U.S. researchers at Saint LouisUniversity (SLU) have discovered the key brain chemical that causes Parkinson's disease -- a breakthrough finding that could pave the way for new, far more effective therapies to treat one of the most common and debilitating neurological disorders.
"For the first time, we've identified the chemical that triggers the events in the brain that cause this disorder," said William Burke, the study's lead author. "We believe these findings can be used to develop therapies that can actually stop or slow this process."
The findings are published Tuesday in an early online edition of the journal Acta Neuropathologica.
Parkinson's disease occurs when some nerve cells in a part of the brain called the substantia nigra die or become impaired. Normally, these cells produce dopamine -- a vital chemical that allows smooth, coordinated function of the body's muscles and movements.
When about 80 percent of these dopamine-producing cells die or are damaged, the symptoms of Parkinson's disease begin to appear.
Scientists have long known that a key protein called alpha-synuclein plays a role in the development of Parkinson's disease. Alpha-synuclein is found throughout the brain -- but in some people, the protein clumps together. This causes the death of the dopamine-producing cells, which in turn causes Parkinson's to develop.
The SLU researchers discovered that dopamine itself actually plays a role in destroying the cells that produce it.
In the process that leads to Parkinson's disease, dopamine is converted into a highly toxic chemical called DOPAL. Using test-tube, cell-culture and animal models, the researchers found that it is DOPAL that causes alpha-synuclein protein in the brain to clump together, which in turn triggers the death of dopamine-producing cells and leads to Parkinson's.
"This is the first time that anyone has ever established that it is a naturally occurring byproduct of dopamine that causes alpha-synuclein to aggregate, or clump together. It's actually DOPAL that kicks this whole process off and results in Parkinson's disease," said Burke.
Currently, the main approach for treating Parkinson's disease is to replace dopamine that's lost when the cells that produce it die off and cause the disorder. With this new research, however, scientists can better work toward 'neuroprotective' therapies -- those that actually block dopamine cells from dying off in the first place.