A new study has potentially helped in determining the mechanism behind the harmful effects of salt consumption on blood pressure. The correlation between the two was made clear in the past: excessive salt consumption leads to high blood pressure. But, how does this happen? This is what the new research, published in the journal Neuron, has attempted to decipher.
According to experts, high intake of sodium (the latter obtained from salt mostly) increases the risk of having high blood pressure, thereby causing a rise in the risk of having heart attacks. As a consequence, recommendations were formulated to regulate the desirable daily consumption of salt: a maximum of 5 g of salt per day was decided upon.
Experiments on rats showed that high salt consumption ultimately led to disruptions in brain circuits – this was observed over a long period of time. The brain circuits to be adversely affected were those that are known to suppress high blood pressure.
The lead author, Charles Bourque summarised their observations as to what happened to the rats: “We found that a period of high dietary salt intake in rats causes a biochemical change in the neurones that release vasopressin (VP) into the systemic circulation. This change, which involves a neurotrophic molecule called BDNF (brain-derived neurotrophic factor), prevents the inhibition of these particular neurones by other cells.”
In conditions of low salt intake, the brain circuit detecting arterial pressure stops the VP neurones from releasing the chemicals that would increase it. The opposite happens when salt intake is high: the control circuit is deactivated and the VP neurones are thus not inhibited to release the chemicals that trigger the rise in blood pressure.
This could indicate the pathways in humans. But, many questions still remain unanswered: it is not confirmed if the same mechanism is involved in human systems. Furthermore, a main issue would be whether this effect could be reversed such that treatment strategies could be devised.
Undoubtedly, more experiments have to be performed to get to the mystery.