title: Melatonin attenuates 1-methyl-4-phenylpyridinium-induced PC12 cell death.
abstract: OBJECTIVE
  To explore the effect of melatonin on PC12 cell death induced by 1-methyl-4-phenylpyridinium (MPP+).
  
  
  METHODS
  MTT assay, lactate dehydrogenase (LDH) efflux assay, and immunohistochemistry methods were used to measure neurotoxicity of PC12 cells treated acutely with MPP+ in low glucose and high glucose conditions, and to assess the neuroprotective effect of melatonin on PC12 cell death induced by MPP+.
  
  
  RESULTS
  In a low glucose condition, MPP+ significantly induced PC12 cell death, which showed time and concentration dependence. In a serum-free low glucose condition, the percentages of viability of cells treated with MPP+ for 12, 24, 48, 72, and 96 h were 85.1%, 75.4%, 64.9%, 28.15%, and 9%, respectively. The level of LDH in the culture medium increased and tyrosine hydroxylase positive (TH+) cell count decreased. However, in a serum-free high glucose condition, MPP+ did not significantly induce PC12 cell death compared with control at various concentrations and time regimens. When the cells were preincubated with melatonin 250 micromol/L for 48, 72, and 96 h in a serum-free low glucose condition, cell survival rate significantly increased to 78.1%, 58.8%, and 31.6%, respectively. Melatonin abolished the LDH leakage of cells treated with MPP+ and increased TH+ cells count.
  
  
  CONCLUSIONS
  MPP+ caused concentration-dependent PC12 cell death. The level of glucose was an important factor to MPP+ induced dopaminergic PC12 cell death. Low glucose level could potentiate MPP+ toxicity, while high glucose level could reduce the toxicity. In addition, melatonin attenuated PC12 cell death induced by MPP+.
authors.affiliation: Department of Pharmacology, School of Pharmaceutical Sciences, Beijing 100083, China. srgltlsn93@hotmail.com
authors.forename: Jin-feng
authors.initials: JF
authors.lastname: Bao
authors.forename: Ren-gang
authors.initials: RG
authors.lastname: Wu
authors.forename: Xiao-ping
authors.initials: XP
authors.lastname: Zhang
authors.forename: Yan
authors.initials: Y
authors.lastname: Song
authors.forename: Chang-ling
authors.initials: CL
authors.lastname: Li
mesh_terms: D015655:1-Methyl-4-phenylpyridinium / Q000037:antagonists & inhibitors* / Q000633:toxicity; D000818:Animals; D016923:Cell Death / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D016895:Culture Media, Serum-Free; D005947:Glucose / Q000008:administration & dosage / Q000494:pharmacology*; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008550:Melatonin / Q000494:pharmacology*; D018696:Neuroprotective Agents / Q000494:pharmacology*; D016716:PC12 Cells / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism
chemical_list: D016895:Culture Media, Serum-Free; D018696:Neuroprotective Agents; D007770:L-Lactate Dehydrogenase; D014446:Tyrosine 3-Monooxygenase; D005947:Glucose; D008550:Melatonin; D015655:1-Methyl-4-phenylpyridinium