Meeting Abstract

P1.70  Saturday, Jan. 4 15:30  Stress as a modulator of immune function and sickness behavior in Passer domesticus MCDANIEL, DK*; DAVIS, J; Radford University; Radford University dkmcdaniel@radford.edu

The vertebrate HPA axis is responsible for responding to external stressors that may or may not threaten the life of an organism. It does this by releasing glucocorticoids that regulate aspects of the stress-coping response, one of which is the immune response. Lipopolysaccharide (LPS) is commonly used in the lab to induce an immune response in animals. Once an immune response is induced, the animal will exhibit sickness behaviors, increased white blood cells, and increased hemagglutination and hemolysis. An invasion of a pathogen is considered an external stressor and is therefore coupled with the release of glucocorticoids. Glucocorticoids decrease immune function and are thought to be protective, by not allowing the immune system to damage healthy tissue. Because previous research has shown that stress attenuates the immune response, we hypothesized that birds pretreated with corticosterone would have a weaker immune response and exhibit less sickness behaviors than birds given LPS alone. This situation is analogous to a bird experiencing a stressor, such as a predator, prior to an infection. In order to further elucidate the interaction between the HPA axis and the immune response, house sparrows (Passer domesticus) were either pretreated with dimethylsulfoxide (DMSO) and corticosterone and then given LPS, or received a DMSO control treatment alone followed by LPS. Blood was taken from the subjects at various time points and measured for heterophil:lymphocyte ratio, hemagglutination, and corticosterone (via ELISA). Alterations in movement, feeding and water intake were recorded and quantified using Ethovision XT.