scholarly journals Clearing-factor lipase in adipose tissue. Studies with puromycin and actinomycin

1968 ◽  
Vol 106 (3) ◽  
pp. 667-676 ◽  
Author(s):  
D. R. Wing ◽  
D S Robinson
Keyword(s):  
Enzyme Activity ◽  
Adipose Tissue ◽  
Lipase Activity ◽  
Half Life ◽  
Incubation Medium ◽  
Time Course

1. When adipose tissue from starved rats is incubated in a medium containing glucose, insulin, heparin and actinomycin (5μg./ml.) the total clearing-factor lipase activity of the system increases at least tenfold over a period of 9hr. In the absence of actinomycin, enzyme activity also increases, but to a lesser extent and for only about 3hr. Some enzyme activity appears in the incubation medium in both the presence and the absence of actinomycin. 2. When the glucose and insulin of the incubation medium are replaced by pyruvate and heparin is omitted, an increase in the total clearing-factor lipase activity in the presence of actinomycin still occurs, but only after a lag of several hours. When only heparin is omitted from the medium, the rise in enzyme activity begins immediately, but there is a shoulder in the time-course curve after a few hours. In the absence of heparin, little enzyme activity appears in the incubation medium. 3. The increases in enzyme activity in the presence of actinomycin are prevented if puromycin (0·5mg./ml.) is present in the incubation medium. 4. Catecholamines and corticotrophin inhibit the increase in enzyme activity caused by actinomycin. 5. The clearing-factor lipase activity of adipose tissue from fed animals declines with a half-life of between 1 and 1·5hr. when the tissue is incubated in the presence of puromycin. The clearing-factor lipase activity of adipose tissue from starved animals is stable under similar circumstances, as is the raised activity found after such tissue has been incubated in the presence of actinomycin. 6. Clearing-factor lipase extracted from adipose tissue of fed animals is less stable in solution than that extracted from the tissue of starved animals after this has been incubated in the presence of actinomycin.

scholarly journals The clearing-factor lipase activity of isolated fat-cells

1975 ◽  
Vol 146 (2) ◽  
pp. 481-488 ◽  
Author(s):  
A Cryer ◽  
P Davies ◽  
E R Williams ◽  
D S Robinson
Keyword(s):  
Enzyme Activity ◽  
Adipose Tissue ◽  
Lipase Activity ◽  
Incubation Medium ◽  
Cell Activity ◽  
Molecular Forms ◽  
Epididymal Adipose Tissue ◽  
Fat Cells ◽  
Isolated Fat Cells ◽  
Fat Cell

1. When fat-cells are isolated from the epididymal adipose tissue of 24h-starved rats and incubated at 25 degrees C in the presence of dialysed serum, glucose, insulin, amino acids and heparin, the total clearing-factor lipase acitivity of the incubation system increases progressively over a period of several hours. 2. All of the increase in activity is accounted for by the appearance of enzyme in the appearance of enzyme in the incubation medium and the fat-cell activity does not change significantly. Cycloheximids, at a concentration that prevents protein synthesis, does not affect the appearance of enzyme in the incubation medium, but the fat-cell enzyme activity is decreased in its presence. 3. The magnitude of the increase in total clearing factor lipase activity is unaffected by the omission of heparin from the medium. However, less enzyme is extracted in tis absence and the fat-cell activity increases. Cycloheximide again only affects the rise in cell activity and does not alter the activity in the incubation medium. 4. When serum in the incubation medium is replaced by casein, the distribution of enzyme between the cells and the medium is changed, but the magnitudes of the increases in total enzyme activity are similar. 5. These characteristics of the clearing-factor lipase response of isolated fat-cells differ in several respects from those observed earlier with intact adipose tissue from 24h-starved rats (Robinson & Wing, 1971; Cryer et al., 1973). The differences could be due, in part, to changes in the relative amounts of two different molecular forms of the enzyme that occur during the isolation of the fat-cells.

Refeeding and insulin increase lipoprotein lipase activity in rat brown adipose tissue

1989 ◽  
Vol 256 (5) ◽  
pp. E645-E650 ◽  
Author(s):  
C. M. Carneheim ◽  
S. E. Alexson
Keyword(s):  
Enzyme Activity ◽  
Adipose Tissue ◽  
Brown Adipose Tissue ◽  
Lipoprotein Lipase ◽  
Lipase Activity ◽  
Starvation Period ◽  
Lipoprotein Lipase Activity ◽  
Mrna Synthesis ◽  
Beta Adrenergic ◽  
Brown Adipose

Induction of lipoprotein lipase activity in brown adipose tissue (BAT) in response to cold stress has earlier been shown to be regulated by a beta-adrenergic mechanism and to be dependent on mRNA synthesis. In the present study, we have investigated the acute effects of refeeding after a short starvation period and the hormonal mechanism underlying the observed effects. Refeeding was found to rapidly increase tissue wet weight and lipoprotein lipase activity. The increase in enzyme activity could be blocked by the RNA synthesis inhibitor actinomycin D, indicating a gene activation. beta-Adrenergic blockade had no effect on this elevation of enzyme activity, but the increase could be mimicked by insulin injection. The results suggest that BAT contains two different pathways for regulation of lipoprotein lipase activity, both involving mRNA synthesis.

Effect of exercise on hormone-sensitive lipase activity in rat adipocytes

1976 ◽  
Vol 230 (2) ◽  
pp. 385-388 ◽  
Author(s):  
JA McGarr ◽  
LB Oscai ◽  
J Borensztajn
Keyword(s):  
Fatty Acids ◽  
Enzyme Activity ◽  
Adipose Tissue ◽  
Free Fatty Acids ◽  
Lipase Activity ◽  
Exercise Program ◽  
Treadmill Running ◽  
Hormone Sensitive Lipase ◽  
Hormone Sensitive ◽  
Fat Pads

Hormone-sensitive lipase activity was measured in adipocytes of rats subjected to a 12-wk program of treadmill running. Enzyme activity in the runners sacrificed immediately after exercise increased 2.5-fold (P less than 0.001) in tissue exposed to epinephrine and threefold (P less than 0.001) in tissue not exposed to epinephrine, when the results were expressed per gram of adipose tissue. Increases of almost the same magnitude were observed in runners sacrificed 24 h after their last bout of work. These significant increases in enzyme activity, however, were the result of a significant reduction in the size of cells in the epididymal fat pads of the exercisers compared with those of the freely eating sedentary animals (68.7 +/- 2.7 mum vs. 82.0 +/- 2.7 mum; P less than 0.01). When the results were expressed on a per-cell basis, therefore, hormone-sensitive lipase activity, assayed in the presence or absence of epinephrine, was unaffected by the exercise program. These results provide evidence that the lipolytic capacity of adipocytes of normal, untrained rats is sufficiently large to meet the increased demand for free fatty acids imposed by the exercise program without the need for an adaptive increase in enzyme activity.

scholarly journals Changes in the lipoprotein lipase (clearing-factor lipase) activity of white adipose tissue during development of the rat

1978 ◽  
Vol 172 (2) ◽  
pp. 319-325 ◽  
Author(s):  
A Cryer ◽  
H M Jones
Keyword(s):  
Enzyme Activity ◽  
Adipose Tissue ◽  
Lipoprotein Lipase ◽  
White Adipose Tissue ◽  
Lipase Activity ◽  
Plasma Insulin ◽  
Serum Concentrations ◽  
Lipoprotein Lipase Activity ◽  
Activity Change ◽  
Adipose Tissue Lipoprotein Lipase

The lipoprotein lipase (clearing-factor lipase) activity of the white adipose tissue from rats aged between 1 and 145 days was determined. Five adipose-tissue sites (epididymal, uterine, subcutaneous, perirenal and intramuscular) together with serum concentrations of triacylglycerol, cholesterol and glucose were studied. The pattern of enzyme-activity change was remarkably similar in all the sites studied, although the growth of the tissues proceeded non-uniformly. After a peak of activity early in suckling, lipoprotein lipase activity fell to low values by 20 days of age. At weaning (21 days) the activity increased sharply and within 5 days high values were regained. The serum triacylglycerol and cholesterol concentrations were low at birth and reached peaks of concentration coincidentally with the minima of white-adipose-tissue lipoprotein lipase activities, seen late in suckling. The changes in enzyme activity were related to other metabolic changes in adipose tissue and with the known changes in plasma insulin concentrations occurring during development.

Time course of changes in serum glucose, insulin, lipids and tissue lipase activities in macrosomic offspring of rats with streptozotocin-induced diabetes

1999 ◽  
Vol 98 (1) ◽  
pp. 21-30 ◽  
Author(s):  
H. MERZOUK ◽  
S. MADANI ◽  
D. CHABANE SARI ◽  
J. PROST ◽  
M. BOUCHENAK ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Lipase Activity ◽  
Time Course ◽  
Hepatic Lipase ◽  
Serum Insulin ◽  
Serum Glucose ◽  
Lipid Levels ◽  
Citrate Buffer ◽  
Pregnant Rats ◽  
Metabolic Complications

The aim of this investigation was to determine the time course of changes in serum glucose, insulin and lipid levels, as well as lipid and protein content and lipolytic activities in insulin target organs (liver, adipose tissue and muscle), in macrosomic offspring of streptozotocin-induced mildly hyperglycaemic rats. Food intake and nutritional efficiency were also evaluated. Mild hyperglycaemia in pregnant rats was induced by intraperitoneal injection of streptozotocin (40 mg/kg body weight) on day 5 of gestation. Control pregnant rats were injected with citrate buffer. At birth, macrosomic pups (birth weight > 1.7 S.D. greater than the mean value for the control pups) had higher serum insulin, glucose and lipid levels than control pups. These macrosomic rats maintained accelerated postnatal growth combined with high adipose tissue weight up to 12 weeks of age. These rats were not hyperphagic; however, they had higher food efficiency and fat storage capacity with higher adipocyte lipoprotein lipase activity, which contributed to persisting obesity. Hepatic lipase activity was increased in macrosomic rats at all ages. Moreover, macrosomia was associated with metabolic disturbances that varied according to age and sex. After 1 month, several alterations observed at birth had disappeared. Serum glucose, insulin and lipid levels in male and female macrosomic rats became similar to those of their respective controls. At 2 months of age, hepatic and serum triacylglycerol levels were higher in macrosomic females than in controls. By 3 months, macrosomic rats (both males and females) had developed insulin resistance with hyperinsulinaemia, hyperglycaemia, and higher serum and hepatic lipids. In conclusion, macrosomia was associated with alterations in glucose and lipid metabolism through to adulthood. It should be considered as an important potential risk factor for obesity and its metabolic complications.

scholarly journals Effects of platelet-activating factor on lipid metabolism in rats in vivo. Origin of the hypertriglyceridaemia

1991 ◽  
Vol 280 (2) ◽  
pp. 541-543 ◽  
Author(s):  
R D Evans ◽  
V Ilic ◽  
D H Williamson
Keyword(s):  
Adipose Tissue ◽  
Lipid Metabolism ◽  
Brown Adipose Tissue ◽  
Lipase Activity ◽  
Half Life ◽  
Platelet Activating Factor ◽  
Lipoprotein Lipase Activity ◽  
Brown Adipose ◽  
Important Site

Administration of platelet-activating factor (1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine; PAF) did not alter the rate of triacylglycerol entry into the plasma. The gastrointestinal absorption of [1-14C]triolein was, however, inhibited by PAF, yet there was increased accumulation of [14C]lipid in the plasma and hypertriglyceridaemia. The half-life of injected [9,10(n)-3H]triolein in the plasma increased by 47%, and there was decreased accumulation of [3H]lipid in brown adipose tissue. This was accompanied by a decrease in lipoprotein lipase activity. The hypertriglyceridaemia induced by PAF appears to be mainly due to decreased peripheral removal, one important site affected being brown adipose tissue.

The hysteretic effect of Gpp(NH)p on adenylate cyclase is not altered by Mg2+ in adipocyte membranes of ob/ob mice

1986 ◽  
Vol 64 (9) ◽  
pp. 855-863 ◽  
Author(s):  
Nicole Bégin-Heick
Keyword(s):  
Adipose Tissue ◽  
Steady State ◽  
Adenylate Cyclase ◽  
Cholera Toxin ◽  
Incubation Medium ◽  
Time Course ◽  
Inhibitory Effect ◽  
Lag Phase ◽  
Guanine Nucleotide ◽  
Hysteretic Effect

We have established previously that the regulation of adenylate cyclase is abnormal in adipose tissue membranes of ob/ob mice. To help establish the nature of the defect, we studied the time course of guanine nucleotide activation and inhibition of adenylate cyclase. The activation of adenylate cyclase by Gpp(NH)p in adipocyte membranes of normal (+/+) and ob/ob mice proceeds with a lag phase. In +/+ membranes, this lag could be shortented by increasing the concentration of Mg2+ in the incubation medium or by pretreatment of the membranes with cholera toxin, and it could be abolished by isoproterenol in combination with 4 mM MgCl2. In contrast, in the ob/ob membranes, only pretreatment with cholera toxin was effective in shortening the lag phase. These results indicate an impediment in the activation of adenylate cyclase in ob/ob membranes. In the +/+ membranes, Gpp(NH)p inhibited forskolin-stimulated adenylate cyclase, following a short lag phase, producing lower steady-state velocities than those seen with forskolin alone. The inhibitory effect of Gpp(NH)p on forskolin-stimulated activity was abolished by pertussis but not by cholera toxin treatment. In the ob/ob membranes, neither Gpp(NH)p nor pertussis treatment had any effect on the steady-state velocity of the forskolin-stimulated activity. These data have been interpreted as meaning that an anomaly in Ni rather than in Ns is likely to be responsible for the impairment of adenylate cyclase activity in the membranes of the ob/ob mouse.

scholarly journals Developmental changes in the activity of lipoprotein lipase (clearing-factor lipase) in rat lung, cardiac muscle, skeletal muscle and brown adipose tissue

1978 ◽  
Vol 174 (2) ◽  
pp. 447-451 ◽  
Author(s):  
A Cryer ◽  
H M Jones
Keyword(s):  
Skeletal Muscle ◽  
Enzyme Activity ◽  
Adipose Tissue ◽  
Brown Adipose Tissue ◽  
Lipoprotein Lipase ◽  
Time Course ◽  
Adult Life ◽  
Unit Weight ◽  
Normal Delivery ◽  
Brown Adipose

The lipoprotein lipase activity of the lung, skeletal muscle, heart muscle and brown adipose tissue of the rat was studied during the period from late foetal to adult life. The enzyme activity in all four tissues emerged substantially during the first 24th after birth. Subsequently, heart and lung enzyme activity remained relatively constant per unit wet weight of tissue. The enzyme activity present in brown adipose tissue and skeletal muscle was elevated per unit weight of tissue during suckling compared with other periods of life. Delivery of near-term foetuses stimulated the emergence of enzyme activity in all four tissues with the same time course as that evoked by normal delivery. The significance of the presence of the enzyme in the tissues and the activity changes which occurred during development are discussed in relation to possible mechanisms of control.

scholarly journals Regulation of lipoprotein lipase activity and mRNA in the mammary gland of the lactating mouse

1994 ◽  
Vol 298 (2) ◽  
pp. 321-327 ◽  
Author(s):  
D R Jensen ◽  
S Gavigan ◽  
V Sawicki ◽  
D L Witsell ◽  
R H Eckel ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Adipose Tissue ◽  
Mammary Gland ◽  
Lipoprotein Lipase ◽  
Lipase Activity ◽  
Physiological State ◽  
Mouse Mammary Gland ◽  
Reproductive Stage ◽  
Lipoprotein Lipase Activity ◽  
Translational Level

We examined the effects of reproductive stage and fasting on lipoprotein lipase (LPL) activity and mRNA in the mouse mammary gland. Heparin-releasable and cell-associated LPL activity rose immediately after birth, followed 1-2 days later by an increase in LPL mRNA. Fasting decreased LPL activity in the mammary gland at all reproductive stages. During lactation, both milk and heparin-releasable LPL were substantially decreased by an overnight fast, whereas cell-associated LPL was less affected and LPL mRNA did not change. These studies indicate that the extracellular, heparin-releasable, fraction of mammary LPL activity responds most rapidly to alterations in physiological state, usually accompanied by smaller changes in cellular enzyme activity. Changes in the level of LPL mRNA were seen only during the transition from pregnancy to lactation, and these tended to follow, rather than precede, changes in enzyme activity. We conclude that in the mammary gland as in adipose tissue, LPL is regulated primarily at the translational and post-translational level.

Comparative effects of insulin and isoproterenol on lipoprotein lipase in rat adipose cells

1996 ◽  
Vol 270 (5) ◽  
pp. C1461-C1467 ◽  
Author(s):  
G. E. Chiappe de Cingalani ◽  
J. W. Goers ◽  
M. Giannotti ◽  
C. I. Caldiz
Keyword(s):  
Enzyme Activity ◽  
Lipoprotein Lipase ◽  
Lipase Activity ◽  
Incubation Medium ◽  
Cell Membranes ◽  
Lipoprotein Lipase Activity ◽  
Rat Adipocytes ◽  
Enzyme Degradation ◽  
Cell Incubation ◽  
Adipose Cells

The effects of insulin and isoproterenol on lipoprotein lipase mass and enzyme activity were investigated in rat adipocytes. Cells were pulse labeled for 1 h with [35S]methionine to measure immunoprecipitable lipoprotein lipase. The results showed that 80% of the newly synthesized enzyme was membrane associated and 20% was secreted into the cell incubation medium. Enzyme activity was mainly associated with lipoprotein lipase secreted into the medium. A 10-min incubation with 10(-7) M insulin stimulated the secretion of lipoprotein lipase activity and the activity associated with adipocyte membranes. Conversely, 10(-6) M isoproterenol decreased the activity in all fractions. In addition, insulin increased lipoprotein lipase mass associated with cell membranes and decreased that in the incubation medium, whereas isoproterenol induced a decrease in both cell membranes and medium. Insulin and isoproterenol stimulated phosphorylation of lipoprotein lipase. These findings suggest that insulin stimulates the secretion of active lipoprotein lipase and a reuptake of inactive secreted enzyme, and isoproterenol decreases the activity by enzyme degradation. Moreover, because both agents stimulate phosphorylation of lipoprotein lipase, phosphorylation may play a role in the effect of insulin increasing enzyme activity, in secretion or reuptake, and in the effect of isoproterenol inducing degradation of lipoprotein lipase.

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