A new study published in the journal Toxicological Sciences finds that traffic-related air pollution can harm the brain cells and increases the risk of Parkinson’s disease. The presence of chemicals in diesel exhaust can trigger the harmful development of a protein in the brain called alpha-synuclein, which is commonly found in individuals with the disease.
Previous studies have also confirmed that individuals living in regions with increased levels of traffic-related air pollution tend to have higher rates of Parkinson’s disease.
Dr. Jeff Bronstein is a professor of neurology and director of the UCLA Movement Disorders Program. In this study, he tested the impacts of diesel exhaust on zebrafish in the lab to understand the effect of traffic-related air pollution on the brain.
He tells that it’s extremely important to have the option to determine whether it is the effect of air pollution or it’s something different in urban environments. While testing the chemicals on zebrafish in the lab, he stated that lets researchers coax out whether traffic-related air pollution components affect the brain cells in a way that could enhance the risk of Parkinson’s disease.
The freshwater fish functions admirably for examining molecular changes in the brain because the neurons of this fish behave similarly to humans. Also, the fish are transparent that enables researchers to study the biological processes easily without killing the animals.
Symptoms of Parkinson’s disease can be different for everyone including impaired posture and balance, speech changes, slowed movement (bradykinesia), rigid muscles, tremors, and writing changes.
A UCLA postdoctoral fellow and the study’s first author, Lisa Barnhill tells that it was easy to see what was happening inside the brains of zebrafish at different time-points during the study.
She added the chemicals present in the diesel exhaust to water in which the zebrafish were kept. Researchers observed changes in the behavior of animals that were caused due to the presence of these chemicals. They found that neurons were dying off in the exposed fish.
After this, they researched the brain activity in several pathways known to be identified with Parkinson’s disease to see how traffic-related air pollution was contributing to cell death.
Parkinson’s disease is related to the poisonous accumulation of alpha-synuclein proteins in human brains. One way these proteins can develop is through the interruption of autophagy, the process in which old or damaged proteins are broken down.
Proteins continuously form and disposes of in healthy brains, it requires communication between neurons but when the disposal process doesn’t work then only new proteins are formed and old or damaged proteins never get cleared away.
In Parkinson’s disease, alpha-synuclein proteins do not dispose of and pile up in harmful clumps in and around neurons, eventually kills them and interfere with the best possible working of the brain. This can bring about different symptoms like muscle rigidity and tremors.
The researchers examined the neurons of fishes for tell-tale pouches that engulf old and damaged proteins including alpha-synuclein proteins before exposing them into diesel particles. Bronstein says that they observe that pouches moved along, and appeared and disappeared.
The researchers replicated the experiment using cultured human cells to ensure that traffic-related air pollution could similarly affect human neurons as they affected neurons of zebrafish. Exposure to diesel exhaust had similar effects on those human cells.
Bronstein concluded that the outcomes of the present study explain why air pollution increases the risk of Parkinson’s disease.