Excessive salt intake "reprogrammes" the brain, interfering with a natural safety mechanism that normally prevents the body's arterial blood pressure from rising, scientists say. The link between salt and hypertension is well known, but scientists until now have not understood how high salt intake increased blood pressure. By studying the brains of rats, a team led by Professor Charles Bourque of McGill University's Faculty of Medicine discovered that ingesting large amounts of dietary salt causes changes in key brain circuits. "We found that a period of high dietary salt intake in rats causes a biochemical change in the neurons that release vasopressin (VP) into the systemic circulation," said Bourque who is also a researcher at the The Research Institute of the McGill University Health Centre (RI-MUHC). "This change, which involves a neurotrophic molecule called BDNF (brain-derived neurotrophic factor), prevents the inhibition of these particular neurons by other cells," he said. The team's findings, published in the journal Neuron, said that high salt intake prevents the inhibition of VP 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 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, researchers said.