Corticosterone response in Broad-snouted caiman (Caiman latirostris) after restraint conditions

MARIA VIRGINIA PARACHU MARCÓ; PABLO A. SIROSKI; GRACIELA JHAN; CARLOS I. PIÑA

Lake Charles, Louisiana.

Congreso; 23rd Working Meeting of the Crocodile Specialist Group; 2014

Corticosterone (CORT), the main stress hormone in reptiles, helps these organisms to recover homeostasis state after acute or chronic stressors. In this study we investigated plasma CORT profiles in juvenile Broad-snouted caimans in response to acute stress. Ten juvenile caimans raised under controlled conditions were held in restraint circumstances inducing stress. Half of animals were maintained at indoor temperature (IT) (20±1.2°C) and the rest at outdoor temperature (OT) (12.7±1.5°C) during the 12 hours experiment. Animals were bled at different time periods: 15 min, 30 min, and 1, 2, 4, 8 and 12 hours. Corticosterone levels were measured by radioimmunoassay (RIA). At the beginning of the study, CORT concentrations (time 0) ranged between 0.06 and 6.85 ng/mL. Maximum values were detected in the IT group ranged from 11.01 to 56.5 ng/mL, and OT group from 9.78 to 38.8 ng/mL. Under IT, CORT levels increased progressively reaching maximum values between 4 to 8 hours and after that CORT decreased until 6 ng/mL approximately. Some animals of the group OT presented a plateau with maximum values from 2 to 12 hours, and other rose progressively until 12 hours, possibly because ambient temperature dropped by the end of the experiment causing an additive stress effect. Only some individuals presented an increase of CORT after the first bleeding, while others presented low values until 2 hours. In order to avoid the interference generated for the action of CORT on other mechanisms, it is convenient to collect samples as soon as possible or within 30 min after capture.