Shivering and nonshivering thermogenic responses of cold-exposed rats to hypothalamic warming

1975 ◽  
Vol 228 (5) ◽  
pp. 1519-1524 ◽  
Author(s):  
CA Fuller ◽  
BA Horwitz ◽  
JM Horowitz
Keyword(s):  
Oxygen Consumption ◽  
Heat Production ◽  
Neural Control ◽  
Nonshivering Thermogenesis ◽  
Neural Controllers ◽  
Rate Of Oxygen Consumption ◽  
Exposed Animal ◽  
Unanesthetized Animals ◽  
Shivering Thermogenesis ◽  
Rule Out

The concurrent neural control of two thermoregulatory responses, shivering thermogenesis (ST) and nonshivering thermogenesis (NST), was investigated in chronically implanted cold-exposed rats. The effects of heating the preoptic/anterior hypothalamus (POAH) on shivering and on the rate of oxygen consumption (Vo2) were measured in these unanesthetized animals. With ambient temperature maintained constant (at some value between 10 and 16 degrees C), warming the hypothalamus 2-3 degrees C resulted in a significant decrease in Vo2 (Psmaller than 0.001) and an increase in shivering (Psmaller than .01), these responses being reversed on cessation of hypothalamic warming. These results are consistent with the proposal that, in the cold-exposed animal, elevated POAH temperatures directly inhibit NST even though shivering may increase (possibly as a compensation for the decrease in nonshivering heat production). They also rule out the possibility that, in the rat, signals from cutaneous and hypothalamic thermoreceptors are integrated in an indentical manner by the neural controllers for ST and NST.

Halothane Selectively Inhibits Nonshivering Thermogenesis 

1995 ◽  
Vol 82 (2) ◽  
pp. 491-501 ◽  
Author(s):  
Andrea Dicker ◽  
Kerstin B. E. Ohlson ◽  
Lennart Johnson ◽  
Barbara Cannon ◽  
Sten G.E. Lindahl ◽  
...  
Keyword(s):  
Oxygen Consumption ◽  
Inhibitory Effect ◽  
Nonshivering Thermogenesis ◽  
Halothane Anesthesia ◽  
Control Series ◽  
Mechanically Ventilated ◽  
Anesthetized Rats ◽  
Rate Of Oxygen Consumption ◽  
Spontaneously Breathing ◽  
Thermogenic Response

Background During halothane anesthesia, infants fail to increase oxygen consumption in response to a cold stimulus in the form of an increase in temperature gradient between body and environment. Based on recent observations with isolated brown-fat cells, it seemed feasible that this inability to respond could be due to an inhibition of nonshivering thermogenesis during halothane anesthesia. Methods The rate of oxygen consumption was measured in cold-acclimated hamsters and rats. The rate evoked by norepinephrine injection in hamsters at an environmental temperature of approximately 24 degrees C was used as a measure of the capacity for nonshivering thermogenesis. Anesthesia was induced by 3% halothane and maintained by 1.5% halothane. One experimental series with spontaneously breathing hamsters and a second control series with spontaneously breathing rats and with rats whose lungs were mechanically ventilated were conducted. Results Norepinephrine injection led to a fourfold increase in the rate of oxygen consumption in control hamsters; after this response had subsided, a second injection led to a similar effect. Halothane anesthesia caused an approximately 20% decrease in resting metabolic rate (P < 0.05) and a 70% inhibition of the thermogenic response to norepinephrine (P < 0.001). The halothane concentration yielding half-maximal inhibitory effect was estimated to be less than 1.0%. After the animals had recovered from halothane anesthesia, a completely restored thermogenic response to norepinephrine was observed. The inhibitory effect of halothane also was observed in hamsters maintained at normothermia and was therefore not secondary to the slight hypothermia that otherwise developed during anesthesia. In a series of control experiments, it was confirmed that rats also showed large thermogenic responses to norepinephrine injections, and it was found that, in spontaneously breathing halothane-anesthetized rats, the thermogenic response to norepinephrine was also much inhibited. Further, in halothane-anesthetized rats whose lungs were mechanically ventilated, and where blood gases were kept at virtually normal levels, the thermogenic response to norepinephrine was found to be similarly markedly inhibited. Conclusions A much diminished or abolished thermogenic response to injected norepinephrine was demonstrated in halothane-anesthetized animals. This implies that there would be a diminished ability to elicit nonshivering thermogenesis even when this process is physiologically induced. Such a diminished ability could in part explain the susceptibility of neonates and infants to hypothermia during halothane anesthesia.

Nonshivering thermogenesis in skeletal muscle of seasonally acclimatized mice, Peromyscus

1981 ◽  
Vol 241 (3) ◽  
pp. R185-R189
Author(s):  
S. J. Wickler
Keyword(s):  
Skeletal Muscle ◽  
Oxygen Consumption ◽  
Arterial Pressure ◽  
Flow Rate ◽  
Heat Production ◽  
Major Contributor ◽  
Nonshivering Thermogenesis ◽  
Perfusion System ◽  
Apparent Increase ◽  
Hindlimb Muscle

Nonshivering thermogenesis (NST) is a major contributor to total heat production capabilities of Peromyscus and the magnitude of the NST response increases dramatically in winter-acclimatized animals. To directly assess the contribution from skeletal muscle to this NST, a hindlimb perfusion system was developed for Peromyscus. Oxygen consumption was then measured with and without norepinephrine (the mediator of NST) in freshly captured animals in summer and winter. Norepinephrine (NE) was infused at 0.001, 0.01, and 0.1 micrograms . g hindlimb muscle-1 . min-1. Vascular resistance (VR), calculated as arterial pressure divided by flow rate, increased during all NE infusions. At doses of 0.001 and 0.01, VR stabilized after approximately 10 min, but at 0.1 VR continued to rise. Resting oxygen consumption was 0.817 +/- 0.037 and 0.805 +/- 0.049 mumol O2 . g-1 . min-1 in summer (n = 8) and winter (n = 7) animals, respectively. There was no apparent increase in oxygen consumption with any dosage of NE. It appears that the increase in NST in winter animals is not due to an increased NST in skeletal muscle.

Nonshivering thermogenesis in the newborn lamb

1969 ◽  
Vol 47 (3) ◽  
pp. 249-253 ◽  
Author(s):  
G. E. Thompson ◽  
D. McEwan Jenkinson
Keyword(s):  
Adipose Tissue ◽  
Oxygen Consumption ◽  
Heat Production ◽  
Microscopic Examination ◽  
Early Age ◽  
Nonshivering Thermogenesis ◽  
Newborn Lamb

Microscopic examination of adipose tissue from lambs of varying ages between birth and 20 days showed that most cells were multivacuolar on the first day of life, but most were univacuolar at 10 days of age and older. The oxygen consumption of four lambs aged between 6 h and [Formula: see text] days was approximately doubled after injection with (−)noradrenaline (400 μg/kg subcutaneously) in an environment of 20 °C. Five lambs between [Formula: see text] days and 12 days showed a reduced response or no response. Three lambs between 14 days and 20 days of age showed virtually no change in oxygen consumption after noradrenaline. It is concluded that the mechanism for nonshivering heat production is present in the newborn lamb, but disappears at a relatively early age.

scholarly journals Transcriptome Profiles of the Liver in Two Cold-Exposed Sheep Breeds Revealed Different Mechanisms and Candidate Genes for Thermogenesis

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Dan Jiao ◽  
Kaixi Ji ◽  
Wenqiang Wang ◽  
Hu Liu ◽  
Jianwei Zhou ◽  
...  
Keyword(s):  
Candidate Genes ◽  
Heat Production ◽  
Theoretical Foundation ◽  
Nonshivering Thermogenesis ◽  
Ewe Lambs ◽  
Air Temperatures ◽  
Liver Transcriptome ◽  
The Difference ◽  
Shivering Thermogenesis

Cold-induced thermogenesis plays an important role in the survival of lambs exposed to low air temperatures. The liver produces and mediates heat production in mammals; however, to date, little is known about the role of liver genes in cold-induced thermogenesis in lambs. In this study, the difference in the liver transcriptome between Altay and Hu ewe lambs was compared. Because of different backgrounds of the two breeds, we hypothesized that the transcriptome profiles of the liver would differ between breeds when exposed to cold. Cold-exposed Altay lambs activated 8 candidate genes (ACTA1, MYH1, MYH2, MYL1, MYL2, TNNC1, TNNC2, and TNNT3) involved in muscle shivering thermogenesis; 3 candidate genes (ATP2A1, SLN, and CKM) involved in muscle nonshivering thermogenesis related to the Ca2+ signal and creatine cycle; and 6 candidate genes (PFKM, ALDOC, PGAM2, ENO2, ENO3, and ENO4) involved in enhancing liver metabolism. In contrast, the liver may not act as the main tissue for thermogenesis in cold-exposed Hu lambs. We concluded that Altay lambs rely on liver-mediated shivering and nonshivering thermogenesis by muscle tissue to a greater extent than Hu lambs. Results from this study could provide a theoretical foundation for the breeding and production of cold-resistant lambs.

Spinal cord thermosensitivity and sorting of neural signals in cold-exposed rats

1977 ◽  
Vol 42 (2) ◽  
pp. 154-158 ◽  
Author(s):  
C. A. Fuller ◽  
J. M. Horowitz ◽  
B. A. Horwitz
Keyword(s):  
Spinal Cord ◽  
Oxygen Consumption ◽  
Study Data ◽  
Direct Influence ◽  
Nonshivering Thermogenesis ◽  
Neural Signals ◽  
Spinal Cord Temperature ◽  
Identical Manner ◽  
Rate Of Oxygen Consumption ◽  
Spinal Cord Thermosensitivity

In the present study, data relevant to the presence or absence of sorting of neural signals were obtained by evaluating the thermal responses to spinal warming in the chronically prepared rat. Specifically, shivering activity and the rate of oxygen consumption (VO2) were measured in unanesthetized rats during cold exposure (10–16 degrees C). Warming the spinal cord at the level of T2 resulted in a significant decrease in shivering (P less than 0.001), without a significant change in VO2. The shivering response was reversed upon cessation of heating. These results are interpreted as indicating a direct influence of spinal cord temperature on shivering but not nonshivering thermogenesis in the rat. Similarly, in previous work with the rat, we have obtained data supporting hypothalamic receptor control of nonshivering but not shivering heat production. These findings are thus consistent with the suggestion that in the rat there occurs a sorting of neural signals. That is, impulses from the three thermoreceptor locations are not integrated in an identical manner for the control of shivering and nonshivering thermogenesis.

ACUTE EXPOSURE OF HUMAN SUBJECTS TO AN AMBIENT TEMPERATURE OF 10 °C

1964 ◽  
Vol 42 (2) ◽  
pp. 233-243 ◽  
Author(s):  
D. A. Hurley ◽  
E. D. L. Topliff ◽  
F. Girling
Keyword(s):  
Oxygen Consumption ◽  
Ambient Temperature ◽  
Heat Production ◽  
Human Subjects ◽  
Healthy Male ◽  
Cold Acclimatization ◽  
Seasonal Acclimatization ◽  
Time Of Year ◽  
Male Subjects ◽  
Shivering Thermogenesis

Acute exposures to cold (10 °C) for 1 hour were carried out in early April on five unclothed healthy male subjects to follow their shivering responses, oxygen consumption, ventilation, skin and oral temperatures. Exposure to the cold resulted in immediate (within 5 minutes) and sustained increases in oxygen consumption, ventilation, and heat production. These subjects did not show generalized shivering, however, until after 30 minutes of exposure, even though short bursts of shivering were noted before this time. The immediate increase in heat production without shivering is indicative of a non-shivering thermogenesis which may be the result of cold-acclimatization in these subjects. Seasonal acclimatization would be maximal at the time of year during which the experiments were carried out.

scholarly journals THE OXYGEN CONSUMPTION OF ESCHERICHIA COLI DURING THE LAG AND LOGARITHMIC PHASES OF GROWTH

1932 ◽  
Vol 15 (6) ◽  
pp. 691-708 ◽  
Author(s):  
Donald S. Martin
Keyword(s):  
Escherichia Coli ◽  
Oxygen Consumption ◽  
Surface Area ◽  
Growth Curve ◽  
Heat Production ◽  
Lag Phase ◽  
Maximum Oxygen Consumption ◽  
Average Cell ◽  
Co2 Output ◽  
Rate Of Oxygen Consumption

The oxygen consumption of rapidly growing cultures of Esch. coli (S) have been measured by means of Fenn's respirometer. The rate of oxygen consumption of a growing culture uniformly attains a phase of logarithmic increase before the growth curve of the organisms becomes logarithmic. The rate of oxygen consumption per cell increases rapidly from the time of inoculation to a point of maximum respiration near the end of the lag phase of the growth curve, followed by a gradual decrease in the respiratory rate. The surface area of the average cell when plotted against time passes through a point of maximum surface area which coincides with the point of maximum oxygen consumption per cell. Figures obtained by different methods, CO2 output and heat production when reduced to the same units, agree remarkably well.

Propranolol and pyrogen effects of shivering and nonshivering thermogenesis in rats

1976 ◽  
Vol 230 (3) ◽  
pp. 637-642 ◽  
Author(s):  
BA Horwitz ◽  
GE Hanes
Keyword(s):  
Oxygen Consumption ◽  
Heat Production ◽  
Bacterial Endotoxin ◽  
Nonshivering Thermogenesis ◽  
Beta Adrenergic ◽  
Differential Effects ◽  
Adrenergic Antagonist ◽  
Colonic Temperature ◽  
Beta Adrenergic Antagonist

Injection of bacterial endotoxin (Piromen) into unanesthetized rats elicited increases in shivering and nonshivering thermogenesis as well as in colonic temperature. In animals exposed to 24-25 degrees C, treatment with propranolol (a beta-adrenergic antagonist) markedly diminished the pyrogen-induced increases in oxygen consumption (heat production) and colonic temperature with little change occurring in shivering activity. In contrast, in rats exposed to mild cold (17-18 degrees C), propranolol did not significantly alter the magnitude of the pyrogen-evoked thermogenesis. Rather in these animals, shivering tended to increase when nonshivering thermogenesis was blocked. These data are interpreted as reflecting differential effects of pyrogen on the pathways controlling the two modes of heat production in the rat.

scholarly journals THE OXYGEN CONSUMPTION OF FROG NERVE DURING STIMULATION

1927 ◽  
Vol 10 (5) ◽  
pp. 767-779 ◽  
Author(s):  
Wallace O. Fenn
Keyword(s):  
Oxygen Consumption ◽  
Sciatic Nerve ◽  
Oxygen Tension ◽  
Heat Production ◽  
Nerve Impulse ◽  
Excess Oxygen ◽  
Causal Connection ◽  
Cent Increase ◽  
Rate Of Oxygen Consumption ◽  
Frequency Of Stimulation

1. The resting rate of oxygen consumption of the excised sciatic nerve of the frog is 1.23 c.mm. of oxygen per gm. of nerve per minute. 2. During stimulation with an induction coil with 100 make and 100 break shocks per second there is an excess oxygen consumption amounting on the average to 0.32 c.mm. of oxygen per gm. of nerve per minute of stimulation, or a 26 per cent increase over the resting rate. 3. The magnitude of the excess oxygen consumption in stimulation, in agreement with the all-or-none law, is not markedly influenced by considerable variations in the intensity of stimulation. 4. Increasing the frequency of stimulation from 100 to 200 shocks per second increases the extra oxygen used only 1.12–1.18 times. The same change in frequency of stimulation increases the negative variation 1.15 times and the heat production about 1.25 times (Hill). 5. This parallelism between the excess oxygen and the negative variation argues definitely for some causal connection between the excess oxygen and the nerve impulse itself. 6. Calculation shows that the oxygen tension inside these nerves was not zero.

Chamber cold acclimatization in man

1961 ◽  
Vol 16 (6) ◽  
pp. 1011-1015 ◽  
Author(s):  
Thomas R. A. Davis
Keyword(s):  
Oxygen Consumption ◽  
Air Temperature ◽  
Rectal Temperature ◽  
Heat Production ◽  
Cold Exposure ◽  
Technical Assistance ◽  
Exposure Period ◽  
Seasonal Difference ◽  
Nonshivering Thermogenesis ◽  
Cold Acclimatization

In March, ten nude subjects were exposed 8 hr daily for 31 days to an air temperature of 11.8 C. In September, another six subjects were similarly acclimatized to an air temperature of 13.5 C. Measurements were made of the responses of shivering, oxygen consumption, rectal temperature, and skin temperature to a standard cold exposure. By the 14th day, shivering in both groups decreased significantly. Heat production remained unchanged in the winter group but decreased in the summer group. Basal metabolism did not change in either group. In both groups, rectal temperatures were maintained at lower values after the exposure period. In the winter group extremity temperatures were unchanged; those in the summer group were lowered by a small amount. The decrease in heat production and mean surface temperature in the summer group is related to the seasonal difference in cold acclimatization. Failure of cold-elevated metabolism to decrease despite a highly significant decrease in shivering indicates the presence of nonshivering thermogenesis in man. It is concluded that man can be artificially cold acclimatized. Note: With the Technical Assistance of D. R. Johnston, F. C. Bell, W. Rawlings, and L. Lee Submitted on May 8, 1961

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