The proper functioning of the heart depends on the complex interaction between the central nervous system and the local neuronal networks present within the heart. Although the central innervation of the heart has been thoroughly investigated, the structure and function of the intracardiac nervous system (IcNS) are still largely uncharted.
Recent findings from Karolinska Institutet and Columbia University has revealed that the heart has a mini-brain – its own intrinsic nervous system responsible for regulating the heartbeat. Gaining a deeper insight into this system, which is far more intricate and varied than previously understood, may pave the way for developing innovative treatments for heart diseases.
For years, the heart was thought to be entirely regulated by the autonomic nervous system, which transmits instructions from the brain. The neural network embedded within the heart wall was dismissed as a simple relay for these signals.
However, recent findings reveal that this network is much more advanced and critical than previously recognized. Understanding heartbeat regulation Researchers have now demonstrated that the heart has its own sophisticated nervous system, which is crucial for ensuring its rhythm is maintained.
“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 various types of neurons in the heart, revealing significant differences in their functions. Notably, they identified a small group of neurons exhibiting pacemaker properties, challenging the long-held belief about heartbeat control. This discovery challenges the prevailing understanding of heartbeat regulation, potentially affecting clinical outcomes.
“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.”
Conducted using zebrafish—an animal model closely resembling human cardiac function—the study effectively mapped the heart’s neuron composition, organization, and functionality. Through innovative techniques, including single-cell RNA sequencing, anatomical studies, and electrophysiological methods, the researchers have laid the groundwork for new advancements in cardiovascular health.
“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 research was conducted in partnership with scholars from Columbia University, USA, and was supported, among others, by the Dr. Margaretha Nilsson Foundation, Erik and Edith Fernström Foundation, StratNeuro, and Karolinska Institutet. No conflicts of interest have been disclosed.
Journal reference:
- Andrea Pedroni, Elanur Yilmaz, Lisa Del Vecchio, Prabesh Bhattarai, Inés Talaya Vidal, Yu-Wen E. Dai, Konstantinos Koutsogiannis, Caghan Kizil & Konstantinos Ampatzis. Decoding the molecular, cellular, and functional heterogeneity of zebrafish intracardiac nervous system. Nature Communications, 2024; DOI: 10.1038/s41467-024-54830-w