Validation of a Radioimmunoassay for Measuring Fecal Cortisol Metabolites in the Hystricomorph Rodent, Octodon degus

Soto-Gamboa, M; Gonzalez S.; Hayes, LD; Ebensperger, LA

Abstract

Determination of fecal steroid metabolites is a noninvasive technique that characterizes the physiological state of organisms without the physiological and psychological stress of handling. Although this technique has many applications in the study of wildlife and/or captive animals without the necessity of capturing individuals, it requires a species-specific validation before use. A complete validation includes an analytical and a physiological one. In the latter changes in fecal hormone metabolites are induced by previous manipulations of the respective plasma hormones. Here we validated a method for measuring fecal cortisol metabolites (FCM) in the hystricomorph rodent Octodon degus. We extracted feces with 80% ethanol and quantified steroids using a commercial available cortisol radioimmunoassay. We first compared baseline levels of blood cortisol and FCM, and then performed a challenge test with adrenocorticotropic hormone (ACTH) to demonstrate that FCM accurately reflect adrenocortical activity. We found a significantly positive relationship between concentrations of blood cortisol and its fecal metabolites. During the ACTH challenge test, blood cortisol levels peaked 30min after injection, and FCM mirrored this peak with a delay of about 6hr. Our successfully validated noninvasive method provides new opportunities for studies assessing the influence of social and ecological factors on degus under natural conditions. © 2009 Wiley-Liss, Inc.

Más información

Título según WOS: Validation of a Radioimmunoassay for Measuring Fecal Cortisol Metabolites in the Hystricomorph Rodent, Octodon degus
Título según SCOPUS: Validation of a radioimmunoassay for measuring fecal cortisol metabolites in the hystricomorph rodent, octodon degus
Título de la Revista: JOURNAL OF EXPERIMENTAL ZOOLOGY PART A-ECOLOGICAL AND INTEGRATIVE PHYSIOLOGY
Volumen: 311A
Número: 7
Editorial: Wiley
Fecha de publicación: 2009
Página de inicio: 496
Página final: 503
Idioma: English
URL: http://doi.wiley.com/10.1002/jez.546
DOI:

10.1002/jez.546

Notas: ISI, SCOPUS