scholarly journals Insulin modifies the properties of glucose transporters in rat brown adipose tissue

1987 ◽  
Vol 247 (1) ◽  
pp. 63-68 ◽  
Author(s):  
R Greco-Perotto ◽  
F Assimacopoulos-Jeannet ◽  
B Jeanrenaud
Keyword(s):  
Adipose Tissue ◽  
Plasma Membrane ◽  
Brown Adipose Tissue ◽  
Cytochalasin B ◽  
Fold Increase ◽  
Glucose Transporters ◽  
Hill Coefficient ◽  
Brown Adipose ◽  
Microsomal Membranes ◽  
The Hill

The properties of glucose transporters associated with plasma and microsomal membranes have been studied in brown adipose tissue of rats after treatment by saline infusion or hyperinsulinaemic/euglycaemic clamp. In this tissue, insulin produces a 40-fold increase in glucose utilization as measured by the 2-deoxy-D-glucose technique, and therefore a 40-fold increase in the rate-limiting glucose transport. This increase, promoted by insulin, is associated with: (a) translocation of the transporters from a pool associated with the microsomal fraction to the plasma membrane without modification of the total number of transporters; (b) an increase in the Hill coefficient of the plasma-membrane glucose transporters for cytochalasin B from 1.1 to 2.5, indicating the presence of positive co-operativity; (c) a decrease in the Kd (apparent dissociation constant) of the transporters towards cytochalasin B from 148 to 82 nM; (d) no change in the Hill coefficient or Kd for the transporters associated with the microsomal membranes. These data indicate that, in addition to causing translocation of the glucose transporters, insulin modifies their properties and behaviour towards cytochalasin B. This may reflect modifications in their properties and behaviour towards glucose, and by this contribute to bringing about the marked effect of this hormone on glucose transport in brown adipose tissue.

scholarly journals Effects of insulin on glucose transport and glucose transporters in rat heart

1988 ◽  
Vol 250 (1) ◽  
pp. 277-283 ◽  
Author(s):  
D Zaninetti ◽  
R Greco-Perotto ◽  
F Assimacopoulos-Jeannet ◽  
B Jeanrenaud
Keyword(s):  
Glucose Transport ◽  
Rat Heart ◽  
Plasma Membranes ◽  
Cytochalasin B ◽  
Glucose Transporters ◽  
Hill Coefficient ◽  
Maximal Velocity ◽  
Microsomal Membranes ◽  
The Hill ◽  
Intracellular Glucose

The effect of insulin on glucose transport and glucose transporters was studied in perfused rat heart. Glucose transport was measured by the efflux of labelled 3-O-methylglucose from hearts preloaded with this hexose. Insulin stimulated 3-O-methylglucose transport by: (a) doubling the maximal velocity (Vmax); (b) decreasing the Kd from 6.9 to 2.7 mM; (c) increasing the Hill coefficient toward 3-O-methylglucose from 1.9 to 3.1; (d) increasing the efficiency of the transport process (k constant). Glucose transporters in enriched plasma and microsomal membranes from heart were quantified by the [3H]cytochalasin-B-binding assay. When added to normal hearts, insulin produced the following changes in the glucose transporters: (a) it increased the translocation of transporters from an intracellular pool to the plasma membranes; (b) it increased (from 1.6 to 2.7) the Hill coefficient of the transporters translocated into the plasma membranes toward cytochalasin B, suggesting the existence of a positive co-operativity among the transporters appearing in these membranes; (c) it increased the affinity of the transporters (and hence, possibly, of glucose) for cytochalasin B. The data provide evidence that the stimulatory effect of insulin on glucose transport may be due not to the sole translocation of intracellular glucose transporters to the plasma membrane, but to changes in the functional properties thereof.

Hormonal regulation of iodothyronine 5'-deiodinase in rat brown adipose tissue

1986 ◽  
Vol 251 (6) ◽  
pp. E639-E643 ◽  
Author(s):  
J. E. Silva ◽  
P. R. Larsen
Keyword(s):  
Adipose Tissue ◽  
Brown Adipose Tissue ◽  
Hormonal Regulation ◽  
Fold Increase ◽  
Growth Hormones ◽  
Mrna Synthesis ◽  
Brown Adipose ◽  
Streptozotocin Induced Diabetes ◽  
Complex Regulation ◽  
Intact Rats

Norepinephrine, isoproterenol, insulin, and glucagon increase the type II (low Km) iodothyronine 5'-deiodinase (5'-D) in the brown adipose tissue (BAT) of intact rats. Cycloheximide or actinomycin D blocks the increase after norepinephrine, suggesting new mRNA synthesis is required for this effect. The 3- to 10-fold increase in BAT 5'-D after insulin administration was also blocked by cycloheximide. The effects of all stimulators are blunted by fasting or streptozotocin-induced diabetes. While all these hormones have the potential for stimulating BAT 5'-D, the dose-response relationships suggest that norepinephrine and insulin are the most potent. These and our earlier studies showing additional effects of thyroid and growth hormones on BAT 5'-D point to the complex regulation of this enzyme, suggesting that the triiodothyronine produced from its action has an important role in the thermogenic response of this tissue.

The influence of starvation and natural refeeding on the rate of triacylglycerol/fatty acid substrate cycling in brown adipose tissue and different white adipose sites of the rat in vivo. The role of insulin and the sympathetic nervous system

1988 ◽  
Vol 8 (2) ◽  
pp. 147-153 ◽  
Author(s):  
Stewart W. Mercer ◽  
Dermot H. Williamson
Keyword(s):  
Adipose Tissue ◽  
Fatty Acid ◽  
Brown Adipose Tissue ◽  
Fold Increase ◽  
Chow Diet ◽  
Fatty Acid Substrate ◽  
Brown Adipose ◽  
Acute Increase ◽  
Acid Substrate

Triacylglycerol/fatty acid substrate cycling was measured in vivo in brown adipose tissue (BAT) and white adipose tissue (WAT) of fed, starved and refed rats. Starvation (24 h) significantly decreased the rate of cycling in BAT, and refeeding chow diet led to a rapid, 6-fold increase in cycling. Cycling rate in WAT was much lower than in BAT, and was not influenced by fasting or refeeding. Similar rates of cycling were found in epididymal, mesenteric, subcutaneous, and scapular WAT depots. Sympathetic denervation of interscapular BAT abolished the response of the tissue to refeeding, as did acute suppression of insulin secretion. Similarly, rats fasted for 3 days showed no acute increase in the activity of the cycle following refeeding.

Control mechanisms in brown adipose tissue plasma membrane

1984 ◽  
Vol 62 (7) ◽  
pp. 631-636 ◽  
Author(s):  
N. Bégin-Heick ◽  
H. M. C. Heick
Keyword(s):  
Adipose Tissue ◽  
Plasma Membrane ◽  
Adenylate Cyclase ◽  
Brown Adipose Tissue ◽  
Heat Production ◽  
Metabolic Effects ◽  
Maximal Response ◽  
Obese Mouse ◽  
Control Mechanisms ◽  
Brown Adipose

It is generally agreed that the site of heat production during nonshivering thermogenesis is the brown adipose tissue (BAT) and that the triggering event for heat production is the interaction of noradrenaline (NA) with its receptor on the plasma membrane. Following this initial event, several changes occur which result in increased rates of cAMP synthesis, redistribution of ions across the membrane, enhanced rates of lipolysis, and increased mitochondrial oxidation of substrates. BAT is also a target for the anabolic effect of insulin. Available evidence shows that insulin receptors are present on the BAT plasma membrane and that insulin can oppose the metabolic effects of catecholamine on BAT. We have studied more particularly the response of BAT adenylate cyclase to catecholamines in an animal model (the ob/ob mouse) which has a defective thermogenic response. The capacity of adenylate cyclase to be stimulated by catecholamines was significantly less in the tissue of obese mice than in lean controls. To produce a response equal to the half-maximal response in the lean mouse, a 10-fold increase in the NA concentration was required in the BAT of the obese mouse. These results are in harmony with those of others showing that the lipolytic response to catecholamines is abnormal in the BAT of the obese mouse. The adenylate cyclase activity can be altered by changes in the lipid composition of the diet and by manipulation of hormone levels. It is likely that the alteration in adenylate cyclase responsiveness is one of the contributing factors in the impaired thermogenesis and obesity in this animal.

scholarly journals Glucose utilization by interscapular brown adipose tissue in vivo during nutritional transitions in the rat

1991 ◽  
Vol 273 (1) ◽  
pp. 233-235 ◽  
Author(s):  
M J Holness ◽  
Y L Liu ◽  
J S Beech ◽  
M C Sugden
Keyword(s):  
Adipose Tissue ◽  
Brown Adipose Tissue ◽  
Glucose Utilization ◽  
Fold Increase ◽  
Interscapular Brown Adipose Tissue ◽  
Overall Response ◽  
Brown Adipose ◽  
Control Post

Glucose utilization indices (GUI) of interscapular brown adipose tissue (IBAT) declined by 84% after 48 h starvation. Two-thirds of the overall response was observed within 6 h, correlating with decreased insulin concentrations. Re-feeding 48 h-starved rats restored insulin concentrations and evoked a rapid 15-fold increase in IBAT GUI. GUI values after re-feeding were markedly higher than those observed at equivalent insulin concentrations in control post-absorptive rats.

Beta-adrenoreceptors in rat brown adipose tissue: proportions of beta 1- and beta 2-subtypes

1985 ◽  
Vol 248 (4) ◽  
pp. E397-E402 ◽  
Author(s):  
N. J. Rothwell ◽  
M. J. Stock ◽  
D. K. Sudera
Keyword(s):  
Adipose Tissue ◽  
Brown Adipose Tissue ◽  
Binding Sites ◽  
Scatchard Analysis ◽  
Single Class ◽  
Brown Adipose ◽  
Ici 118,551 ◽  
Microsomal Membranes ◽  
Beta 2 ◽  
Equilibrium Dissociation

Binding of (-)-[3H]dihydroalprenolol [( 3H]DHA) to isolated brown adipose tissue (BAT) microsomal membranes was used to estimate beta-adrenoreceptor density, and this was found to be saturable, reversible, and stereospecific. Scatchard analysis indicated a single class of binding sites of equilibrium dissociation constant 2.2 nM, with a maximum number of binding sites of 160-170 fmol/mg protein. These values were unaffected by the age or sex of the animals, and similar Kd values were obtained for binding to heart and lung membranes. The kinetically derived Kd from forward and reverse reactions was 1.4 nM for BAT. Hofstee analysis of displacement of [3H]DHA produced linear plots for propranolol but curvilinear plots for atenolol and ICI 118,551. Atenolol showed 50-fold selectivity for beta 1-receptors and ICI 118,551 50-fold selectivity for beta 2-receptors in heart, lung, and BAT membranes. These plots indicated beta 1:beta 2-receptor ratios of 59:41 for BAT and heart and 25:75 for lung. It is possible that both beta-adrenoreceptor subtypes in BAT may be involved in the activation of thermogenesis in the tissue.

Altered effect of insulin and catecholamines in brown adipose tissue of cold-acclimated rats

1979 ◽  
Vol 57 (3) ◽  
pp. 320-324 ◽  
Author(s):  
Nicole Bégin-Heick ◽  
Iris Noland ◽  
Marthe Dalpé ◽  
H. M. C. Heick
Keyword(s):  
Adipose Tissue ◽  
Plasma Membrane ◽  
Adenylate Cyclase ◽  
Brown Adipose Tissue ◽  
Cold Acclimation ◽  
Inhibitory Action ◽  
Cyclase Activity ◽  
Relative Response ◽  
Brown Adipose ◽  
Glucose Incorporation

Data are presented indicating that in brown adipose tissue (BAT) of cold-acclimated (CA), but not cold-exposed (CE) rats, there was an alteration in the relative response to catecholamines and insulin as evidenced by increased binding of alprenolol and decreased binding of insulin to plasma membrane enriched fractions. In addition, the stimulatory effect of insulin on glucose incorporation into glycogen and its inhibitory action on adenylate cyclase activity were both blunted in the CA tissues. It is proposed that shifts in the capacity of BAT to respond to catecholamines and insulin may be involved in the mechanism of cold acclimation.

scholarly journals Distribution of the integral plasma membrane glycoprotein CE9 (MRC OX-47) among rat tissues and its induction by diverse stimuli of metabolic activation

1995 ◽  
Vol 310 (2) ◽  
pp. 693-698 ◽  
Author(s):  
C L Nehme ◽  
B E Fayos ◽  
J R Bartles
Keyword(s):  
Adipose Tissue ◽  
Plasma Membrane ◽  
Brown Adipose Tissue ◽  
Plasma Membranes ◽  
Metabolic Activation ◽  
Blast Transformation ◽  
Rat Tissues ◽  
Membrane Glycoprotein ◽  
Brown Adipose ◽  
Different Tissues

We have compared the levels of the integral plasma membrane glycoprotein CE9 (MRC OX-47) in different tissues of the rat and have ascertained that the levels of CE9 protein and mRNA in selected tissues and cells exhibit moderate increases in response to diverse stimuli of metabolic activation. When normalized on the basis of total protein, the level of CE9 detected in the different tissues was found to vary over a 50-fold range. In addition, the apparent molecular mass of CE9 was observed to vary from 40 kDa to 68 kDa as a consequence of tissue-specific glycosylation. The highest level of CE9 was detected in brown adipose tissue, where the protein was found to be localized to the plasma membranes of the adipocytes. The metabolic activation of brown adipose tissue that occurs upon exposure of rats to the cold was found to be accompanied by 3.0 +/- 0.4-fold and 1.7 +/- 0.2-fold increases in the levels of CE9 mRNA and protein respectively. An intermediate level of CE9 was detected in the liver, where the protein is known to be expressed within the basolateral domain of the hepatocyte plasma membrane. The metabolic activation of hepatocytes that occurs upon administration of thyroid hormone to euthyroid rats was found to be accompanied by 2.2 +/- 0.3-fold and 1.9 +/- 0.3-fold increases in the levels of CE9 mRNA and protein respectively. A low level of CE9 was detected in the lymphoid organs, such as thymus and spleen. The metabolic activation of isolated rat splenocytes that occurs upon concanavalin A-mediated blast transformation in culture was found to be accompanied by 2.1 +/- 0.2-fold and 1.6 +/- 0.2-fold increases in the levels of CE9 mRNA and protein respectively. On the basis of these and other observations, we suggest that the level, and possibly also the localization, of the integral plasma membrane glycoprotein CE9 may be correlated in a positive fashion with metabolic activity in a diverse array of cell types.

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