Amazing stuff!
"... heart has its own network of nerves, the intrinsic cardiac nervous system (ICNS) ...
The heart's nerve cells fine-tune signals coming from the brain to control heart function, including heart rate. But because they are so few, doctors have struggled to determine exactly what they do. To solve this, researchers from Yale University School of Medicine genetically engineered adult mice so their heart nerves would glow, making them much easier to study.
After locating the nerves, the team analyzed which genes were active in them. They discovered that the nerves fell into two categories, which they called Npy neurons and Ddah1 neurons. ...
Mapping nerve pathways
To determine their exact roles, the researchers traced their pathways across the heart using 3D imaging. The images revealed that both groups were wired to completely different areas.
When the study authors tested the Npy neurons, they found that stimulating them slowed the heart. But when they destroyed the population of cells, heart function rapidly deteriorated, ultimately leading to death. This suggests that these nerves are vital for keeping the heart beating. ..."
From the highlights and abstract:
"Highlights
• Npy and Ddah1 mark two major neuronal subtypes in the intrinsic cardiac nervous system
• Npy+ and Ddah1+ intrinsic cardiac neurons differ in neural inputs and cardiac projections
• Npy+ intrinsic cardiac neurons control heart rate and support baseline cardiac function
• Ddah1+ intrinsic cardiac neurons are essential for cardiac stability during stress
Summary
The intrinsic cardiac nervous system (ICNS) is a key node in heart-brain communication and an emerging target for cardiac therapy, yet its physiological importance and functional organization remain poorly understood.
Here, we show that the ICNS is essential for cardiac performance and survival across conditions.
Using integrated genetic and imaging approaches in mice, we identify two molecularly distinct intrinsic cardiac neuron (ICN) subtypes that differ in extrinsic inputs, projection architectures, and physiological roles.
Npy⁺ ICNs preferentially receive vagal input and mediate parasympathetic control of heart rate and coronary perfusion, and their ablation leads to fatal cardiac failure. By contrast, Ddah1⁺ ICNs receive sympathetic input and are required to preserve electrical stability and prevent sudden cardiac arrest under extreme physiological or psychological stress, with their activation providing cardioprotection.
Together, these findings establish the ICNS as a critical regulator of cardiac function, providing a framework for precise, cell-type-targeted neuromodulatory therapies."
Graphical abstract
Figure 1 Molecular architecture of the ICNS reveals two major ICN subtypes
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