The signaling from the heart to brain may not be so distant. Chemical alterations and cardiac function from our heart can cause changes in brain activity, as witnessed in the behavior of some animal models.

Such findings have emerged from the study Cardiac AC8 Over-Expression Increases Locomotion by Altering Heart-Brain Communication published in the Journal of the American College of Cardiology (Clinical Electrophysiology, thanks to the research coordinated by Prof. Jacopo Agrimi of the Department of Biomedical Sciences of University of Padua. The study is a collaboration of those from the Italian universities of Padua and Pisa, along with Johns Hopkins and the National Institute of Aging in Baltimore, Maryland. Their work highlights how the brain interprets augmented myocardial humoral/functional output as a “sustained exercise-like” situation and responds by activating central nervous system output controlling locomotion.

Mice models were used in which the level, and therefore the activity, of a particular enzyme called adenylate cyclase type 8 (AC8) was genetically increased at those of the cells that set the heart rhythm. This enzyme promotes the synthesis of chemical signals (hormones) which are essential for increasing the frequency of heartbeats and the force of contraction of the heart muscle. And some of them, like dopamine, are fundamental for the perfect execution of our voluntary movements.

The mice model, known as Transgenic AC8 (TGAC8), lives in a condition of permanent physical exercise. In fact, not only do such models have the frequency and strength of contraction of the cardiac muscle increased, but spend this time in constant movement (compared to the resting state) at an average speed with which they move in the environment around them.

In particular, some hypotheses suggest that a substantial increase in gamma waves start from a particular region of the brain called the hippocampus that is responsible for many activities including memory consolidation, exploration and navigation in the surrounding space in large as well as small mammals.

Prof. Agrimi explains, "The bioinformatic part of the study revealed that the level of the hippocampus of TGAC8 mice were significantly increased in the receptors of a chemical messenger, which are very important for the initiation and maintenance of motor activity, namely dopamine. Finally, a marked increase in the flow of information between the heart and the brain are shown in terms of increased mutual influence between EEG and ECG signals."

Our study provides new information and crucial perspectives on how the brain communicates with the heart and vice versa. More specifically, it shows that the humoral/electrical changes generated peripherally at the myocardial level are sufficiently incisive to modify the commands exiting the brain and directed to the various compartments/organs of our body. We must therefore begin to consider possible new scenarios and new actors, including dopamine produced by heart cells, when we must evaluate the functional consequences - both central and peripheral - of possible alterations in the constant (and bidirectional) dialogue between brain and heart.