Physiological Stress in Birds.

The article focuses on physiological stress in birds. Responses to environmental stressors by complex organisms such as birds depend on the integrative capacities of the nervous and endocrine systems. As in all vertebrates, 80 to 90% of the circulating corticosteroids of birds are specifically bound to plasma proteins called corticosteroid-binding globulins (CBGs). CBGs have an important role in the stress response because the unbound or free corticosteroids pass through the cell membranes of target tissue and exert specific effects. Thus, the quantity and binding capacity of CBGs act as modifiers of corticosteroid activity by controlling their distribution and metabolic fate.