If you silence the gene that makes BDNF (a brain signal molecule) in rats, even eating a lot of salt won’t break the brain’s natural brake on blood pressure — proving BDNF is the key trigger.

Salt makes brain cells release a chemical called BDNF, which turns off a safety switch (KCC2) that normally calms down blood pressure neurons — blocking BDNF stops this from happening.

When rats eat too much salt for a week, their brain cells that control blood pressure stop responding to the body’s natural 'slow down' signal, because a key chloride pump gets turned down, making the signal backfire and push blood pressure higher.

Too much salt doesn’t make the brain’s salt pump work harder — it just turns off the main salt-removing valve (KCC2), causing neurons to get overexcited.

Too much salt makes brain cells release a signal that turns off a brake (KCC2) by activating a receptor called TrkB — but if you block that signal, the brake works again and blood pressure doesn’t rise.

Rats that eat too much salt for a week have overactive brain cells that pump out more of a hormone that tightens blood vessels, causing their blood pressure to rise — but if you block that hormone, the pressure doesn’t go up as much.