BUNKERS, J.L.*; KELLY, S.A.; BHANVADIA, A.; BLANK, K.M.; PLATZER, E.G.; GARLAND, T., JR.; Univ. of California, Riverside: Susceptibility of Mice with Chronically Elevated Plasma Corticosterone to a Parasitic Nematode Infection

Chronically elevated plasma glucocorticoid levels can have suppressive effects on immune function in mammals. House mice (Mus domesticus) that have been selectively bred for high-voluntary wheel running (Swallow et al., 1998, Behavior Genetics 28:227-237) are an interesting model to study possible glucocorticoid-induced immune suppression because they exhibit chronically elevated levels of an endogenous glucocorticoid, corticosterone (CORT) (Girard and Garland, 2002, Journal of Applied Physiology 92:1553-1561; Bunkers et al., 2003, Integrative and Comparative Biology 43:839). As an initial test of their immunocompetence, we compared the four replicate High-Runner (HR) lines of mice with their four randomly bred Control lines by subjecting them to infection by a parasitic nematode, Nippostrongylus brasiliensis. Ten adult male mice from each of the eight lines were inoculated subcutaneously with approximately 600 third-stage larval N. brasiliensis suspended in 0.1 ml of saline. After inoculation, N. brasiliensis migrate to the lungs, are coughed up, swallowed, and mature in the small intestine. Immunocompetent mice typically flush the infestation from the gut in approximately ten days (Katona et al., 1988). Mice in the present study were sacrificed twelve days after injection and the small intestine and spleen were removed. The small intestine was quartered and nematode infestation was quantified. We hypothesize that mice from the HR lines will have more nematodes remaining in the small intestine as compared with the C lines. Supported by NSF IBN-0212567 to T.G.