A surgical technique called deep brain stimulation relieves Parkinson's symptoms by halting the death of dopamine-producing brain cells, scientists at the Neuroscience Institute at the University of Cincinnati (UC) and University Hospital have found.
During a study on mice, the researchers found that the act of stimulating neurons with electrodes boosted the amount of an important protein in the animals' brains called BDNF (brain-derived neurotrophic factor), a growth-promoting chemical.
The researchers say that their findings attain significance as they may help alter the current recommended timetable for surgical intervention.
"Demonstrating that deep brain stimulation halts the progression of dopamine-cell loss was basically a confirmation and extension of previous findings," said Caryl Sortwell, PhD, associate professor of neurology at UC and the study's lead author.
"But finding the mechanism is a novel discovery that is even more critical. We now know not only that it works, we also are beginning to understand how it is working," Sortwell added.
In the study, researchers implanted high-frequency stimulating electrodes in the subthalamic nucleus, an area of the brain associated with movement, in rats and then induced dopamine neuron loss.
When the rats had experienced a 50 percent loss of dopamine neurons, the researchers initiated brain stimulation in half of the group. Measurements of surviving, functioning dopamine neurons in rats implanted with active stimulators were then compared to a control group implanted with inactive stimulators.
The researchers found while the control group's loss of dopamine neurons increased to 75 percent after two weeks, the rats implanted with active stimulators experienced no further loss of cells during that time.
Subsequent tissue analysis revealed that in rats implanted with active stimulators the trophic factor BDNF had tripled in the striatum, a part of the brain that houses dopamine terminals and "receives" the dopamine neurotransmitters that are produced in the substantia nigra.
The study was presented at a professional conference held by the Cleveland Clinic and the National Institute of Neurological Disorders and Stroke.