Relationship between blood corticosterone concentration and immune function in juvenile Broad-Snouted Caimans (Caiman latirostris) under stress

MOLEÓN M.S; PABLO BELDOMENICO; PABLO SIROSKI; MARÍA V. PARACHÚ MARCÓ

Skukuza

Congreso; 24rd Working Meeting of the IUSN-SSC. Crocodile Specialist Group; 2016

Relationship between blood corticosterone concentration and immune function in juvenile Broad-Snouted Caiman (Caiman latirostris) under stress.Moleón, M.S.1,2; Parachú Marcó, M. V.1,2,3; Beldomenico, P. M.1,4 and Siroski, P. A.1,21-Instituto de Ciencias Veterianarias del Litoral (ICiVet Litoral-UNL-CONICET). 2-Proyecto Yacaré-Lab. Zoología Aplicada: Anexo Vertebrados (FHUC-UNL/MASPyMA). 3-Facultad de Humanidades y Ciencias, Universidad Nacional del Litoral. 4-Facultad de Ciencias Veterinarias, Universidad Nacional del Litoral.soledadmoleon@yahoo.com.arCaiman latirostris (Broad-snouted caiman) is one of the two species of Crocodilians living in Argentina, with ecological and economic importance. In the wild, they have to face numerous stressors including climatic factors, toxicant exposure, infection, etc. Stressors can affect the components of the immune system that might be involved in an organism?s survival as they actively participate in resistance and rapid response to infection. The goals of this study were to experimentally investigate the effect of three potential environmental stressors on the corticosterone levels (CORT) and immune parameters: total and differential count of leukocytes (WBC), natural antibodies (NAbs), complement system activity (CS) and growth (snout-vent length and weight). We exposed 96 Broad-snouted caiman hatchlings, randomly distributed to four groups exposed to different stressors during one month. They consisted of limited water availability, food restriction, periods of overheating, and a control. Results showed that CORT levels were lower in heat treatment than control. The titers of Nabs in food restriction and heat treatment were higher than in controls; and changes in the percentage of leukocytes were detected in all groups. There was not difference in CS activity, WBC and clutch effects. Corticosterone was not associated with immune parameters but there were negatively associated with growth (snout-vent length and weight). These results suggest that these immunological indices were not associated with the type of stressors tested; and in the terms of this study, the immune parameters evaluated in C. latirostris hatchlings seem to be independent of the hypothalamic-pituitary-adrenal cortical axis activation.