title: Apocynin prevents mitochondrial burdens, microglial activation, and pro-apoptosis induced by a toxic dose of methamphetamine in the striatum of mice via inhibition of p47phox activation by ERK.
abstract: BACKGROUND
  Activation of NADPH oxidase (PHOX) plays a critical role in mediating dopaminergic neuroinflammation. In the present study, we investigated the role of PHOX in methamphetamine (MA)-induced neurotoxic and inflammatory changes in mice.
  
  
  METHODS
  We examined changes in mitogen-activated protein kinases (MAPKs), mitochondrial function [i.e., mitochondrial membrane potential, intramitochondrial Ca(2+) accumulation, mitochondrial oxidative burdens, mitochondrial superoxide dismutase expression, and mitochondrial translocation of the cleaved form of protein kinase C delta type (cleaved PKCδ)], microglial activity, and pro-apoptotic changes [i.e., cytosolic cytochrome c release, cleaved caspase 3, and terminal deoxynucleotidyl transferase dUDP nick-end labeling (TUNEL) positive populations] after a neurotoxic dose of MA in the striatum of mice to achieve a better understanding of the effects of apocynin, a non-specific PHOX inhibitor, or genetic inhibition of p47phox (by using p47phox knockout mice or p47phox antisense oligonucleotide) against MA-induced dopaminergic neurotoxicity.
  
  
  RESULTS
  Phosphorylation of extracellular signal-regulated kinases (ERK1/2) was most pronounced out of MAPKs after MA. We observed MA-induced phosphorylation and membrane translocation of p47phox in the striatum of mice. The activation of p47phox promoted mitochondrial stresses followed by microglial activation into the M1 phenotype, and pro-apoptotic changes, and led to dopaminergic impairments. ERK activated these signaling pathways. Apocynin or genetic inhibition of p47phox significantly protected these signaling processes induced by MA. ERK inhibitor U0126 did not exhibit any additional positive effects against protective activity mediated by apocynin or p47phox genetic inhibition, suggesting that ERK regulates p47phox activation, and ERK constitutes the crucial target for apocynin-mediated inhibition of PHOX activation.
  
  
  CONCLUSIONS
  Our results indicate that the neuroprotective mechanism of apocynin against MA insult is via preventing mitochondrial burdens, microglial activation, and pro-apoptotic signaling process by the ERK-dependent activation of p47phox.
authors.affiliation: Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon, South Korea. dkluckystar@yahoo.com.
authors.forename: Duy-Khanh
authors.initials: DK
authors.lastname: Dang
authors.affiliation: Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon, South Korea. shinej@kangwon.ac.kr.
authors.forename: Eun-Joo
authors.initials: EJ
authors.lastname: Shin
authors.affiliation: Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon, South Korea. namsaak@naver.com.
authors.forename: Yunsung
authors.initials: Y
authors.lastname: Nam
authors.affiliation: Department of Biological Sciences, College of Natural Sciences, Kangwon National University, Chunchon, South Korea. ryoosw08@kangwon.ac.kr.
authors.forename: Sungwoo
authors.initials: S
authors.lastname: Ryoo
authors.affiliation: Department of Pharmacology, College of Medicine, Chung-Ang University, Seoul, South Korea. jhjeong3@cau.ac.kr.
authors.forename: Ji Hoon
authors.initials: JH
authors.lastname: Jeong
authors.affiliation: Department of Pharmacology, School of Pharmacy, Sungkyunkwan University, Suwon, South Korea. jang@skku.edu.
authors.forename: Choon-Gon
authors.initials: CG
authors.lastname: Jang
authors.affiliation: Department of Regional Pharmaceutical Care and Sciences, Graduate School of Pharmaceutical Sciences, Meijo University, Nagoya, Japan. tnabeshi@ccalumni.meijo-u.ac.jp.|NPO, Japanese Drug Organization of Appropriate Use and Research, Nagoya, Japan. tnabeshi@ccalumni.meijo-u.ac.jp.
authors.forename: Toshitaka
authors.initials: T
authors.lastname: Nabeshima
authors.affiliation: Neuropharmacology Section, Laboratory of Toxicology and Pharmacology, National Institute of Environmental Health Sciences, Research Triangle Park, Durham, NC, USA. hong3@niehs.nih.gov.
authors.forename: Jau-Shyong
authors.initials: JS
authors.lastname: Hong
authors.affiliation: Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon, South Korea. kimhc@kangwon.ac.kr.
authors.forename: Hyoung-Chun
authors.initials: HC
authors.lastname: Kim
mesh_terms: D000098:Acetophenones / Q000494:pharmacology*; D000818:Animals; D015703:Antigens, CD / Q000235:genetics / Q000378:metabolism; D000975:Antioxidants / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D002118:Calcium / Q000378:metabolism; D000697:Central Nervous System Stimulants / Q000633:toxicity*; D003342:Corpus Striatum / Q000187:drug effects* / Q000473:pathology / Q000648:ultrastructure; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008694:Methamphetamine / Q000633:toxicity*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D017628:Microglia / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects*; D019255:NADPH Oxidases / Q000235:genetics / Q000378:metabolism*; D020319:Oligodeoxyribonucleotides, Antisense / Q000494:pharmacology; D013997:Time Factors; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism
chemical_list: D000098:Acetophenones; D015703:Antigens, CD; D000975:Antioxidants; D000697:Central Nervous System Stimulants; D020319:Oligodeoxyribonucleotides, Antisense; D008694:Methamphetamine; C056165:acetovanillone; D014446:Tyrosine 3-Monooxygenase; D019255:NADPH Oxidases; C060505:neutrophil cytosolic factor 1; D002118:Calcium