Exercise reshapes heart's nerve network, study finds

Regular aerobic exercise may do more than just strengthen the heart muscle; it can also reshape the neural networks that control its rhythm. A recent study has revealed that aerobic exercise can influence the structure of the cardiac stellate ganglia, key nerve clusters regulating the heart's autonomic nervous system.

Researchers from the University of Bristol, University College London, and the University of São Paulo jointly conducted the study using 3D imaging analysis. Their investigation focused on the stellate ganglia, located in the upper chest, which act as a central hub for the autonomic nervous system, controlling heart rate and blood pressure. The study observed rats that underwent 10 weeks of aerobic exercise.

The findings indicated that exercise induced distinct changes in the left and right sides of the stellate ganglia. The right ganglia showed a significant increase in the number of nerve cells, while the left ganglia exhibited a more pronounced growth in the size of nerve cells, with some nearly doubling in size. Conversely, nerve cells on the right side slightly decreased in size.

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This discovery highlights an unexpected left-right difference in the body's automatic control system for the heart and how moderate exercise alters this regulation differently on each side.

This asymmetry suggests that the autonomic nervous system's control over the heart is not bilaterally symmetrical and that different sides may have unique roles and adaptive mechanisms. Professor Augusto Coppi, a lead author from the University of Bristol, likened the stellate ganglia to a "dimmer switch" or "accelerator pedal" for the heart. He stated that the discovery highlights an unexpected left-right difference in the body's automatic control system for the heart and how moderate exercise alters this regulation differently on each side.

These insights could pave the way for more refined treatments for cardiac conditions such as arrhythmias, angina, and stress-induced cardiomyopathy (broken-heart syndrome). Current treatments often involve suppressing the overactive stellate ganglia. Understanding how exercise modifies the structure of these ganglia could enable more targeted interventions, potentially involving selective treatment of either the left or right ganglia based on a patient's specific condition. However, the researchers emphasize that this is an early-stage study conducted on rats, and further research is needed to confirm these changes in humans and their direct impact on heart function and disease prevention.

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The next step is to confirm how these structural changes relate to actual heart function.