title: MDMA-induced neurotoxicity of serotonin neurons involves autophagy and rilmenidine is protective against its pathobiology.
abstract: Toxicity of 3,4-methylenedioxymethamphetamine (MDMA) towards biogenic amine neurons is well documented and in primate brain predominantly affects serotonin (5-HT) neurons. MDMA induces damage of 5-HT axons and nerve fibres and intracytoplasmic inclusions. Whilst its pathobiology involves mitochondrially-mediated oxidative stress, we hypothesised MDMA possessed the capacity to activate autophagy, a proteostatic mechanism for degradation of cellular debris. We established a culture of ventral pons from embryonic murine brain enriched in 5-HT neurons to explore mechanisms of MDMA neurotoxicity and recruitment of autophagy, and evaluated possible neuroprotective actions of the clinically approved agent rilmenidine. MDMA (100 μM-1 mM) reduced cell viability, like rapamycin (RM) and hydrogen peroxide (H2O2), in a concentration- and time-dependent manner. Immunocytochemistry revealed dieback of 5-HT arbour: MDMA-induced injury was slower than for RM and H2O2, neuritic blebbing occurred at 48 and 72 h and Hoechst labelling revealed nuclear fragmentation with 100 μM MDMA. MDMA effected concentration-dependent inhibition of [3H]5-HT uptake with 500 μM MDMA totally blocking transport. Western immunoblotting for microtubule associated protein light chain 3 (LC3) revealed autophagosome formation after treatment with MDMA. Confocal analyses and immunocytochemistry for 5-HT, Hoechst and LC3 confirmed MDMA induced autophagy with abundant LC3-positive puncta within 5-HT neurons. Rilmenidine (1 μM) protected against MDMA-induced injury and image analysis showed full preservation of 5-HT arbours. MDMA had no effect on GABA neurons, indicating specificity of action at 5-HT neurons. MDMA-induced neurotoxicity involves autophagy induction in 5-HT neurons, and rilmenidine via beneficial actions against toxic intracellular events represents a potential treatment for its pathobiology in sustained usage.
authors.affiliation: Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, Victoria 3010, Australia.
authors.forename: Linda D
authors.initials: LD
authors.lastname: Mercer
authors.affiliation: Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, Victoria 3010, Australia.
authors.forename: Gavin C
authors.initials: GC
authors.lastname: Higgins
authors.affiliation: Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, Victoria 3010, Australia.
authors.forename: Chew L
authors.initials: CL
authors.lastname: Lau
authors.affiliation: Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, Victoria 3010, Australia.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Lawrence
authors.affiliation: Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, Victoria 3010, Australia. Electronic address: philip.beart@florey.edu.au.
authors.forename: Philip M
authors.initials: PM
authors.lastname: Beart
mesh_terms: D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000818:Animals; D001343:Autophagy / Q000187:drug effects* / Q000502:physiology; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D005260:Female; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018817:N-Methyl-3,4-methylenedioxyamphetamine / Q000633:toxicity*; D018696:Neuroprotective Agents / Q000494:pharmacology*; D010080:Oxazoles / Q000494:pharmacology*; D011247:Pregnancy; D000077769:Rilmenidine; D059326:Serotonergic Neurons / Q000187:drug effects* / Q000473:pathology* / Q000502:physiology; D018490:Serotonin Agents / Q000633:toxicity
chemical_list: D000316:Adrenergic alpha-Agonists; D018696:Neuroprotective Agents; D010080:Oxazoles; D018490:Serotonin Agents; D018817:N-Methyl-3,4-methylenedioxyamphetamine; D000077769:Rilmenidine
keywords: MDMA; Neuroprotection; Programmed cell death; Rilmenidine; Serotonin neuron; mTOR-independent autophagy