Oxidative damage in the dopaminergic neurons of substantia nigra pars compacta (SNpc) plays an important role in the pathogenesis of Parkinson's disease (PD). Heat shock proteins 70 kDa (HSP70s) are a sub-family of molecular chaperones involved in not only protein folding and degradation but also antioxidant defense and anti-apoptotic pathways. Here, a transgenic mice over-expressing an inducible form of Hsp70 was used to determine whether HSP70 affects 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced nigrostriatal degeneration, an experimental model of PD. The Hsp70 transgenic animals exhibited a high level of expression of HSP70 protein in ventral mesencephalon. Dopaminergic cell death in the SNpc was similar between wild-type and Hsp70 transgenic mice with either acute (40 mg/kg, single dose) or chronic (20 mg/kg, three times/week during 1 month) MPTP treatment. In addition, striatal dopamine loss was not different between wild-type and transgenic animals. Three months after the acute MPTP treatment, dopamine loss was partially recovered into a similar level between wild-type and transgenic groups. In conclusion, over-expression of Hsp70 does not suppress dopaminergic neuronal damage at either the somata or the axon terminals of dopaminergic neurons. Hsp70 over-expression does not help axon terminal regeneration either. These results indicate that HSP70 alone is not sufficient to reduce MPTP-induced dopaminergic neuronal damage.
Copyright © 2011 IBRO. Published by Elsevier Ltd. All rights reserved.