Document Type
Article
Publication Date
2025
Published In
Conservation Physiology
Abstract
For aquatic and semi-aquatic vertebrates like amphibians, it is possible to estimate excreted hormone levels using non-invasive methods such as waterborne and salivary sampling. These techniques allow monitoring of endocrine activity over varying, repeated and simultaneous integration periods while minimizing handling-related stress that can ‘contaminate’ hormone estimates, including estimates of baseline glucocorticoids. Here we have validated the extraction and quantification of three steroid hormones (corticosterone, CORT; 17-b estradiol, E₂; testosterone, TST) in Couch’s spadefoots (Scaphiopus couchii)—a desert-adapted anuran of special interest for physiology, evolution and conservation—using non-invasive waterborne and minimally invasive salivary hormone methods. We combined extraction and enzyme immunoassay methods to conduct conventional technical validations of parallelism, recovery and time-course. Next, we carried out biological validations by testing the correlation between excreted and circulating concentrations and conducting pharmacological challenges. We found that all three hormones can be precisely estimated from 60-min water baths, exhibit robust parallelism, and have high recoveries. Further, we demonstrated that secretory responses to pharmacological challenges can be detected in waterborne CORT in male and female frogs; in TST and E₂ in male frogs, but not consistently for TST or E₂ in female frogs. Lastly, plasma hormone concentrations were consistently correlated with their waterborne complements for CORT (both sexes), as well as TST and E₂ in males (but not females). Plasma CORT was also positively correlated with salivary CORT. Together, our findings suggest that sampling waterborne and salivary hormones offers a minimally invasive method that field endocrinologists and conservation physiologists can use to obtain biologically informative endocrine estimates from desert-adapted amphibians.
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Recommended Citation
Alexander T. Baugh; Callie Cho , '23; Alice Onyango-Opiyo , '23; Sophie A. Rodner , '25; Senna Mieth , '25; Daniel Oakes , '24; and Liam Halstead , '25.
(2025).
"Validation Of Non-Invasive Methods For The Measurement Of Gonadal And Inter-Renal Steroid Hormones In A Desert-Adapted Amphibian (Scaphiopus couchii)".
Conservation Physiology.
Volume 13,
Issue 1.
DOI: 10.1093/conphys/coaf007
https://works.swarthmore.edu/fac-biology/707
Comments
This work is freely available under a Creative Commons license.