McClelland Sara J, Woodley Sarah K
Department of Biological Sciences, Duquesne University, 600 Forbes Avenue, Pittsburgh, PA 15218, United States.
Department of Biological Sciences, Duquesne University, 600 Forbes Avenue, Pittsburgh, PA 15218, United States.
Gen Comp Endocrinol. 2021 Oct 1;312:113858. doi: 10.1016/j.ygcen.2021.113858. Epub 2021 Jul 21.
There is a particular need to develop conservation tools for use in amphibian populations, which are declining rapidly. Glucocorticoid hormones like corticosterone (CORT) are often used as biomarkers of amphibian stress. A relatively new method of assessing CORT in amphibians is to measure CORT concentrations in water that has held amphibians (water-borne (WB) CORT). Here, we tested whether WB CORT is a valid measure of CORT in larval and metamorphic Northern Leopard Frogs (Lithobates pipiens). We assessed whether levels of WB CORT are different among groups of animals that should have different levels of CORT due to a handling challenge, a pharmacological challenge (ACTH), or developmental stage. We also assessed whether WB CORT was correlated with plasma CORT within individuals. Results indicated that measurement of WB CORT is valid in prometamorphic tadpoles because injection with ACTH increased WB CORT, and WB CORT and plasma CORT levels were correlated within an animal in most cases. However, were unable to fully validate the use of WB CORT in metamorphic frogs (metamorphs) because although injection with ACTH elevated levels of WB CORT, WB CORT was not correlated with plasma CORT within individual metamorphs. Also, there was no correlation between WB CORT and plasma CORT in early stage (premetamorphic) tadpoles or tadpoles undergoing metamorphic climax, indicating that WB CORT is not sensitive enough to detect natural variation of organismal CORT in these groups. Together, results indicated that WB CORT is a valid method of assessing plasma CORT in Northern Leopard Frogs, but only for some life-history stages. Our results illustrate the importance of carefully validating the use of WB CORT for appropriate interpretation of results.
迫切需要开发适用于两栖动物种群的保护工具，因为两栖动物种群数量正在迅速下降。像皮质酮（CORT）这样的糖皮质激素常被用作两栖动物应激的生物标志物。一种相对较新的评估两栖动物体内CORT的方法是测量曾饲养过两栖动物的水中的CORT浓度（水生CORT）。在此，我们测试了水生CORT是否是评估北美豹蛙幼体和变态期个体体内CORT的有效指标。我们评估了在因处理挑战、药理学挑战（促肾上腺皮质激素）或发育阶段而应具有不同CORT水平的动物组中，水生CORT水平是否存在差异。我们还评估了个体内部水生CORT与血浆CORT是否相关。结果表明，在近变态期蝌蚪中测量水生CORT是有效的，因为注射促肾上腺皮质激素会增加水生CORT，并且在大多数情况下，动物体内水生CORT和血浆CORT水平是相关的。然而，我们无法完全验证在变态期青蛙（变态个体）中使用水生CORT的有效性，因为尽管注射促肾上腺皮质激素会提高水生CORT水平，但在单个变态个体中，水生CORT与血浆CORT并不相关。此外，在早期（近变态期）蝌蚪或处于变态高峰期的蝌蚪中，水生CORT与血浆CORT之间没有相关性，这表明水生CORT在检测这些群体中机体CORT的自然变化方面不够敏感。总之，结果表明水生CORT是评估北美豹蛙血浆CORT的有效方法，但仅适用于某些生活史阶段。我们的结果说明了仔细验证水生CORT的使用以正确解释结果的重要性。
