Scientists from the University of Arizona have shown for the first time in animal experiments that glyphosate can cross the blood-brain barrier. The researchers wrote that the active ingredient in the herbicide interfered with the metabolism of messenger substances in a dose-dependent manner in a way that could cause diseases such as Alzheimer’s.
They had given mice concentrations of 150 to 500 milligrams of glyphosate per kilogram of body weight in their feed for two weeks. Subsequent analysis of the brains showed that the glyphosate had crossed the blood-brain barrier. This is a layer of cells that is designed to prevent dissolved substances from the bloodstream from easily entering the fluid in the central nervous system. However, the glyphosate could not only be detected in the liquid that washes around the nerve cells – it also had an effect there. Depending on the respective dose, the scientists detected increased levels of TNFα. The abbreviation stands for tumor necrosis factor alpha, an important messenger of the immune system. Elevated levels of TNFα are associated with symptoms of inflammation. In the brain, elevated levels of TNFα are associated with nerve diseases such as Alzheimer’s.
In addition, the scientists had mixed the nerve cells of the mice in the test tube with the glyphosate concentrations found in the brain. They found that the formation of soluble amyloid beta (Aβ) increased in relation to the dose and that the viability of the nerve cells was reduced. Beta-amyloids are sticky proteins that can clump together in the brain to form solid deposits – the main hallmark of Alzheimer’s. Finally, the scientists examined how the glyphosate in the brains of the mice affected the work of the genes in the brain cells. They found numerous changes that indicate disruptions in the expression of genes associated with neurodegenerative diseases, the University of Arizona said in a statement.
In their study, the authors interpret their results as follows: Glyphosate exposure could presumably contribute to an earlier onset or accelerated progression of Alzheimer’s disease. However, much work is still needed before a causal link can be established. In their experiments, the scientists worked with relatively high glyphosate concentrations, which are common in safety research. The authors wrote in the discussion section of their study that the experiments with glyphosate concentrations as they occur in the environment would now have to be repeated. In addition, it is necessary to repeat the tests with ready-to-use pesticides containing glyphosate and not just with the active substance alone. It was also to be investigated whether glyphosate could be detected in the brains of people who had died of Alzheimer’s. [lf]