scholarly journals The effects of starvation and re-feeding on glycogen metabolism in mouse tail skin

1983 ◽  
Vol 212 (3) ◽  
pp. 679-683 ◽  
Author(s):  
C S Harmon ◽  
P J R Phizackerley
Keyword(s):  
Glycogen Content ◽  
Glycogen Synthase ◽  
Glycogen Synthesis ◽  
Glycogen Metabolism ◽  
Access To Food

Although the glycogen content of mouse tail skin was decreased during starvation and was restored on re feeding, the proportion of glycogen synthase in the I form remained constant throughout at about 10% of the total. During the phase of net glycogen synthesis 1.5h after access to food was restored, the concentration of UDP glucose was markedly increased and the proportion of phosphorylase in the a form was significantly decreased.

Effect of hypercorticism on regulation of skeletal muscle glycogen metabolism by insulin

1992 ◽  
Vol 262 (4) ◽  
pp. E427-E433 ◽  
Author(s):  
L. Coderre ◽  
A. K. Srivastava ◽  
J. L. Chiasson
Keyword(s):  
Muscle Glycogen ◽  
Glycogen Content ◽  
Activity Ratio ◽  
Glycogen Synthase ◽  
Glycogen Synthesis ◽  
Glycogen Metabolism ◽  
Dexamethasone Treatment ◽  
Muscle Glycogen Content ◽  
Glycogen Synthase Activity ◽  
Muscle Glycogen Concentration

The effects of hypercorticism on the regulation of glycogen metabolism by insulin in skeletal muscles was examined by using the hindlimb perfusion technique. Rats were injected daily with either saline or dexamethasone (0.4 mg.kg-1.day-1) for 14 days and were studied in the fed or fasted (24 h) state under saline or insulin (1 mU/ml) treatment. In fed controls, insulin resulted in glycogen synthase activation and in enhanced glycogen synthesis. In dexamethasone-treated animals, basal muscle glycogen concentration remained normal, but glycogen synthase activity ratio was decreased in white and red gastrocnemius and plantaris muscles. Furthermore, insulin failed to activate glycogen synthase and glycogen synthesis. In the controls, fasting was associated with decreased glycogen concentrations and with increased glycogen synthase activity ratio in all four groups of muscles (P less than 0.01). Dexamethasone treatment, however, completely abolished the decrease in muscle glycogen content as well as the augmented glycogen synthase activity ratio associated with fasting. Insulin infusion stimulated glycogen synthesis in fasted controls but not in dexamethasone-treated rats. These data therefore indicate that dexamethasone treatment inhibits the stimulatory effect of insulin on glycogen synthase activity and on glycogen synthesis. Furthermore, hypercorticism suppresses the decrease in muscle glycogen content associated with fasting.

Hormonal regulation of glycogen metabolism in white muscle slices from rainbow trout (Oncorhynchus mykiss Walbaum)

2004 ◽  
Vol 287 (6) ◽  
pp. R1344-R1353 ◽  
Author(s):  
Jason Frolow ◽  
C. Louise Milligan
Keyword(s):  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Muscle Glycogen ◽  
Hormonal Regulation ◽  
White Muscle ◽  
Glycogen Content ◽  
Glycogen Synthase ◽  
Glycogen Synthesis ◽  
Glycogen Metabolism ◽  
Rainbow Trout Oncorhynchus Mykiss

To test the hypothesis that cortisol and epinephrine have direct regulatory roles in muscle glycogen metabolism and to determine what those roles might be, we developed an in vitro white muscle slice preparation from rainbow trout ( Oncorhynchus mykiss Walbaum). In the absence of hormones, glycogen-depleted muscle slices obtained from exercised trout were capable of significant glycogen synthesis, and the amount of glycogen synthesized was inversely correlated with the initial postexercise glycogen content. When postexercise glycogen levels were <5 μmol/g, about 4.3 μmol/g of glycogen were synthesized, but when postexercise glycogen levels were >5 μmol/g, only about 1.7 μmol/g of glycogen was synthesized. This difference in the amount of glycogen synthesized was reflected in the degree of activation of glycogen synthase. Postexercise glycogen content also influenced the response of the muscle to 10−8 M epinephrine and 10−8 M dexamethasone (a glucocorticoid analog). At high glycogen levels (>5 μmol/g), epinephrine and dexamethasone stimulated glycogen phosphorylase activity and net glycogenolysis, whereas at low (<5 μmol/g) glycogen levels, glycogenesis and activation of glycogen synthase activity prevailed. These data clearly indicate not only is trout muscle capable of in situ glycogenesis, but the amount of glycogen synthesized is a function of initial glycogen content. Furthermore, whereas dexamethasone and epinephrine directly stimulate muscle glycogen metabolism, the net effect is dependent on initial glycogen content.

scholarly journals Postprandial Glycogen Content Is Increased in the Hepatocytes of Human and Rat Cirrhotic Liver

Cells ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 976
Author(s):  
Natalia N. Bezborodkina ◽  
Sergey V. Okovityi ◽  
Boris N. Kudryavtsev
Keyword(s):  
Rat Liver ◽  
Liver Tissue ◽  
Glycogen Content ◽  
Glycogen Synthase ◽  
Fibrous Tissue ◽  
Glycogen Metabolism ◽  
Liver Parenchyma ◽  
Dry Mass ◽  
Cirrhotic Liver ◽  
Liver Biopsies

Chronic hepatitises of various etiologies are widespread liver diseases in humans. Their final stage, liver cirrhosis (LC), is considered to be one of the main causes of hepatocellular carcinoma (HCC). About 80–90% of all HCC cases develop in LC patients, which suggests that cirrhotic conditions play a crucial role in the process of hepatocarcinogenesis. Carbohydrate metabolism in LC undergoes profound disturbances characterized by altered glycogen metabolism. Unfortunately, data on the glycogen content in LC are few and contradictory. In this study, the material was obtained from liver biopsies of patients with LC of viral and alcohol etiology and from the liver tissue of rats with CCl4-induced LC. The activity of glycogen phosphorylase (GP), glycogen synthase (GS), and glucose-6-phosphatase (G6Pase) was investigated in human and rat liver tissue by biochemical methods. Total glycogen and its labile and stable fractions were measured in isolated individual hepatocytes, using the cytofluorometry technique of PAS reaction in situ. The development of LC in human and rat liver was accompanied by an increase in fibrous tissue (20- and 8.8-fold), an increase in the dry mass of hepatocytes (by 25.6% and 23.7%), and a decrease in the number of hepatocytes (by 50% and 28%), respectively. The rearrangement of the liver parenchyma was combined with changes in glycogen metabolism. The present study showed a significant increase in the glycogen content in the hepatocytes of the human and the rat cirrhotic liver, by 255% and 210%, respectively. An increased glycogen content in cells of the cirrhotic liver can be explained by a decrease in glycogenolysis due to a decreased activity of G6Pase and GP.

Insulin promotes glycogen synthesis in the absence of GSK3 phosphorylation in skeletal muscle

2008 ◽  
Vol 294 (1) ◽  
pp. E28-E35 ◽  
Author(s):  
Michale Bouskila ◽  
Michael F. Hirshman ◽  
Jørgen Jensen ◽  
Laurie J. Goodyear ◽  
Kei Sakamoto
Keyword(s):  
Skeletal Muscle ◽  
Glucose Uptake ◽  
Muscle Glycogen ◽  
Glycogen Content ◽  
Glycogen Synthase ◽  
Glycogen Synthesis ◽  
Wild Type ◽  
Muscle Glycogen Synthesis ◽  
Mutant Forms

Insulin promotes dephosphorylation and activation of glycogen synthase (GS) by inactivating glycogen synthase kinase (GSK) 3 through phosphorylation. Insulin also promotes glucose uptake and glucose 6-phosphate (G-6- P) production, which allosterically activates GS. The relative importance of these two regulatory mechanisms in the activation of GS in vivo is unknown. The aim of this study was to investigate if dephosphorylation of GS mediated via GSK3 is required for normal glycogen synthesis in skeletal muscle with insulin. We employed GSK3 knockin mice in which wild-type GSK3α and -β genes are replaced with mutant forms (GSK3α/βS21A/S21A/S9A/S9A), which are nonresponsive to insulin. Although insulin failed to promote dephosphorylation and activation of GS in GSK3α/βS21A/S21A/S9A/S9Amice, glycogen content in different muscles from these mice was similar compared with wild-type mice. Basal and epinephrine-stimulated activity of muscle glycogen phosphorylase was comparable between wild-type and GSK3 knockin mice. Incubation of isolated soleus muscle in Krebs buffer containing 5.5 mM glucose in the presence or absence of insulin revealed that the levels of G-6- P, the rate of [14C]glucose incorporation into glycogen, and an increase in total glycogen content were similar between wild-type and GSK3 knockin mice. Injection of glucose containing 2-deoxy-[3H]glucose and [14C]glucose also resulted in similar rates of muscle glucose uptake and glycogen synthesis in vivo between wild-type and GSK3 knockin mice. These results suggest that insulin-mediated inhibition of GSK3 is not a rate-limiting step in muscle glycogen synthesis in mice. This suggests that allosteric regulation of GS by G-6- P may play a key role in insulin-stimulated muscle glycogen synthesis in vivo.

scholarly journals Transgenic overexpression of protein targeting to glycogen markedly increases adipocytic glycogen storage in mice

2007 ◽  
Vol 292 (3) ◽  
pp. E952-E963 ◽  
Author(s):  
Michael J. Jurczak ◽  
Arpad M. Danos ◽  
Victoria R. Rehrmann ◽  
Margaret B. Allison ◽  
Cynthia C. Greenberg ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Fatty Acid ◽  
Glycogen Synthase ◽  
Glycogen Synthesis ◽  
Transgenic Animals ◽  
Glycogen Metabolism ◽  
Glycogen Storage ◽  
Fatty Acid Binding ◽  
Fat Depots

Adipocytes express the rate-limiting enzymes required for glycogen metabolism and increase glycogen synthesis in response to insulin. However, the physiological function of adipocytic glycogen in vivo is unclear, due in part to the low absolute levels and the apparent biophysical constraints of adipocyte morphology on glycogen accumulation. To further study the regulation of glycogen metabolism in adipose tissue, transgenic mice were generated that overexpressed the protein phosphatase-1 (PP1) glycogen-targeting subunit (PTG) driven by the adipocyte fatty acid binding protein (aP2) promoter. Exogenous PTG was detected in gonadal, perirenal, and brown fat depots, but it was not detected in any other tissue examined. PTG overexpression resulted in a modest redistribution of PP1 to glycogen particles, corresponding to a threefold increase in the glycogen synthase activity ratio. Glycogen synthase protein levels were also increased twofold, resulting in a combined greater than sixfold enhancement of basal glycogen synthase specific activity. Adipocytic glycogen levels were increased 200- to 400-fold in transgenic animals, and this increase was maintained to 1 yr of age. In contrast, lipid metabolism in transgenic adipose tissue was not significantly altered, as assessed by lipogenic rates, weight gain on normal or high-fat diets, or circulating free fatty acid levels after a fast. However, circulating and adipocytic leptin levels were doubled in transgenic animals, whereas adiponectin expression was unchanged. Cumulatively, these data indicate that murine adipocytes are capable of storing far higher levels of glycogen than previously reported. Furthermore, these results were obtained by overexpression of an endogenous adipocytic protein, suggesting that mechanisms may exist in vivo to maintain adipocytic glycogen storage at a physiological set point.

Glycogen Metabolism in Psoriatic Epidermis and in Regenerating Epidermis

1984 ◽  
Vol 67 (3) ◽  
pp. 291-298 ◽  
Author(s):  
C. S. Harmon ◽  
P. J. R. Phizackerley
Keyword(s):  
Glycogen Content ◽  
Glycogen Synthase ◽  
Quantitative Estimation ◽  
Glycogen Synthesis ◽  
Pentose Phosphate ◽  
Normal Epithelium ◽  
Glycogen Synthase Activity ◽  
Psoriatic Lesions ◽  
Wound Epithelium

1. The observation that the glycogen content of epidermis from psoriatic lesions and from regenerating wound epithelium is increased has been confirmed by quantitative estimation. 2. In epidermis from psoriatic lesions, although the proportion of glycogen synthase in the I form is only about 5% of the total and similar to control values, total glycogen synthase activity is increased approximately 4-fold and hence glycogen synthase I activity is increased to the same extent. In contrast, total phosphorylase activity is only slightly increased and, since the proportion of the enzyme in the a form is reduced, phosphorylase a activity is similar to control values. 3. In epidermis from psoriatic lesions, the concentration of UDP-glucose is approximately doubled, and the concentrations of fructose 1,6-bisphosphate and of 6-phosphogluconate are increased approximately 5-fold. It is concluded that rates of glycogen synthesis, of glycolysis and of the pentose phosphate pathway are all enhanced in vivo and in consequence the rate of glucose uptake by psoriatic epidermis must be increased. 4. In the non-involved epidermis of psoriatic patients the glycogen content is within normal limits, and although total glycogen synthase activity is increased the ratio of glycogen synthase I to phosphorylase a is maintained at normal levels by the appropriate phosphorylation of both enzymes. 5. In regenerating wound epithelium in the pig, the changes in enzyme activity and in metabolite concentration closely resemble those found in epithelium from psoriatic lesions except that in wound epithelium the proportion of phosphorylase in the a form is increased relative to normal epithelium.

scholarly journals Link between Phosphate Starvation and Glycogen Metabolism in Corynebacterium glutamicum, Revealed by Metabolomics

2010 ◽  
Vol 76 (20) ◽  
pp. 6910-6919 ◽  
Author(s):  
Han Min Woo ◽  
Stephan Noack ◽  
Gerd M. Seibold ◽  
Sabine Willbold ◽  
Bernhard J. Eikmanns ◽  
...  
Keyword(s):  
Stationary Phase ◽  
Corynebacterium Glutamicum ◽  
Carbon Flux ◽  
Glycogen Content ◽  
Glycogen Synthesis ◽  
Glycogen Metabolism ◽  
Metabolite Analysis ◽  
Glycogen Level ◽  
Flux Balance ◽  
Balance Analysis

ABSTRACT In this study, we analyzed the influence of phosphate (Pi) limitation on the metabolism of Corynebacterium glutamicum. Metabolite analysis by gas chromatography-time-of-flight (GC-TOF) mass spectrometry of cells cultivated in glucose minimal medium revealed a greatly increased maltose level under Pi limitation. As maltose formation could be linked to glycogen metabolism, the cellular glycogen content was determined. Unlike in cells grown under Pi excess, the glycogen level in Pi-limited cells remained high in the stationary phase. Surprisingly, even acetate-grown cells, which do not form glycogen under Pi excess, did so under Pi limitation and also retained it in stationary phase. Expression of pgm and glgC, encoding the first two enzymes of glycogen synthesis, phosphoglucomutase and ADP-glucose pyrophosphorylase, was found to be increased 6- and 3-fold under Pi limitation, respectively. Increased glycogen synthesis together with a decreased glycogen degradation might be responsible for the altered glycogen metabolism. Independent from these experimental results, flux balance analysis suggested that an increased carbon flux to glycogen is a solution for C. glutamicum to adapt carbon metabolism to limited Pi concentrations.

scholarly journals Heating after intense repeated contractions inhibits glycogen accumulation in mouse EDL muscle: role of phosphorylase in postexercise glycogen metabolism

2018 ◽  
Vol 315 (5) ◽  
pp. C706-C713 ◽  
Author(s):  
Sarah J. Blackwood ◽  
Ester Hanya ◽  
Abram Katz
Keyword(s):  
Glycogen Synthase ◽  
Glycogen Synthesis ◽  
Glycogen Metabolism ◽  
Type Ii ◽  
Muscle Type ◽  
Phosphorylase Activity ◽  
Glycogen Accumulation ◽  
Longus Muscle ◽  
Edl Muscle

The effects of heating on glycogen synthesis (incorporation of [14C]glucose into glycogen) and accumulation after intense repeated contractions were investigated. Isolated mouse extensor digitorum longus muscle (type II) was stimulated electrically to perform intense tetanic contractions at 25°C. After 120 min recovery at 25°C, glycogen accumulated to almost 80% of basal, whereas after recovery at 35°C, glycogen remained low (~25% of basal). Glycogen synthesis averaged 0.97 ± 0.07 µmol·30 min−1·g wet wt−1 during recovery at 25°C and 1.48 ± 0.08 during recovery at 35°C ( P < 0.001). There were no differences in phosphorylase and glycogen synthase total activities nor in phosphorylase fractional activity, whereas glycogen synthase fractional activity was increased by ~50% after recovery at 35°C vs. 25°C. Inorganic phosphate (Pi, substrate for phosphorylase) was markedly increased (~300% of basal) following contraction but returned to control levels after 120 min recovery at 25°C. In contrast, Pi remained elevated after recovery at 35°C (>2-fold higher than recovery at 25°C). Estimates of glycogen breakdown indicated that phosphorylase activity (either via inhibition at 25°C or activation at 35°C) was responsible for ~60% of glycogen accumulation during recovery at 25°C and ~45% during recovery at 35°C. These data demonstrate that despite the enhancing effect of heating on glycogen synthesis during recovery from intense contractions, glycogen accumulation is inhibited owing to Pi-mediated activation of phosphorylase. Thus phosphorylase can play a quantitatively important role in glycogen biogenesis during recovery from repeated contractions in isolated type II muscle.

Liver and peripheral tissue glycogen metabolism in obese mice: effect of a mixed meal

1993 ◽  
Vol 265 (5) ◽  
pp. E743-E751
Author(s):  
C. Chen ◽  
P. F. Williams ◽  
I. D. Caterson
Keyword(s):  
Skeletal Muscle ◽  
Adipose Tissue ◽  
Cardiac Muscle ◽  
White Adipose Tissue ◽  
Glycogen Content ◽  
Glycogen Synthase ◽  
Glycogen Metabolism ◽  
Glycogen Storage ◽  
Obese Mice ◽  
Entire Study

Glycogen metabolism in the liver, skeletal muscle, cardiac muscle, and white adipose tissue was studied in gold thioglucose (GTG) obese mice after fasting and during refeeding. Prolonged (48 h) fasted control and GTG mice were refed with standard laboratory diet for 24 h. During fasting and refeeding, the changes in glycogen content and the activity of glycogen synthase I and R and phosphorylase alpha in the liver were similar in lean and GTG mice. However, the glycogen storage in the livers from GTG mice was always greater than that in lean animals. In GTG mice the activity of liver glycogen synthase I and R was significantly higher than that in lean animals 3 and 6 h after refeeding. The activity of liver phosphorylase alpha in GTG mice was higher than that in lean mice after refeeding. There were no significant differences in the glycogen content of white adipose tissue, cardiac muscle, and skeletal muscle from lean and GTG mice during the entire study. The results of this study suggest that increased glycogen storage in the liver is a major alteration in nonoxidative glucose metabolism and contributes to the development of insulin resistance and glucose intolerance in GTG obese mice.

Effect of hypercorticism on regulation of skeletal muscle glycogen metabolism by epinephrine

1992 ◽  
Vol 262 (4) ◽  
pp. E434-E439 ◽  
Author(s):  
L. Coderre ◽  
A. K. Srivastava ◽  
J. L. Chiasson
Keyword(s):  
Skeletal Muscle ◽  
Muscle Glycogen ◽  
Glycogen Content ◽  
Activity Ratio ◽  
Glycogen Synthase ◽  
Glycogen Metabolism ◽  
Dexamethasone Treatment ◽  
Fed State ◽  
Glycogen Concentration ◽  
Glycogen Synthase Activity

The effect of hypercorticism on the regulation of glycogen metabolism by epinephrine was examined in skeletal muscles using a hindlimb perfusion technique. Rats were injected with either saline or dexamethasone (0.4 mg.kg-1.day-1) for 14 days and were studied in the fed and fasted (24 h) states under saline or epinephrine (10(-7) M) treatment. In the fed state, dexamethasone administration did not affect basal glycogen concentration but decreased glycogen synthase activity ratio in white and red gastrocnemius muscles. Epinephrine failed to decrease glycogen content despite the expected activation of glycogen phosphorylase in the fed dexamethasone-treated rats. Dexamethasone treatment resulted in a threefold increase in the level of muscle adenosine, a phosphorylase a inhibitor. In control rats, fasting was associated with a decrease in muscle glycogen concentration (P less than 0.01) and with an increase in the glycogen synthase activity ratio. Dexamethasone treatment, however, totally abolished both the decreased muscle glycogen content and glycogen synthase activation observed in fasting controls. In the dexamethasone-treated group, fasting restored the glycogenolytic effect of epinephrine. Interestingly, it was associated with decreased muscle adenosine concentrations. These data indicate that, in the fed state, dexamethasone treatment inhibits skeletal muscle glycogenolysis in response to epinephrine despite phosphorylase activation and glycogen synthase inactivation. It is suggested that this abnormality could be due to the inhibition of phosphorylase a by increased muscle adenosine levels.

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