06.01.2025.
New findings from Karolinska Institutet and Columbia University reveal that the heart possesses its own intricate nervous system, often referred to as a “mini-brain,” that plays a critical role in regulating its rhythm. This neural network, embedded in the outer layers of the heart wall, is far more complex and diverse than previously understood.
Published in Nature Communications, the research—conducted using zebrafish—offers a fresh perspective on how the heart functions. Traditionally, it was believed that the autonomic nervous system, which sends signals from the brain, solely controlled the heartbeat.
The heart’s internal neural network was thought to act merely as a conduit, transmitting those signals. However, the study uncovers that this “mini-brain” actively governs the heart’s rhythm with remarkable sophistication.
Understanding this self-contained system opens doors to innovative treatments for heart diseases, potentially transforming cardiac care by targeting the heart’s own neural mechanisms.
This ‘little brain’ has a key role in maintaining and controlling the heartbeat, similar to how the brain regulates rhythmic functions such as locomotion and breathing,
explains Konstantinos Ampatzis, principal researcher and docent at the Department of Neuroscience, Karolinska Institutet, Sweden, who led the study.
The researchers identified several types of neurons in the heart that have different functions, including a small group of neurons with pacemaker properties. The finding challenges the current view on how the heartbeat is controlled, which may have clinical implications.
Similar to the human heart
“We were surprised to see how complex the nervous system within the heart is,” says Konstantinos Ampatzis. “Understanding this system better could lead to new insights into heart diseases and help develop new treatments for diseases such as arrhythmias.”
The study was conducted on zebrafish, an animal model that exhibits strong similarities to human heart rate and overall cardiac function.
The researchers were able to map out the composition, organisation and function of neurons within the heart using a combination of methods such as single-cell RNA sequencing, anatomical studies and electrophysiological techniques.
New therapeutic targets
“We will now continue to investigate how the heart’s brain interacts with the actual brain to regulate heart functions under different conditions such as exercise, stress, or disease,” says Konstantinos Ampatzis.
“We aim to identify new therapeutic targets by examining how disruptions in the heart’s neuronal network contribute to different heart disorders.”
The study was done in close collaboration with researchers at Columbia University, USA, and was funded by, among others, the Dr. Margaretha Nilsson Foundation, Erik and Edith Fernström Foundation, StratNeuro and Karolinska Institutet. There are no reported conflicts of interest.
Publication
”Decoding the molecular, cellular, and functional heterogeneity of zebrafish intracardiac nervous system”, Andrea Pedroni, Elanur Yilmaz, Lisa Del Vecchio, Prabesh Bhattarai, Inés Talaya Vidal, Yu-Wen E. Dai, Konstantinos Koutsogiannis, Caghan Kizil, Konstantinos Ampatzis, Nature Communications, online 4 December 2024, doi: 10.1038/s41467-024-54830-w.
