Identification of Koala (Phascolarctos cinereus) Faecal Cortisol Metabolites Using Liquid Chromatography-Mass Spectrometry and Enzyme Immunoassays

Metabolites

卷:11

Rupert Palme¹  Rolf Schlagloth²  Flavia Santamaria²  Ralf B. Schittenhelm³  Christopher K. Barlow³  Joerg Henning⁴ 

[1] Department of Biomedical Sciences, University of Veterinary Medicine, 1210 Vienna, Austria;

[2] Flora, Fauna and Freshwater Research and Koala Research Central Queensland, School of Health, Medical and Applied Sciences, Central Queensland University, North Rockhampton, QLD 4702, Australia;

[3] Monash Proteomics and Metabolomics Facility, Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC 3800, Australia;

[4] School of Veterinary Science, The University of Queensland, Gatton, QLD 4343, Australia;

关键词: Phascolarctos cinereus;    koala;    non-invasive;    stress;    faecal glucocorticoid metabolites;    LC-MS;   

DOI  :  10.3390/metabo11060393

来源: DOAJ

【 摘 要 】

The koala (Phascolarctos cinereus) is an arboreal folivorous marsupial endemic to Australia. Anthropogenic activities and climate change are threats to this species’ survival and are potential stressors. A suitable non-invasive method is needed to objectively detect stress in koalas. Under conditions of stress, the concentration of the hormone cortisol in plasma or in saliva is elevated, and this would provide a convenient measure; however, collecting blood or saliva from wild animals is both practically difficult and stressful, and so likely to confound any measurement. In contrast, measurement of cortisol metabolites in faeces provides a practical and non-invasive method to objectively measure stress in koalas. Unfortunately, the identity of the main faecal cortisol metabolites of koalas is unknown. In this study, we have used both untargeted liquid chromatography–mass spectrometry (LC-MS) and enzyme immunoassays (EIAs) to identify several faecal cortisol metabolites in two koalas, one female (18 months old, 4.1 kg) and one male (4 years old, 6.95 kg) upon administration of hydrocortisone (cortisol) sodium succinate. The LC-MS analysis identified tetrahydrocortisol along with several other isomers as cortisol metabolites. After a survey of five enzyme immunoassays, we found that two metabolites, tetrahydrocortisol and 3β-allotetrahydrocortisol, could be detected by EIAs that used antibodies that were raised against their structurally similar corticosterone counterparts, tetrahydrocorticosterone and 3β-allotetrahydrocorticosterone, respectively. While the 3β-allotetrahydrocortisol metabolite was detected in the faeces of only one of the two animals studied, tetrahydrocortisol was detected in both. These results ultimately indicate that tetrahydrocortisol is likely the main faecal cortisol metabolite in koalas, and we demonstrate that it can be measured by an EIA (50c) that was originally developed to measure tetrahydrocorticosterone.

【 授权许可】

Unknown