The brain-sympathetic-chromaffin cell axis and catecholamines.

The brain-sympathetic-chromaffin cell axis is one of the main components of the stress response, enabling organisms to face and fight stressful stimuli. The activation of this axis during acute stress is common among vertebrates and is particularly important in fish, whose autonomic system is poorly developed. The release of catecholamines from the chromaffin cells, following sympathetic stimulation, affects energy metabolism and oxygen transport, increases ventilatory and heart rates, heart stroke volume, blood perfusion in gills and muscles, and provides glucose supply to critical tissues.