title: Paeoniflorin, a potent natural compound, protects PC12 cells from MPP+ and acidic damage via autophagic pathway.
abstract: BACKGROUND
  Paeoniflorin (PF) is the principal bioactive component of Radix Paeoniae alba, which is widely used in Traditional Chinese Medicine for the treatment of neurodegenerative disorders such as Parkinson's disease (PD).
  
  
  OBJECTIVE
  To evaluate the neuroprotective effects of PF on MPP(+)- or acid- (pH 5.0) induced injury in cultured PC12 cells and to investigate the activity of autophagy-lysosome pathway (ALP). Amiloride (Ami), a non-selective blocker of acid-sensing ion channels (ASICs), as a positive control drug, since it is neuroprotective in rodent models of PD.
  
  
  METHODS
  The cell viability was analyzed with MTT assay. The cell injury was assessed by lactate dehydrogenase (LDH) assay. Flow cytometry and Western blot analysis were used to study the apoptotic, calcium influx and autophagic mechanisms.
  
  
  RESULTS
  Ami (100 microM) and PF (50 microM) both protected PC12 cells against MPP(+)- or acid-induced injury as assessed by MTT assay, lactate dehydrogenase release, and apoptosis rate. The concentrations of cytosolic free Ca(2+) were raised after exposure to MPP(+) or acidosis, while Ami and PF both reduced the influx of Ca(2+). More importantly, we found that the mechanisms of neuroprotective effects of Ami and PF were closely associated with the upregulation of LC3-II protein, which is specifically associated with autophagic vacuole membranes. Furthermore, application of MPP(+) or acid induced the overexpression of LAMP2a, which is directly correlated with the activity of the chaperone-mediated autophagy pathway. However, Ami and PF inhibited the overexpression of LAMP2a.
  
  
  CONCLUSIONS
  Our data provide the first experimental evidence that PF modulates autophagy in models of neuron injury, as well as providing the first indication of a relationship between ASICs and ALP.
authors.affiliation: Department of Neurology, Second Affiliated Hospital of Soochow University, Suzhou 215004, China.
authors.forename: Bi-Yin
authors.initials: BY
authors.lastname: Cao
authors.forename: Ya-Ping
authors.initials: YP
authors.lastname: Yang
authors.forename: Wei-Feng
authors.initials: WF
authors.lastname: Luo
authors.forename: Cheng-Jie
authors.initials: CJ
authors.lastname: Mao
authors.forename: Rong
authors.initials: R
authors.lastname: Han
authors.forename: Xue
authors.initials: X
authors.lastname: Sun
authors.forename: Jing
authors.initials: J
authors.lastname: Cheng
authors.forename: Chun-Feng
authors.initials: CF
authors.lastname: Liu
mesh_terms: D015655:1-Methyl-4-phenylpyridinium / Q000633:toxicity*; D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D001343:Autophagy / Q000187:drug effects* / Q000502:physiology; D001565:Benzoates / Q000302:isolation & purification / Q000494:pharmacology*; D001952:Bridged-Ring Compounds / Q000302:isolation & purification / Q000494:pharmacology*; D002470:Cell Survival / Q000187:drug effects* / Q000502:physiology; D005960:Glucosides / Q000302:isolation & purification / Q000494:pharmacology*; D039821:Monoterpenes; D016716:PC12 Cells; D029596:Paeonia; D051381:Rats; D006027:Glycosides
chemical_list: D015655:1-Methyl-4-phenylpyridinium; D001565:Benzoates; D001952:Bridged-Ring Compounds; D005960:Glucosides; D039821:Monoterpenes; C015423:peoniflorin; D006027:Glycosides