Department of Anthropology, Durham University, DH1 3LE, Durham, UK.
Gen Comp Endocrinol. 2012 Nov 1;179(2):167-77. doi: 10.1016/j.ygcen.2012.08.008. Epub 2012 Aug 19.
Enzymeimmunoassays (EIAs) allow researchers to monitor stress hormone output via measurement of fecal glucocorticoid metabolites (FGCMs) in many vertebrates. They can be powerful tools which allow the acquisition of otherwise unobtainable physiological information from both captive animals and wild animals in remote forest habitats, such as great apes. However, methods for hormone measurement, extraction and preservation need to be adapted and validated for field settings. In preparation for a field study of Western lowland gorillas (Gorilla gorilla gorilla) in the Central African Republic we used samples from captive gorillas collected around opportunistic stressful situations to test whether four different glucocorticoid EIAs reflected adrenocortical activity reliably and to establish the lag-time from the stressor to peak excretion. We also validated a field extraction technique and established a simple, non-freezer-reliant method to preserve FGCMs in extracts long-term. We determined the rate of FGCM change over 28 days when samples cannot be extracted immediately and over 12h when feces cannot be preserved immediately in alcohol. Finally, we used repeat samples from identified individuals to test for diurnal variation in FGCM output. Two group-specific assays measuring major cortisol metabolites detected the predicted FGCM response to the stressor reliably, whereas more specific cortisol and corticosterone assays were distinctly less responsive and thus less useful. We detected a lag time of 2-3 days from stressor to peak FGCM excretion. Our field extraction method performed as well as an established laboratory extraction method and FGCMs in dried extracts stored at ambient temperatures were as stable as those at -20 °C over 1 yr. Hormones in non-extracted feces in alcohol were stable up to 28 days at ambient temperatures. FGCMs in un-fixed gorilla feces deteriorated to almost 50% of the original values within 6h under field conditions. We detected no diurnal variation in FGCMs in samples from wild gorillas. Our study highlights the importance of thorough biological and immunological validation of FGCM assays, and presents validated, practical methods for the application of non-invasive adrenocortical monitoring techniques to field conservation contexts where it is crucially needed.
酶免疫分析（EIAs）允许研究人员通过测量粪便中糖皮质激素代谢物（FGCMs）来监测许多脊椎动物的应激激素分泌。它们是强大的工具，可以从圈养动物和生活在偏远森林栖息地的野生动物（如大猩猩）中获取原本无法获得的生理信息。然而，激素测量、提取和保存方法需要适应和验证野外环境。在为中非共和国西部低地大猩猩（Gorilla gorilla gorilla）的一项实地研究做准备时，我们使用了在机会性应激情况下收集的圈养大猩猩的样本，以测试四种不同的糖皮质激素 EIA 是否可靠地反映了肾上腺皮质的活动，并确定从应激源到峰值排泄的滞后时间。我们还验证了一种野外提取技术，并建立了一种简单的、不依赖于冰箱的方法，长期保存提取物中的 FGCM。我们确定了在不能立即提取样本的情况下，FGCM 变化的速度在 28 天内，在粪便不能立即用酒精保存的情况下，FGCM 变化的速度在 12 小时内。最后，我们使用已识别个体的重复样本测试 FGCM 输出的昼夜变化。两种组特异性测定法，测量主要的皮质醇代谢物，可靠地检测到应激源对 FGCM 的预期反应，而更特异性的皮质醇和皮质酮测定法反应明显较差，因此用处较小。我们检测到从应激源到 FGCM 排泄峰值的滞后时间为 2-3 天。我们的野外提取方法与已建立的实验室提取方法一样有效，在环境温度下干燥提取物中的 FGCM 在 1 年内与 -20°C 下一样稳定。在环境温度下，酒精中的非提取粪便中的激素在 28 天内稳定。在野外条件下，未固定的大猩猩粪便中的 FGCM 在 6 小时内恶化到原始值的近 50%。我们在来自野生大猩猩的样本中没有检测到 FGCM 的昼夜变化。我们的研究强调了对 FGCM 测定进行彻底的生物学和免疫学验证的重要性，并提出了经过验证的、实用的方法，用于将非侵入性肾上腺皮质监测技术应用于野外保护环境，在这些环境中，这些技术是至关重要的。
