The heart has a ‘little brain’ — and it protects against stress - Nature

What the report says

Nature reported that researchers studying mice have identified specialized nerve cells within the heart that help regulate heartbeat and protect the organ during acute stress. The work, published in Cell, focuses on the intrinsic cardiac nervous system, a small network of neurons embedded in fat tissue around the heart that communicates with both the brain and other cardiac neurons.

The study was led by a team including Yale School of Medicine neuroscientist Rui Chang and graduate student Qian Xu. Because these neurons are extremely uncommon in heart tissue, the researchers engineered mice so their cardiac neurons could be labeled, then analyzed gene activity to distinguish two subtypes. One group, identified as Npy+ neurons, appeared to slow the heart when activated; when the researchers destroyed those cells, the mice developed heart failure and died, suggesting the cells are essential for maintaining rhythm as well as preventing excessive acceleration.

A second group, called Ddah1+ neurons, initially seemed less important because mice survived when the cells were removed or stimulated under ordinary conditions. The role became clearer during stressful procedures such as blood-pressure measurement, when many mice lacking functional Ddah1+ neurons died after a sharp fall in heart rate. Additional stress tests produced similar outcomes, while stimulating the neurons improved survival in stressed animals, according to Nature’s account.

The findings matter because they challenge the idea that the heart’s own neurons perform broadly similar roles. They also point to a possible route for future heart-disease therapies, though the evidence described comes from mouse experiments and would need further work before any relevance to human treatment is established.