A heart attack occurs when arteries become clogged, blood flow is restricted, and oxygen is cut off. The standard approach to studying them is to treat the heart as an isolated organ. However, new research in mice sheds light on how these events are interconnected with other systems.
Heart attacks can damage the heart’s muscles and trigger molecular changes across its tissues. Earlier research has shown that the vagus nerve, which is a key pathway that connects the brain to other parts of the body, sends signals to the brain after a heart attack. Heart attacks can also trigger the body’s “fight-or-flight” response, which can cause inflammation in the heart tissue, leading to cardiac failure.
“Heart attacks are obviously centered in the heart, but we’re flipping the switch on heart attack research to show that it’s not just the heart itself that is involved,” said Vineet Augustine, a neuroscientist at the University of California, San Diego.
To understand this further, Augustine and his colleagues experimentally induced heart attacks in mice by permanently blocking an artery. Augustine said that during a heart attack in mice, he found that certain vagal neurons (TRPV1-expressing neurons) “literally wrap around the injury site.” Because of this, the team wondered if the heart attacks in mice could be prevented if communication was blocked through those nerve cells. Later on, the team was able to see improvements in pumping efficiency and electrical signals of the heart by turning off a small group of TRPV1 nerve cells.
The TRPV1 neurons carry signals from the heart to the hypothalamus, which is part of the brain that is able to regulate body temperature, thirst, hunger, and sleep. Other cells in the hypothalamus receive those signals, relay them to a different group of nerve cells, which then project back to the heart. This releases an immune protein that causes inflammation. The team was able to discover that blocking any part of this loop was able to relieve heart attack issues within the mice.
Even though these findings will take years before entering human trials, it does provide a lot of information regarding heart attacks for further study. Future research can focus on how other parts of the brain may also be involved in this and how they can be affected.
Research on “brain–body connections is now reaching a new chapter, says Shivkumar. The current work “sets the stage for the next set of studies,” he adds.
