Meeting Abstract
Corticosterone (CORT) is a frequently quantified hormone in the field of avian endocrinology. CORT is a metabolic hormone that fluctuates daily, seasonally and in response to acute challenges (stressors). Because of the hydrophobic nature of CORT, the majority of CORT is carried on hydrophilic corticosterone binding globulin (CBG). The need to measure CBG in comparative studies is debated and several different hypotheses have been proposed to explain the functional role of CBG. These hypotheses focus on either total hormone (CORT bound to CBG plus free CORT), free hormone (total CORT minus CORT bound to CBG) bound hormone (total CORT minus free CORT). We propose that increased inclusion of CBG in comparative studies will help elucidate the role of CBG in CORT physiology and help identify the functionally accurate hypothesis. However, a major impediment to the inclusion of CBG in comparative studies is the lack of a simple assay, such as an enzyme linked immunosorbent assay (ELISA) typically used to quantify CORT. Here we report on our progress generating an avian CBG ELISA using a novel CBG antibody against zebra finch (Taeniopygia guttata), and developing a standard for use in the ELISA for quantifying CBG. We report on the efficacy of using this assay with four typical avian models, White-crowned sparrows (Zonotrichia leucophrys), White-throated sparrows (Zonotrichia albicollis), Dark-eyed Juncos and Zebra Finch (Junco hyemalis). Routine quantification of CBG may lead to a better understanding of the role of CBG in CORT physiology for comparative studies.
