Physiological stress in captive Greater rheas ( Rhea americana ): Highly sensitive plasma corticosterone response to an ACTH challenge

Abstract Up to the present no studies have been conducted either on baseline concentrations of adrenal hormones or on hormonal responses to stress in Greater rhea ( Rhea americana ) and most ratite species. The aims of this work were to assess the presence of corticosterone in plasma of Greater rhea...

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Bibliographic Details
Published in:General and comparative endocrinology 2009-06, Vol.162 (2), p.188-191
Main Authors: Lèche, Alvina, Busso, Juan M, Hansen, Cristian, Navarro, Joaquín L, Marín, Raúl H, Martella, Mónica B
Format: Article
Language:English
Subjects:
ACTH
Adrenocorticotropic Hormone - pharmacology
Animals
Chromatography, High Pressure Liquid
Corticosterone
Corticosterone - blood
Endocrinology & Metabolism
Female
Glucocorticoids
Greater rhea
HPLC
Male
Plasma
Radioimmunoassay
Rheiformes - blood
Stress response
Stress, Physiological - drug effects
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Summary:Abstract Up to the present no studies have been conducted either on baseline concentrations of adrenal hormones or on hormonal responses to stress in Greater rhea ( Rhea americana ) and most ratite species. The aims of this work were to assess the presence of corticosterone in plasma of Greater rhea, to validate a corticosterone125 I-radioimmunoassay for determining corticosterone levels in plasma samples and to study the activation of the adrenal gland after an adrenocorticotrophic hormone (ACTH) challenge. Six captive Greater rhea juveniles of 10 months of age received an intravenous ACTH injection. Blood samples were taken at 0 min (baseline pre-ACTH levels), and post-injection at 15, 30, 60 min and at 24 and 48 h. The high pressure liquid chromatography (HPLC) analysis of pooled plasma showed that corticosterone is the glucocorticoid found in the plasma of Greater rhea. Biochemical assays of standard validation (e.g., parallelism, exogenous corticosterone recovery) showed that measurements of corticosterone present in the plasma of the Greater rhea provided by commercial corticosterone125 I-radioimmunoassay were accurate and precise. ACTH challenge induced a more than 40-fold increase in plasma corticosterone at 60 min post-ACTH (from 4.0 to 166.5 ng/ml, on average). The corticosterone response to ACTH in Greater rhea was higher than is usual in birds, an apparently typical characteristic of ratites.
ISSN:0016-6480
1095-6840
DOI:10.1016/j.ygcen.2009.03.014