title: "Ecstasy"-induced toxicity in SH-SY5Y differentiated cells: role of hyperthermia and metabolites.
abstract: 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.
authors.affiliation: REQUIMTE (Rede de Química e Tecnologia), Toxicology Laboratory, Department of Biological Sciences, Faculty of Pharmacy, University of Porto, Rua Jorge Viterbo Ferreira 228, 4050-313, Porto, Portugal, daniel.barbosa@ff.up.pt.
authors.forename: Daniel José
authors.initials: DJ
authors.lastname: Barbosa
authors.forename: João Paulo
authors.initials: JP
authors.lastname: Capela
authors.forename: Renata
authors.initials: R
authors.lastname: Silva
authors.forename: Luísa Maria
authors.initials: LM
authors.lastname: Ferreira
authors.forename: Paula Sério
authors.initials: PS
authors.lastname: Branco
authors.forename: Eduarda
authors.initials: E
authors.lastname: Fernandes
authors.forename: Maria Lourdes
authors.initials: ML
authors.lastname: Bastos
authors.forename: Félix
authors.initials: F
authors.lastname: Carvalho
mesh_terms: D015104:3,4-Methylenedioxyamphetamine / Q000378:metabolism / Q000633:toxicity; D000111:Acetylcysteine / Q000378:metabolism / Q000494:pharmacology; D053148:Caspase 3 / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D002454:Cell Differentiation / Q000187:drug effects*; D002460:Cell Line / Q000187:drug effects; D003846:Deoxyepinephrine / Q000031:analogs & derivatives / Q000378:metabolism / Q000633:toxicity; D005334:Fever / Q000139:chemically induced* / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism; D006801:Humans; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D018817:N-Methyl-3,4-methylenedioxyamphetamine / Q000378:metabolism* / Q000493:pharmacokinetics / Q000633:toxicity*; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism; D020258:Neurotoxicity Syndromes / Q000378:metabolism / Q000473:pathology; D013696:Temperature
chemical_list: D015104:3,4-Methylenedioxyamphetamine; C023492:alpha-methyldopamine; D053148:Caspase 3; D005978:Glutathione; D018817:N-Methyl-3,4-methylenedioxyamphetamine; D003846:Deoxyepinephrine; D000111:Acetylcysteine