Protective effects of valproic acid on the nigrostriatal dopamine system in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine mouse model of Parkinson's disease.

The use of animal models (including the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine [MPTP] mouse model) to mimic dopaminergic (DAergic) cell loss and striatal dopamine (DA) depletion, as seen in Parkinson's disease (PD), has implicated a multitude of factors that might be associated with DAergic cell death in PD including excitotoxicity, inflammation, and oxidative stress. All of these factors have been shown to be reduced by administration of histone deacetylase (HDAC) inhibitors (HDACis) resulting in some degree of neuroprotection in various models of neurodegenerative disease including in Huntington's disease and amyotrophic lateral sclerosis. However, there is limited information of effects of HDACis in PD models. We have previously shown HDACis to be partially protective against 1-methyl-4-phenylpyridinium (MPP(+))-mediated cell loss in vitro. The present study was conducted to extend these findings to an in vivo PD model. The HDACi valproic acid (VPA) was co-administered with MPTP for 5 days to male FVBn mice and continued for an additional 2 weeks, throughout the period of active neurodegeneration associated with MPTP-mediated DAergic cell loss. VPA was able to partially prevent striatal dopamine depletion and almost completely protect against substantia nigra DAergic cell loss. These results suggest that VPA may be a potential disease-modifying therapy for PD.