The study of familial Parkinson disease indicates that the loss of nerve cells of a brain structure named the substantia nigra may be related to the accumulation of proteins aggregating within these cells. This aggregation phenomenon seems to be related to a change of the three dimensional structure of specific proteins which are mutated in rare forms of familial Parkinson disease. One of them is called alpha-synuclein. Our laboratory proposes to study the effect of expressing proteins called chaperones, which specialize in preventing conformational changes of proteins. Parkinson disease will be created in rats by expressing a mutated form of alpha-synuclein in the substantia nigra. To do so, a virus will be injected through a small needle acting as a delivery shuttle which will infect the substantia nigra cells and deliver the mutated gene. In a second step the same kind of virus will be injected in the same brain area this time carrying a gene responsible for the expression of the chaperone proteins. After sacrificing the animals, we will analyze their brains to see if the chaperones were efficacious in preventing the cell death of the substantia nigra nerve cells.