scholarly journals Acute effects of a β-adrenoceptor agonist (BRL 26830A) on rat brown-adipose-tissue mitochondria. Increased GDP binding and GDP-sensitive proton conductance without changes in the concentration of uncoupling protein

1988 ◽  
Vol 249 (3) ◽  
pp. 759-763 ◽  
Author(s):  
R E Milner ◽  
S Wilson ◽  
J R Arch ◽  
P Trayhurn
Keyword(s):  
Adipose Tissue ◽  
Brown Adipose Tissue ◽  
Binding Sites ◽  
Uncoupling Protein ◽  
Beta Agonist ◽  
Proton Conductance ◽  
Binding Data ◽  
Adrenoceptor Agonist ◽  
Brown Adipose ◽  
Acute Increase

GDP binding, proton conductance and the specific concentration of uncoupling protein were measured in brown-adipose-tissue mitochondria of rats treated acutely with the novel beta-agonist, BRL 26830A. At 1 h after dosing with BRL 26830A, mitochondrial GDP binding was increased more than 2-fold. The increase in binding resulted from an increase in the number of binding sites. An iterative analysis of Scatchard binding data suggested that there is only one high-affinity GDP-binding site (Kd 0.3 microM) in brown-adipose-tissue mitochondria. The acute increase in GDP binding produced by treatment with BRL 26830A occurred without any alteration in the specific mitochondrial concentration of uncoupling protein, as determined by radioimmunoassay. Treatment with the beta-agonist did, however, lead to a small increase in the GDP-sensitive component of mitochondrial proton conductance. These results indicate that GDP-binding sites on uncoupling protein can be rapidly unmasked after treatment with a brown-fat-specific beta-agonist, and that the increase in binding reflects an increase in the activity of the mitochondrial proton-conductance pathway.

A commentary on the interpretation of in vitro biochemical measures of brown adipose tissue thermogenesis

1989 ◽  
Vol 67 (8) ◽  
pp. 811-819 ◽  
Author(s):  
Paul Trayhurn ◽  
Rachel E. Milner
Keyword(s):  
Adipose Tissue ◽  
Brown Adipose Tissue ◽  
Binding Sites ◽  
Protein Concentration ◽  
Uncoupling Protein ◽  
Proton Conductance ◽  
Binding Studies ◽  
Brown Adipose ◽  
Brown Adipose Tissue Thermogenesis

In this article we comment on the various in vitro biochemical measurements employed to assess the thermogenic activity and capacity of brown adipose tissue. The meaning and significance of changes in tissue weight, protein content, cell number, and mitochondrial mass are each summarized. In addition, various indices of the proton conductance pathway – mitochondrial swelling, proton conductance, uncoupling protein concentration, and GDP binding studies – are discussed. The issue of unmasking and masking of GDP binding sites is reviewed; recent reports have clearly demonstrated unmasking and masking, and it is concluded that GDP binding studies are an index of the activity of uncoupling protein, rather than a measure of its concentration. It is suggested that tissue mass, mitochondrial content, mitochondrial GDP binding, and uncoupling protein concentration represent core measurements for the biochemical assessment of the thermogenic activity and capacity of brown adipose tissue. Auxiliary measurements include Scatchard analysis of GDP binding data to distinguish changes in the number of binding sites from potential changes in Kd, and mitochondrial swelling studies, as an additional index of proton permeability. The distinction between thermogenic activity (GDP binding, proton permeability) and capacity (uncoupling protein content), both on a per unit of mitochondrial protein and per tissue basis, is emphasized.Key words: brown adipose tissue, thermogenesis, uncoupling protein, mitochondria.

Rapid changes in number of GDP binding sites on brown adipose tissue mitochondria

1986 ◽  
Vol 251 (2) ◽  
pp. E192-E195
Author(s):  
A. G. Swick ◽  
R. W. Swick
Keyword(s):  
Adipose Tissue ◽  
Brown Adipose Tissue ◽  
Binding Sites ◽  
Uncoupling Protein ◽  
Membrane Integrity ◽  
Binding Activity ◽  
Bat Mitochondria ◽  
Brown Adipose ◽  
Rapid Changes ◽  
Binding To Mitochondria

GDP binding to brown adipose tissue (BAT) mitochondria increased more than twofold in 20 min when rats were moved from 27 to 4 degrees C. When animals housed at 4 degrees C for 2 h were returned to 27 degrees C, GDP binding decreased sharply in 20 min and returned to control levels in 2 h. These results are consistent with a rapid unmasking and remasking of GDP binding sites. GDP binding to mitochondria from warm and acutely cold treated rats was not modified by prior swelling, by freeze-thawing, nor by sonication of the mitochondria before assay. GDP-inhibitable proton conductance, as measured by passive swelling, was unaffected by this brief exposure to cold but more than doubled in rats kept at 4 degrees C for 10 days. We hypothesize that the rate of GDP-inhibitable swelling may be a reflection of uncoupling protein concentration in the BAT mitochondria, whereas physiological thermogenic activity is more appropriately indicated by GDP binding. The alterations in binding activity appear not to be due to changes in the mitochondrial membrane integrity.

scholarly journals Evidence for masking of brown adipose tissue mitochondrial GDP-binding sites in response to fasting in rats made obese by dietary manipulation. Effects of reversion to standard diet

1991 ◽  
Vol 279 (2) ◽  
pp. 575-579 ◽  
Author(s):  
P Puigserver ◽  
I Lladó ◽  
A Palou ◽  
M Gianotti
Keyword(s):  
Adipose Tissue ◽  
Brown Adipose Tissue ◽  
Binding Sites ◽  
Uncoupling Protein ◽  
Cafeteria Diet ◽  
Standard Diet ◽  
Dietary Manipulation ◽  
Bat Mitochondria ◽  
Brown Adipose ◽  
Obese Rats

A specific immunoassay of uncoupling protein (UCP) and measurement of GDP binding were used to study the chronic responses of brown adipose tissue (BAT) mitochondria from rats made obese by dietary means (cafeteria rats) and from obese rats subsequently fed a standard diet (post-cafeteria rats). We studied the response to fasting in order to assess the masking/unmasking responses in these groups. These studies have shown the following. (1) In the obese rats (cafeteria and post-cafeteria) the chronic increase in mitochondrial UCP concentration compared with controls parallels the increase in GDP binding. (2) In 24 h-fasted control rats the decrease in GDP binding is associated with a change in UCP concentration, but in fasting cafeteria and post-cafeteria obese rats the decrease in GDP binding is not associated with any change in UCP concentration. (3) Post-cafeteria obese rats showed increased GDP binding and higher UCP concentrations than the controls, but these values were less than in cafeteria obese rats. (4) Control rats at 8 months old showed greater GDP binding and had a higher UCP concentration than 11-month-old control rats. (5) The responses of GDP binding and UCP concentration to fasting in post-cafeteria obese rats were similar to those in cafeteria obese rats, suggesting that such abbreviations are related to the obese status itself rather than to the composition of the cafeteria diet. The evidence supports the hypothesis that the response of the cafeteria and post-cafeteria obese rats to fasting is associated with a masking of UCP, whereas with chronic manipulation of diet changes in UCP concentration predominate.

scholarly journals Contrasts between the effects of zinc-α2-glycoprotein, a putative β3/2-adrenoceptor agonist and the β3/2-adrenoceptor agonist BRL35135 in C57Bl/6 (ob/ob) mice

2012 ◽  
Vol 216 (2) ◽  
pp. 157-168 ◽  
Author(s):  
Edward T Wargent ◽  
Jacqueline F O'Dowd ◽  
Mohamed S Zaibi ◽  
Dan Gao ◽  
Chen Bing ◽  
...  
Keyword(s):  
Gene Expression ◽  
Adipose Tissue ◽  
Brown Adipose Tissue ◽  
Uncoupling Protein ◽  
Fasting Blood Glucose ◽  
Plasma Concentrations ◽  
Mrna Levels ◽  
Plasma Insulin Concentration ◽  
Adrenoceptor Agonist ◽  
Brown Adipose

Previous studies by Tisdaleet al. have reported that zinc-α2-glycoprotein (ZAG (AZGP1)) reduces body fat content and improves glucose homeostasis and the plasma lipid profile in Aston (ob/ob) mice. It has been suggested that this might be mediated via agonism of β3- and possibly β2-adrenoceptors. We compared the effects of dosing recombinant human ZAG (100 μg, i.v.) and BRL35135 (0.5 mg/kg, i.p.), which is in rodents a 20-fold selective β3- relative to β2-adrenoceptor agonist, given once daily for 10 days to male C57Bl/6Lepob/Lepobmice. ZAG, but not BRL35135, reduced food intake. BRL35135, but not ZAG, increased energy expenditure acutely and after sub-chronic administration. Only BRL35135 increased plasma concentrations of glycerol and non-esterified fatty acid. Sub-chronic treatment with both ZAG and BRL35135 reduced fasting blood glucose and improved glucose tolerance, but the plasma insulin concentration 30 min after administration of glucose was lowered only by BRL35135. Both ZAG and BRL35135 reduced β1-adrenoceptor mRNA levels in white adipose tissue, but only BRL35135 reduced β2-adrenoceptor mRNA. Both ZAG and BRL35135 reduced β1-adrenoceptor mRNA levels in brown adipose tissue, but neither influenced β2-adrenoceptor mRNA, and only BRL35135 increased β3-adrenoceptor and uncoupling protein-1 (UCP1) mRNA levels in brown adipose tissue. Thus, ZAG and BRL35135 had similar effects on glycaemic control and shared some effects on β-adrenoceptor gene expression in adipose tissue, but ZAG did not display the thermogenic effects of the β-adrenoceptor agonist, nor did it increase β3-adrenoceptor orUCP1gene expression in brown adipose tissue. ZAG does not behave as a typical β3/2-adrenoceptor agonist.

Abnormal brown adipose tissue in genetically obese mice (ob/ob): effect of thyroxine

1981 ◽  
Vol 241 (6) ◽  
pp. E436-E443
Author(s):  
S. Hogan ◽  
J. Himms-Hagen
Keyword(s):  
Adipose Tissue ◽  
Brown Adipose Tissue ◽  
Binding Sites ◽  
Mitochondrial Membrane ◽  
Cold Resistance ◽  
Proton Conductance ◽  
Obese Mice ◽  
Brown Adipose ◽  
Endogenous Noradrenaline

Lean and genetically obese (ob/ob): mice were treated daily for 2 wk with thyroxine (T4), noradrenaline, or thyroxine plus noradrenaline. T4 treatment of obese mice increased the abnormally low binding of GDP to brown adipose tissue mitochondria and permitted a cold-induced increase to occur. It also brought about a return to a more normal ultrastructure of the mitochondria of the obese mice. T4 treatment did not alter the binding of GDP to brown adipose tissue mitochondria of lean mice. The binding of GDP to brown adipose tissue mitochondria is known to be to a 32,000-dalton polypeptide associated with the thermogenic proton conductance pathway. T4 treatment did not alter the proportion of this polypeptide in the mitochondrial membrane in either lean or obese mice. Treatment with noradrenaline did not alter the binding of GDP to brown adipose tissue mitochondria in either lean or obese mice. The effect of T4 is thought to be due to an improvement in the defective responsiveness of brown adipose tissue to endogenous noradrenaline in the obese mice, known to be related to their poor cold resistance and obesity. The improvement allows a more normal noradrenaline-induced unmasking of GDP binding sites, both in response to diet and in response to cold. Such treatment is known to improve cold resistance of the obese mice, and this appears to be correlated with an improvement in the functioning of their defective brown adipose tissue.

scholarly journals Evidence for unmasking of rat brown-adipose-tissue mitochondrial GDP-binding sites in response to acute cold exposure. Effects of washing with albumin on GDP binding

1986 ◽  
Vol 233 (3) ◽  
pp. 743-747 ◽  
Author(s):  
C L Gribskov ◽  
M F Henningfield ◽  
A G Swick ◽  
R W Swick
Keyword(s):  
Adipose Tissue ◽  
Brown Adipose Tissue ◽  
Cold Exposure ◽  
Binding Sites ◽  
Uncoupling Protein ◽  
Fold Increase ◽  
Scatchard Analysis ◽  
Mitochondrial Uncoupling ◽  
Mitochondrial Uncoupling Protein ◽  
Brown Adipose

Rats, previously acclimated to 29 degrees C, were moved into the cold (4 degrees C) for 2 h. Scatchard analysis of GDP binding to the brown-adipose-tissue mitochondria of these animals showed a 2.3-fold increase in the number of high-affinity sites and a 1.5-fold increase in the number of low-affinity sites compared with binding in animals maintained at 29 degrees C. Immunochemical determination showed no increase in the amount of mitochondrial uncoupling protein during this period. This strongly suggests an unmasking of existing GDP-binding sites before a detectable increase in synthesis of uncoupling protein can occur. Washing with albumin increased the number of GDP-binding sites of brown-adipose-tissue mitochondria from both warm-housed and cold-exposed animals to the same extent. This indicates that the effects of washing with albumin and cold exposure are independent and additive.

Brown fat thermogenesis during hibernation and arousal in Richardson's ground squirrel

1989 ◽  
Vol 256 (1) ◽  
pp. R42-R48 ◽  
Author(s):  
R. E. Milner ◽  
L. C. Wang ◽  
P. Trayhurn
Keyword(s):  
Adipose Tissue ◽  
Brown Adipose Tissue ◽  
Cold Acclimation ◽  
Binding Sites ◽  
Ground Squirrel ◽  
Protein Concentration ◽  
Uncoupling Protein ◽  
Ground Squirrels ◽  
Mitochondrial Content ◽  
Brown Adipose

The thermogenic activity [mitochondrial guanosine 5'-diphosphate (GDP) binding] and capacity (uncoupling protein concentration, cytochrome oxidase activity) of brown adipose tissue have been investigated at different phases of the seasonally linked hibernation cycle in Richardson's ground squirrel. The amount of axillary brown adipose tissue and the total mitochondrial content of the tissue were substantially greater in hibernating squirrels than in squirrels caught posthibernation in April or May; cold acclimation induced qualitatively similar differences. The specific mitochondrial concentration of uncoupling protein was high under all conditions (compared with other species), differing little between hibernating, posthibernating, and cold-acclimated squirrels. The thermogenic capacity of brown adipose tissue in Richardson's ground squirrels is therefore modulated almost exclusively by changes in the mitochondrial content of the tissue. Mitochondrial GDP binding was increased on cold acclimation, but similar binding levels were observed in hibernating and posthibernation (May) animals. GDP binding and the GDP-sensitive component of acetate-induced mitochondrial swelling were increased during the early stages of arousal from hibernation. These changes, which indicate an activation of the thermogenic proton conductance pathway in arousal, occurred without an alteration in the specific mitochondrial concentration of uncoupling protein. Increased GDP binding during arousal is clearly due to the unmasking of binding sites, reflecting an acute activation of preexisting uncoupling protein.

Anti-obesity and anti-diabetic effects of CL316,243, a highly specific β3-adrenoceptor agonist, in Otsuka Long-Evans Tokushima Fatty rats: induction of uncoupling protein and activation of glucose transporter 4 in white fat

1997 ◽  
Vol 136 (4) ◽  
pp. 429-437 ◽  
Author(s):  
Tsunekazu Umekawa ◽  
Toshihide Yoshida ◽  
Naoki Sakane ◽  
Masayuki Saito ◽  
Kenzo Kumamoto ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Brown Adipose Tissue ◽  
White Adipose Tissue ◽  
Glucose Transporter ◽  
Uncoupling Protein ◽  
Glucose Transporter 4 ◽  
Adrenoceptor Agonist ◽  
Brown Adipose ◽  
Long Evans ◽  
White Fat

Abstract The anti-obesity and anti-diabetic effects of a highly specific β3-adrenoceptor agonist, CL316.243 (CL; β1:β2:β3=0:1:100 000), were investigated in Otsuka Long-Evans Tokushima Fatty (fatty) and LongEvans Tokushima Otsuka (control) rats. Daily injection of CL (0·1 mg/kg, s.c.) to these rats (10 weeks old) for 14 weeks caused a significant reduction in body weight (fatty, 27% control, 15%), associated with a marked decrease in fat pad weight (inguinal: fatty, 60%; control, 36%; retroperitoneal: fatty, 75%; control, 77%) without affecting food intake. The levels of uncoupling protein mRNA and protein levels of uncoupling protein (UCP), as well as guanosine 5′-diphosphate-binding (a reliable index of thermogenesis) in brown adipose tissue, were lower in the fatty than in the control rats. However, after CL treatment, these parameters in brown adipose tissue increased significantly 2- to 3-fold in both groups. Furthermore, uncoupling protein was induced in white adipose tissue as well as in brown adipose tissue. The fatty rats showed hyperglycemia and hyperinsulinemia during the glucose tolerance test, but CL ameliorated these parameters. These findings suggest that decreased thermogenesis in brown adipose tissue may be one of the causes of obesity in the fatty rats and that administration of CL prevents obesity by decreasing white fat mass, by activating brown adipose tissue thermogenesis, and by inducing uncoupling protein in white adipose tissue. Furthermore, CL treatment may inhibit diabetes mellitus by ameliorating obesity and by activating glucose transporter 4 in white adipose tissue and brown adipose tissue. European Journal of Endocrinology 136 429–437

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