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This study, led by Masha Prager-Khoutorsky, a scientist at McGill University, in collaboration with an interdisciplinary team from the University and the Research Institute of the McGill University Health Centre, suggests that the brain could be the missing link in some forms of high blood pressure usually attributed to the kidneys.
"These new findings suggest that high blood pressure may originate in the brain, thus opening the door to the development of treatments that act on the brain," says Masha Prager-Khoutorsky, Associate Professor in the Department of Physiology at McGill University.
High blood pressure affects two-thirds of people over 60 and contributes to the death of 10 million people worldwide each year. Often asymptomatic, it increases the risk of heart disease, stroke, and other serious health problems.
About one-third of patients do not respond to common medications, which primarily target blood vessels and kidneys because it has long been believed that hypertension originates there. The study, published in the journal Neuron, suggests that the brain also plays an important role in this condition, particularly in treatment-resistant cases.
How does salt disrupt the brain?
To replicate human eating habits, the team gave rats water containing 2% salt, which corresponds to a daily diet high in fast food and certain foods like bacon, instant noodles, and processed cheese.
This high-salt diet activated immune cells in a specific region of the brain, causing inflammation and a rapid increase in vasopressin, a hormone that in turn raised blood pressure. The research team observed these changes using recently developed advanced brain imaging and laboratory techniques.
"The role of the brain in hypertension has been largely ignored, partly because it is more difficult to study," notes the Associate Professor. "But thanks to new techniques, we are able to observe these changes in action."
The research was conducted on rats rather than the more commonly used mice because the rat's body has more similarities to the human body regarding salt and water regulation. Therefore, the results are more likely to apply to humans, points out Masha Prager-Khoutorsky.
Scientists now plan to determine whether similar processes are at work in other forms of hypertension.