Department of Biological Sciences, Duquesne University, 201 Mellon Hall, Pittsburgh, PA 15282, USA.
Gen Comp Endocrinol. 2010 Dec 1;169(3):269-75. doi: 10.1016/j.ygcen.2010.09.004. Epub 2010 Sep 17.
Stressors elicit allostatic responses that allow animals to cope with changing and challenging environments and also cause release of glucocorticoid hormones (GCs). Compared to other vertebrate classes, relatively little is known about amphibian behavioral and physiological responses to GCs. To understand the effects of elevated plasma GCs in amphibians, exogenous application of GCs is necessary, but traditional methods to elevate GCs require handling and/or anesthesia which themselves are stressors. A less invasive alternative successfully used in birds and reptiles utilizes transdermal delivery by applying GCs via a dermal patch. We asked whether dermal patches containing corticosterone (CORT, the main GC in amphibians) would elevate plasma CORT in terrestrial salamanders and frogs. We explored the use of the dermal patch to deliver CORT in an acute, sustained, and repeated manner. Patches adhered well to the amphibians' moist skin and were easily removed to regulate the time course of CORT delivery. Application of CORT treated patches elevated plasma CORT concentrations compared to vehicle patches in all species. Patches delivered physiological levels of plasma CORT in ecologically relevant time frames. Repeated application and removal of CORT patches were used to simulate exposure to repeated stressors. Application of patches did not represent a stressor because plasma CORT concentrations were similar between animals that received vehicle patches and untreated animals. Thus, transdermal delivery of GCs represents a potentially useful tool to better understand amphibian allostatic responses to stressors, and perhaps amphibian population declines.
应激源会引发适应反应，使动物能够应对不断变化和具有挑战性的环境，同时也会导致糖皮质激素（GCs）的释放。与其他脊椎动物类群相比，人们对两栖动物对 GCs 的行为和生理反应知之甚少。为了了解升高的血浆 GCs 对两栖动物的影响，需要外源性应用 GCs，但传统的升高 GCs 的方法需要处理和/或麻醉，而这些本身就是应激源。一种在鸟类和爬行动物中成功应用的非侵入性替代方法是通过皮肤贴片将 GCs 经皮给药。我们询问了含有皮质酮（CORT，两栖动物中的主要 GC）的皮肤贴片是否会升高陆生蝾螈和青蛙的血浆 CORT。我们探索了以急性、持续和重复的方式使用皮肤贴片来输送 CORT。贴片很好地贴附在两栖动物的湿润皮肤上，并且很容易去除以调节 CORT 输送的时间过程。与载体贴片相比，应用 CORT 处理的贴片会升高所有物种的血浆 CORT 浓度。贴片以生态相关的时间框架输送生理水平的血浆 CORT。重复应用和去除 CORT 贴片被用来模拟反复暴露于应激源。贴片的应用并不代表应激源，因为接受载体贴片和未处理动物的动物之间的血浆 CORT 浓度相似。因此，GCs 的经皮给药代表了一种有用的工具，可以更好地了解两栖动物对应激源的适应反应，也许还有两栖动物的种群减少。
