DISSERTATION RESEARCH: Energetic Regulation of Seasonal Sickness Behaviors

一旦感染，动物就会表现出一系列被称为“疾病行为”的行为。对季节性繁殖物种的疾病行为的研究表明，动物对感染的反应程度因季节而异。疾病行为的季节性调节可能是一种避免过度消耗能量或错过繁殖机会的机制，但抑制这些行为的表达可能会使生物体面临更大的无法清除感染的风险。因此，一个有机体表达疾病的程度将对它的生存和繁殖成功产生深远的影响。当比较这些研究时，一个明显的模式出现了，在动物能量储备最低的季节，疾病行为会减弱；然而，这种关系的因果性质尚未经过实验检验。该项目的工作假设是，疾病行为的季节性变化是由于能量储存的季节性变化。本研究的具体目的是：1)确定食物可得性的季节变化对患病行为的贡献；2)确定代谢激素对患病行为变化的影响；3)评估食物可得性和代谢激素的实验操作对直接介导季节性繁殖西伯利亚仓鼠患病行为的内分泌和免疫因素的贡献。对调节疾病行为表现的生理信号的理解将增强我们对环境条件如何影响动物对感染的反应的认识。这项研究的结果将有助于当前了解疾病易感性作为病原体流行（即疾病生态学）和宿主免疫功能（即生态免疫学）的功能的举措。此外，这项工作为不同的本科生提供了参与研究培训的机会，并将在这些项目完成后继续这样做。数据将通过研究数据综合中心（RDC）提供，网址为http://pervasive.iu.edu/hps/rdc

Upon infection, animals display a collection of behaviors called "sickness behaviors." Studies of sickness behaviors in seasonally breeding species have shown that the magnitude of an animal's response to infection varies across seasons. Seasonal modulation of sickness behaviors may be a mechanism to avoid over-expending energy or missing a reproductive opportunity, but suppressing the expression of these behaviors may put an organism at greater risk of not being able to clear an infection. Therefore, the degree to which an organism expresses sickness will have profound effects on its survival and reproductive success. When comparing across studies, a clear pattern emerges in that sickness behaviors are attenuated in the season in which an animal has the lowest energy reserves; however, the causative nature of this relationship has not been tested experimentally. The project's working hypothesis is that seasonal variation in sickness behaviors is due to seasonal variation in energy stores. The specific aims of the research are to: 1) determine the contributions of seasonal changes in food availability on sickness behaviors, 2) determine how metabolic hormones influence variation in sickness behaviors, and 3) evaluate the contributions of experimental manipulations of food availability and metabolic hormones on endocrine and immunological factors that directly mediate sickness behavior in seasonally breeding Siberian hamsters. An understanding of the physiological signals that act to modulate the display of sickness behaviors will enhance our knowledge of how environmental conditions affect how an animal responds to an infection. The results of this research will contribute to the current initiatives to understand disease susceptibility as a function of pathogen prevalence (i.e., disease ecology) and host immune function (i.e., ecoimmunology). Additionally, this work has provided opportunities to engage diverse undergraduates in research training and will continue to do so as these projects are completed.Data will be made available on Research Data Complex (RDC), http://pervasive.iu.edu/hps/rdc