Pesticides Associated with Environmentally-Linked Parkinson's Disease

Animal models exposed to the pesticide ziram formed clumps of a protein that damaged neurons and resulted in a Parkinson’s-like condition.

A recent study discovered more information about how a group of pesticides, dithiocarbamates, can potentially increase the risk of developing Parkinson’s disease.

A link between these pesticides and Parkinson’s disease was known previously, but has not been fully established. Researchers in the study, published by Environmental Health Perspectives, focused on the fungicide ziram than can cause the loss of dopaminergic neurons, which is linked to Parkinson’s disease.

Ziram is able to increase the amount of α-synuclein. When these proteins gather in the brain, they can cause harm to the neurons. This also occurs in Parkinson’s disease unrelated to pesticide exposure.

Researchers first created a model of Parkinson’s disease in zebrafish, and found that fish exposed to ziram could not swim properly, which indicates loss of dopamine and a condition similar to Parkinson’s.

Researchers then removed the α-synuclein protein from zebrafish, and found these animal models were protected against the loss of dopaminergic neurons due to exposure to ziram.

Then, non-modified zebrafish were given CLRO1, an experimental drug that destroys protein aggregates. They study found that these fish were protected against the Parkinson’s-like condition.

"Getting rid of the protein genetically or breaking up the aggregates with this drug protected against ziram toxicity,” said lead study author Jeff Bronstein, MD, PhD “This is important -- it establishes that environmental toxins work on same pathway that is in play in those genetically disposed to Parkinson's. Most important, we can use drugs being developed now on patients who get Parkinson's because of ziram exposure."

Researchers said they plan to find other environmental factors that can cause Parkinson’s disease, and believe their findings could potentially be vital to approximately 70% of patients whose disease was not caused by genetics.

"These findings add to the growing literature linking pesticide exposure and the development of Parkinson's disease and offers important insights into the mechanisms of ziram toxicity," concluded Dr Bronstein. "A better understanding of the pathogenesis of Parkinson's disease will ultimately lead to new treatments and eventually a cure."