UMR Institut National de la Recherche Agronomique/AgroParisTech 914, 16 Rue Claude Bernard, Laboratory of Nutrition Physiology and Feeding Behavior, 75005, Paris, France.
Am J Physiol Regul Integr Comp Physiol. 2012 Sep 1;303(5):R459-76. doi: 10.1152/ajpregu.00137.2012. Epub 2012 Jun 20.
In this article, we review some fundamentals of indirect calorimetry in mice and rats, and open the discussion on several debated aspects of the configuration and tuning of indirect calorimeters. On the particularly contested issue of adjustment of energy expenditure values for body size and body composition, we discuss several of the most used methods and their results when tested on a previously published set of data. We conclude that neither body weight (BW), exponents of BW, nor lean body mass (LBM) are sufficient. The best method involves fitting both LBM and fat mass (FM) as independent variables; for low sample sizes, the model LBM + 0.2 FM can be very effective. We also question the common calorimetry design that consists of measuring respiratory exchanges under free-feeding conditions in several cages simultaneously. This imposes large intervals between measures, and generally limits data analysis to mean 24 h or day-night values of energy expenditure. These are then generally compared with energy intake. However, we consider that, among other limitations, the measurements of Vo(2), Vco(2), and food intake are not precise enough to allow calculation of energy balance in the small 2-5% range that can induce significant long-term alterations of energy balance. In contrast, we suggest that it is necessary to work under conditions in which temperature is set at thermoneutrality, food intake totally controlled, activity precisely measured, and data acquisition performed at very high frequency to give access to the part of the respiratory exchanges that are due to activity. In these conditions, it is possible to quantify basal energy expenditure, energy expenditure associated with muscular work, and response to feeding or to any other metabolic challenge. This reveals defects in the control of energy metabolism that cannot be observed from measurements of total energy expenditure in free feeding individuals.
本文回顾了一些关于小鼠和大鼠间接测热法的基本原理，并对间接测热仪的配置和调整的几个有争议的方面展开了讨论。在针对体表面积和体成分的能量消耗值调整这一特别有争议的问题上，我们讨论了几种最常用的方法，以及当应用于一组已发表的数据时的结果。我们的结论是，体重（BW）、BW 的指数或去脂体重（LBM）都不足以作为调整能量消耗值的依据。最好的方法是将 LBM 和脂肪量（FM）同时作为独立变量进行拟合；对于小样本量，模型 LBM+0.2FM 可以非常有效。我们还对常见的测热设计提出了质疑，该设计包括在几个同时饲养的笼子中测量自由喂养条件下的呼吸交换。这会导致测量之间的间隔很大，并且通常将数据分析限制为能量消耗的 24 小时或昼夜平均值。然后，这些值通常与能量摄入进行比较。然而，我们认为，除了其他限制之外，Vo(2)、Vco(2)和食物摄入的测量不够精确，无法在能够引起能量平衡显著长期改变的 2-5%范围内计算能量平衡。相比之下，我们建议有必要在以下条件下进行工作，即温度设置在热中性范围内，食物摄入完全受控制，活动量精确测量，并且以非常高的频率进行数据采集，以获取与活动相关的呼吸交换的部分。在这些条件下，可以量化基础能量消耗、与肌肉工作相关的能量消耗以及对喂养或任何其他代谢挑战的反应。这揭示了在自由喂养个体的总能量消耗测量中无法观察到的能量代谢控制缺陷。
