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

MOLEÓN, SOLEDAD; MARIA VIRGINIA PARACHÚ MARCÓ; BELDOMÉNICO, PABLO; PABLO ARIEL SIROSKI

Congreso; 24th Crocodile Working Meeting; 2016

Crocodile Specialist Group of the Species Survival Commision of the UICN

Caiman latirostris(Broad-snouted caiman) is one of the two species of Crocodilians living inArgentina, with ecological and economic importance. In the wild, they have to facenumerous stressors including climatic factors, toxicant exposure, infection,etc. Stressors can affect the components of the immune system that might beinvolved in an organism?s survival as they actively participate in resistanceand rapid response to infection. The goals of this study were to experimentallyinvestigate the effect of three potential environmental stressors on the corticosteronelevels (CORT) and immune parameters: total and differential countof leukocytes (WBC), natural antibodies(NAbs), complement system (CS) activity and growth (snout-vent length andweight). We exposed 96 Broad-snoutedcaiman hatchlings, randomly distributed to four groups exposed to differentstressors during one month. They consisted of: limited water availability, foodrestriction, periods of overheating, and a control. Resultsshowed that CORT levels were lower in heat treatment than control. The titersof 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 wasnot difference in CS activity, WBC and clutch effects.CORT was not associated with immune parameters but there were negativelyassociated with growth (snout-vent length and weight). These results suggest that immunological indiceswere not associated with the type of stressors tested; and in the terms of thisstudy, the immune parameters evaluated in C.latirostris hatchlings seem to be independent of thehypothalamic-pituitary-adrenal cortical axis activation.