ABSTRACT
Rat whole-brain spheroids were used to assess the intrinsic neurotoxicity of methylenedioxy-methamphetamine (MDMA, Ecstasy) and two of its metabolites, dihydroxymethamphetamine (DHMA) and 6-hydroxy-MDMA (6-OH MDMA). Exposure of brain spheroids to MDMA or the metabolite 6-OH MDMA (up to 500 micromol/L) for 5 days in culture did not alter intracellular levels of glutathione (GSH), glial fibrillary acidic protein (GFAP) or serotonin (5-HT). In contrast, exposure to the metabolite DHMA, which can deplete intracellular thiols, significantly increased GSH levels (up to 170% of control) following exposure to 50 and 100 micromol/L DHMA. There was also a significant reduction in the levels of glial fibrillary acidic protein (GFAP) and GSH by DHMA at the highest concentration tested (500 micromol/L) but there was no effect on 5HT. This may constitute a sublethal neurotoxic compensatory response to DHMA in an attempt to replenish depleted intraneural GSH levels following metabolite exposure. Rat whole-brain spheroids may thus be a useful in vitro model to delineate mechanisms and effects of this class of neurotoxin.
Subject(s)
3,4-Methylenedioxyamphetamine/analogs & derivatives , Brain Diseases/chemically induced , Brain/drug effects , Deoxyepinephrine/analogs & derivatives , N-Methyl-3,4-methylenedioxyamphetamine/toxicity , Serotonin Agents/toxicity , Spheroids, Cellular/drug effects , 3,4-Methylenedioxyamphetamine/metabolism , 3,4-Methylenedioxyamphetamine/toxicity , Animals , Biomarkers , Brain/cytology , Brain/enzymology , Brain/metabolism , Brain Diseases/enzymology , Brain Diseases/metabolism , Cytosol/enzymology , Deoxyepinephrine/metabolism , Deoxyepinephrine/toxicity , Dose-Response Relationship, Drug , Fetus , Glial Fibrillary Acidic Protein/metabolism , Glutathione/metabolism , L-Lactate Dehydrogenase/metabolism , N-Methyl-3,4-methylenedioxyamphetamine/metabolism , Rats , Serotonin/metabolism , Serotonin Agents/metabolismABSTRACT
Both excitotoxicity and oxidative stress are implicated in the pathophysiology of central nervous system (CNS) ischaemia-reperfusion injury whereby astrocytes offer neural protection through the production of endogenous antioxidants and removal of glutamate from the extracellular milieu. This study investigated whether exogenous alpha-tocopherol, an antioxidant, could prevent N-methyl-D-aspartate (NMDA)-produced increases of the glial specific proteins, glutamine synthetase (GS) and glial fibrillary acidic protein (GFAP) in rat brain spheroids in vitro. NMDA (320 microM; 3 days in vitro (DIV)) was unable to induce lipid peroxidation in rat brain spheroids implying that excitotoxicity in this system did not involve substantial free radical formation. However at non-cytotoxic concentrations, increases in astroglial GS were prevented by alpha-tocopherol treatment, suggesting a role for ROS in the excitotoxic process. In contrast, NMDA-induced increases in GFAP remained unchanged by alpha-tocopherol indicating that oxidative stress may not be involved in reactive gliosis at non-cytotoxic NMDA concentrations.
