[U.S. Right to Know, by Pamela Ferdinand Dec 26 2024] -- Exposure to a widely used herbicide called atrazine (AT) can make nerve cells age faster and harm the hypothalamus, an essential part of the brain, increasing the risk of neurodegenerative disease, according to a recently released study in mice.
A complete nerve cell (neuron) structure and sufficient mature nerve cells are critical for the central nervous system to work properly. The study, published this month [Dec. 13, 2024] in Research, shows the number of nerve cells and mature nerve cells in the mouse brain “significantly decreased” after exposure to atrazine.
“These results directly proved the neurotoxicity of AT,” the researchers say
Atrazine is a common surface water/drinking water pollutant and endocrine disruptorthat poses environmental and health risks. It has been linked to reproductive complications, including fetal development problems and birth defects, and certain cancers in humans. Atrazine has also been associated with liver, kidney, and heart damage in animals, according to the CDC.
The new study shows that atrazine exposure ages certain brain cells in mice, causing them to stop dividing and growing. It also highlights for the first time the role of a specific stress response pathway in disrupting the processes healthy cells use to detect, repair or remove damaged parts.
In addition, the study reveals how atrazine exposure can seriously damage the hypothalamus, which is important for controlling hormones and helps regulate the body’s stress response, growth, metabolism, and reproduction. Most research on the hypothalamus has focused on how atrazine affects hormones—and not how it damages the structure and shape of the hypothalamus, the researchers say.
The research comes as the EPA considers a proposal to raise the acceptable level of atrazine in watersheds from an average of 3.4 micrograms per liter to nearly three times as much.
The study’s findings show that atrazine in mice:
Damages nerve cells (neurons) and activates microglia, immune cells in the brain that act as its “first responders” to injury, infection, or disease
Sends certain brain stem cells (Hypothalamic Neural Stem Cells, or HtNSCs) to the areas of injury in the hypothalamus
Overly activates the body’s stress response system (Integrated Stress Response pathway, or ISR), which makes these HtNSCs age prematurely (stop dividing and growing) and impairs their ability to maintain and repair the hypothalamus by multiplying and turning into other types of nerve cells
In other words, even though the mouse brain tried to repair damage to the hypothalamus by recruiting stem cells, these cells wound up being “aged” and ineffective at healing.
Growing evidence suggests that persistent exposure to pesticides such as atrazine is linked to the prevalence of age-related neurodegenerative diseases like Alzheimer’s disease and Parkinson’s disease.
