Two daily glucagon injections induce nonshivering thermogenesis in Muscovy ducklings

1987 ◽  
Vol 252 (5) ◽  
pp. E616-E620 ◽  
Author(s):  
H. Barre ◽  
F. Cohen-Adad ◽  
J. L. Rouanet
Keyword(s):  
Body Temperature ◽  
Metabolic Rate ◽  
Ambient Temperature ◽  
Cold Acclimation ◽  
Saline Control ◽  
Nonshivering Thermogenesis ◽  
Control Value ◽  
Glucagon Injection ◽  
Significant Change

In 6-wk-old chronically glucagon-treated (GT) ducklings, the calorigenic effect of intraperitoneal test injection of glucagon was measured at 25 and 4 degrees C ambient temperature (Ta). At 25 degrees C Ta, the increase in metabolic rate (MR) due to test injection of glucagon (360 micrograms/kg) reached 5.3 W/kg (i.e., 98% above the saline control value) in GT ducklings and only 1.7 W/kg (i.e., 29% above the control value) in control (TN) ducklings. After the injection, GT ducklings developed a hyperthermia, reaching 2.4 degrees C, accompanied by intense panting, whereas thermal body temperature did not change in TN ducklings. At 4 degrees C Ta for the same dose of glucagon, no significant change in MR was observed in GT ducklings during 180 min of exposure, whereas a 25% decrease in MR occurred in the same conditions in TN ducklings. In the cold, glucagon injection inhibited shivering in both groups of ducklings but thermogenesis was not suppressed in GT ducklings, showing a true nonshivering thermogenesis in these birds. This nonshivering thermogenesis was estimated to be 3 W/kg (i.e., 55% above resting MR). Such changes produced by chronic glucagon treatment resemble the artificial cold acclimation of rats chronically treated by norepinephrine.

Effects of hypoxia and cold acclimation on thermoregulation in the rat

1991 ◽  
Vol 71 (4) ◽  
pp. 1355-1363 ◽  
Author(s):  
H. Gautier ◽  
M. Bonora ◽  
S. B. M'Barek ◽  
J. D. Sinclair
Keyword(s):  
Body Temperature ◽  
Metabolic Rate ◽  
Cold Acclimation ◽  
Cold Exposure ◽  
Marked Decrease ◽  
Nonshivering Thermogenesis ◽  
Tb Control ◽  
Before And After ◽  
Different Sources ◽  
Made In

The effects of hypoxia (inspired O2 fraction = 0.12) on thermoregulation and on the different sources of thermogenesis were studied in rats before and after periods of 1–4 wk of cold acclimation. Measurements of metabolic rate (VO2) and body temperature (Tb) were made at 5-min intervals, and shivering activity was recorded continuously in groups of rats subjected to three protocols. In protocol 1, rats were exposed to normoxia to an ambient temperature (Ta) of 5 degrees C for 2 h. In protocol 2, at Ta of 5 degrees C, rats were exposed for 30 min to normoxia, then for 45 min to hypoxia, and finally for 30 min to normoxia. In protocol 3, in the non-cold-acclimated (NCA) rats, Ta was decreased from 30 to 5 degrees C in steps of 5 degrees C and of 30-min duration while in cold-acclimated (CA) rats at 5 degrees C for 4-wk, Ta was increased from 5 to 30 degrees C in steps of 5 degrees C and of 30-min duration. Recordings were made in normoxia and in hypoxia on different days in the same animals. The results showed that 1) in NCA rats, cold exposure in normoxia induced increases in VO2 and shivering that were proportional to the decrease in Ta; 2) in CA rats in normoxia, for a given Ta, VO2 and Tb were higher than in NCA rats, whereas shivering was generally lower; and 3) in both NCA and CA rats, hypoxia induced a transient decrease in shivering and a sustained decrease in nonshivering thermogenesis associated with a marked decrease in Tb that was about the same in NCA and CA rats. We speculate that hypoxia acts on Tb control to produce a general inhibition of thermogenesis. Nonshivering thermogenesis is markedly sensitive to hypoxia, especially demonstrable in CA rats; a recovery or even an increase in shivering can compensate for the decrease in nonshivering thermogenesis.

Calorigenic effect of glucagon and catecholamines in king penguin chicks

1983 ◽  
Vol 244 (6) ◽  
pp. R758-R763 ◽  
Author(s):  
H. Barre ◽  
J. L. Rouanet
Keyword(s):  
Metabolic Rate ◽  
Ambient Temperature ◽  
Negligible Effect ◽  
King Penguin ◽  
Maximum Response ◽  
Low Doses ◽  
Nonshivering Thermogenesis ◽  
Apparent Effect ◽  
Control Value ◽  
The Mean

The calorigenic action of glucagon and catecholamine infusion was evaluated in winter-acclimatized king penguin chicks at 20 and 0 degrees C ambient temperature (Ta). At Ta = 20 degrees C the mean increase in metabolic rate was 0.73 W . kg-1 for epinephrine (80 micrograms . kg-1), 0.42 W . kg-1 for norepinephrine (150 micrograms . kg-1), and 1.16 W . kg-1 for glucagon (0.75 micrograms . kg-1); i.e., respectively 30, 17, and 47% of the control value. The maximum response to glucagon reached 89% over control. At Ta = 0 degrees C, for the same glucagon infusion, the mean increase in specific metabolic rate was 0.84 W . kg-1, 27% of control rate. In the cold, glucagon infusion inhibited shivering and substituted its calorigenic action, resulting in a less apparent effect. In contrast with the negligible effect of catecholamines, glucagon infused at low doses exerted a powerful calorigenic action in young king penguins and could be considered as a possible nonshivering thermogenesis mediator.

Cold acclimation-recruited nonshivering thermogenesis: the Syrian hamster is not an exception

1995 ◽  
Vol 269 (4) ◽  
pp. R767-R774 ◽  
Author(s):  
A. Dicker ◽  
B. Cannon ◽  
J. Nedergaard
Keyword(s):  
Metabolic Rate ◽  
Cold Acclimation ◽  
Resting Metabolic Rate ◽  
High Rate ◽  
In Vivo Studies ◽  
Nonshivering Thermogenesis ◽  
Brown Adipose ◽  
Thermogenic Response

Biochemical evidence from in vitro studies of brown adipose tissue in Syrian hamsters indicates a significant degree of recruitment of the tissue as an effect of cold acclimation. However, earlier in vivo studies indicate a lack of recruitment of nonshivering thermogenesis in the intact animal as a result of cold acclimation. Because of this apparent discrepancy, the occurrence of cold acclimation-recruited nonshivering thermogenesis in hamsters was investigated. Hamsters were cold acclimated to 6 degrees C or remained at 24 degrees C (controls), and their thermogenic response was investigated in an open-circuit system at 24 degrees C. Cold acclimation resulted in a small increase in resting metabolic rate and a major increase in the thermogenic response to norepinephrine (61% increase over resting metabolic rate in controls and 156% increase in cold-acclimated animals). The absolute beta 3-specific adrenergic agonist CGP-12177 also induced a high rate of nonshivering thermogenesis, which was similarly recruited. It was concluded that, concerning the relative effect of recruitment on the capacity for nonshivering thermogenesis, the intact hamsters responded as would be predicted from in vitro experiments. Thus the hamster does not seem to constitute an exception to the general patterns described for other rodents concerning recruitment of nonshivering thermogenesis due to cold acclimation.

scholarly journals Heart rate reveals torpor at high body temperatures in lowland tropical free-tailed bats

2017 ◽  
Vol 4 (12) ◽  
pp. 171359 ◽  
Author(s):  
M. Teague O'Mara ◽  
Sebastian Rikker ◽  
Martin Wikelski ◽  
Andries Ter Maat ◽  
Henry S. Pollock ◽  
...  
Keyword(s):  
Heart Rate ◽  
Body Temperature ◽  
Metabolic Rate ◽  
Ambient Temperature ◽  
The Body ◽  
Metabolic Rates ◽  
Body Temperatures ◽  
Wide Range ◽  
Save Energy ◽  
Molossus Molossus

Reduction in metabolic rate and body temperature is a common strategy for small endotherms to save energy. The daily reduction in metabolic rate and heterothermy, or torpor, is particularly pronounced in regions with a large variation in daily ambient temperature. This applies most strongly in temperate bat species (order Chiroptera), but it is less clear how tropical bats save energy if ambient temperatures remain high. However, many subtropical and tropical species use some daily heterothermy on cool days. We recorded the heart rate and the body temperature of free-ranging Pallas' mastiff bats ( Molossus molossus ) in Gamboa, Panamá, and showed that these individuals have low field metabolic rates across a wide range of body temperatures that conform to high ambient temperature. Importantly, low metabolic rates in controlled respirometry trials were best predicted by heart rate, and not body temperature . Molossus molossus enter torpor-like states characterized by low metabolic rate and heart rates at body temperatures of 32°C, and thermoconform across a range of temperatures. Flexible metabolic strategies may be far more common in tropical endotherms than currently known.

Body temperature and standard metabolic rate of the female viviparous lizard Eremias multiocellata during reproduction

2012 ◽  
Vol 90 (1) ◽  
pp. 79-84 ◽  
Author(s):  
Feng Yue ◽  
Xiao-Long Tang ◽  
De-Jiu Zhang ◽  
Xue-Feng Yan ◽  
Ying Xin ◽  
...  
Keyword(s):  
Body Temperature ◽  
Metabolic Rate ◽  
Ambient Temperature ◽  
Energy Cost ◽  
Energy Requirement ◽  
Standard Metabolic Rate ◽  
The Body ◽  
Energetic Cost ◽  
Pregnant Females ◽  
Eremias Multiocellata

The body temperature (Tb) and standard metabolic rate (SMR) of female Eremias multiocellata Günther, 1872, a viviparous lizard, were measured at 25, 30, and 35 °C during pregnancy and after parturition to assess energy requirement of reproduction. The results showed that the Tbs of female lizards were slightly higher than actual ambient temperature in the 25 and 30 °C groups, while they were slightly lower than ambient temperature in the 35 °C group. Ambient temperature significantly affected SMR and gestation period of females. Energy requirement was constant in nonpregnant females, whereas it was increased in pregnant females. The maximal estimates of maintenance costs of pregnancy (MCP) were 4.219, 4.220, and 4.448 mg CO2·min–1, which accounted for 19.40%, 14.15%, and 12.32% of the total metabolic rate in the 25, 30, and 35 °C group, respectively. The results indicated the MCP was an important component of total energy cost for the lizard E. multiocellata and the MCP in this lizard incurs a relative fixed energetic cost irrespective of ambient temperature.

Temperature regulation and cold acclimation in the golden hamster

1965 ◽  
Vol 20 (3) ◽  
pp. 405-410 ◽  
Author(s):  
Hermann Pohl
Keyword(s):  
Oxygen Consumption ◽  
Body Temperature ◽  
Ambient Temperature ◽  
Cold Acclimation ◽  
Heat Production ◽  
Golden Hamster ◽  
Thermal Conductance ◽  
Muscular Activity ◽  
The Body ◽  
Ambient Temperatures

Characteristics of cold acclimation in the golden hamster, Mesocricetus auratus, were 1) higher metabolic rate at -30 C, 2) less shivering when related to ambient temperature or oxygen consumption, and 3) higher differences in body temperature between cardiac area and thoracic subcutaneous tissues at all ambient temperatures tested, indicating changes in tissue insulation. Cold-acclimated hamsters also showed a rise in temperature of the cardiac area when ambient temperature was below 15 C. Changes in heat distribution in cold-acclimated hamsters suggest higher blood flow and heat production in the thoracic part of the body in the cold. The thermal conductance through the thoracic and lumbar muscle areas, however, did not change notably with lowering ambient temperature. Marked differences in thermoregulatory response to cold after cold acclimation were found between two species, the golden hamster and the thirteen-lined ground squirrel, showing greater ability to regulate body temperature in the cold in hamsters. hibernator; oxygen consumption— heat production; body temperature — heat conductance; muscular activity — shivering; thermoregulation Submitted on July 6, 1964

Effect of age on cold acclimation in rats: metabolic and behavioral responses

1991 ◽  
Vol 260 (2) ◽  
pp. R284-R289 ◽  
Author(s):  
T. L. Owen ◽  
R. L. Spencer ◽  
S. P. Duckles
Keyword(s):  
Body Temperature ◽  
Metabolic Rate ◽  
Cold Acclimation ◽  
Cold Exposure ◽  
Resting Metabolic Rate ◽  
Age Groups ◽  
Behavioral Responses ◽  
Mortality And Morbidity ◽  
Ambient Temperatures ◽  
Reduced Body

To determine whether senescence affects the metabolic and behavioral responses of rats to chronic cold exposure, 8- and 22-mo-old male Fischer 344 rats were studied before and after 6 wk of cold (6-10 degrees C) exposure. Measurements of body weight, food consumption, oxygen consumption, body temperature, and ambient temperature selection in a thermocline (7-37 degrees C linear gradient) were made at regular intervals throughout the acclimation period. Before acclimation, age groups differed significantly only by weight. During acclimation, older rats had increased mortality and morbidity below 10 degrees C. After acclimation at 10 degrees C, younger and older rats both selected cooler ambient temperatures (7 and 5 degrees C cooler than preacclimation, respectively), and older rats had a significantly greater decrease in body temperature in the thermocline. Both age groups increased resting metabolic rate at 25 degrees C with cold acclimation (16.5 and 10% increase for younger and older rats, respectively). This study indicates distinct differences in metabolic and behavioral responses of younger and older rats to cold acclimation. Chronic cold exposure is detrimental to thermoregulatory function in older rats, since it is not as effective in stimulating sustained increases in metabolic rate in older rats as in young adults and it leads to a preference for cooler ambient temperatures, resulting in increased heat loss and reduced body temperature.

Short photoperiod and cold activate brown fat lipoprotein lipase in the Djungarian hamster

1989 ◽  
Vol 257 (5) ◽  
pp. R1123-R1127 ◽  
Author(s):  
M. Klingenspor ◽  
S. Klaus ◽  
H. Wiesinger ◽  
G. Heldmaier
Keyword(s):  
Ambient Temperature ◽  
Cold Acclimation ◽  
Lipoprotein Lipase ◽  
Brown Fat ◽  
Short Photoperiod ◽  
Slight Reduction ◽  
Nonshivering Thermogenesis ◽  
Djungarian Hamster ◽  
Substrate Supply ◽  
Long Photoperiod

Activation of lipoprotein lipase (LPL) in brown fat of the Djungarian hamster ensures substrate supply for nonshivering thermogenesis. Cold acclimation [5 degrees C ambient temperature (Ta)] in long photoperiod [light-dark (LD) 16:8] increased brown fat LPL activity from 4.7 to 22.7 nmol oleate.mg-1.min-1 within 1 day. Slight reduction of this high LPL activity was observed during prolonged cold exposure for up to 4 wk. Deacclimation (transfer from 5 to 23 degrees C Ta) caused total inactivation of brown fat LPL within 4 days. Short photoperiod (LD 8:16) also stimulates brown fat LPL activity. Its effect can be summarized by three different observations. At thermoneutrality short photoperiod elevated LPL activity to 7.1 instead of 4.7 nmol.mg-1.min-1 observed in long photoperiod. Second, at low ambient temperature short photoperiod reinforces the effect of cold acclimation. Maximum LPL activity of cold-exposed Djungarian hamsters averaged 23.7 nmol.mg-1.min-1 in long photoperiod and was elevated to 35.5 nmol.mg-1.min-1 in short photoperiod. Third, inactivation of LPL during deacclimation was delayed in short photoperiod. These results demonstrate that photoperiod as well as ambient temperature may be cooperatively used as environmental cues for seasonal acclimation of brown fat substrate supply for nonshivering thermogenesis.

Sign in / Sign up

Export Citation Format

Share Document