ENDOTHERMY AND BEHAVIORAL THERMOREGULATION IN INFANTS

婴儿吸热和行为体温调节

• 批准号: 6097419
• 负责人: Mark Samuel Blumberg
• 金额: $ 22.05万
• 依托单位: UNIVERSITY OF IOWA
• 依托单位国家: 美国
• 财政年份: 1994
• 资助国家: 美国
• 起止时间: 1994-05-01 至 2004-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6097419
• 关键词: arousal; behavioral /social science research tag; body temperature regulation; brown fat; chordate locomotion; cold temperature; developmental neurobiology; ethology; ganglionic blocking agents; hamsters; heat; infrared radiation; laboratory rat; newborn animals; orientation; preference; psychophysiology; sensorimotor system; species difference; thermometry

Infant mammals devote considerable resources to thermal, fluid, and cardiovascular homeostasis. Recent work in the PI's laboratory has shown that infant rats, long considered poor thermoregulators because of their high rates of heat loss during cold exposure, actually exhibit many signs of successful thermoregulation when tested under appropriate conditions. Their success depends on the ability to produce heat internally using brown adipose tissue (BAT), as well as the delivery of this heat to the heart and other temperature-sensitive organs. We have learned that infants that possess endothermic capabilities (i.e., rats) exhibit significantly different behavioral and physiological responses to cold than infants that do not (i.e., hamsters). We still do not understand, however, how infants of either species orient and locomote toward warmth and whether the ability to produce heat internally interferes with the expression of thermoregulatory behavior. Therefore, this proposal represents the logical next step in a research program that addresses basic issues in biobehavioral research and aims to develop a better understanding of the myriad physiological and behavioral mechanisms by which infants regulate their internal thermal environment and select their external thermal environment. This work has important implications for the thermal management of preterm and full-term human infants, sick or healthy, who differ in their abilities to produce heat endogenously and about whose thermoregulatory behavior we know very little. First, with our new appreciation of the thermoregulatory capabilities of individual infant rats, the behavioral and physiological responses of huddling rat pups during cold exposure are examined. Group regulatory behavior is examined in infant rats after ganglionic blockade, after selective activation of BAT thermogenesis in ganglionically blocked pups, and in mixed huddles comprised of infant rats and hamsters. These experiments will reveal how endothermy contributes to the expression and effectiveness of huddling behavior. Second, thermoregulatory behaviors in isolated individuals are examined using a newly- developed, novel apparatus - a multi-tiled "checkerboard" apparatus composed of peltier diodes - that provides fine control over the thermal environment. In addition, the use of infrared thermography provides essential thermal data without interfering with behavioral expression. The combination of these approaches places us in an ideal position to critically examine behavioral arousal, locomotion, orientation, and thermal preference in infant rats and hamsters during cold exposure, as well as the contributions of endothermy to each of these behavioral processes. Finally, subsequent experiments will address the sensory and neural mechanisms that mediate behavioral responses to cold.

婴儿哺乳动物投入大量的资源，热，流体和心血管的稳态。 PI实验室最近的工作表明，由于在寒冷暴露期间热量损失率高，长期以来被认为是较差的体温调节器的幼鼠，在适当的条件下进行测试时，实际上表现出许多成功的体温调节迹象。 它们的成功取决于使用棕色脂肪组织（BAT）在内部产生热量的能力，以及将这种热量传递到心脏和其他温度敏感器官的能力。 我们已经了解到，具有吸热能力的婴儿（即，大鼠）表现出与不冷的婴儿显著不同的对冷的行为和生理反应（即，仓鼠）。 然而，我们仍然不知道这两种物种的婴儿是如何朝向温暖的方向和方向移动的，以及内部产生热量的能力是否会干扰体温调节行为的表达。 因此，这一提议代表了研究计划的逻辑下一步，该计划解决了生物行为研究中的基本问题，旨在更好地理解婴儿调节其内部热环境和选择其外部热环境的无数生理和行为机制。 这项工作对早产和足月人类婴儿的热管理具有重要意义，无论是生病还是健康，他们内源性产生热量的能力不同，我们对其体温调节行为知之甚少。首先，我们的新认识的体温调节能力的个别婴儿大鼠，行为和生理反应的蜷缩在寒冷暴露的大鼠幼崽进行检查。 在神经节阻滞后的幼鼠中、在神经节阻滞的幼鼠中选择性激活BAT产热后以及在由幼鼠和仓鼠组成的混合群中检查群体调节行为。 这些实验将揭示内温性如何有助于表达和有效性的蜷缩行为。 第二，在孤立的个人的体温调节行为进行检查，使用新开发的，新颖的设备-一个多瓦的“棋盘”装置组成的珀尔帖二极管-提供了良好的控制热环境。 此外，红外热成像的使用提供了基本的热数据，而不会干扰行为表达。 这些方法的结合使我们处于一个理想的位置，以批判性地研究行为唤醒，运动，方向，和热偏好在幼年大鼠和仓鼠在冷暴露期间，以及这些行为过程中的每个endothermy的贡献。 最后，后续的实验将解决介导对寒冷的行为反应的感觉和神经机制。