Caspase inhibitors attenuate 1-methyl-4-phenylpyridinium toxicity in primary cultures of mesencephalic dopaminergic neurons

J Neurosci. 2002 Apr 1;22(7):2637-49. doi: 10.1523/JNEUROSCI.22-07-02637.2002.


Parkinson's disease is characterized by a loss of dopaminergic nigrostriatal neurons. This neuronal loss is mimicked by the neurotoxin 1-methyl-4-phenylpyridinium (MPP+). MPP+ toxicity is mediated through inhibition of mitochondrial complex I, decreasing ATP production, and upregulation of oxygen radicals. There is evidence that the cell death induced by MPP+ is apoptotic and that inhibition of caspases may be neuroprotective. In primary cultures of rat mesencephalic dopaminergic neurons, MPP+ treatment decreased the number of surviving dopaminergic neurons in the cultures and the ability of the neurons to take up [3H]dopamine ([3H]DA). Caspase inhibition using the broad-spectrum inhibitor benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone (zVAD-fmk) spared MPP+-treated dopaminergic neurons and increased somatic size. There was a partial restoration of neurite length in zVAD-fmk-treated cultures, but little restoration of [3H]DA uptake. Peptide inhibitors of caspases 2, 3, and 9, but not of caspase 1, caused significant neuroprotection. Two novel caspase inhibitors were tested for neuroprotection, a broad spectrum inhibitor and a selective caspase 3 inhibitor; both inhibitors increased survival to >90% of control. No neuroprotection was observed with an inactive control compound. MPP+ treatment caused chromatin condensation in dopaminergic neurons and increased expression of activated caspase 3. Inhibition of caspases with either zVAD-fmk or a selective caspase 3 inhibitor decreased the number of apoptotic profiles, but not expression of the active caspase. We conclude that MPP+ toxicity in primary dopaminergic neurons involves activation of a pathway terminating in caspase 3 activation, but that other mechanisms may underlie the neurite loss.

MeSH terms

  • 1-Methyl-4-phenylpyridinium / antagonists & inhibitors
  • 1-Methyl-4-phenylpyridinium / toxicity*
  • Amino Acid Chloromethyl Ketones / pharmacology
  • Animals
  • Caspase 3
  • Caspase Inhibitors*
  • Caspases / metabolism
  • Cell Survival / drug effects
  • Cells, Cultured
  • Dopamine / metabolism
  • Dopamine / pharmacokinetics
  • Dose-Response Relationship, Drug
  • Enzyme Inhibitors / pharmacology*
  • Mesencephalon / cytology
  • Mesencephalon / drug effects*
  • Mesencephalon / embryology
  • Neurites / drug effects
  • Neurites / ultrastructure
  • Neurons / cytology
  • Neurons / drug effects*
  • Neurons / metabolism
  • Neuroprotective Agents / pharmacology
  • Parkinson Disease / etiology
  • Parkinson Disease / prevention & control
  • Rats
  • Rats, Sprague-Dawley
  • Tyrosine 3-Monooxygenase / biosynthesis


  • Amino Acid Chloromethyl Ketones
  • Caspase Inhibitors
  • Enzyme Inhibitors
  • Neuroprotective Agents
  • benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone
  • Tyrosine 3-Monooxygenase
  • Casp3 protein, rat
  • Caspase 3
  • Caspases
  • 1-Methyl-4-phenylpyridinium
  • Dopamine