Meeting Abstract

P2.162  Sunday, Jan. 5 15:30  Corticosterone Treatment Alters Blood Cell Differentials and Function for Long-term Periods in Laboratory and Wild-caught Amphibian Models. FALSO, P.G*; NOBLE, C.A.; HAYES, T.B.; Slippery Rock University; University of California, Berkeley; University of California, Berkeley paul.falso@sru.edu

Amphibians may experience stressful habitat conditions as a result of human habitat alteration. Interrenal dysfunction and increased plasma glucocorticoids (corticosterone) have been observed in amphibians in altered habitats. The effect of long-term stress on amphibian immunity is not well understood, however. We modeled a long-term endocrine stress scenario by elevating plasma corticosterone in two species of adult amphibians and examined effects on white blood cell differentials and innate immune activity. Plasma corticosterone was elevated in adult American bullfrogs (Lithobates catesbeianus) by surgically implanting corticosterone capsules and in adult African clawed frogs (Xenopus laevis) by immersion in corticosterone-treated water. Elevated plasma corticosterone levels increased the ratio of peripheral neutrophils to lymphocytes in both L. catesbeianus and X. laevis, and decreased blood eosinophil concentrations in L. catesbeianus over a long-term period. Whole blood oxidative burst activity generally correlated with blood neutrophil concentrations, and thus was increased with CORT treatment, significantly in L. catesbeianus. In L. catesbeianus, an endogenous response of eosinophils and lymphocytes to implanted capsules was generally attenuated by corticosterone treatment, suggesting an alteration of immune response to large particles or macroparasites. Blood monocyte concentrations and blood basophil concentrations were not significantly altered by corticosterone treatment in either L. catesbeianus or X. laevis. Our results show that long-term stress can alter amphibian immune parameters for extended periods of time and may play a crucial role in disease.