ENDOTHERMY AND BEHAVIORAL THERMOREGULATION IN INFANTS

婴儿吸热和行为体温调节

• 批准号: 6392058
• 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/6392058
• 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资源来维持热、体液和心血管稳态。 PI实验室最近的研究表明，长期以来，由于暴露在寒冷环境中热量损失率较高，幼鼠一直被认为体温调节能力较差，但在适当的条件下进行测试时，它们实际上表现出许多成功的体温调节迹象。 它们的成功取决于利用棕色脂肪组织 (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。 我们了解到，具有吸热能力的婴儿（即大鼠）对寒冷的行为和生理反应与不具有吸热能力的婴儿（即仓鼠）表现出显着不同。 然而，我们仍然不明白这两个物种的婴儿如何向温暖方向和移动，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，该提案代表了研究计划中合乎逻辑的下一步，该计划解决了生物行为研究的基本问题，旨在更好地理解婴儿调节内部热环境和选择外部热环境的无数生理和行为机制。 这项工作对于早产和足月人类婴儿（无论是患病还是健康）的热管理具有重要意义，他们内源产生热量的能力不同，而且我们对他们的体温调节行为知之甚少。首先，随着我们对个体幼鼠体温调节能力的新认识，我们检查了在寒冷暴露期间蜷缩的幼鼠的行为和生理反应。 在神经节阻断后的幼年大鼠中、在神经节阻断后的幼鼠中选择性激活 BAT 生热作用后以及在由幼年大鼠和仓鼠组成的混合群中检查群体调节行为。 这些实验将揭示吸热现象如何促进拥挤行为的表达和有效性。 其次，使用新开发的新颖装置（由珀耳帖二极管组成的多层“棋盘”装置）检查孤立个体的体温调节行为，该装置可以对热环境进行精细控制。 此外，红外热成像技术的使用可提供必要的热数据，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，可以批判性地检查幼年大鼠和仓鼠在寒冷暴露期间的行为唤醒、运动、定向和热偏好，以及吸热对这些行为过程的贡献。 最后，后续实验将解决介导对寒冷的行为反应的感觉和神经机制。