Metabolic influences on enzymes of glycogen synthesis and breakdown in adipose tissue

1964 ◽  
Vol 207 (6) ◽  
pp. 1215-1220 ◽  
Author(s):  
Alisa Gutman ◽  
Eleazar Shafrir
Keyword(s):  
Adipose Tissue ◽  
Protein Content ◽  
Glycogen Synthesis ◽  
Total Activity ◽  
Epididymal Adipose Tissue ◽  
Control Value ◽  
Prolonged Fast ◽  
Rat Adipose Tissue

Rat adipose tissue from different body sites was shown to contain uridine diphosphoglucose (UDPG)-transglucosylase activity, which on the basis of protein content was comparable to or higher than that reported for muscle or liver. In epididymal adipose tissue, the activity of UDPG-glycogen transglucosylase and phosphorylase, as well as the content of glycogen per wet weight, decreased with increasing age of the animals in parallel with the decrease of tissue protein content. On prolonged fast the activity of UDPG-glycogen transglucosylase and phosphorylase per milligram protein dropped by 25–50% of the control value. On refeeding, the extent of changes was variable but, in general, at 24 hr control or higher levels of activity were reached and at 48 hr the activities were elevated. The ratio of glucose 6-phosphate independent activity of UDPG-glycogen transglucosylase to total activity was not affected by fasting and refeeding or by the administration of glucose with insulin. In adrenalectomized rats, with high adipose tissue glycogen, no change in UDPG-glycogen transglucosylase was found, whereas the levels of phosphorylase were elevated. Epinephrine in vivo and in vitro did not affect the activity of UDPG-glycogen transglucosylase of adipose tissue.

scholarly journals The effect of insulin and glucocorticoids on the synthesis and degradation of phosphoenolpyruvate carboxykinase (GTP) in rat adipose tissue cultured in vitro

1976 ◽  
Vol 158 (1) ◽  
pp. 9-16 ◽  
Author(s):  
O Meyuhas ◽  
L Reshef ◽  
F J Ballard ◽  
R W Hanson
Keyword(s):  
Protein Synthesis ◽  
Adipose Tissue ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Epididymal Adipose Tissue ◽  
Large Size ◽  
A Value ◽  
Rat Adipose Tissue ◽  
Synthesis And Degradation

1. Epididymal adipose tissue from the rat was maintained in culture for periods of up to 96h. 2. After an initial decrease in protein synthesis during the first 24h of culture, the adipose tissue recovered its capacity to synthesize and accumulate proteins of a relatively large size. 3. The activity of phosphoenolpyruvate carboxykinase decreased in a parallel manner, but increased again after 24h of incubation of the tissue in culture, to a value twice that noted in the tissue in vivo. This increase in enzyme activity was due to an increase in its rate of synthesis. 4. Both insulin and dexamethasone (9alpha-fluoro-16alpha-methyl-11beta,17,-21-trihydroxypregna-1,4-diene-3,20-dione) inhibited phosphoenolpyruvate carboxykinase synthesis, but dexamethasone also decreased total protein synthesis. 5. The half-life of phosphoenolpyruvate carboxykinase in adipose tissue cultured in vitro was 5-7h and was not altered by insulin or dexamethasone. 6. It is concluded that both insulin and glucocroticoids lower the activity of phosphoenolpyruvate carboxykinase in rat adipose tissue by decreasing its rate of synthesis.

Isoproterenol decreases leptin release from rat and human adipose tissue through posttranscriptional mechanisms

2005 ◽  
Vol 288 (4) ◽  
pp. E798-E804 ◽  
Author(s):  
Matthew R. Ricci ◽  
Mi-Jeong Lee ◽  
Colleen D. Russell ◽  
Yanxin Wang ◽  
Sean Sullivan ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Relative Rate ◽  
Human Adipose Tissue ◽  
Rapid Decline ◽  
Mrna Levels ◽  
Adrenergic Regulation ◽  
Obese Subjects ◽  
Rat Adipose Tissue

In vivo and in vitro studies indicate that β-adrenergic receptor agonists decrease leptin release from fat cells in as little as 30 min. Our objective was to determine whether alterations in leptin biosynthesis or secretion were involved in the short-term adrenergic regulation of leptin in human and rat adipose tissue. Isoproterenol (Iso) decreased leptin release from incubated adipose tissue of both nonobese and obese subjects to similar extent (−28 vs. −21% after 3 h). Inhibition of protein synthesis with cycloheximide did not block the effect of Iso on leptin release from human adipose tissue, suggesting that the Iso effect is independent of leptin synthesis. Iso also tended to increase tissue leptin content at the end of the 3-h incubation, as expected from the observed inhibition of release. Consistent with a posttranslational mechanism, Iso treatment did not affect leptin mRNA levels or relative rate of leptin biosynthesis as directly assessed by [35S]methionine incorporation into immunoprecipitable leptin. In contrast to these results in human adipose tissues, Iso did not decrease basal leptin release from rat adipose tissue. However, Iso did decrease insulin-stimulated leptin release by inhibiting the ability of insulin to increase leptin biosynthesis without detectably affecting leptin mRNA levels. Thus, in both human and rat, adrenergic regulation of posttranscriptional events (secretion in humans, translation in rats) may contribute to the rapid decline in circulating leptin that occurs when the sympathetic nervous system is activated, such as during fasting and cold exposure. Furthermore, the rat does not provide an ideal model to study mechanisms of cellular leptin regulation in humans.

scholarly journals Regulation by glucocorticoids of angiotensinogen gene expression and secretion in adipose cells

1997 ◽  
Vol 328 (2) ◽  
pp. 701-706 ◽  
Author(s):  
Jérôme AUBERT ◽  
Christian DARIMONT ◽  
Irina SAFONOVA ◽  
Gérard AILHAUD ◽  
Raymond NEGREL
Keyword(s):  
Gene Expression ◽  
Adipose Tissue ◽  
Transcriptional Activation ◽  
Ex Vivo ◽  
Activation Product ◽  
Potential Link ◽  
Rat Adipose Tissue ◽  
Adipose Cells

Adipose cells are an important source of angiotensinogen (AT). Its activation product, angiotensin II, stimulates in vitro and in vivo the production and release of prostacyclin which acts as a potent adipogenic signal in promoting the terminal differentiation of preadipocytes to adipocytes. Since glucocorticoids are known to promote adipose cell differentiation in vitro as well as in vivo, their role in the regulation of AT gene expression and secretion has been investigated in cultured Ob1771 mouse adipose cells. In contrast with liver cells, which are the major source of AT and the target of several hormones for the regulation of its expression, adipose cells are only responsive to glucocorticoids, which are able to up-regulate AT gene expression and AT secretion rapidly and dose-dependently. On exposure to glucocorticoids, accumulation of AT mRNA appears primarily to be due to transcriptional activation of the gene and is parallelled by secretion of the protein. Similar results on AT mRNA expression and AT secretion were obtained using explants of rat adipose tissue ex vivo demonstrating a major if not exclusive mechanism of regulation of AT production by glucocorticoids in mature adipose cells. Together these results provide a potential link between glucocorticoids, AT, the growth of adipose tissue and increased blood pressure.

EFFECT OF INSULIN AND INSULIN ANTIBODY UPON RAT ADIPOSE TISSUE MEMBRANE RESTING ELECTRICAL POTENTIAL (REP)

1965 ◽  
Vol 50 (4) ◽  
pp. 648-656 ◽  
Author(s):  
Paul M. Beigelman ◽  
Philip B. Hollander ◽  
David Shube
Keyword(s):  
Adipose Tissue ◽  
Electrical Potential ◽  
Insulin Antibody ◽  
Epididymal Adipose Tissue ◽  
Young Rats ◽  
Electrical Potentials ◽  
Rat Adipose Tissue

ABSTRACT In vitro penetrations of rat epididymal adipose tissue by glass microelectrodes, containing 3 m KCl, elicit resting membrane electrical potentials (REP). Adipose tissue REP in young rats is reversibly increased by 1–1000 μU insulin/ml. Insulin antibody, diluted 1/1000–1/4800, significantly inhibits this elevation of REP by insulin.

scholarly journals EFFECTS OF PHTHALAZINOL (EG 626) AND PYRIDINOLCARBAMATE (ANGININ) ON LIPOLYTIC ENZYME ACTIVITIES IN RAT ADIPOSE TISSUE -IN VIVO AND IN VITRO-

1980 ◽  
Vol 30 (1) ◽  
pp. 65-73 ◽  
Author(s):  
Takako TOMITA ◽  
Ikumi YONEKURA ◽  
Yasufumi SHIRASAKI ◽  
Eiichi HAYASHI ◽  
Fujio NUMANO
Keyword(s):  
Adipose Tissue ◽  
Enzyme Activities ◽  
Lipolytic Enzyme ◽  
Rat Adipose Tissue

scholarly journals Regulation of lipoprotein lipase activity and mRNA content in rat epididymal adipose tissue in vitro by recombinant tumour necrosis factor

1990 ◽  
Vol 269 (1) ◽  
pp. 123-126 ◽  
Author(s):  
A G Mackay ◽  
J D Oliver ◽  
M P Rogers
Keyword(s):  
Adipose Tissue ◽  
Tumour Necrosis Factor ◽  
Lipoprotein Lipase ◽  
Tumour Necrosis ◽  
Epididymal Adipose Tissue ◽  
Mrna Levels ◽  
Isolated Adipocytes ◽  
Necrosis Factor

Tumour necrosis factor (TNF) has previously been shown to decrease lipoprotein lipase (LPL) activity and mRNA levels in 3T3-L1 cells and in adipose tissue from rats and guinea pigs when injected in vivo, but not to alter LPL activity in human adipocytes incubated in vitro. The effect of recombinant human TNF on LPL activity and mRNA levels in rat epididymal adipose tissue incubated in vitro was examined. LPL activity and mRNA levels fell in adipose tissue taken from fed rats and incubated in Krebs-Henseleit bicarbonate medium with glucose. The addition of insulin and dexamethasone prevented these falls. TNF (400 ng/ml) produced a fall of approx. 50% in LPL activity after 2 h of incubation and of approx. 30% in LPL mRNA levels after 3 h. TNF did not decrease LPL activity in isolated adipocytes. These results demonstrate that rat adipose tissue incubated in vitro is responsive to TNF whereas isolated adipocytes are not.

OBSERVATIONS ON THE LIPOLYTIC ACTION IN VITRO OF A FAT-MOBILIZING SUBSTANCE EXTRACTED FROM URINE OF FASTING RATS

1966 ◽  
Vol 44 (1) ◽  
pp. 103-113 ◽  
Author(s):  
John R. Beaton ◽  
A. J. Szlavko ◽  
J. A. F. Stevenson
Keyword(s):  
Adipose Tissue ◽  
Young Male ◽  
High Protein Diet ◽  
Inhibitory Effect ◽  
Male Rat ◽  
Lipolytic Action ◽  
Electrolytic Ablation ◽  
Rat Adipose Tissue

An investigation has been carried out of factors in the lipolytic response of adipose tissue to a fat-mobilizing substance (FMS IB) extracted from the urine of fasting rats. Response was increased when rats were exposed to cold prior to removal of adipose tissue and was decreased in adipose tissue of rats rendered hyperphagic and obese by bilateral electrolytic ablation of the ventromedial region of the hypothalamus. These observations in vitro are consistent with observations on fat catabolism or storage in vivo after cold exposure and in hypothalamic hyperphagia.Previous feeding of a high-protein diet inhibited lipolytic response in vitro of adipose tissue to both FMS IB and adrenaline; previous feeding of a noncarbohydrate high-fat diet also inhibited lipolytic response to FMS IB but not to adrenaline. Of the adipose tissues tested, lipolytic response to FMS IB was in the order epididymal > perinephric > omentum. There was no sex difference in the response of adipose tissue; the response of adipose tissue of the young male rat was considerably less than that of the adult male rat. Adipose tissue of fasted rats was much more responsive to FMS IB than was that of fed rats. This response could be almost completely abolished by the addition of glucose (180 mg/100 ml) to the incubating medium; lesser concentrations of glucose had a smaller inhibitory effect. A linear lipolytic response of adipose tissue to increasing amounts of FMS IB has been demonstrated.

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