the mechanisms behind the heart’s reaction brought to light

When faced with a stressful situation, heart rate and blood pressure increase sharply. Researchers from the University of Tsukuba (Japan) have discovered one of the mechanisms behind these changes. They are controlled by the brain. Dopamine neurons in particular seem to play a mediating role in this stress response.

Their work was detailed in the journal Frontiers in Physiology last November.

The mechanisms of increased heart rate in the face of stress revealed

To better understand the link between stress, heart rate and the brain, Japanese researchers focused on the habenula, a brain area located in the dorsal and middle part of the thalamus where neurons are activated in response to stress.

During their study, they stimulated the habenula of rats, placed under anesthesia, with electrodes. They left at least 60 seconds between each stimulation. The animals’ heart rate and blood pressure were recorded during the procedure.

“Activation of the lateral habenula caused changes in blood pressure and heart rate”note the scientists in their press release. On the other hand, when the rodents received drugs blocking dopamine neurotransmission, their heart rate or blood pressure did not vary when the brain area was stimulated. There were also no cardiovascular changes when the activity of the ventral tegmental area – known to have a large number of neurons producing the neurotransmitter dopamine and to receive information from the habenula – was pharmacologically inhibited.

“These results suggest that the cardiovascular responses caused by activation of the lateral habenula (by stress, Editor’s note) are mediated by the dopaminergic system, in particular by the dopaminergic neurons of the ventral tegmental area”the team advances. So, for her, there is no doubt: the dopaminergic system originating from the habenula could be essential for cardiovascular responses linked to stress.

Stress and heart rate: further research needed

The Japanese scientists add that further research into the neural mechanisms regulating cardiovascular responses during stress is therefore necessary. They believe that this new work would provide a fairer and more precise vision of “behavioral changes induced by stress and the mechanisms that maintain homeostasis (the body’s ability to maintain balance, Editor’s note) in the body”.