Analysis of energy expenditure at different ambient temperatures in mice lacking DGAT1

2003 ◽  
Vol 284 (1) ◽  
pp. E213-E218 ◽  
Author(s):  
Hubert C. Chen ◽  
Zuleika Ladha ◽  
Steven J. Smith ◽  
Robert V. Farese
Keyword(s):  
Food Intake ◽  
Energy Expenditure ◽  
Ambient Temperature ◽  
Cold Environment ◽  
Normal Surface ◽  
Ambient Temperatures ◽  
Active Mechanism ◽  
Key Enzyme ◽  
Secondary Mechanism ◽  
Obesity Resistance

Mice lacking acyl-CoA:diacylglycerol acyltransferase 1 (DGAT1), a key enzyme in triglyceride synthesis, have increased energy expenditure and therefore are resistant to obesity. Because ambient temperature can significantly affect energy expenditure in mice, we undertook these studies to determine the effects of different ambient temperatures on energy expenditure, food intake, and thermoregulation in DGAT1-deficient [ Dgat1(−/−)] mice. Dgat1(−/−) mice had increased energy expenditure irrespective of changes in the ambient temperature. Although core temperature was normal, surface temperature was increased in Dgat1(−/−) mice, most likely reflecting an active mechanism to dissipate heat from increased thermogenesis. Dgat1(−/−) mice had increased food intake at baseline, and this hyperphagia became more pronounced upon exposure to cold. When fasted in a cold environment, Dgat1(−/−) mice developed hypothermia, which was associated with hypoglycemia. These results suggest that the hyperphagia in Dgat1(−/−) mice is a secondary mechanism that compensates for the increased utilization of fuel substrates. Our findings offer insights into the mechanisms of hyperphagia and increased energy expenditure in a murine model of obesity resistance.

Ambient temperature effects on physiological traits of white-tailed deer

1975 ◽  
Vol 53 (6) ◽  
pp. 679-685 ◽  
Author(s):  
J. B. Holter ◽  
W. E. Urban Jr. ◽  
H. H. Hayes ◽  
H. Silver ◽  
H. R. Skutt
Keyword(s):  
Heart Rate ◽  
Body Temperature ◽  
Energy Expenditure ◽  
Ambient Temperature ◽  
Temperature Effects ◽  
Temperature Changes ◽  
Wind Chill ◽  
Ambient Temperatures ◽  
Energy Equilibrium ◽  
Body Energy

Six adult white-tailed deer (Odocoileus virginianus borealis) were exposed to 165 periods of 12 consecutive hours of controlled constant ambient temperature in an indirect respiration calorimeter. Temperatures among periods varied from 38 to 0 (summer) or to −20C (fall, winter, spring). Traits measured were energy expenditure (metabolic rate), proportion of time spent standing, heart rate, and body temperature, the latter two using telemetry. The deer used body posture extensively as a means of maintaining body energy equilibrium. Energy expenditure was increased at low ambient temperature to combat cold and to maintain relatively constant body temperature. Changes in heart rate paralleled changes in energy expenditure. In a limited number of comparisons, slight wind chill was combatted through behavioral means with no effect on energy expenditure. The reaction of deer to varying ambient temperatures was not the same in all seasons of the year.

Effect of Changes in Ambient Temperature on Spontaneous Activity, Food Intake and Body Weight of Goldthioglucose-Obese and Nonobese Mice

1957 ◽  
Vol 188 (3) ◽  
pp. 435-438 ◽  
Author(s):  
M. J. Fregly ◽  
N. B. Marshall ◽  
J. Mayer
Keyword(s):  
Body Weight ◽  
Food Intake ◽  
Ambient Temperature ◽  
The Body ◽  
Lower Body ◽  
Obese Mice ◽  
Ambient Temperatures ◽  
Exposure To Cold ◽  
Running Activity ◽  
Body Weights

Goldthioglucose-obese mice cannot adjust their food intake to meet the increased energy requirements due to cold. At all ambient temperatures above 15°C the spontaneous running activity of these animals is less than that observed for nonobese controls. Activity of obese mice is maximal at 19°C and minimal at 15°C or lower. Body weights decrease during exposure to cold. In contrast to that of obese mice, running activity of nonobese controls is maximal at an ambient temperature of 25°C but nearly ceases at 15°C or lower. The food intake of these animals increases in the cold and remains elevated even at temperatures at which activity decreases. The body weight of nonobese controls is either maintained constant or increases during exposure to cold air.

scholarly journals Gqα/G11α deficiency in dorsomedial hypothalamus leads to obesity resulting from decreased energy expenditure and impaired sympathetic nerve activity

2020 ◽  
Author(s):  
Eric A. Wilson ◽  
Hui Sun ◽  
Zhenzhong Cui ◽  
Marshal T. Jahnke ◽  
Mritunjay Pandey ◽  
...  
Keyword(s):  
Gene Expression ◽  
Adipose Tissue ◽  
Food Intake ◽  
Energy Expenditure ◽  
Energy Homeostasis ◽  
Dorsomedial Hypothalamus ◽  
Ambient Temperatures ◽  
Brown Adipose ◽  
Inhibit Food Intake ◽  
Specific Deletion

The G protein subunits Gqα and G11α (Gq/11α) couple receptors to phospholipase C, leading to increased intracellular calcium. In this study we investigated the consequences of Gq/11α deficiency in the dorsomedial hypothalamus (DMH), a critical site for the control of energy homeostasis. Mice with DMH-specific deletion of Gq/11α (DMHGq/11KO) were generated by stereotaxic injection of AAV-Cre-GFP into the DMH of Gqαflox/flox:G11α-/- mice. Compared to control mice that received DMH injection of AAV-GFP, DMHGq/11KO mice developed obesity associated with reduced energy expenditure without significant changes in food intake or physical activity. DMHGq/11KO mice showed no defects in the ability of the melanocortin agonist melanotan II to acutely stimulate energy expenditure or to inhibit food intake. At room temperature (22oC) DMHGq/11KO mice showed reduced sympathetic nervous system activity in brown adipose tissue (BAT) and heart, accompanied with decreased basal BAT Ucp1 gene expression and lower heart rates. These mice were cold intolerant when acutely exposed to cold (6oC for 5 hours) and had decreased cold-stimulated BAT Ucp1 gene expression. DMHGq/11KO mice also failed to adapt to gradually declining ambient temperatures and to develop adipocyte browning in inguinal white adipose tissue although their BAT Ucp1 was proportionally stimulated. Consistent with impaired cold-induced thermogenesis, the onset of obesity in DMHGq/11KO mice was significantly delayed when housed under thermoneutral conditions (30ºC). Thus, our results show that Gqα and G11α in the DMH are required for the control of energy homeostasis by stimulating energy expenditure and thermoregulation.

scholarly journals Cold-induced hyperphagia requires AgRP-neuron activation in mice

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Jennifer Deem ◽  
Chelsea L Faber ◽  
Christian Pedersen ◽  
Bao Anh Phan ◽  
Sarah A Larsen ◽  
...  
Keyword(s):  
Food Intake ◽  
Energy Expenditure ◽  
Energy Intake ◽  
Cold Exposure ◽  
Energy Homeostasis ◽  
Cold Environment ◽  
Energy Demands ◽  
Acute Cold Exposure ◽  
Neuron Activation ◽  
Increase Food Intake

To maintain energy homeostasis during cold exposure, the increased energy demands of thermogenesis must be counterbalanced by increased energy intake. To investigate the neurobiological mechanisms underlying this cold-induced hyperphagia, we asked whether agouti-related peptide (AgRP) neurons are activated when animals are placed in a cold environment and, if so, whether this response is required for the associated hyperphagia. We report that AgRP-neuron activation occurs rapidly upon acute cold exposure, as do increases of both energy expenditure and energy intake, suggesting the mere perception of cold is sufficient to engage each of these responses. We further report that silencing of AgRP neurons selectively blocks the effect of cold exposure to increase food intake but has no effect on energy expenditure. Together, these findings establish a physiologically important role for AgRP neurons in the hyperphagic response to cold exposure.

Effects of ambient temperature and head cooling on energy expenditure, food intake and heat tolerance of Brahman and Brahman × Friesian cattle working on treadmills

1986 ◽  
Vol 43 (1) ◽  
pp. 83-90 ◽  
Author(s):  
C. K. Thomas ◽  
R. Anne Pearson
Keyword(s):  
Food Intake ◽  
Energy Expenditure ◽  
Ambient Temperature ◽  
Weight Changes ◽  
Local Cooling ◽  
Head Region ◽  
Body Weight Changes ◽  
Head Cooling ◽  
Physiological Reactions ◽  
Friesian Cattle

ABSTRACTEnergy expenditure, food intake and some physiological reactions of Brahman and Brahman × British Friesian cattle working on an inclined treadmill at 33°C were studied. The effect of work at a lower ambient temperature (15°C) and local cooling of the head region while at 33°C were also investigated. Whilst walking up a 6° gradient at 1 m/s, animals expended about four times as much energy as when standing. Heat production during work (W/kgM0·75) was similar in both breeds and was not influenced by the treatments imposed. Crossbred animals showed significantly higher respiration rates and sweating rates than the Brahmans immediately after working for 30 min at 33°C. Food intake and body-weight changes in the crossbreds at 33°C compared with Brahmans provided further evidence that these animals were less tolerant of the conditions. Head cooling during work appeared to reduce depression in food intake associated with work at 33°C in both breeds although it had no effect on physiological changes.

Heart rate and energy expenditure in resting and running Svalbard and Norwegian reindeer

1984 ◽  
Vol 246 (6) ◽  
pp. R963-R967 ◽  
Author(s):  
K. J. Nilssen ◽  
H. K. Johnsen ◽  
A. Rognmo ◽  
A. S. Blix
Keyword(s):  
Heart Rate ◽  
Energy Expenditure ◽  
Metabolic Rate ◽  
Ambient Temperature ◽  
High Arctic ◽  
O2 Consumption ◽  
Ambient Temperatures ◽  
Svalbard Reindeer ◽  
The Relationship ◽  
Cost Of Transportation

The purpose of this study was to determine whether a convenient relationship could be found between heart rate (HR) and energy expenditure at rest and during running in the high arctic Svalbard reindeer (SR) and the subarctic Norwegian reindeer (NR). Measurements of HR and energy expenditure (O2 consumption) were made at different ambient temperatures, at rest, and during running at different speeds during both summer and winter. Cost of transportation (Science 177: 222-228, 1972) was 3.56 and 2.67 J X g-1 X km-1 in SR and NR, respectively. The y-intercept value obtained for NR was close to the predicted value (J. Exp. Biol. 97: 1-22, 1982), whereas that of SR was much lower. In NR the relationship between HR and energy expenditure at running speeds from 0 to 9.2 km X h-1 is, regardless of ambient temperature (in the -30 to +10 degrees C range), described by the following equations: y = 8.04x + 48.70, r = 0.92, n = 27 (summer); and y = 7.48x + 31.20, r = 0.95, n = 52 (winter). In SR, the corresponding equations were y = 7.60x + 49.20, r = 0.94, n = 29 (summer); and y = 8.90x + 32.10, r = 0.96, n = 44 (winter), where y is HR (beats X min-1) and x is metabolic rate (W X kg-1).

scholarly journals Cold-induced hyperphagia requires AgRP neuron activation in mice

2020 ◽  
Author(s):  
Jennifer D. Deem ◽  
Chelsea L. Faber ◽  
Christian Pedersen ◽  
Bao Anh Phan ◽  
Sarah A. Larsen ◽  
...  
Keyword(s):  
Food Intake ◽  
Energy Expenditure ◽  
Energy Intake ◽  
Cold Exposure ◽  
Energy Homeostasis ◽  
Cold Environment ◽  
Energy Demands ◽  
Acute Cold Exposure ◽  
Neuron Activation ◽  
Increase Food Intake

ABSTRACTTo maintain energy homeostasis during cold exposure, the increased energy demands of thermogenesis must be counterbalanced by increased energy intake. To investigate the neurobiological mechanisms underlying this cold-induced hyperphagia, we asked whether agouti-related peptide (AgRP) neurons are activated when animals are placed in a cold environment and, if so, whether this response is required for the associated hyperphagia. We report that AgRP-neuron activation occurs rapidly upon acute cold exposure, as do increases of both energy expenditure and energy intake, suggesting the mere perception of cold is sufficient to engage each of these responses. We further report that silencing of AgRP neurons selectively blocks the effect of cold exposure to increase food intake. Together, these findings establish a physiologically important role for AgRP neurons in the hyperphagic response to cold exposure.

Evidence of a defect in energy expenditure in 7-day-old Zucker rat (fa/fa)

1983 ◽  
Vol 245 (2) ◽  
pp. E107-E113 ◽  
Author(s):  
E. Planche ◽  
M. Joliff ◽  
P. de Gasquet ◽  
X. Leliepvre
Keyword(s):  
Energy Expenditure ◽  
Core Temperature ◽  
Co2 Production ◽  
Cold Environment ◽  
Zucker Rat ◽  
Ambient Temperatures ◽  
The Core ◽  
The Difference ◽  
Thermogenic Response

The aim of the investigation was to see whether a defect in energy expenditure could be found in the Zucker rat at the onset of obesity. Obese (fa/fa) and lean (Fa/fa) 7-day-old pups were studied at three ambient temperatures. At 33 degrees C fa/fa pups showed a reduction in oxygen consumption, respiratory CO2 production, in vivo oxidation of injected [1-14C]palmitic acid, as well as in core temperature. When the pups were kept at 28 degrees C, the difference between genotypes was considerably accentuated, thus indicating a subnormal thermogenic response of the fa/fa pups to a mildly cold environment. At 20 degrees C, however, the metabolic rates dropped to the same low level, and the core temperature equilibrated with ambient temperature in both genotypes. The results demonstrate that the 1-wk-old fa/fa pup has a defect in thermoregulatory thermogenesis. The magnitude of the deficit in energy expenditure was more than adequate to account for the 50% greater fat content of 7-day-old fa/fa pups.

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