Center for Ecological Sciences, Indian Institute of Science, Bangalore 560012, India.
Theriogenology. 2010 May;73(8):1051-60. doi: 10.1016/j.theriogenology.2010.01.004. Epub 2010 Mar 5.
Asian elephants (Elephas maximus), prominent "flagship species", are listed under the category of endangered species (EN - A2c, ver. 3.1; IUCN Red List 2009) and there is a need for their conservation. This requires understanding demographic and reproductive dynamics of the species. Monitoring reproductive status of any species is traditionally being carried out through invasive blood sampling and this is restrictive for large animals such as wild or semi-captive elephants due to legal, ethical, and practical reasons. Hence, there is a need for a non-invasive technique to assess reproductive cyclicity profiles of elephants, which will help in the species' conservation strategies. In this study, we developed an indirect competitive enzyme linked immuno-sorbent assay (ELISA) to estimate the concentration of one of the progesterone-metabolites i.e., allopregnanolone (5 alpha-P-3OH) in fecal samples of Asian elephants. We validated the assay which had a sensitivity of 0.25 microM at 90% binding with an EC(50) value of 1.37 microM. Using female elephants, kept under semi-captive conditions in the forest camps of Mudumalai Wildlife Sanctuary, Tamil Nadu and Bandipur National Park, Karnataka, India, we measured fecal progesterone-metabolite (5 alpha-P-3OH) concentrations in six animals and showed their clear correlation with those of serum progesterone, measured by a standard radio-immuno assay. Statistical analyses using a Linear Mixed Effect model showed a positive correlation (P<0.1) between the profiles of fecal 5 alpha-P-3OH (range: 0.5-10 microg/g) and serum progesterone (range: 0.1-1.8 ng/mL). Therefore, our studies show, for the first time, that the fecal progesterone-metabolite assay could be exploited to predict estrus cyclicity and to potentially assess the reproductive status of captive and free-ranging female Asian elephants, thereby helping to plan their breeding strategy.
亚洲象（Elephas maximus）是杰出的“旗舰物种”，被列为濒危物种（EN-A2c，第 3.1 版；IUCN 红色名录 2009 年），需要对其进行保护。这需要了解该物种的人口统计学和生殖动态。传统上，通过侵入性血液采样来监测任何物种的生殖状况，但由于法律、道德和实际原因，这种方法对野生动物或半圈养大象等大型动物具有限制性。因此，需要一种非侵入性技术来评估大象的生殖周期性，这将有助于制定物种保护策略。在这项研究中，我们开发了一种间接竞争酶联免疫吸附测定（ELISA）来估计亚洲象粪便样本中一种孕酮代谢物即异孕烷醇酮（5α-P-3OH）的浓度。我们验证了该测定法，其在 90%结合时的灵敏度为 0.25 microM，EC50 值为 1.37 microM。使用在印度泰米尔纳德邦的 Mudumalai 野生动物保护区和卡纳塔克邦的 Bandipur 国家公园的森林营地中半圈养的雌性大象，我们测量了 6 只动物的粪便孕酮代谢物（5α-P-3OH）浓度，并与通过标准放射免疫测定法测量的血清孕酮浓度进行了比较。使用线性混合效应模型进行的统计分析显示，粪便 5α-P-3OH （范围：0.5-10 μg/g）和血清孕酮（范围：0.1-1.8 ng/mL）的图谱之间存在正相关（P<0.1）。因此，我们的研究首次表明，粪便孕酮代谢物测定法可用于预测发情周期，并有可能评估圈养和自由放养的雌性亚洲象的生殖状况，从而有助于制定其繁殖策略。
