Energy intake and fur in summer- and winter-acclimated Siberian hamsters (Phodopus sungorus)

2001 ◽  
Vol 281 (2) ◽  
pp. R519-R527 ◽  
Author(s):  
Alexander S. Kauffman ◽  
Alessandra Cabrera ◽  
Irving Zucker
Keyword(s):  
Food Intake ◽  
Energy Intake ◽  
Ventral Surface ◽  
Phodopus Sungorus ◽  
Ambient Temperatures ◽  
Siberian Hamsters ◽  
Daily Food ◽  
Brown Adipose ◽  
Wide Range ◽  
The Impact

Few studies have directly addressed the impact of fur on seasonal changes in energy intake. The daily food intake of Siberian hamsters ( Phodopus sungorus) was measured under simulated summer and winter conditions in intact animals and those with varying amounts of pelage removed. Energy intake increased up to 44% above baseline control values for approximately 2–3 wk after complete shaving. Increases in food intake varied with condition and were greater in hamsters housed in short than long day lengths and at low (5°C) than moderate (23°C) ambient temperatures. Removal of 8 cm2 of dorsal fur, equivalent to 30% of the total dorsal fur surface, increased food intake, but removal of 4 cm2 had no effect. An 8-cm2 fur extirpation from the ventral surface did not increase food consumption. Food intake was not influenced differentially by fur removal from above brown adipose tissue hot spots. Fur plays a greater role in energy balance in winter- than summer-acclimated hamsters and conserves energy under a wide range of environmental conditions.

Limits to sustained energy intake

2001 ◽  
Vol 204 (11) ◽  
pp. 1947-1956 ◽  
Author(s):  
M. S. Johnson ◽  
S. C. Thomson ◽  
J. R. Speakman
Keyword(s):  
Food Intake ◽  
Energy Intake ◽  
Litter Size ◽  
Resting Metabolic Rate ◽  
Control Group ◽  
Lower Mass ◽  
Daily Food Intake ◽  
Energy Demands ◽  
Daily Food ◽  
Pregnancy And Lactation

SUMMARYTo determine whether mice were limited in their capacity to absorb energy during late lactation, we attempted to increase the energy burden experienced by a group of female mice during late lactation by mating them at the postpartum oestrus, hence combining the energy demands of pregnancy and lactation. These experimental mice were therefore concurrently pregnant and lactating in their first lactation, and were followed through a normal second lactation. In a control group, females also underwent two lactations but sequentially, with the second mating after the first litter had been weaned. Maternal mass and food intake were measured throughout the first lactation, second pregnancy and second lactation. Maternal resting metabolic rate (RMR) was measured prior to the first mating and then at the peak of both the first and second lactations. Litter size and litter mass were also measured throughout both lactations. In the first lactation, experimental mice had a lower mass-independent RMR (F1,88=5.15, P=0.026) and raised significantly heavier pups (t=2.77, d.f.=32, P=0.0093) than the control mice. Experimental mice delayed implantation at the start of the second pregnancy. The extent of the delay was positively related to litter size during the first lactation (F1,19=4.58, P=0.046) and negatively related to mean pup mass (F1,19=5.78, P=0.027) in the first lactation. In the second lactation, the experimental mice gave birth to more (t=2.75, d.f.=38, P=0.0092) and lighter (t=−5.01, d.f.=38, P<0.0001) pups than did the controls in their second lactation. Maternal asymptotic daily food intake of control mice in the second lactation was significantly higher (t=−4.39, d.f.=37, P=0.0001) than that of the experimental mice and higher than that of controls during their first lactation. Despite the added burden on the experimental females during their first lactation, there was no increase in their food intake, which suggested that they might be limited by their capacity to absorb energy. However, control females appeared to be capable of increasing their asymptotic food intake beyond the supposed limits estimated previously, suggesting that the previously established limit was not a fixed central limitation on food intake. As RMR increased in parallel with the increase in food intake during the second lactation of control mice, the sustained energy intake remained at around 7.0×RMR.

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.

NPY Y1 receptor antagonist prevents NPY-induced torporlike hypothermia in cold-acclimated Siberian hamsters

2008 ◽  
Vol 294 (1) ◽  
pp. R236-R245 ◽  
Author(s):  
John Dark ◽  
Kimberly M. Pelz
Keyword(s):  
Body Temperature ◽  
Receptor Antagonist ◽  
Receptor Agonist ◽  
Phodopus Sungorus ◽  
Food Ingestion ◽  
Research Groups ◽  
Ambient Temperatures ◽  
Y1 Receptor ◽  
Siberian Hamsters ◽  
Intracerebroventricular Injections

Siberian hamsters ( Phodopus sungorus) undergo bouts of daily torpor during which body temperature decreases by as much as 20°C and provides a significant savings in energy expenditure. Natural torpor in this species is normally triggered by winterlike photoperiods and low ambient temperatures. Intracerebroventricular injection of neuropeptide Y (NPY) reliably induces torporlike hypothermia that resembles natural torpor. NPY-induced torporlike hypothermia is also produced by intracerebroventricular injections of an NPY Y1 receptor agonist but not by injections of an NPY Y5 receptor agonist. In this research, groups of cold-acclimated Siberian hamsters were either coinjected with a Y1 receptor antagonist (1229U91) and NPY or were coinjected with a Y5 receptor antagonist ( CGP71683 ) and NPY in counterbalanced designs. Paired vehicle + NPY induced torporlike hypothermia in 92% of the hamsters, whereas coinjection of Y1 antagonist + NPY induced torporlike hypothermia in 4% of the hamsters. In contrast, paired injections of vehicle + NPY and Y5 antagonist + NPY induced torporlike hypothermia in 100% and 91% of the hamsters, respectively. Although Y5 antagonist treatment alone had no effect on body temperature, Y1 antagonist injections produced hyperthermia compared with controls. Both Y1 antagonist and Y5 antagonist injections significantly reduced food ingestion 24 h after treatment. We conclude that activation of NPY 1 receptors is both sufficient and necessary for NPY-induced torporlike hypothermia.

Rapid orocecal transit in chronically active persons with high energy intake

1991 ◽  
Vol 70 (4) ◽  
pp. 1550-1553 ◽  
Author(s):  
A. Harris ◽  
A. K. Lindeman ◽  
B. J. Martin
Keyword(s):  
Physical Activity ◽  
Food Intake ◽  
Energy Intake ◽  
Energy Demand ◽  
High Energy ◽  
H2 Production ◽  
Fiber Intake ◽  
Passage Rate ◽  
Food Passage ◽  
Wide Range

Although chronic physical activity by humans can raise energy requirements and energy intake severalfold above sedentary levels, whether these increases alter digestive strategy remains unknown. To investigate this possibility, food passage rate (mouth-to-large intestinal lactulose transit) and absorption (xylose) were compared in a cross section of young men chosen to represent a wide range of daily physical activity and food intake. In 20 men (energy intake 1,272-5,342 kcal/day), resting mouth-to-cecum transit was faster in high caloric consumers (r = -0.69, P less than 0.01). In contrast, xylose absorption (n = 26; measured either as urinary xylose excretion or integrated breath H2 production from the sugar) was unrelated to food intake. Dietary fiber intake was uncorrelated with energy intake. This apparent human digestive strategy of rapid transit across the gut absorptive surface, without a sacrifice in absorption, parallels the adaptations made by several animal species similarly faced with increased energy demand at constant fiber intake. We therefore conclude that the hyperphagia of chronic exercise in humans may be linked with significant gastrointestinal adaptations.

Effect of diurnally fluctuating high ambient temperatures on performance and feeding behaviour of multiparous lactating sows

2000 ◽  
Vol 71 (3) ◽  
pp. 571-575 ◽  
Author(s):  
N. Quiniou ◽  
D. Renaudeau ◽  
S. Dubois ◽  
J. Noblet
Keyword(s):  
Food Intake ◽  
Milk Production ◽  
Feeding Behaviour ◽  
Post Partum ◽  
Lactation Performance ◽  
Large White ◽  
Ambient Temperatures ◽  
Total Food Intake ◽  
Daily Food ◽  
Ad Libitum

AbstractForty-two multiparous Large White sows were used to investigate the effect of diurnally fluctuating temperature (T) on lactation performance and feeding behaviour. The animals were allocated to one of the four thermic treatments: constant T at 25°C (25C) and 29°C (29C) or equal-mean diurnal cyclic T varying from 21 to 29°C (25V) and from 25 to 33°C (29V). Photoperiod was fixed to 14 h of light. The sows were given food ad libitum between the 7th and the 19th day post partům. Lactation performance was measured for all sows whereas the feeding behaviour was recorded only on 28 sows. The ad libitum food intake was comparable at 25C and 25V (6•31 kg/day) as were milk production and body reserves mobilization. In contrast, food intake at 29V was higher than at 29C (4•53 v. 3•48 kg/day) with no difference in milk production between the two treatments. The increased daily food intake at 29V resulted from higher intakes over the coolest periods of the day and especially during the dark period. Neither meal size nor daily number of meals were significantly affected by T. Feeding behaviour was mainly diurnal but with differences between treatments: 0•90 of total food intake at 29C v. 0•78 at the other three T It appears that the effects of diurnally fluctuating T on lactation performance of sows depend on the mean level of T

Emergence of heat stress hazards in the CMIP6 models

2020 ◽  
Author(s):  
Natalie S. Lord ◽  
Dann M. Mitchell
Keyword(s):  
Heat Stress ◽  
Mortality Rates ◽  
Ambient Temperatures ◽  
Metabolic Heat ◽  
Number Of Factors ◽  
Event Attribution ◽  
Wide Range ◽  
Effects Of Temperature ◽  
The Impact ◽  
Extreme Heat Stress

<p>Hazards associated with the combined effects of temperature and humidity can have a wide range of impacts, particularly on human health and agriculture. The human body removes metabolic heat through sweating and heat conduction, and the efficiency of these processes is reduced when ambient temperatures and humidity are high, resulting in heat stress. The effects of this range from general discomfort to increased morbidity and mortality rates, trends that have been observed during recent severe heatwaves such as those that occurred during the summer of 2019 in Europe. A number of factors may exacerbate heat stress, including intense physical activity and being located in an urban area as opposed to a rural area.</p><p>As global temperatures increase, the risk associated with heat stress hazards is expected to increase, and this signal is expected to emerge from natural variability over the coming decades, if not sooner. Here, simulations from the new CMIP6 models are analysed to investigate the timing of emergence of heat stress hazards, in order to identify regions of the globe that are particularly vulnerable to extreme heat stress and/or imminent emergence of these hazards. Event attribution techniques are also applied to estimate the impact of anthropogenic warming on the hazard risk.</p>

Effects of ovarian hormones on energy balance and brown adipose tissue thermogenesis

1986 ◽  
Vol 250 (2) ◽  
pp. R245-R249 ◽  
Author(s):  
D. Richard
Keyword(s):  
Adipose Tissue ◽  
Energy Balance ◽  
Food Intake ◽  
Energy Expenditure ◽  
Brown Adipose Tissue ◽  
Energy Intake ◽  
Ovarian Hormones ◽  
Ovariectomized Rats ◽  
Brown Adipose ◽  
Brown Adipose Tissue Thermogenesis

This study was carried out to investigate the nutritional energetics of ovariectomized rats with or without ovarian hormone replacement. Rats were divided into five groups: 1) sham operated, 2) ovariectomized, 3) ovariectomized and treated with progesterone, 4) ovariectomized and treated with estradiol, or 5) ovariectomized and treated with estradiol and progesterone. After 36 days of treatment, energy contents of all five groups were determined together with energy content of food and feces. Brown adipose tissue thermogenesis was assessed through mitochondrial GDP binding assay. Results show that ovariectomy leads to a 16% increase in metabolizable energy intake. This increase was accompanied by a twofold increase in body energy gain. Progesterone did not further affect energy intake and gain in ovariectomized rats. However, increases in both food intake and energy gain were prevented by the estradiol replacement therapy. There was no difference in energy expenditure between sham-operated and ovariectomized rats in the absence of estradiol. In estradiol-treated animals, energy expenditure (kJ.kg body wt-0.75 . day-1) showed a slight increase. There was no difference in protein content of interscapular brown adipose tissue between all five groups. GDP binding was slightly reduced in ovariectomized estradiol-treated rats. It is concluded from this study that ovarian hormones produce their effects on energy balance mainly by altering food intake.

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