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Research reveals missing link in Parkinson’s disease and suggests new therapeutic target

July 5, 2007

Canadian researchers have identified a novel enzyme that may explain the link between Parkinson’s disease and toxic cellular by-products called reactive oxygen species. Dr. David Park and his team at the University of Ottawa and the Ottawa Hospital Research Institute found that the anti-oxidant enzyme Prx2 is inactivated by a chemical that induces Parkinson’s disease in mice, and restoring the active enzyme provides significant protection. The group also detected high levels of inactive Prx2 in brain tissue from human Parkinson’s patients compared to tissue from normal patients, suggesting that this enzyme may play a role in the human disease as well. The results will be published in the July 5, 2007 edition of the journal Neuron.

“The major symptoms of Parkinson’s disease are caused by the death of dopamine-producing cells in the brain,” explained Dr. Park, a Senior Scientist and Associate Professor specializing in neuroscience. “While conventional therapies mask symptoms by increasing dopamine levels, our research suggests that increasing Prx2 activity might help prevent the damage that destroys these cells in the first place.”

Reactive oxygen species are produced naturally by all cells in the body, but in a process that is not well understood, they sometimes go ‘haywire’ and cause damage. One theory of Parkinson’s disease holds that as the brain ages, its ability to inactivate reactive oxygen species decreases, and vulnerable cells, such as those that produce dopamine, become damaged. This process could be affected by genetic and environmental factors. Identifying the role of Prx2 provides an important missing link in the theory.

Dr. Park noted that reactive oxygen species also play a role in stroke and other brain conditions, so the potential of Prx2 as a therapeutic target is quite broad. “These results are very exciting,” he said, “but we have to be pretty cautious about it because we are at an early stage and it takes many years to develop and test a potential therapy.”

Neurologists are encouraged by the results: “This discovery represents an important step in our efforts to understand the basic processes that are going wrong in Parkinson’s disease,” said Dr. David Grimes, Director of The Ottawa Hospital’s Parkinson’s Disease and Movement Disorders Clinic. “It also provides an exciting new avenue to explore as we try to develop better treatments.”

Parkinson's disease is the most common neurodegenerative disease after Alzheimer's, affecting at least 100,000 Canadians with the number of cases expected to double by the year 2050. Dr. Park is a member of Ottawa’s Parkinson’s Research Consortium, a group of 18 scientists working collaboratively to tackle this disease from all angles. This study was supported by the Parkinson’s Research Consortium, along with the Parkinson’s Disease Foundation, the Parkinson’s Society of Canada, the Heart and Stroke Foundation of Canada, the Canadian Institutes of Health Research and the US Army.

About the Ottawa Hospital Research Institute
The Ottawa Hospital Research Institute (OHRI) is the research arm of The Ottawa Hospital and an affiliated institute of the University of Ottawa. The OHRI includes more than 1,200 scientists, clinicians, graduate students, postdoctoral fellows, and staff conducting research to improve the understanding, prevention, diagnosis and treatment of human disease. For more information visit www.ohri.ca.

Media Contact
Jennifer Paterson
Director, Communications and Public Relations
Ottawa Hospital Research Institute
613-798-5555, extension 19691
jpaterson@ohri.ca