Brown Adipose Tissue and Its Uncoupling Protein in Chronically Hypoxic Rats

1997 ◽  
Vol 93 (4) ◽  
pp. 349-354 ◽  
Author(s):  
Jacopo P. Mortola ◽  
Lina Naso

1. Hypoxia is known to decrease thermogenesis. We set out to determine whether this is accompanied by alterations in the brown adipose tissue, which is a major source of non-shivering thermogenesis. 2. Measurements were performed on 25- and 64-day-old rats, after 4 days of hypoxia (10% inspired O2), and on ∼3.5-month-old rats in hypobaric hypoxia since birth, at an ambient temperature of 25°C. 3. All hypoxic rats had higher haematocrit and lower body mass than corresponding controls. 4. In the 25-day-old rats, hypoxia had minimal and non significant effects on brown adipose tissue mass, proteins and DNA concentration. The content of the mitochondrial uncoupling protein thermogenin, evaluated by immunoblot after electrophoretic separation, relative to the cytoskeleton actin (UCP/Act), was not significantly altered. 5. In 25-day-old rats exposed for 4 days to cold (ambient temperature = 7–9°C), brown adipose tissue was hyperplastic, with increased UCP/Act; hypoxia did not appreciably alter the response to cold. 6. In the 2-month-old rats, after 4 days of hypoxia UCP/Act was reduced to about 40% of control. 7. In the 3.5-month-old rats maintained in hypoxia since birth, brown adipose tissue mass was reduced in proportion to body mass, with little effect on total proteins and DNA; UCP/Act was decreased to about 50% of control. 8. We conclude that chronic hypoxia had a minimal effect on brown adipose tissue total proteins and DNA content. However, the uncoupling protein content can be greatly reduced, depending upon age and duration of hypoxia.

2016 ◽  
Vol 66 (2) ◽  
pp. 201-217 ◽  
Author(s):  
Wen-rong Gao ◽  
Wan-long Zhu ◽  
Fang-yan Ye ◽  
Mu-lin Zuo ◽  
Zheng-kun Wang

Physiological adjustments are important strategies for small mammals in response to variation in food availability. To determine the physiological mechanisms affected by food restriction and refeeding, tree shrews were restricted to 85% of initial food intake for 4 weeks and refedad libitumfor another 4 weeks. Changes in food intake, body mass, thermogenesis, body composition, mitochondrial cytochromecoxidase activity, uncoupling protein-1 content in brown adipose tissue and serum leptin levels were measured. The results showed that body mass, body fat mass and serum leptin levels significantly decreased in food restricted tree shrews, and increased when the restriction ended, showing a short “compensatory growth” rather than over-weight or obesity compared withad libitumcontrols. Resting metabolic rate, non-shivering thermogenesis, brown adipose tissue mass (mg), and uncoupling protein-1 content decreased significantly in response to food restriction, and returned to the control levels after the animals were refedad libitum, while the brown adipose tissue mass (%) and cytochromecoxidase activity remained stable during food restriction and refeeding. Food intake increased shortly after refeeding, which perhaps contributed to the rapid regaining of body mass. These results suggest thatTupaia belangerican adjust the status of its physiology integratively to cope with the lack of food by means of decreasing body mass, thermogenesis and serum leptin levels. Leptin may act as a starvation signal to predominantly mediate the reduction in body mass and energy expenditure.


Diabetes ◽  
2018 ◽  
Vol 67 (Supplement 1) ◽  
pp. 277-OR ◽  
Author(s):  
FARNAZ SHAMSI ◽  
TIAN LIAN HUANG ◽  
YU-HUA TSENG

Endocrinology ◽  
2003 ◽  
Vol 144 (11) ◽  
pp. 4831-4840 ◽  
Author(s):  
Márcio Pereira-da-Silva ◽  
Márcio A. Torsoni ◽  
Hugo V. Nourani ◽  
Viviane D. Augusto ◽  
Cláudio T. Souza ◽  
...  

Abstract Short-term cold exposure of homeothermic animals leads to higher thermogenesis and food consumption accompanied by weight loss. An analysis of cDNA-macroarray was employed to identify candidate mRNA species that encode proteins involved in thermogenic adaptation to cold. A cDNA-macroarray analysis, confirmed by RT-PCR, immunoblot, and RIA, revealed that the hypothalamic expression of melanin-concentrating hormone (MCH) is enhanced by exposure of rats to cold environment. The blockade of hypothalamic MCH expression by antisense MCH oligonucleotide in cold-exposed rats promoted no changes in feeding behavior and body temperature. However, MCH blockade led to a significant drop in body weight, which was accompanied by decreased liver glycogen, increased relative body fat, increased absolute and relative interscapular brown adipose tissue mass, increased uncoupling protein 1 expression in brown adipose tissue, and increased consumption of lean body mass. Thus, increased hypothalamic MCH expression in rats exposed to cold may participate in the process that allows for efficient use of energy for heat production during thermogenic adaptation to cold.


1998 ◽  
Vol 156 (2) ◽  
pp. 307-314 ◽  
Author(s):  
I Clarke ◽  
L Heasman ◽  
ME Symonds

We have previously shown that lambs delivered by caesarean section 1 week prematurely become hypothermic due to reduced brown adipose tissue function in conjunction with low plasma concentrations of cortisol and thyroid hormones. The present study therefore aimed to determine whether maternal dexamethasone (a synthetic corticosteroid) administration could improve thermoregulation in premature lambs to the extent that they become similar to term lambs. Lambs were either delivered by caesarean section into a warm (30 degrees C; WD) or cool (15 degrees C; CD) ambient temperature at 140 days of gestation, 2 days after maternal dexamethasone treatment, or at 146 days for controls. During the first 30 min of life the decline in colonic temperature was greater in dexamethasone treated lambs compared with controls delivered into the same ambient temperature. All lambs then restored colonic temperature although this adaptation took longest in dexamethasone treated lambs CD but these subsequently attained highest plateau colonic temperatures. Oxygen consumption, breathing frequency and plasma free fatty acid concentrations were highest in dexamethasone treated lambs CD. There were no differences in plasma thyroid hormones between groups, but cortisol concentrations were lower in dexamethasone treated lambs irrespective of delivery temperature. Analysis of brown adipose tissue samples at 6 h of life demonstrated that dexamethasone treated lambs WD had more uncoupling protein and, in both dexamethasone treated and control lambs, uncoupling protein content was higher in lambs CD compared with those WD. An effect of ambient temperature on thermogenic activity was only observed in the dexamethasone treated group. It is concluded that maternal dexamethasone treatment can significantly improve thermoregulation after birth following premature delivery by caesarean section. As a consequence, dexamethasone treated lambs delivered 1 week prematurely do not remain hypothermic and have higher or similar colonic temperatures compared with untreated lambs born 1-2 days before term.


1985 ◽  
Vol 5 (1) ◽  
pp. 57-62 ◽  
Author(s):  
John Arnold ◽  
Hasmukh V. Patel ◽  
Robert G. Ridley ◽  
Karl B. Freeman

Rats are known to respond to a cold stimulus by increasing the activity and amount of the uncoupling protein in brown adipose tissue. A 48 h cold stimulus was found to increase the synthesis of uncoupling protein 3.g-fold in 4–5 week old rats whereas no change was observed with newborn rabbits. The lack of response in the latter case may reflect a difference between rabbits and rats or that synthesis is already maximal in newborn rabbits.


2017 ◽  
Vol 6 (7) ◽  
pp. 715-724 ◽  
Author(s):  
Dries Bauters ◽  
Mathias Cobbaut ◽  
Lotte Geys ◽  
Johan Van Lint ◽  
Bianca Hemmeryckx ◽  
...  

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