Doctoral Dissertation Improvement: Feeding on Phytoestrogens - Implications for Red Colobus Monkey Physiological Ecology

几千年来，含有改变脊椎动物内分泌系统的化学物质的植物物种一直被人类出于营养或医疗目的而消耗。然而，这些植物化学物质，如植物雌激素，对人类和非人类灵长类生态和进化的重要性仍然不清楚，而且在很大程度上没有研究。植物雌激素是指在功能和/或结构上与内源性脊椎动物雌激素相似的天然存在的植物化合物，存在于许多文化中驯化的农作物食物中，并已被证明对圈养啮齿动物和灵长类动物的生殖和应激生理产生影响。然而，关于植物雌激素在野生植物物种中的流行率及其对自由放牧的非人类灵长类动物的潜在影响的信息很少。由于人类历史上99%以上的人依赖于以野生植物为基础的食物的狩猎-采集生存策略，因此有必要调查野生植物中植物雌激素的流行情况，以提高我们对人类起源的理解。此外，通过在自然环境中研究现存的非人类灵长类动物，特别是以植物性饮食为主的东非灵长类动物，可以最好地重建人类祖先进化的营养环境。由于植物雌激素可能对人类和非人类灵长类动物的生理和行为进化产生重大影响，本项目将通过研究这些植物化合物在乌干达红鳞猴(Procolbus Rufomitratus Tephrosceles)生理生态中的作用，更深入地研究这些植物化合物与摄入它们的灵长类动物之间的关系。这将通过回答三个主要问题来完成：1)植物雌激素在热带森林乔木群落中有多普遍？2)植物雌激素的存在是否影响红鳞猴的饮食选择？3)植物雌激素的摄入是否影响红根瘤猴的应激或性类固醇水平？在乌干达Kibale国家公园进行的一项为期12个月的研究中，将通过收集一组红色根瘤菌的取食行为数据和粪便样本来解决这些问题。将通过生物测定和高效液相分析筛选食用和非食用植物物种的雌激素活性，并将通过免疫分析对28个已知成虫的粪便样本的类固醇激素(雌二醇、孕酮、睾酮和皮质醇)含量进行量化。利用这些数据，将检验植物中植物雌激素含量、灵长类取食行为和类固醇激素水平之间的关系。通过结合灵长类动物学、生态学、内分泌学和营养化学等领域的方法论，该项目将提供有助于更深入了解人类和非人类灵长类生物学的信息。对社会的其他好处包括增进与公共卫生问题有关的关于植物雌激素消费对人类福利的影响的知识。关于在人类饮食中摄入植物雌激素的成本和收益的讨论目前在医学文献中非常流行。在药店找到的草药，以及大豆和以大豆为基础的产品，可能含有高浓度的这些化合物。达尔文的医学方法将极大地帮助人们准确理解植物雌激素消费对公众健康的潜在影响。

For millennia, plant species containing chemicals that alter the vertebrate endocrine system have been consumed by humans for nutritional or medicinal purposes. However, the importance of these plant chemicals, such as phytoestrogens, to human and non-human primate ecology and evolution remains unclear and largely unstudied. Phytoestrogens, defined as naturally occurring plant compounds similar in function and/or structure to endogenous vertebrate estrogens, are present in the domesticated crop foods of many cultures and have been shown to impact both reproductive and stress physiology in captive rodents and primates. Yet, little information exists on the prevalence of phytoestrogens in wild plant species and their potential impact on free-ranging, non-human primates. Because more than 99% of human history has relied on a hunter-gatherer subsistence strategy mainly dependent on wild plant-based foods, investigating the prevalence of phytoestrogens in wild plants is necessary to improve our understanding of human origins. Furthermore, the nutritional environment in which human ancestors evolved can be best reconstructed by studying living non-human primates in a natural setting, especially East African primates with a plant-based diet. Since phytoestrogens likely had a significant influence on the evolution of both human and non-human primate physiology and behavior, this project will take a deeper look at the relationship between these plant compounds and the primates ingesting them by examining their role in the physiological ecology of the Uganda red colobus monkey (Procolobus rufomitratus tephrosceles). This will be accomplished by answering three main questions: 1) How prevalent are phytoestrogens in the tropical forest tree community? 2) Does the presence of phytoestrogens influence diet choice in red colobus monkeys? 3) Does the ingestion of phytoestrogens impact stress or sex steroid levels in red colobus individuals? These questions will be addressed by collecting feeding behavior data and fecal samples from one group of red colobus during a 12-month study in Kibale National Park, Uganda. Food and non-food plant species will be screened for estrogenic activity via bioassays and HPLC analysis, and steroid hormone content (estradiol, progesterone, testosterone, and cortisol) of fecal samples from 28 individually known adults will be quantified via immunoassays. Using this data, the relationship between phytoestrogen content of plant items, primate feeding behavior, and steroid hormone levels will be examined. By combining methodology from the fields of primatology, ecology, endocrinology, and nutritional chemistry, this project will provide information that contributes to a deeper understanding of human and non-human primate biology. Additional benefits for society include improved knowledge relevant to the public health issue of the effects of phytoestrogen consumption on human welfare. Discussions of the costs and benefits of phytoestrogen consumption in human diet are currently very popular in the medical literature. Herbal treatments found in drugstores, along with soy and soy-based products, can contain high levels of these compounds. An accurate understanding of the potential impacts of phytoestrogen consumption on public health will be greatly aided by a Darwinian medical approach.