Duvauchelle, Christine L.Monks, Terrence J.686264592008-08-282008-08-282004http://hdl.handle.net/2152/2029text3,4-Methylenedioxyamphetamine (MDA) and 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) are widely abused amphetamine derivatives that target the serotonin (5-HT) system. The direct administration of MDA/MDMA into the brain fails to reproduce the ìserotonin syndromeî that defines the neurotoxicity of MDA/MDMA; thus, the neurotoxicity of MDA and MDMA appears dependent on their systemic metabolism. 5-(Glutathion-S-yl)-α- methyldopamine and 2,5-bis(glutathion-S-yl)-α-methyldopamine, metabolites of MDA/MDMA, are potent serotonergic neurotoxicants, and produce behavioral and neurochemical changes similar to those observed with MDA/MDMA. Therefore, we investigated the transport of α- MeDA thioethers into the brain, and the biochemical mechanisms underling the development of neurotoxicity. Collection of extracellular fluid samples with microdialysis and subsequent analysis by HPLC and LC-MS/MS lead to the identification of thioether metabolites of N-Me-α- MeDA in the brain following peripheral administration of MDMA. GSH conjugate concentrations increased rapidly prior to a rapid decrease, whereas brain concentrations of the Nacetylcysteine conjugates increased slowly. Correlations exist between the concentration of NMe-α-MeDA in the brain and decreases in brain 5-HT and 5-HIAA induced by MDMA. MDMA is demethylenated to N-Me-α-MeDA; we therefore, examined the potential neurotoxicity of 5- (NAC)-N-Me-α-MeDA. Following intrastriatal injections, 5-(NAC)-N-Me-α-MeDA produced decreases in 5-HT, 5-HIAA, and dopamine (DA). We subsequently utilized three different cell models to investigate the potential mechanisms by which 5-(GSyl)-α-MeDA and 2,5-bis(GSyl)- α-MeDA induce neurotoxicity. 5-(GSyl)-α-MeDA and 2,5-bis(GSyl)-α-MeDA are more potent than MDA/MDMA at inhibiting 5-HT transport into i) SK-N-MC cells transfected with the human serotonin transporter (SERT), ii) JAR cells, and iii) primary rat hippocampal cells. 5- (GSyl)-α-MeDA and 2,5-bis(GSyl)-α-MeDA induced an increase in (DA) transport into all three cell models, an effect attenuated by fluoxetine, indicating that DA transport was SERTdependent. 5-(GSyl)-α-MeDA and 2,5-bis(GSyl)-α-MeDA increased reactive oxygen species (ROS) in each cell model. Fluoxetine attenuated the increase in ROS generation in hSERTexpressing cells. Finally, 5-(GSyl)-α-MeDA and 2,5-bis(GSyl)-α-MeDA produced loss of cell viability and apoptosis in SERT-transfected SK-N-MC cells, JAR cells and hippocampal cells. These results are consistent with the view that the serotonergic neurotoxicity of MDA/MDMA requires i) the systemic metabolism to α-MeDA and N-Me-α-MeDA and conjugation to GSH, and ii) is likely mediated through ROS generation and the stimulation of DA transport into serotonergic neurons.electronicengCopyright is held by the author. Presentation of this material on the Libraries' web site by University Libraries, The University of Texas at Austin was made possible under a limited license grant from the author who has retained all copyrights in the works.Ecstasy (Drug)--MetabolismSerotoninergic mechanismsNeurotoxicologyAlpha-methyldopamineThesis3143898