Neurotoxicity of Ecstasy Metabolites in Rat Cortical Neurons, and Influence of Hyperthermia

Abstract

3,4-Methylenedioxymethamphetamine (MDMA or "Ecstasy") is a widely abused, psychoactive recreational drug. There is growing evidence that the MDMA neurotoxic profile may be highly dependent on both its hepatic metabolism and body temperature. 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-␣-methyldopamine (N-Me-␣-MeDA) and ␣-methyldopamine (␣-MeDA), respectively, both of which are catechols that can undergo oxidation to the corresponding ortho-quinones. In the presence of glutathione (GSH), ortho-quinones may be conjugated with GSH to form glutathionyl adducts. In this study, we evaluated the neurotoxicity of MDMA and three of its metabolites obtained by synthesis, N-Me-␣-MeDA, ␣-MeDA, and 5-(GSH)-␣-MeDA [5-(glutathion-S-yl)-␣-methyldopamine] in rat cortical neuronal serum-free cultures under normal (36.5°C) and hyperthermic (40°C) conditions. Cell viability was assessed, and the mechanism of cell death was also evaluated. Our study shows that these metabolites are more neurotoxic [5-(GSH)-␣-MeDA being the most toxic] than the parent compound MDMA. The neurotoxicity of MDMA metabolites was partially prevented by the antioxidants N-acetylcystein and also, in a minor extent, by ␣-phenyl-N-tert-butyl nitrone. All the tested compounds induced apoptotic cell death in cortical neurons, and their neurotoxic effect was potentiated under hyperthermic conditions. These data suggest that MDMA metabolites, especially under hyperthermic conditions, contribute to MDMA-induced neurotoxicity.

The risky cocktail: what combination effects can we expect between ecstasy and other amphetamines?

“…The tested concentrations used in the present study are in the range of concentrations used in several mechanistic in vitro studies (Simantov and Tauber 1997;Stumm et al 1999a;Carvalho et al 2004a, b;Capela et al 2006). They are higher than concentrations commonly found in human abusers.…”

“…The obtained salts were purified and fully characterized by nuclear magnetic resonance (NMR) Arch Toxicol and mass spectrometry (MS) methodologies. d-AMP sulphate was generously provided by Dr Frederico Pereira (IBILI, Faculty of Medicine, University of Coimbra, Portugal), and 4-hydroxy-3-methoxymethamphetamine (HMMA, 3-O-Me-N-Me-a-MeDA) and 4-hydroxy-3-methoxyamphetamine (HMA, 3-O-Me-a-MeDA) were synthesized at the Chemistry Department, Faculty of Science and Technology, University Nova de Lisboa, Portugal, following a previously described procedure (Capela et al 2006). 1 cc (30 mg) OASIS MCX SPE extraction cartridges were purchased from Waters (Lisbon, Portugal).…”

Molecular and Cellular Mechanisms of Ecstasy-Induced Neurotoxicity: An Overview

“…Studies in rats suggested that N-Me-α-MeDA and α-MeDA can undergo oxidation to the corresponding ortho-quinones, which can form adducts with glutathione (GSH) and other thiol-containing compounds [72][73][74][75]. These GSH conjugates remain redox active and, as already shown in rats, can undergo the addition of a second molecule of GSH, yielding a 2,5-bisglutathionyl conjugate [72,76,77]. The systemic formation of GSH conjugates of α-MeDA and N-Me-α-MeDA in the liver is followed by their distribution into other organs, and their uptake into the brain is well established [78].…”

“…The systemic formation of GSH conjugates of α-MeDA and N-Me-α-MeDA in the liver is followed by their distribution into other organs, and their uptake into the brain is well established [78]. GSH conjugates can undergo further metabolism via the mercapturic acid pathway by γ-glutamyl transpeptidase (γ-GT) and dipeptidase to the corresponding cysteine conjugates and finally by N-acetyltransferase to the corresponding Nacetylcysteine (NAC) conjugates [76][77][78]. A detailed pathway of MDMA metabolism is represented in Fig.…”

MDMA (Ecstasy) Decreases the Number of Neurons and Stem Cells in Embryonic Cortical Cultures

“…The cell death is potentiated by hyperthermia, a common side effect of ecstasy abuse (Capela et al 2006b). The embryonic cortex cultures used by most investigators are a mixture of cells consisting of *10% astrocytes (Capela et al 2006a), while the remainder consists primarily of cortical neurons. However, many nestinpositive cells also reside in the rat cortex at E17 and subsequently also in the cortical cultures.…”