Effects of ACTH, capture, and short term confinement on glucocorticoid concentrations in harlequin ducks (Histrionicus histrionicus).

Little is known about baseline concentrations of adrenal hormones and hormonal responses to stress in sea ducks, although significant population declines documented in several species suggest that sea ducks are exposed to increased levels of environmental stress. Such declines have been observed in geographically distinct harlequin duck populations. We performed an adrenocorticotropic hormone (ACTH) challenge to evaluate adrenal function and characterize corticosterone concentrations in captive harlequin ducks and investigated the effects of capture, surgery, and short term confinement on corticosterone concentrations in wild harlequin ducks.

Variability in leptin and adrenal response in juvenile Steller sea lions (Eumetopias jubatus) to adrenocorticotropic hormone (ACTH) in different seasons.

Eight free-ranging juvenile Steller sea lions (SSL; 6 males, 2 females; 14-20 months) temporarily held under ambient conditions at the Alaska SeaLife Center were physiologically challenged through exogenous administration of adrenocorticotropic hormone (ACTH). Four individuals (3 males, 1 female) underwent ACTH challenge in each of two seasons, summer and winter. Following ACTH injection serial blood and fecal samples were collected for up to 3 and 96 h, respectively.

Seasonal and predator influences on adrenal function in adult Steller sea lions: gender matters.

Chronically heightened adrenal activity indexed by fecal corticosteroids has been shown to be a valid descriptor of stress in many species. As part of an ongoing investigation of adrenal activity in Steller sea lions (SSL), adrenocorticotropic hormone (ACTH) challenges were performed during the summer at the Alaska SeaLife Center (ASLC). These results were compared to earlier data from winter months.

Postnatal ontogeny of erythropoietin and hematology in free-ranging Steller sea lions (Eumetopias jubatus).

The hormone erythropoietin (EPO) is responsible for the increased production of red blood cells (RBC) in response to tissue hypoxia. While the role of EPO in hematological development has been established in humans and terrestrial mammals, this relationship has never been examined in marine mammals that rely heavily on stored oxygen to maintain aerobic metabolism while diving. Since blood is the major oxygen storage site in marine mammals, it was hypothesized that EPO may have a significant influence on the development of hematology parameters associated with the expansion of blood oxygen stores during development.

Evaluation of adrenal function in serum and feces of Steller sea lions (Eumetopias jubatus): influences of molt, gender, sample storage, and age on glucocorticoid metabolism.

Fecal corticosterone concentrations, measured via radioimmunoassay (RIA), were validated as a method to monitor adrenal function in Steller sea lion physiology. Quantification of adrenal response to an acute stressor and relevance of data produced by developed methodologies was determined through physiological challenge with exogenous administration of adrenocorticotropic hormone (ACTH) to captive adult, reproductively intact, Steller sea lions of both sexes (n=3, 1 male, 2 female) during seasonal molt. Following ACTH administration, serial blood and fecal samples were collected and analyzed by RIA to determine adrenal response.