The metabolite of a drug that is helping patients battle multiple sclerosis appears to significantly slow the onset of Parkinson’s disease, researchers say.
The oral drug, dimethylfumarate, or DMF, and its metabolite, monomethylfumarate, or MMF, both increase activity of Nrf2, a protein that helps protect the body from oxidative stress and inflammation, hallmarks of both diseases, said Dr. Bobby Thomas, neuroscientist in the Department of Pharmacology and Toxicology at the Medical College of Georgia at Augusta University.
But the new study provides the first evidence that the metabolite, which is essentially the active portion of the parent drug, more directly targets Nrf2, potentially reducing known side effects of the parent drug that include flushing, diarrhea, nausea, vomiting, abdominal pain and the brain infection encephalopathy, said Thomas, corresponding author of the study in The Journal of Neuroscience.
Particularly, the gastrointestinal side effects can exacerbate some problems patients with Parkinson’s already experience, said Dr. John Morgan, neurologist, neuroscientist and Parkinson’s disease specialist in the MCG Department of Neurology. In addition to destroying neurons in the brain that produce dopamine, a neurotransmitter that enables movement and learning, Parkinson’s causes nerve cell death in the gastrointestinal tract and related problems such as severe constipation.
“Nrf2 is a natural protective mechanism we have for oxidative stress,” Thomas said. The fact that multiple sclerosis and Parkinson’s have in common evidence of declining activity of the Nrf2 pathway has generated interest in the drug for Parkinson’s and other neurodegenerative diseases.
DMF was approved for multiple sclerosis three years ago by the Food and Drug Administration. While its metabolite MMF is not quite as potent as the parent drug in increasing Nrf2 activity, the new study indicates that its action is sufficient to dramatically slow the loss of dopamine-producing neurons as well as the parent drug, in an animal model of Parkinson’s.
In their model, mice given the neurotoxin MPTP experience a dramatic loss of dopamine-producing neurons, losing about half within a handful of days, and rapidly develop Parkinson’s-like symptoms. Patients, on the other hand, slowly develop symptoms over many years. By the time they seek medical care, patients may have lost 30-50 percent of their dopaminergic neurons, said Morgan, a study coauthor. “Presentation is after the disease is kind of out of the gate.”