Stress in Domestic Animals: The Roles of the Adrenal Chromaffin and Cortical Tissue

The adrenal glands play a critical response to stressors or danger in livestock, horses, dogs, cats, poultry, and other amniote animals. In response to stressors, the adrenal cortical cells produce glucocorticoids (cortisol in livestock, horses, dogs, and cats and corticosterone in poultry), modifying metabolism and other physiological processes. The chromaffin cells produce either epinephrine (EP) or norepinephrine (NE) in response to external and internal threats. These hormones affect effects on metabolism and blood flow. The EP- and NE-chromaffin cells are located in the adrenal medulla in mammals but distributed in poultry. Moreover, there are multiple intra-adrenal peptides, each with different roles related to stress and other physiological functions. These peptides originate from both chromaffin and cortical cells and exert local autocrine and paracrine effects. The release of Met-enkephalin is also provoked by stressors.