Immune, hormonal and neural mechanisms of ingestive behavior

所有生物体都需要解决从环境中获取营养物质（蛋白质、碳水化合物、脂肪和其他必需物质）的问题，而不需要摄入大量毒素，而毒素通常存在于各种食物中。许多植物（和一些动物）通过产生毒素来保护自己，这样它们就不太可能被吃掉。哺乳动物，包括人类，已经进化出许多方法（避毒系统）来减少摄入食物中的毒素。毒素可以根据味道、摄入后的影响和学习来避免。我们一直在使用将品尝剂注入口腔时产生的行为反应（味觉反应性测试）来研究这种避毒系统。我们可以在食物（蔗糖溶液）中引入低水平的毒素（LiCl），或者在动物吃完食物后注射毒素，并检查毒素摄入后对老鼠行为的影响。用一种细菌衍生的化合物（脂多糖）治疗老鼠也会使它们生病，这种化合物会产生一种疾病行为综合征（对饮食的兴趣降低，嗜睡加剧）。我们正在研究细菌感染对避毒系统敏感性的影响。我们有一些证据表明，细菌感染使毒素避免系统变得敏感，或者可以阻止与食物有关的学习。我们感兴趣的是控制这些过程的大脑系统。我们也对暴露在压力下对毒素避免系统的激活和敏化过程的影响感兴趣。许多因免疫系统激活而生病的患者，例如在细菌或病毒感染期间，因其他问题（癌症，艾滋病）而暴露于有毒的化疗治疗中，他们的饮食行为可能会受到损害，导致治疗成功率较低。这项研究应该为解决这个问题提供重要的信息。

All organisms need to solve the problem of obtaining nutrients (protein, carbohydrates, fats, and other essential substances) from their environment without eating significant amounts of toxins which are often found in various foods. Many plants (and some animals) protect themselves by producing toxins so that they are less likely to be eaten. Mammals, including humans, have evolved a number of ways (poison avoidance system) to reduce exposure to toxins in the foods eaten. Toxins can be avoided on the basis of taste, post-ingestional effects, and learning. We have been using behavioral responses produced when tastants are infused into the mouth (taste reactivity test), to study this poison avoidance system. We can introduce low levels of a toxin (LiCl) into a food (sucrose solution) or inject the toxin after the animal has eaten a food, and examine changes in the rat's behavior as a result of post-ingestive effects of the toxin. Rats can also be made sick by treating them with a bacteria derived compound (lipopolysaccharide) which produces a syndrome of sickness behaviors (reduced interest in eating, drinking, and increased lethargy). We are studying the effects of bacterial infection on the sensitivity of the poison avoidance system. We have some evidence to suggest that bacterial infection sensitizes the toxin avoidance system, or can block food related learning. We are interested in the brain system(s) that control these processes. We are also interested in the effects of exposure to stress on this process of activating and sensitizing the toxin avoidance system. Many patients that are sick because of immune system activation, such as during bacterial or viral infections, are exposed to toxic chemotherapy treatments for other problems (cancer, AIDS) and their eating behaviors may be compromised leading to lower success for the treatments. This research should provide important information to help with this problem.