Valproic acid and other histone deacetylase inhibitors induce microglial apoptosis and attenuate lipopolysaccharide-induced dopaminergic neurotoxicity

Neuroscience. 2007 Oct 12;149(1):203-12. doi: 10.1016/j.neuroscience.2007.06.053. Epub 2007 Jul 28.


Valproic acid (VPA), a widely prescribed drug for seizures and bipolar disorder, has been shown to be an inhibitor of histone deacetylase (HDAC). Our previous study has demonstrated that VPA pretreatment reduces lipopolysaccharide (LPS)-induced dopaminergic (DA) neurotoxicity through the inhibition of microglia over-activation. The aim of this study was to determine the mechanism underlying VPA-induced attenuation of microglia over-activation using rodent primary neuron/glia or enriched glia cultures. Other histone deacetylase inhibitors (HDACIs) were compared with VPA for their effects on microglial activity. We found that VPA induced apoptosis of microglia cells in a time- and concentration-dependent manner. VPA-treated microglial cells showed typical apoptotic hallmarks including phosphatidylserine externalization, chromatin condensation and DNA fragmentation. Further studies revealed that trichostatin A (TSA) and sodium butyrate (SB), two structurally dissimilar HDACIs, also induced microglial apoptosis. The apoptosis of microglia was accompanied by the disruption of mitochondrial membrane potential and the enhancement of acetylation levels of the histone H3 protein. Moreover, pretreatment with SB or TSA caused a robust decrease in LPS-induced pro-inflammatory responses and protected DA neurons from damage in mesencephalic neuron-glia cultures. Taken together, our results shed light on a novel mechanism whereby HDACIs induce neuroprotection and underscore the potential utility of HDACIs in preventing inflammation-related neurodegenerative disorders such as Parkinson's disease.

Publication types

  • Research Support, N.I.H., Intramural

MeSH terms

  • Animals
  • Animals, Newborn
  • Apoptosis / drug effects*
  • Brain / cytology
  • Cell Cycle / drug effects
  • Cells, Cultured
  • Dopamine / metabolism*
  • Dose-Response Relationship, Drug
  • Enzyme Inhibitors / pharmacology*
  • Female
  • Histone Acetyltransferases / antagonists & inhibitors
  • Histone Acetyltransferases / metabolism
  • In Situ Nick-End Labeling / methods
  • Lipopolysaccharides / toxicity*
  • Membrane Potential, Mitochondrial / drug effects
  • Neuroglia / drug effects*
  • Neurons / drug effects*
  • Nitrites / metabolism
  • Pregnancy
  • Rats
  • Rats, Inbred F344
  • Tumor Necrosis Factor-alpha / metabolism
  • Valproic Acid / pharmacology*


  • Enzyme Inhibitors
  • Lipopolysaccharides
  • Nitrites
  • Tumor Necrosis Factor-alpha
  • Valproic Acid
  • Histone Acetyltransferases
  • Dopamine