WHITMAN, B.A.*; BREUNER, C.W.; DUFTY, A.M; Boise State University; University of Texas at Austin; Boise State University: Investigator Handling, Stress, and Nestlings: Should We be Concerned?

It is well established in the mammalian literature that early developmental environment and experiences can have profound and lasting consequences. For example, neonatal stressors can alter gene expression to increase glucocorticoid receptors in the hippocampus, thus sensitizing the glucocorticoid negative feedback mechanism. In addition, the hippocampus may be organized as a preemptive modulator of the glucocorticoid stress response; i.e., pre-negative feedback mechanism dampening. We set out to explore this phenomenon in an avian species, the American kestrel (Falco sparverious). Using daily handling (15 min. /day) from hatching to 25 days post-hatch as a chronic neonatal stressor, we tested the idea that repeated handling will modulate the development of stress responsiveness. Previous work has shown that daily neonatal handling attenuated the glucocorticoid stress response to a novel stressor and increased glucocorticoid receptors in the hippocampus in rat pups. We implemented a standard capture and restraint protocol on day 26 post-hatch, with blood samples taken at: T0, T5, T15, T30, and T60. Baseline glucocorticoid levels did not differ between handled and control groups. At all other sampling points handled birds had significantly lower glucocorticoid titers. Corticosterone biding globulins were also measured, with handled birds having lower levels than controls. Moreover, estimates of free CORT were made. Brain samples were collected; however, analysis of glucocorticoid receptors has yet to be performed.