Responses of brown adipose tissue activity to unloading in rats

1995 ◽  
Vol 78 (2) ◽  
pp. 384-387 ◽  
Author(s):  
H. Yamashita ◽  
Y. Ohira ◽  
T. Wakatsuki ◽  
M. Yamamoto ◽  
T. Kizaki ◽  
...  

To study the responses of thermogenic activity in brown adipose tissue (BAT) to unloading, male Wistar rats were hindlimb suspended for 10 days. Compared with control rats, a significant increase in the BAT-to-body mass ratio and considerable differences in chemical components in BAT were observed in the hindlimb-suspended rats. These findings indicate a marked increase in the thermogenic capacity in BAT of the experimental group. Likewise, the thermogenic activity (which was assessed by guanosine 5′-diphosphate binding to BAT mitochondria) was markedly greater in the mitochondria recovered from BAT of the hindlimb-suspended rats than in those from the control rats (1,610 +/- 450 vs. 202 +/- 132 pmol recovered). Moreover, the uncoupling protein content in the BAT mitochondrial fraction of the hindlimb-suspended rats was significantly higher (1.6-fold) than that in the control rats. As was expected, the uncoupling protein mRNA expression was greater in hindlimb-suspended rats than in control animals. These results suggest that chronic hindlimb suspension leads to an increase in both the thermogenic capacity and the activity in BAT of rats.

1992 ◽  
Vol 15 ◽  
pp. 174-175
Author(s):  
L. Clarke ◽  
S. van de Waal ◽  
M. A. Lomax ◽  
M. E. Symonds

In the ovine foetus brown adipose tissue (BAT) is mainly found in the perirenal region and grows rapidly relative to body weight between 70 to 120 days of gestation (Alexander, 1978). After this stage only a small amount of BAT growth occurs in comparison with that of the whole foetus, and in the case of undernutrition may decline (Alexander, 1978). Maternal cold stress, induced by winter shearing twin-bearing pregnant ewes 8 weeks before parturition improves lamb birth weight and lamb growth rate independently of effects on maternal food intake (Symonds, Bryant and Lomax, 1986 and 1990). At the same time this can stimulate the in vivo capacity for non-shivering thermogenesis in newborn lambs (Stott and Slee, 1985). The following study extends these findings by investigating the extent to which changing the maternal metabolic environment influences BAT development over the final month of gestation.Thirty-two Bluefaced Leicester × Swaledale ewes were housed individually at ambient temperature (−6 to 19°C) 6 weeks prior to lambing and 2 weeks later 15 ewes were shorn. Ewes were offered daily a diet comprising 200 g barley concentrate and 1 kg chopped hay. Between 116 and 145 days of gestation and within 2 h of birth ewes were humanely slaughtered with an overdose of barbiturate and foetal or neonatal perirenal BAT sampled, born from shorn or unshorn ewes. The thermogenic capacity of BAT was assessed by guanosine-5′-diphosphate (GDP) binding to uncoupling protein in mitochondrial preparations (Cooper, Dascombe, Rothwell and Vale, 1989) and the amount of mitochondrial protein measured from cytochrome Coxidase activity.


1988 ◽  
Vol 254 (1) ◽  
pp. R11-R16 ◽  
Author(s):  
P. Trayhurn ◽  
G. Jennings

The effects of fasting and refeeding on nonshivering thermogenesis and the properties of brown adipose tissue have been investigated in mice. Fasting for 48 h led to a substantial reduction in the capacity for nonshivering thermogenesis, and there was no recovery of thermogenic capacity during the first 5 days of refeeding. A period of 10-15 days of refeeding was required for full restoration of thermogenic capacity. The mice were hyperphagic during the first 6 days of refeeding, but body weight was recovered after 24 h. The amount of interscapular brown adipose tissue decreased substantially on fasting, but it recovered 24 h after the initiation of refeeding. Cytochrome oxidase activity, the level of mitochondrial GDP binding, and the specific mitochondrial concentration of uncoupling protein in brown adipose tissue were each reduced by fasting. Although both GDP binding and the specific concentration of uncoupling protein rapidly returned to normal on refeeding, the activity of cytochrome oxidase was not normalized until 10 days after the end of the fast. These results indicate that a prolonged period of refeeding is required for the recovery in the capacity for nonshivering thermogenesis following a fast, a similar time course being evident for the recovery of cytochrome oxidase activity in brown adipose tissue. It is suggested that the fasting-induced reduction in the capacity for nonshivering thermogenesis is linked primarily to a loss of mitochondria from brown adipose tissue and that the normalization of thermogenic capacity is dependent on the restoration of mitochondrial mass.


1996 ◽  
Vol 319 (2) ◽  
pp. 529-534 ◽  
Author(s):  
Juan C MATAMALA ◽  
Magdalena GIANOTTI ◽  
Jordi PERICÁS ◽  
Santiago QUEVEDO ◽  
Pilar ROCA ◽  
...  

The effects of starvation on the thermogenic parameters of three different mitochondrial subpopulations in brown adipose tissue (BAT) of both post-cafeteria obese and lean rats were investigated. Tissue from different BAT depots from fed and 24 h starved rats were collected, pooled and three mitochondrial subpopulations were isolated by differential centrifugation; the M1 fraction (1000 g), the M3 fraction (3000 g) and the M15 fraction (15000 g). Thermogenic parameters were measured in the three mitochondrial subtypes, and uncoupling protein (UCP) mRNA was determined in BAT. The results showed that starvation induced a decrease in mitochondrial turnover in BAT from both lean and obese rats. Moreover, a selective net loss of UCP from the lightest mitochondrial fraction (M15) in lean rats, with a concomitant reduction of UCP mRNA was observed. The reductions did not occur in obese rats and, as a result, a change in UCP distribution between the mitochondrial subpopulations was produced, with an increase in the M1 mitochondrial subtype. The lack of response of UCP to starvation observed in BAT of obese rats compared with the decrease seen in lean animals, is a consequence of a different mitochondrial subpopulation composition and/or a different response of a particular subpopulation to starvation.


1992 ◽  
Vol 263 (1) ◽  
pp. R59-R69
Author(s):  
J. Thornhill ◽  
I. Halvorson

Temperature experiments of 4- and 21 degrees C-acclimated conscious and anesthetized Sprague-Dawley (SD) and Long-Evans (LE) rats revealed that the LE groups or SD rats acclimated to 4 degrees C had significant increases in intracapsular brown adipose tissue (IBAT) temperature above core after ventromedial hypothalamic nucleus (VMH) electrical stimulation or after norepinephrine (NE) infusion (50 micrograms/kg total dose), whereas IBAT temperatures of SD rats (acclimated to 21 degrees C) rose only after intravenous NE. Another study of 21- or 4 degrees C-acclimated SD rats revealed that only the 4 degrees C-acclimated group showed graded increases in IBAT temperature after VMH electrical stimulation as current amplitude or total current duration (not pulse frequency) of the electrical stimulus was increased. In vitro analysis of isolated IBAT tissues of age-matched anesthetized LE or SD rats acclimated to 21 degrees C showed that many indicators of thermogenic capacity including mitochondrial uncoupling protein were significantly lower in the SD group. The results demonstrate that lean male SD rats acclimated to 21 degrees C have suppressed IBAT temperature responses to VMH electrical stimulation compared with lean LE rats due to a reduced thermogenic capacity of that tissue.


1995 ◽  
Vol 73 (11) ◽  
pp. 1625-1631 ◽  
Author(s):  
Hugues Oudart ◽  
Christiane Calgari ◽  
Margaret Andriamampandry ◽  
Yvon Le Maho ◽  
André Malan

Despite anorexia, cancer development is frequently accompanied by an increase of energy expenditure. Considering the pivotal role played by brown adipose tissue (BAT) in the energy metabolism of small mammals, we investigated the functional and compositional modification in BAT of anorexic tumor-bearing (Yoshida sarcoma) and pair-fed control rats. BAT thermogenic activity (assessed by maximal mitochondrial GDP binding) was 1.8-fold greater in tumor-bearing rats than in controls, while the thermogenic capacity (assessed by measurement of uncoupling protein) was unchanged. This suggests that tumor bearing had induced an unmasking of uncoupling protein sites. BAT hypertrophy and hyperplasia, characteristic of full-fledged BAT activation, did not occur. The mitochondrial oxidative capacity of BAT (assessed by cytochrome c oxidase activity) was 1.6-fold lower in tumor-bearing than in control rats. The main compositional modification observed in BAT of tumor-bearing rats was an increase in the saturation of cardiolipin fatty acids. These results suggest that the BAT stimulation induced by tumor bearing after 10 days is almost exclusively functional and that the tissue development is limited, probably by anorexia. However, a suppressive effect of anorexia inhibition by tumor bearing cannot be excluded.Key words: cancer cachexia, nonshivering thermogenesis, brown adipose tissue cardiolipins.


1994 ◽  
Vol 300 (2) ◽  
pp. 463-468 ◽  
Author(s):  
M Moreno ◽  
P Puigserver ◽  
J Llull ◽  
M Gianotti ◽  
A Lanni ◽  
...  

The effect of cold exposure on thermogenic parameters such as mitochondrial protein content, GDP-binding and uncoupling protein (UCP) levels in different mitochondrial fractions from rat brown adipose tissue has been investigated. Rats were exposed from 12 h to 5 days at 4 degrees C, and three mitochondrial fractions were isolated by differential centrifugation: the M1 fraction (1000 g), the M3 fraction (3000 g) and the M15 fraction (15,000 g). Cytochrome c oxidase activity as an index of mitochondrial mass showed an increase during cold exposure. During the first 24 h of cold exposure UCP was incorporated specifically into the M3 and M15 mitochondrial fractions, and thereafter UCP appeared in the heaviest M1 fraction. However, specific GDP binding was increased during the first 24 h in the same way in all subpopulations, and this increase continued up to 72 h of cold exposure. Results suggest that different molecular events are involved during acute and chronic adaptation to cold: during the first 24 h of cold acclimatization, thermogenic activity is increased by an unmasking process of the UCP binding sites in the M1 mitochondrial fraction as UCP levels were constant and GDP binding increased, but in the M3 and M15 fraction the increase in thermogenic activity was completely due to an increase in GDP binding induced by a specific incorporation of UCP targeted to these mitochondria. Thus thermogenic parameters change in a different way in the brown-fat mitochondrial subpopulations during cold acclimatization.


2020 ◽  
Author(s):  
Milena Monfort-Pires ◽  
Muuez U-Din ◽  
Guilherme A. Nogueira ◽  
Juliana de Almeida-Faria ◽  
Davi Sidarta-Oliveira ◽  
...  

Sign in / Sign up

Export Citation Format

Share Document