Integration of body temperature into the analysis of energy expenditure in the mouse

Abreu-Vieira, Gustavo; Xiao, Cuiying; Гаврилова, Оксана; Reitman, Marc L.

doi:10.1016/j.molmet.2015.03.001

Cited by 186 publications

(226 citation statements)

References 62 publications

(79 reference statements)

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“…3, DIO mice showed slightly but constantly elevated metabolic rates at all environmental temperatures (Fig. 6A), principally in accord with the findings of Abreu-Vieira et al (1). However, again, the slope of the Scholander curves and the resulting calculated insulation (Fig.…”

Section: Standard Diet-induced Obese Mice Are Not Better Insulated Thsupporting

confidence: 89%

“…Thus, under the current experimental conditions for mice, an insulating effect of increasing obesity would successively diminish the heat loss and thus enhance, in a self-amplifying way, the further development of obesity. Additionally, the adaptation to living at a relatively cold temperature may in itself promote additional insulation (via fur), affecting metabolic rate.Despite these possible profound influences of alterations in thermal insulation, data on the effects of obesity on insulation are scarce and only found for a few specific rodent models in studies concerned mainly with other issues (1,5,17,21,28). We have failed to find studies either in mice or in human that systematically empirically quantitate the effect of a series of different obesities on insulation.…”

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confidence: 99%

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No insulating effect of obesity

Fischer

Csikasz

Essen

et al. 2016

American Journal of Physiology-Endocrinology and Metabolism

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The development of obesity may be aggravated if obesity itself insulates against heat loss and thus diminishes the amount of food burnt for body temperature control. This would be particularly important under normal laboratory conditions where mice experience a chronic cold stress (at Ϸ20°C). We used Scholander plots (energy expenditure plotted against ambient temperature) to examine the insulation (thermal conductance) of mice, defined as the inverse of the slope of the Scholander curve at subthermoneutral temperatures. We verified the method by demonstrating that shaved mice possessed only half the insulation of nonshaved mice. We examined a series of obesity models [mice fed high-fat diets and kept at different temperatures, classical diet-induced obese mice, ob/ob mice, and obesity-prone (C57BL/6) vs. obesityresistant (129S) mice]. We found that neither acclimation temperature nor any kind or degree of obesity affected the thermal insulation of the mice when analyzed at the whole mouse level or as energy expenditure per lean weight. Calculation per body weight erroneously implied increased insulation in obese mice. We conclude that, in contrast to what would be expected, obesity of any kind does not increase thermal insulation in mice, and therefore, it does not in itself aggravate the development of obesity. It may be discussed as to what degree of effect excess adipose tissue has on insulation in humans and especially whether significant metabolic effects are associated with insulation in humans. obesity; insulation; ob/ob DESPITE THE PRESENT INTEREST IN METABOLISM in connection with the global obesity epidemic, there is little knowledge concerning the extent to which obesity as such affects metabolism. There is widespread interest in issues such as the release of adipokines from adipose tissue depots, but many basic issues, such as the ability of adipose tissue to affect metabolism physically, have been little examined. One of these issues is the question of the ability of adipose tissue to function as a thermal insulation barrier, decreasing the heat loss from the organism and in this way decreasing the amount of energy needed to keep the organism warm, thereby increasing the amount of excess energy prone to storage in the form of (additional) fat.Whether an insulating effect of obesity exists is of significance both for humans and for animal models of obesity. However, with regard to experimental animals, the issue of insulation is of further interest. This is because most metabolic experiments are conducted with mice kept under conditions (standard laboratory conditions of Ϸ21°C) that are principally cold for the mouse (10,19,27,37,38,42,44) and thus where a high proportion of total metabolism (nearly half) is devoted to counteracting the resulting heat loss. This is a condition very different from that which is relevant for the metabolic physiology of most humans (living in a thermoneutral environment). Thus, under the current experimental conditions for mice, an insulating effect of increasing obesit...

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Section: Standard Diet-induced Obese Mice Are Not Better Insulated Thsupporting

confidence: 89%

mentioning

confidence: 99%

No insulating effect of obesity

Fischer

Csikasz

Essen

et al. 2016

American Journal of Physiology-Endocrinology and Metabolism

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“…Furthermore, it represents the contribution of different organs, such as skeletal muscle, smooth muscle in the gastrointestinal tract, adipose tissue, liver, and others. Of relevance is also the environmental temperature that strongly affects the overall energy expenditure, and even at vivarium (i.e., 22°C), thermogenesis consists of a major part of animals' total energy expenditure (46). In view of the above information, our correlation between whole-body energy utilization and liver mitochondria activity should be interpreted cautiously and further explored.…”

Section: Discussionmentioning

confidence: 97%

Circadian control of oscillations in mitochondrial rate-limiting enzymes and nutrient utilization by PERIOD proteins

Neufeld-Cohen

Robles

Aviram

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

205

192

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Mitochondria are major suppliers of cellular energy through nutrients oxidation. Little is known about the mechanisms that enable mitochondria to cope with changes in nutrient supply and energy demand that naturally occur throughout the day. To address this question, we applied MS-based quantitative proteomics on isolated mitochondria from mice killed throughout the day and identified extensive oscillations in the mitochondrial proteome. Remarkably, the majority of cycling mitochondrial proteins peaked during the early light phase. We found that rate-limiting mitochondrial enzymes that process lipids and carbohydrates accumulate in a diurnal manner and are dependent on the clock proteins PER1/2. In this conjuncture, we uncovered daily oscillations in mitochondrial respiration that peak during different times of the day in response to different nutrients. Notably, the diurnal regulation of mitochondrial respiration was blunted in mice lacking PER1/2 or on a high-fat diet. We propose that PERIOD proteins optimize mitochondrial metabolism to daily changes in energy supply/demand and thereby, serve as a rheostat for mitochondrial nutrient utilization.M itochondria serve as major suppliers of cellular energy through nutrient oxidation. One of the major challenges that mitochondria face is the adaptation to changes in nutrient supply and energy demand. An inability of mitochondria to deal with altered nutrient environment is associated with metabolic diseases, such as diabetes and obesity (1, 2).Mitochondria oxidize carbohydrates and lipids to generate ATP by a process known as oxidative phosphorylation. Pyruvate and fatty acids are transported from the cytoplasm into the mitochondrial matrix, where they are catabolized into acetyl CoA. Pyruvate is converted to acetyl CoA through the action of the pyruvate dehydrogenase complex (PDC), whereas fatty acids are oxidized through a cycle of reactions that trim two carbons at a time, generating one molecule of acetyl CoA in each cycle [i.e., fatty acid oxidation (FAO)]. The acetyl groups are then fed into the Krebs cycle for additional degradation, and the process culminates with the transfer of acetyl-derived high-energy electrons along the respiratory chain.Mounting evidence suggests that circadian clocks orchestrate our daily physiology and metabolism (3-6). The mammalian circadian timing system consists of a central pacemaker in the brain that is entrained by daily light-dark cycles and synchronizes subsidiary oscillators in virtually all cells of the body, in part by driving rhythmic feeding behavior. The core clock molecular circuitry relies on interlocked transcription-translation feedback loops that generate daily oscillations of gene expression in cultured cells and living animals (7). Many transcriptomes (8-12) and more recently, several proteomics (13-15) and metabolomics studies (16-21) highlighted the pervasive circadian control of metabolism.Rest-activity and feeding-fasting cycles that naturally occur throughout the day impose pronounced changes in nutrient s...

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“…Physiologists have found major differences between the thermal physiology of mice, other mammals, and humans [3,[5][6][7][8][9][10][11][12], such that at ambient temperatures in which humans feel comfortable, mice experience chronic mild cold stress directly impacting their metabolism and thermoregulatory status. Laboratory mice are almost always housed and studied at mildly cool temperatures well below their 'thermoneutral zone' which is the ambient temperature in which metabolic heat production is minimal and the mouse does not need to work to keep warm or cold.…”

Section: Room Temperature: So Much More Than a Thermometer Readingmentioning

confidence: 99%