title: Autophagy activation is involved in 3,4-methylenedioxymethamphetamine ('ecstasy')--induced neurotoxicity in cultured cortical neurons.
abstract: Autophagic (type II) cell death, characterized by the massive accumulation of autophagic vacuoles in the cytoplasm of cells, has been suggested to play pathogenetic roles in cerebral ischemia, brain trauma, and neurodegenerative disorders. 3,4-Methylenedioxymethamphetamine (MDMA or ecstasy) is an illicit drug causing long-term neurotoxicity in the brain. Apoptotic (type I) and necrotic (type III) cell death have been implicated in MDMA-induced neurotoxicity, while the role of autophagy in MDMA-elicited neurotoxicity has not been investigated. The present study aimed to evaluate the occurrence and contribution of autophagy to neurotoxicity in cultured rat cortical neurons challenged with MDMA. Autophagy activation was monitored by expression of microtubule-associated protein 1 light chain 3 (LC3; an autophagic marker) using immunofluorescence and western blot analysis. Here, we demonstrate that MDMA exposure induced monodansylcadaverine (MDC)- and LC3B-densely stained autophagosome formation and increased conversion of LC3B-I to LC3B-II, coinciding with the neurodegenerative phase of MDMA challenge. Autophagy inhibitor 3-methyladenine (3-MA) pretreatment significantly attenuated MDMA-induced autophagosome accumulation, LC3B-II expression, and ameliorated MDMA-triggered neurite damage and neuronal death. In contrast, enhanced autophagy flux by rapamycin or impaired autophagosome clearance by bafilomycin A1 led to more autophagosome accumulation in neurons and aggravated neurite degeneration, indicating that excessive autophagosome accumulation contributes to MDMA-induced neurotoxicity. Furthermore, MDMA induced phosphorylation of AMP-activated protein kinase (AMPK) and its downstream unc-51-like kinase 1 (ULK1), suggesting the AMPK/ULK1 signaling pathway might be involved in MDMA-induced autophagy activation.
authors.affiliation: Department of Pharmacy Practice, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan.
authors.forename: I-Hsun
authors.initials: IH
authors.lastname: Li
authors.affiliation: Department of Biology and Anatomy, National Defense Medical Center, Taipei, Taiwan.
authors.forename: Kuo-Hsing
authors.initials: KH
authors.lastname: Ma
authors.affiliation: Department of Biology and Anatomy, National Defense Medical Center, Taipei, Taiwan.
authors.forename: Shao-Ju
authors.initials: SJ
authors.lastname: Weng
authors.affiliation: Department of Pharmacology and Institute of Medicine, College of Medicine, Chung Shan Medical University, Taichung, Taiwan.
authors.forename: Shiang-Suo
authors.initials: SS
authors.lastname: Huang
authors.affiliation: Department of Ophthalmology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan; Graduate Institute of Aerospace and Undersea Medicine, National Defense Medical Center, Taipei, Taiwan.
authors.forename: Chang-Min
authors.initials: CM
authors.lastname: Liang
authors.affiliation: Department of Biology and Anatomy, National Defense Medical Center, Taipei, Taiwan.
authors.forename: Yuahn-Sieh
authors.initials: YS
authors.lastname: Huang
mesh_terms: D015104:3,4-Methylenedioxyamphetamine / Q000031:analogs & derivatives* / Q000633:toxicity; D055372:AMP-Activated Protein Kinases / Q000378:metabolism; D000225:Adenine / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D001343:Autophagy / Q000187:drug effects*; D000071189:Autophagy-Related Protein-1 Homolog; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D009474:Neurons / Q000187:drug effects*; D009498:Neurotoxins / Q000633:toxicity*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; D009498:Neurotoxins; C016575:3,4-methylenedioxyphenethylamine; D015104:3,4-Methylenedioxyamphetamine; C025946:3-methyladenine; D000071189:Autophagy-Related Protein-1 Homolog; C586255:ULK1 protein, rat; D055372:AMP-Activated Protein Kinases; D000225:Adenine