Ecstasy induces apoptosis via 5-HT(2A)-receptor stimulation in cortical neurons.
ABSTRACT 3,4-Methylenedioxymethamphetamine (MDMA or "Ecstasy") is a psychoactive and hallucinogenic drug of abuse. MDMA has been shown to produce neurotoxicity both in animals and humans. MDMA and other amphetamines induce serotonergic and dopaminergic terminal neurotoxicity and also neurodegeneration in areas including the cortex, hippocampus, striatum and thalamus. Herein, we investigated the mechanisms involved in MDMA-induced neurotoxicity to neuronal serum free cultures from rat cortex. The hyperthermic effect produced by MDMA has been shown to be a clinically relevant aspect for the neurotoxic events. Thus, MDMA-induced toxicity to cortical neurons was evaluated both under normothermic (36.5 degrees C) and hyperthermic (40 degrees C) conditions. Our findings showed that MDMA produced neuronal apoptosis, accompanied by activation of caspase 3, in a concentration dependent manner. MDMA neurotoxicity was completely prevented by pre-treatment with a 5-HT(2A)-receptor antibody, which acted as an "irreversible non-competitive antagonist" of this receptor. Furthermore, MDMA depleted intracellular glutathione (GSH) levels in a concentration dependent manner, an effect that was attenuated by Ketanserin, a competitive 5-HT(2A)-receptor antagonist. Accordingly, N-acetylcysteine, an antioxidant and GSH precursor, also reduced MDMA-induced toxicity. Specific inhibitors of the inducible and neuronal nitric oxide synthase (NOS) partially prevented MDMA neurotoxicity, ascertaining the involvement of reactive nitrogen species, in the toxic effect. In conclusion, direct MDMA 5-HT(2A)-receptor stimulation produces intracellular oxidative stress that leads to neuronal apoptosis accompanied by caspase 3 activation.
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ABSTRACT: 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.Archives of Toxicology 10/2013; · 5.22 Impact Factor
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ABSTRACT: Methamphetamine is a psychomotor stimulant that produces hyperlocomotion in rodents. Limonene (a cyclic terpene from citrus essential oils) has been reported to induce sedative effects. In this study, we demonstrated that limonene administration significantly inhibited serotonin (5-hydroxytryptamine, 5-HT)-induced head twitch response in mice. In rats, pretreatment with limonene decreased hyperlocomotion induced by methamphetamine injection. In addition, limonene reversed the increase in dopamine levels in the nucleus accumbens of rats given methamphetamine. These results suggest that limonene may inhibit stimulant-induced behavioral changes via regulating dopamine levels and 5-HT receptor function.Phytomedicine: international journal of phytotherapy and phytopharmacology 01/2014; · 2.97 Impact Factor