Noninvasive approach to the assessment of activity of the hypothalamic-pituitary adrenal system of the Amur tigers

Abstract

The state of animals in natural populations can be often assessed only by noninvasive methods. The use of EIA antibodies against corticosterone makes it pos� sible to reveal an increase in the concentration of immunoreactive compounds that bind to antibodies against corticosterone in faeces of tigers both after artificial stimulation of adrenal glands by injection of adrenocorticotropic hormone and after stress (trans� portation of animals). This confirms the possibility of using antibodies against corticosterone for noninva� sive monitoring of the state of the hypothalamicpitu� itaryadrenal system (HPAS) in Amur tigers. The Amur tiger ( Panthera tigris altaica) is a subspe� cies inhabiting the periphery of the species range under conditions that are suboptimal for this species. In this case, exposure to adverse factors with a higher probability may cause an increase in the activity of the hypothalamicpituitaryadrenal system (HPAS), which may suppress breeding and even result in ani� mal's death. Rehabilitation of tigers withdrawn from nature and their subsequent return to natural environ� ment becomes a relevant method to conserve this spe� cies. However, these operations are associated with transportation of animals, which is a strong stressor. With allowance for the fact that the abundance of the Amur tiger is very low (approximately 500 animals (1)), establishing the factors that endanger this species and determination of the effect of transportation on the stress level of animals are very important for con� servation of Amur tigers and development of rehabili� tation programs for these animals. The welfare of animals is estimated primarily by the HPAS activity, because adverse factors stimulate it and cause an increase in the level of glucocorticoids in blood plasma. Changes in the concentration of gluco� corticoids (first of all, cortisol and corticosterone) in blood plasma compared to their baseline level can serve as a reliable indicator of animal's state. At the same time, this method has serious limitations: stress procedures, such as capture, handling, and immobili� zation of animals as such often drastically increase the level of glucocorticoids in blood plasma of animals and leads to a bias in results, because in this case only the response to manipulations is recorded (2).