Celular/efectos de los fármacos , Línea Celular/efectos de los fármacos , Desoxiepinefrina/análogos & derivados , Desoxiepinefrina/metabolismo , Desoxiepinefrina/toxicidad , Fiebre/metabolismo , Glutatión/metabolismo , Humanos , Mitocondrias/efectos de los fármacos , Mitocondrias/metabolismo , N-Metil-3,4-metilenodioxianfetamina/farmacocinética , Neuronas/metabolismo , Síndromes de Neurotoxicidad/metabolismo , Síndromes de Neurotoxicidad/patología , TemperaturaRESUMEN
The neurotoxicity of "ecstasy" (3,4-methylenedioxymethamphetamine, MDMA) is thought to involve hepatic metabolism, though its real contribution is not completely understood. Most in vitro neurotoxicity studies concern isolated exposures of MDMA or its metabolites, at high concentrations, not considering their mixture, as expected in vivo. Therefore, our postulate is that combined deleterious effects of MDMA and its metabolites, at low micromolar concentrations that may be attained into the brain, may elicit neurotoxicity. Using human SH-SY5Y differentiated cells as dopaminergic neuronal model, we studied the neurotoxicity of MDMA and its MDMA metabolites α-methyldopamine and N-methyl-α-methyldopamine and their correspondent glutathione and N-acetylcysteine monoconjugates, under isolated exposure and as a mixture, at normothermic or hyperthermic conditions. The results showed that the mixture of MDMA and its metabolites was toxic to SH-SY5Y differentiated cells, an effect potentiated by hyperthermia and prevented by N-acetylcysteine. As a mixture, MDMA and its metabolites presented a different toxicity profile, compared to each compound alone, even at equimolar concentrations. Caspase 3 activation, increased reactive oxygen species production, and intracellular Ca(2+) raises were implicated in the toxic effect. The mixture increased intracellular glutathione levels by increasing its de novo synthesis. In conclusion, this study demonstrated, for the first time, that the mixture of MDMA and its metabolites, at low micromolar concentrations, which represents a more realistic approach of the in vivo scenario, elicited toxicity to human SH-SY5Y differentiated cells, thus constituting a new insight into the context of MDMA-related neurotoxicity.
Asunto(s)
Diferenciación Celular/efectos de los fármacos , N-Metil-3,4-metilenodioxianfetamina/toxicidad , Neuronas/efectos de los fármacos , Acetilcisteína/farmacología , Calcio/metabolismo , Caspasa 3/metabolismo , Línea Celular/efectos de los fármacos , Desoxiepinefrina/análogos & derivados , Desoxiepinefrina/toxicidad , Dopamina/metabolismo , Dopamina/farmacocinética , Neuronas Dopaminérgicas/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Glutatión/metabolismo , Humanos , Mitocondrias/efectos de los fármacos , Mitocondrias/metabolismo , N-Metil-3,4-metilenodioxianfetamina/administración & dosificación , N-Metil-3,4-metilenodioxianfetamina/metabolismo , Neuronas/patología , Síndromes de Neurotoxicidad/patología , Especies Reactivas de Oxígeno/metabolismoRESUMEN
Identification of the mechanisms by which drugs of abuse cause neuronal dysfunction is essential for understanding the biological bases of their acute and long-lasting effects in the brain. Here, we performed real-time functional experiments of axonal transport of mitochondria to explore the role of in situ mitochondrial dysfunction in 3,4-methylenedioxymethamphetamine (MDMA; "ecstasy")-related brain actions. We showed that MDMA dramatically reduced mitochondrial trafficking in hippocampal neurons in a Tau-dependent manner, in which glycogen synthase kinase 3ß activity was implicated. Furthermore, we found that these trafficking abnormalities were rescued by over-expression of Mitofusin2 and dynamin-related protein 1, but not of Miro1. Given the relevance of mitochondrial targeting for neuronal function and neurotransmission, our data underscore a novel mechanism of action of MDMA that may contribute to our understanding of how this drug of abuse alters neuronal functioning.
Asunto(s)
Dinaminas/metabolismo , GTP Fosfohidrolasas/metabolismo , Mitocondrias/efectos de los fármacos , Dinámicas Mitocondriales/efectos de los fármacos , N-Metil-3,4-metilenodioxianfetamina/toxicidad , Neuronas/efectos de los fármacos , Proteínas tau/metabolismo , Animales , Transporte Axonal/efectos de los fármacos , Calcio/metabolismo , Células Cultivadas , Hipocampo/citología , Hipocampo/efectos de los fármacos , Hipocampo/embriología , Ratones Endogámicos C57BL , Mitocondrias/metabolismo , Neuronas/metabolismo , FosforilaciónRESUMEN
Full treatment of the second most common neurodegenerative disorder, Parkinson's disease (PD), is still considered an unmet need. As the psychostimulants, amphetamine (AMPH) and methylphenidate (MPH), were shown to be neuroprotective against stroke and other neuronal injury diseases, this study aimed to evaluate their neuroprotective potential against two dopaminergic neurotoxicants, 6-hydroxydopamine (6-OHDA) and paraquat (PQ), in differentiated human dopaminergic SH-SY5Y cells. Neither cytotoxicity nor mitochondrial membrane potential changes were seen following a 24-hour exposure to either therapeutic concentration of AMPH or MPH (0.001-10 µM). On the other hand, a 24-hour exposure to 6-OHDA (31.25-500 µM) or PQ (100-5000 µM) induced concentration-dependent mitochondrial dysfunction, assessed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay, and lysosomal damage, evaluated by the neutral red uptake assay. The lethal concentrations 25 and 50 retrieved from the concentration-toxicity curves in the MTT assay were 99.9 µM and 133.6 µM for 6-OHDA, or 422 µM and 585.8 µM for PQ. Both toxicants caused mitochondrial membrane potential depolarization, but only 6-OHDA increased reactive oxygen species (ROS). Most importantly, PQ-induced toxicity was partially prevented by 1 µM of AMPH or MPH. Nonetheless, neither AMPH nor MPH could prevent 6-OHDA toxicity in this experimental model. According to these findings, AMPH and MPH may provide some neuroprotection against PQ-induced neurotoxicity, but further investigation is required to determine the exact mechanism underlying this protection.
RESUMEN
The prevalence of stroke and traumatic brain injury is increasing worldwide. However, current treatments do not fully cure or stop their progression, acting mostly on symptoms. Amphetamine and methylphenidate are stimulants already approved for attention deficit hyperactivity disorder and narcolepsy treatment, with neuroprotective potential and benefits when used in appropriate doses. This review aimed to summarize pre-clinical and clinical trials testing either amphetamine or methylphenidate for the treatment of stroke and traumatic brain injury. We used PubMed as a database and included the following keywords ((methylphenidate) OR (Ritalin) OR (Concerta) OR (Biphentin) OR (amphetamine) OR (Adderall)) AND ((stroke) OR (brain injury) OR (neuroplasticity)). Overall, studies provided inconsistent results regarding cognitive and motor function. Neurite outgrowth, synaptic proteins, dendritic complexity, and synaptic plasticity increases were reported in pre-clinical studies along with function improvement. Clinical trials have demonstrated that, depending on the brain region, there is an increase in motor activity, attention, and memory due to the stimulation of the functionally depressed catecholamine system and the activation of neuronal remodeling proteins. Nevertheless, more clinical trials and pre-clinical studies are needed to understand the drugs' full potential for their use in these brain diseases namely, to ascertain the treatment time window, ideal dosage, long-term effects, and mechanisms, while avoiding their addictive potential.
RESUMEN
Doxorubicin (DOX) is an anthracycline used to treat a wide range of tumours. Despite its effectiveness, it is associated with a long range of adverse effects, of which cognitive deficits stand out. The present study aimed to assess the neurologic adverse outcome pathways of two clinically relevant cumulative doses of DOX. Adult male CD-1 mice received biweekly intraperitoneal administrations for 3 weeks until reaching cumulative doses of 9 mg/kg (DOX9) or 18 mg/kg (DOX18). Animals were euthanized one week after the last administration, and biomarkers of oxidative stress and brain metabolism were evaluated in the whole brain. Coronal sections of fixed brains were used for specific determinations of the prefrontal cortex (PFC) and hippocampal formation (HF). In the whole brain, DOX18 tended to disrupt the antioxidant defences, affecting glutathione levels and manganese superoxide dismutase expression. Considering the regional analysis, DOX18 increased the volume of all brain areas evaluated, while GFAP-immunoreactive astrocytes decreased in the dentate gyrus (DG) and increased in the CA3 region of HF, both in a dose-dependent manner. Concerning the apoptosis pathway, whereas Bax increased in the DOX9 group, it decreased in the DOX18 group. Only in the latter group did Bcl-2 levels also decrease. While p53 only increased in the CA3 region of the DOX9 group, AIF increased in the PFC and DG of DOX18. Finally, phosphorylation of Tau decreased with the highest DOX dose in DG and CA3, while TNF-α levels increased in CA1 of DOX18. Our results indicate new pathways not yet described that could be responsible for the cognitive impairments observed in treated patients.
RESUMEN
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 ß-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.
Asunto(s)
Trastornos Relacionados con Anfetaminas/complicaciones , Anfetamina/toxicidad , Estimulantes del Sistema Nervioso Central/toxicidad , Anfetamina/química , Anfetamina/farmacocinética , Trastornos Relacionados con Anfetaminas/genética , Trastornos Relacionados con Anfetaminas/metabolismo , Animales , Estimulantes del Sistema Nervioso Central/química , Estimulantes del Sistema Nervioso Central/farmacocinética , Enfermedad Hepática Inducida por Sustancias y Drogas/etiología , Predisposición Genética a la Enfermedad , Cardiopatías/inducido químicamente , Humanos , Enfermedades Renales/inducido químicamente , Síndromes de Neurotoxicidad/etiología , Rabdomiólisis/inducido químicamente , Medición de Riesgo , Factores de RiesgoRESUMEN
3,4-Methylenedioxymethamphetamine (MDMA or "ecstasy") is a drug of abuse used by millions worldwide. MDMA human abuse and dependence is well described, but addictive properties are not always consistent among studies. This amphetamine is a substrate type releaser, binding to monoamine transporters, leading to a pronounced release of serotonin and noradrenaline and to a minor extent dopamine. The toxicity of MDMA is well studied at the pre-clinical level, with neurotoxicity and hepatotoxicity being particularly described. In this review, we describe the most relevant MDMA effects at the mitochondrial level found in in vitro and in vivo models, these later conducted in mice and rats. Most of these reports focus on the mitochondria of brain or liver. In in vitro models, MDMA causes depletion of ATP levels and inhibition of mitochondrial complex I and III, loss in mitochondrial membrane potential (ΔΨm) and induction of mitochondrial permeability transition. The involvement of mitochondria in the apoptotic cell death evoked by MDMA has also been shown, such as the release of cytochrome c. Additionally, MDMA or its metabolites impaired mitochondrial trafficking and increased the fragmentation of axonal mitochondria. In animal studies, MDMA decreased mitochondrial complex I activity and decreased ATP levels. Moreover, MDMA-evoked oxidative stress has been shown to cause deletion on mitochondrial DNA and impairment in mitochondrial protein synthesis. Although the concentrations and doses used in some studies do not always correlate to the human scenario, the mitochondrial abnormalities evoked by MDMA are well described and are in part responsible for its mechanism of toxicity.
RESUMEN
"Ecstasy" [(+/-)-3,4-methylenedioxymethamphetamine, MDMA, XTC, X, E] is a psychoactive recreational hallucinogenic substance and a major worldwide drug of abuse. Several reports raised the concern that MDMA has the ability to induce neurotoxic effects both in laboratory animals and humans. Despite more than two decades of research, the mechanisms by which MDMA is neurotoxic are still to be fully elucidated. MDMA induces serotonergic terminal loss in rats and also in some mice strains, but also a broader neuronal degeneration throughout several brain areas such as the cortex, hippocampus, and striatum. Meanwhile, in human "ecstasy" abusers, there are evidences for deficits in seronergic biochemical markers, which correlate with long-term impairments in memory and learning. There are several factors that contribute to MDMA-induced neurotoxicity, namely, hyperthermia, monoamine oxidase metabolism of dopamine and serotonin, dopamine oxidation, the serotonin transporter action, nitric oxide, and the formation of peroxinitrite, glutamate excitotoxicity, serotonin 2A receptor agonism, and, importantly, the formation of MDMA neurotoxic metabolites. The present review covered the following topics: history and epidemiology, pharmacological mechanisms, metabolic pathways and the influence of isoenzyme genetic polymorphisms, as well as the acute effects of MDMA in laboratory animals and humans, with a special focus on MDMA-induced neurotoxic effects at the cellular and molecular level. The main aim of this review was to contribute to the understanding of the cellular and molecular mechanisms involved in MDMA neurotoxicity, which can help in the development of therapeutic approaches to prevent or treat the long-term neuropsychiatric complications of MDMA abuse in humans.
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N-Metil-3,4-metilenodioxianfetamina/farmacología , Síndromes de Neurotoxicidad/metabolismo , Síndromes de Neurotoxicidad/patología , Animales , Humanos , N-Metil-3,4-metilenodioxianfetamina/química , N-Metil-3,4-metilenodioxianfetamina/farmacocinética , Polimorfismo Genético , Factores de TiempoRESUMEN
Synthetic cathinones also known as ß-keto amphetamines are a new group of recreational designer drugs. We aimed to evaluate the cytotoxic potential of thirteen cathinones lacking the methylenedioxy ring and establish a putative structure-toxicity profile using differentiated SH-SY5Y cells, as well as to compare their toxicity to that of amphetamine (AMPH) and methamphetamine (METH). Cytotoxicity assays [mitochondrial 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) reduction and lysosomal neutral red (NR) uptake] performed after a 24-h or a 48-h exposure revealed for all tested drugs a concentration-dependent toxicity. The rank order regarding the concentration that promoted 50 % of toxicity, at 24â¯h exposure, by the MTT assay was: 3,4-dimethylmethcathinone (3,4-DMMC) > METHâ¯>â¯mephedrone ≈ α-pyrrolidinopentiophenoneâ¯>â¯AMPH ≈ methedroneâ¯>â¯pentedroneâ¯>â¯buphedrone ≈ flephedrone >α-pyrrolidinobutiophenoneâ¯>â¯methcathinone ≈ N-ethylcathinone >α-pyrrolidinopropiophenone >N,N-dimethylcathinone ≈ amfepramone. Apoptotic cell death signs were seen for all studied cathinones. 3,4-DMMC, methcathinone and pentedrone triggered autophagy activation, as well as increased reactive oxygen species production, and N-acetyl-L-cysteine (NAC) totally prevented that rise. Importantly, NAC was also able to prevent the cytotoxicity promoted by 6 tested drugs, ruling for an involvement of oxidative stress in the toxic events observed. The increased lipophilic chain on the alpha carbon, the presence and the high steric volume occupied by the substituents on the aromatic ring, and the substitution of the pyrrolidine ring by its secondary amine analogue have proved to be key points for the cytotoxicity profile of these cathinones. The structure-toxicity relationship established herein may enlighten future human relevant mechanistic studies, and future clinical approaches on intoxications.
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Alcaloides/toxicidad , Anfetaminas/toxicidad , Neuronas/efectos de los fármacos , Alcaloides/química , Anfetaminas/química , Apoptosis/efectos de los fármacos , Autofagia/efectos de los fármacos , Línea Celular Tumoral , Relación Dosis-Respuesta a Droga , Humanos , Microscopía de Contraste de Fase , Neuronas/ultraestructura , Propiofenonas/toxicidad , Especies Reactivas de Oxígeno/metabolismo , Relación Estructura-ActividadRESUMEN
5,7-Dihydroxytryptamine (5,7-DHT), is an experimentally widely used selective serotonergic neurotoxin, though the mechanisms of toxicity remain to be fully elucidated. In the present study, we evaluated 5,7-dihydroxitryptamine (5,7-DHT) induced serotonergic neurotoxicity in foetal raphe serum free cultures from the rat. For this purpose, a model of foetal raphe serum free neuronal cultures from the rat was established, containing about 16% serotonergic neurons and studied up to 3 months. Two weeks old raphe cultures were exposed to the serotonergic neurotoxin 5,7-DHT (concentration range 10-100 microM) for 72 h, after which the medium was replaced and neurotoxicity was evaluated by immunocitochemistry 1 week later. Lactate dehydrogenase release into the medium, 72 h after exposure to 5,7-DHT, showed a concentration-dependent neurotoxicity. To access morphologically the serotonergic toxicity tryptophan hydroxylase (TPH) was used as a specific marker of these neurons. Immunocitochemistry using TPH antisera showed a concentration-dependent serotonergic neurotoxicity induced by 5,7-DHT. Serotonergic neurons showed the typical pattern of "pruning" accompanied by axon terminals and dendrites loss, which were either partial or total. The axotomy induced by the neurotoxin was morphologically characteristic of retrograde axonal degeneration. Fluoxetine (0.1 microM) pre-treatment reduced 5,7-DHT-induced serotonergic neurotoxicity. These results indicate that the mechanism by which 5,7-DHT-induces serotonergic neurotoxicity is, at least partially, dependent on the toxin uptake by the serotonin transporter. Finally, we have established a robust model of primary raphe neuronal culture to evaluate serotonergic neurons development and the mechanisms of toxicity involving this neuronal population.
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5,7-Dihidroxitriptamina/toxicidad , Núcleos del Rafe/efectos de los fármacos , Animales , Células Cultivadas , Medio de Cultivo Libre de Suero , Relación Dosis-Respuesta a Droga , Fluoxetina/farmacología , N-Metil-3,4-metilenodioxianfetamina/toxicidad , Degeneración Nerviosa , Fibras Nerviosas/efectos de los fármacos , Núcleos del Rafe/patología , RatasRESUMEN
Abstract Prolonged overexposure to catecholamines causes toxicity, usually credited to continuous adrenoceptor stimulation, autoxidation, and the formation of reactive pro-oxidant species. Non-differentiated SH-SY5Y cells were used to study the possible contribution of oxidative stress in adrenaline (ADR)-induced neurotoxicity, as a model to predict the toxicity of this catecholamine to peripheral nerves. Cells were exposed to several concentrations of ADR (0.1, 0.25, 0.5 and 1mM) and two cytotoxicity assays [lactate dehydrogenase (LDH) release and 3-(4,5-dimethylthiazol-2yl)-2,5-diphenyl tetrazolium bromide (MTT) reduction] were performed at several time-points (24, 48, and 96h). The cytotoxicity of ADR was concentration- and time-dependent in both assays, since the lowest concentration tested (0.1mM) also caused significant cytotoxicity at 96h. N-acetyl-cysteine (1mM), a precursor of glutathione synthesis, prevented ADR-induced toxicity elicited by 0.5mM and 0.25mM ADR following a 96-h exposure, while the antioxidant Tiron (100µM) was non-protective. In conclusion, ADR led to mitochondrial distress and ultimately cell death in non-differentiated SH-SY5Y cells, possibly because of ADR oxidation products. The involvement of such processes in the catecholamine-induced peripheral neuropathy requires further analysis.
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Epinefrina/agonistas , Enfermedades del Sistema Nervioso Periférico/clasificación , Toxicidad , Neuronas/clasificación , Nervios Periféricos/anomalías , Bromuros/antagonistas & inhibidores , Estrés Oxidativo/efectos de los fármacos , Antioxidantes/farmacologíaRESUMEN
The potential neurotoxic effects of anticancer drugs, like doxorubicin (DOX) and mitoxantrone (MTX; also used in multiple sclerosis), are presently important reasons for concern, following epidemiological data indicating that cancer survivors submitted to chemotherapy may suffer cognitive deficits. We evaluated the in vitro neurotoxicity of two commonly used chemotherapeutic drugs, DOX and MTX, and study their underlying mechanisms in the SH-SY5Y human neuronal cell model. Undifferentiated human SH-SY5Y cells were exposed to DOX or MTX (0.13, 0.2 and 0.5 μM) for 48 h and two cytotoxicity assays were performed, the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium (MTT) reduction and the neutral red (NR) incorporation assays. Phase contrast microphotographs, Hoechst, and acridine orange/ethidium bromide stains were performed. Mitochondrial membrane potential was also assessed. Moreover, putative protective drugs, namely the antioxidants N-acetyl-l-cysteine (NAC; 1 mM) and 100 μM tiron, the inhibitor of caspase-3/7, Ac-DEVD-CHO (100 μM), and a protein synthesis inhibitor, cycloheximide (CHX; 10 nM), were tested to prevent DOX- or MTX-induced toxicity. The MTT reduction assay was also done in differentiated SH-SY5Y cells following exposure to 0.2 μM DOX or MTX. MTX was more toxic than DOX in both cytotoxicity assays and according to the morphological analyses. MTX also evoked a higher number of apoptotic nuclei than DOX. Both drugs, at the 0.13 μM concentration, caused mitochondrial membrane potential depolarization after a 48-h exposure. Regarding the putative neuroprotectors, 1 mM NAC was not able to prevent the cytotoxicity caused by either drug. Notwithstanding, 100 μM tiron was capable of partially reverting MTX-induced cytotoxicity in the NR uptake assay. One hundred μM Ac-DEVD-CHO and 10 nM cycloheximide (CHX) also partially prevented the toxicity induced by DOX in the NR uptake assay. MTX was more toxic than DOX in differentiated SH-SY5Y cells, while MTX had similar toxicity in differentiated and undifferentiated SH-SY5Y cells. In fact, MTX was the most neurotoxic drug tested and the mechanisms involved seem dissimilar among drugs. Thus, its toxicity mechanisms need to be further investigated as to determine the putative neurotoxicity for multiple sclerosis and cancer patients.