SICB+ Developmental programming of the HPA axis by mild thermal stressors in the zebra finch Hoffman, AJ*; Wada, H; Auburn University firstname.lastname@example.org
Development is a critical period during which the environmental conditions experienced can have significant and long-lasting effects on phenotype. Prolonged stressors during this period can often result in maladaptive effects. However, developmental stressors may also result in adaptive adjustments in physiology, increasing fitness later on in life in otherwise detrimental environments. The hypothalamic-pituitary-adrenal (HPA) axis, which controls glucocorticoid hormone secretion in response to stressors, can exhibit permanently altered responsiveness as a result of the environment individuals experienced during development. Thus, HPA-axis programming may adaptively tailor an organism’s physiology to cope with future expected conditions. However, such programming may only be beneficial if the later environment matches with that experienced early in life, and may be costly if there is an environmental mismatch. We tested the hypothesis that zebra finches (Taeniopygia guttata) exposed to a prolonged mild stressor early in life will exhibit persistently altered corticosterone (CORT) production, and will be characterized by attenuated CORT secretion compared to the controls in response to a high stressor in adulthood. To test this hypothesis, we subjected juvenile male and female zebra finches to a prolonged mild heat stress (38° C) or control (22° C) temperature every other day for 28 days. As adults, these finches were then subjected to either a high heat stressor (42° C) or control (22° C) temperature for 3 consecutive days. Blood samples were collected from the finches both prior to and following the juvenile and adult treatment periods, and well as later on in life eight months after the adult treatment. ELISA kits were then used to quantify corticosterone in the plasma from all time points.