Abstract
All vertebrates possess an endocrine system, and hormone receptors regulating gene expression are present in nearly every living cell. The endocrine system delicately utilizes over 50 different hormones as unique chemical messengers, which are vital in controlling growth, metabolism and reproduction, and in maintaining homeostasis. This project will focus on the two most important hormone sub-systems - thyroid and steroid - and on interactions between these complex endocrine pathways.1,7,8 Thyroid hormones play a major physiological role in growth, thermogenesis and calorigenesis, and have recently been linked to cognitive development.2,7,8 Steroidogenesis is a highly conserved metabolic pathway responsible for producing a range of precursors and steroid hormones, which are fundamental in the regulation of important biological processes such as behavioural characteristics, sexual development and reproduction.3,5,6
Here, we present the development of a rapid and robust analytical methodology for the simultaneous determination of thyroid and steroid hormones in plasma and various tissues, using the California sea lion Z. californianus as a model species. To establish a causal link between PCBs and the certain hormones, we will apply the novel approach in combination with analysis of polychlorinated biphenyls (PCBs) to sea lion individuals from the Bay Area.
Many wildlife toxicologists seek to identify the effects of endocrine-disrupting compounds on a range of vertebrates, or to determine hormone levels for diagnostic purposes. Immunoassays have typically been used, although it has recently been shown that they lack specificity and may result in false-positive results.4 Chemical analysis using liquid chromatography isotopic-dilution tandem mass spectrometry (LC-ID-MS/MS) is more reliable, accurate, selective and sensitive compared to immunoassays.
Acknowledgements
This work is funded by The Danish Council for Independent Research/Natural Sciences.
*Presenting author
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