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Study IDs New Mechanism Behind Benefit of Exercise in Early Parkinson Disease
In an animal model of early-stage Parkinson disease, intensive exercise eased motor and cognitive symptoms by restoring striatal synaptic plasticity, according to a study published online in Science Advances.
“We have discovered a never observed mechanism, through which exercise performed in the early stages of the disease induces beneficial effects on movement control that may last over time, even after training is suspended,” said study corresponding author Paolo Calabresi, MD, of the Catholic University, Rome campus, and A. Gemelli IRCCS Polyclinic Foundation in Rome, Italy.
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“In the future,” he added, “it would be possible to identify new therapeutic targets and functional markers to be considered for developing nondrug treatments to be adopted in combination with current drug therapies.”
Intensive exercise has previously been linked with a higher production of brain-derived neurotrophic factor (BDNF), the research team explained. For this study, researchers reproduced the effect in a rodent model of early-stage Parkinson disease using a 4-week treadmill training protocol and focused on the biological mechanisms behind the observed change.
According to the study, daily treadmill training reduced the spread of toxic alpha-synuclein aggregates in the animals. In Parkinson disease, expansion of alpha-synuclein aggregates results in progressive dysfunction of neurons in brain areas involved in motor control: specifically, the substantia nigra pars compacta and the striatum, or the nigrostriatal pathway.
Physical activity’s neuroprotective effect allows for the survival of neurons that release dopamine and the continued ability of striatal neurons to express a type of dopamine-dependent plasticity. Consequently, motor control and visuospatial learning, which depend on nigrostriatal activity, are preserved.
The team further reported that BDNF, which increases with exercise, interacts with the N-methyl-D-aspartate glutamate receptor and enables striatal neurons to respond efficiently to stimuli. The effects persist beyond the exercise period.
Dr Calabresi said the research team is currently investigating whether intense exercise could lead to the identification of new markers to help monitor early-stage Parkinson disease progression in patients.
“As Parkinson disease is characterized by important neuroinflammatory and neuroimmune components, which play a key role in the early stages of the disease, the research will keep on investigating the involvement of glial cells, highly specialized groups of cells that provide physical and chemical support to neurons and their environment,” he said. “This will allow us to identify molecular and cellular mechanisms underlying the observed beneficial effects.”
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