An international research team that includes University of Otago scientists has found that excessive salt intake “reprogrammes” the brain, interfering with a natural safety mechanism that normally prevents the body's arterial blood pressure from rising.
While the link between salt and hypertension is well known, scientists until now haven't understood how high salt intake increased blood pressure. By studying the brains of rats, a team led by Professor Charles Bourque of McGill's Faculty of Medicine discovered that ingesting large amounts of dietary salt causes changes in key brain circuits.
Associate Professor Colin Brown of Otago's Centre for Neuroendocrinology and Department of Physiology and Dr Su Young Han, a former PhD student in his laboratory, were members of the team.
Professor Bourque says the team found that a period of high dietary salt intake in rats causes a biochemical change in the neurons that release vasopressin into the systemic circulation. Vasopressin is a hormone that increases vasoconstriction which causes an increase in arterial blood pressure.
“This change, which involves a neurotrophic molecule called BDNF (brain-derived neurotrophic factor), prevents the inhibition of these particular neurons by other cells.”
The team's findings, newly published the journal Neuron, found that high salt intake prevents the inhibition of vasopressin neurons by the body's arterial pressure detection circuit. The disabling of this natural safety mechanism allows blood pressure to rise when a high amount of salt is ingested over a long period of time.
While the team's discovery advances the understanding of the link between salt intake and blood pressure, more work is needed to define new targets that could potentially be explored for therapeutic intervention. Among the questions for further research: Does the same reprogramming effect hold true for humans? If so, how might it be reversed?
In the meantime, Bourque says, the message remains: limit dietary salt.
Scientists from the University of North Texas Health Sciences Centre, Neurocentre Magendie, France and Centre for Neuroendocrinology, University of Otago, New Zealand contributed to this study.
For more information, contact
Associate Professor Colin Brown
Department of Physiology and Centre for Neuroendocrinology
University of Otago
Tel 64 3 479 7354
Email colin.brown@otago.ac.nz
Publication details
"High Salt Intake Increases Blood Pressure via BDNF Mediated Downregulation ofKCC2 and Impaired Baroreflex Inhibition of Vasopressin Neurons" Katrina Y. Choe, Su Y. Han, Perrine Gaub, Brent Shell, Daniel L. Voisin, Blayne A. Knapp, Philip A. Barker, Colin H. Brown, J. Thomas Cunningham, and Charles W. Bourque. Neuron, Jan. 22, 2015.
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