Capela JP, Macedo C, Branco PS, Ferreira LM, Lobo AM, Fernandes E, Remião F, Bastos ML, Dirnagl U, Meisel A, Carvalho F.
“Neurotoxicity mechanisms of thioether ecstasy metabolites”.
Neuroscience. 2007 Jun 28;146(4):1743-57.
3,4-Methylenedioxymethamphetamine MDMA or 'ecstasy', is a widely abused, psychoactive recreational drug that is known to induce neurotoxic effects. Human and rat hepatic metabolism of MDMA involves N-demethylation to 3,4-methylenedioxyamphetamine MDA, which is also a drug of abuse. MDMA and MDA are O-demethylenated to N-methyl-alpha-methyldopamine N-Me-alpha-MeDA and alpha-methyldopamine alpha-MeDA, respectively, which are both catechols that can undergo oxidation to the corresponding ortho-quinones. Ortho-quinones may be conjugated with glutathione GSH to form glutathionyl adducts, which can be transported into the brain and metabolized to the correspondent N-acetylcysteine NAC adducts. In this study we evaluated the neurotoxicity of nine MDMA metabolites, obtained by synthesis: N-Me-alpha-MeDA, alpha-MeDA and their correspondent GSH and NAC adducts. The studies were conducted in rat cortical neuronal cultures, for a 6 h of exposure period, under normal 36.5 degrees C and hyperthermic 40 degrees C conditions. Our findings show that thioether MDMA metabolites are strong neurotoxins, significantly more than their correspondent parent catechols. On the other hand, N-Me-alpha-MeDA and alpha-MeDA are more neurotoxic than MDMA. GSH and NAC conjugates of N-Me-alpha-MeDA and alpha-MeDA induced a concentration dependent delayed neuronal death, accompanied by activation of caspase 3, which occurred earlier in hyperthermic conditions. Furthermore, thioether MDMA metabolites time-dependently increased the production of reactive species, concentration-dependently depleted intracellular GSH and increased protein bound quinones. Finally, thioether MDMA metabolites induced neuronal death and oxidative stress was prevented by NAC, an antioxidant and GSH precursor. This study provides new insights into the neurotoxicity mechanisms of thioether MDMA metabolites and highlights their importance in 'ecstasy' neurotoxicity.