scholarly journals The Role of Hormones in the Regulation of Glycogen Metabolism in the Clawed Toad Xenopus Laevis (Daudin)

2019 ◽  
pp. 17-24
Author(s):  
Daphna Atar-Zwillenberg ◽  
Michael Atar ◽  
Gianni Morson ◽  
Udo Spornitz
Keyword(s):  
Blood Glucose ◽  
Xenopus Laevis ◽  
Muscle Glycogen ◽  
Hormonal Regulation ◽  
Glycogen Content ◽  
Glycogen Metabolism ◽  
Liver Glycogen ◽  
Hepatic Glycogen ◽  
Lipid Levels ◽  
Liver Glycogen Content

The hormonal regulation of amphibian glycogen metabolism was studied in Xenopus laevis as a typical member of the anurans (tailless amphibians).The main focus of this study was given to the effects of various hormones on the glycogen/glucose balance in adult toads. We determined biochemically the liver and muscle glycogen contents as well as the blood glucose and lipid levels for a number of hormones and also diabetes inducing substances. Additionally, we examined ultrastructure changes in hepatocytes induced by the various treatments, and also investigated the activity of carbohydrate-relevant enzymes by histochemistry. With one exception, the liver glycogen content of Xenopus remained basically unchanged by the treatments or was even slightly enhanced. Only human chorionic gonadotropin, through which the vitellogenic response is triggered, prompts a significant decrease of liver glycogen in females. Under the same conditions the male liver glycogen content remained stable. Muscle glycogen contents were not affected by any of the treatments. Blood glucose and lipid levels on the other hand were elevated considerably in both sexes after application of either epinephrine or cortisol. The ultrastructural examination revealed a proliferation of Rough Endoplasmic Reticulum (RER) in hepatocytes from epinephrine treated toads of both sexes as well as from HCG treated females. By histochemistry, we detected an elevated glucose-6-phosphatase activity in the hepatocytes from toads treated with either epinephrine or cortisol. These treatments also led to enhanced glycogen phosphorylase activity in males, and to a slightly elevated glyceraldehyde-3-phosphate dehydrogenase activity in females. Our results show that the hepatic glycogen is extremely stable in adult Xenopus. Only vitellogenesis causes a marked utilization of glycogen. Since the blood glucose levels are elevated in epinephrine or cortisol treated toads without the liver glycogen being affected, we conclude that either protein and/or lipid metabolism are involved in carbohydrate metabolism in Xenopus laevis.

Food deprivation alters liver glycogen metabolism and endocrine responses to hemorrhage

1990 ◽  
Vol 259 (5) ◽  
pp. E692-E698 ◽  
Author(s):  
O. Ljungqvist ◽  
P. O. Boija ◽  
H. Esahili ◽  
M. Larsson ◽  
J. Ware
Keyword(s):  
Blood Glucose ◽  
Food Deprivation ◽  
Glycogen Content ◽  
Glycogen Metabolism ◽  
Liver Glycogen ◽  
Nutritional State ◽  
Adrenergic Blockade ◽  
Insulin Levels ◽  
Liver Glycogen Content ◽  
Glycogen Repletion

Liver glycogen content, blood glucose, insulin, glucagon, and epinephrine were determined during 1 h hemorrhagic hypotension at 60 mmHg and 23 h thereafter in fed and two groups of 24-h food-deprived rats receiving either no infusion or 30% glucose intravenously during hemorrhage. Liver glycogen content was reduced by greater than 90% after 24-h food deprivation. Fed and food-deprived rats given glucose developed similar and substantial elevations of blood glucose during hemorrhage, whereas changes in blood glucose were modest in food-deprived rats given no infusion. In fed rats, liver glycogen was reduced by 60% during the 1-h bleed, but within 2 h after hemorrhage repletion of liver glycogen content commenced. By 6 h, approximately 75% of the glycogen lost during hemorrhage had been restored, and 23 h after hemorrhage liver glycogen content was six times greater compared with nonbled controls. Although glycogen levels increased after hemorrhage in food-deprived animals, the increase was negligible compared with that found in fed rats. Infusion of glucose during hemorrhage or adrenergic blockade after hemorrhage did not alter glycogen repletion in food-deprived rats. Posthemorrhage fed animals had high levels of insulin, glucagon, and epinephrine during hemorrhage, whereas insulin levels remained low in food-deprived rats despite exogenously induced hyperglycemia. It is concluded that rapid and substantial glycogen repletion can occur even immediately poststress. The conditions seem to be related to the nutritional state at the time of the insult.

scholarly journals The effect of fasting on the glycogen metabolism in heat-acclimated rats

2008 ◽  
Vol 60 (1) ◽  
pp. 49-58 ◽  
Author(s):  
Biljana Miova ◽  
Suzana Dinevska-Kjovkarevska ◽  
S. Mitev ◽  
Mirsada Dervisevic
Keyword(s):  
Phosphatase Activity ◽  
Muscle Glycogen ◽  
Glycogen Phosphorylase ◽  
Room Temperature ◽  
Glycogen Content ◽  
Muscle Metabolism ◽  
Glycogen Metabolism ◽  
Liver Glycogen ◽  
Short Term ◽  
Liver Glycogen Content

We investigated the influence of successive fasting for 24,48,72, and 96 h on some key enzymes and substrates of liver, kidney, and muscle in control and heat-acclimated (30days at 35 ? 1?C)rats. Short-term fasting (for 24 and 48 h)resulted in decrease of liver glycogen content, blood glucose level, and concentration of glucose-6-phosphate, as well as increase of glucose-6-phosphatase activity, regardless of the previous temperature of acclimation. During a period of prolonged fasting (for 72 and 96 h),there was a rebound of liver glycogen content only in animals kept at room temperature. Fasting induced increase of renal glycogen content in animals kept at room temperature and increase of renal glucose-6-phosphatase activity in both experimental groups. As for muscle metabolism, endogenous nutrition resulted in decrease of muscle glycogen content in heat-acclimated animals. Activity of muscle glycogen phosphorylase (a+b)was decreased in the control and increased in heat-acclimated animals. The obtained results indicate that the examined carbohydrate-related parameters show time-dependent changes during 4 days of fasting. Twenty-four- and 48-h fasting intensifies glycogenolytic processes, while 72- and 96-h fasting intensifies gluconeogenic processes, doing so to a lesser extent in heat-acclimated animals. The changes caused by the fasting were modified by acclimation to moderate heat, primarily in the liver and to a lesser extent in the kidney and muscle.

Liver glycogen content decreases during meals in rats

1982 ◽  
Vol 243 (3) ◽  
pp. R450-R453
Author(s):  
W. Langhans ◽  
N. Geary ◽  
E. Scharrer
Keyword(s):  
Blood Glucose ◽  
Glycogen Content ◽  
Liver Glycogen ◽  
Glucose Levels ◽  
Blood Glucose Levels ◽  
Liver Glycogen Content ◽  
Ad Libitum ◽  
Portal Veins ◽  
Hepatic Portal

The effects of feeding on liver glycogen content and blood glucose in the hepatic and hepatic portal veins were investigated in rats. Liver glycogen content decreased about 25% during meals both in rats refed after 12 h food deprivation (23 +/- 1 to 17 +/- 1 mg glycogen/g liver) and in ad libitum-fed rats taking fully spontaneous meals (44 +/- 2 to 32 +/- 2 mg/g). Liver glycogen began to increase within 30 min after meals in ad libitum-fed rats. Hepatic vein blood glucose levels at meal onset (118 +/- 4 mg/dl in the food-deprived rats, 127 +/- 4 in ad libitum-fed rats) and at meal end (155 +/- 3 and 166 +/- 5 mg/dl, respectively) were similar in the two groups. Portal vein blood glucose increased during meals in the previously food-deprived rats (83 +/- 4 to 116 +/- 6 mg/dl) but not in the ad libitum-fed rats (127 +/- 5 to 132 +/- 3 mg/dl). Mechanisms that may elicit prandial glycogenolysis and the possible role of this effect in the production of meal ending satiety are discussed.

Selected Contribution: Evidence that the decrease in liver glycogen is associated with the exercise-induced increase in IGFBP-1

2002 ◽  
Vol 93 (2) ◽  
pp. 798-804 ◽  
Author(s):  
Jean-Marc Lavoie ◽  
Yovan Fillion ◽  
Karine Couturier ◽  
Pierre Corriveau
Keyword(s):  
Blood Glucose ◽  
Glycogen Content ◽  
Liver Glycogen ◽  
Lower Blood Glucose ◽  
Insulin Levels ◽  
Liver Glycogen Content ◽  
Lower Blood ◽  
Lipid Response ◽  
Exercise Induced ◽  
Fasted Rats

The purpose of the present study was to test the hypothesis that the exercise-induced increase in insulin-like growth factor binding protein (IGFBP)-1 is not always linked to a decrease in blood glucose level and to examine whether the decreasing levels of liver glycogen during exercise may be associated with the increase in IGFBP-1. Three groups of rats were submitted to a 70-min treadmill exercise. One group of rats was fed normally, and the two other groups had their food intake restricted by 50% (50% fast) the night before the experiment. One of these two 50% fasted groups of rats was infused (intravenously) with glucose throughout exercise to maintain euglycemia. Exercise in noninfused 50% fasted rats, compared with the normally fed rats, resulted in significantly lower blood glucose ( minute 70) and insulin levels, significantly lower liver glycogen content, no change in IGF-I, and significantly higher increases in free fatty acid, glycerol, β-hydroxybutyrate, and IGFBP-1. Maintenance of euglycemia during exercise in glucose-infused 50% fasted rats reduced to a large extent the decrease in insulin levels but only slightly attenuated the lipid response and the IGFBP-1 response seen in noninfused 50% fasted rats. Comparisons of all individual liver glycogen and IGFBP-1 values revealed that liver glycogen values were highly ( P < 0.001) predictive of the IGFBP-1 response during exercise ( R = 0.564). The present results indicate that the IGFBP-1 response during exercise is not always linked to a decrease in plasma glucose and suggest that the increase in IGFBP-1 during exercise may be related to the decrease in liver glycogen content.

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 Effect of carbohydrate ingestion on glycogen resynthesis in human liver and skeletal muscle, measured by 13C MRS

2000 ◽  
Vol 278 (1) ◽  
pp. E65-E75 ◽  
Author(s):  
Anna Casey ◽  
Rob Mann ◽  
Katie Banister ◽  
John Fox ◽  
Peter G. Morris ◽  
...  
Keyword(s):  
Exercise Capacity ◽  
Muscle Glycogen ◽  
Glycogen Content ◽  
Liver Glycogen ◽  
Placebo Control ◽  
Resonance Spectroscopy ◽  
Carbohydrate Ingestion ◽  
Glycogen Resynthesis ◽  
Liver Glycogen Content ◽  
Significant Difference

This study investigated the effect of carbohydrate (CHO) ingestion on postexercise glycogen resynthesis, measured simultaneously in liver and muscle ( n = 6) by 13C magnetic resonance spectroscopy, and subsequent exercise capacity ( n = 10). Subjects cycled at 70% maximal oxygen uptake for 83 ± 8 min on six separate occasions. At the end of exercise, subjects ingested 1 g/kg body mass (BM) glucose, sucrose, or placebo (control). Resynthesis of glycogen over a 4-h period after treatment ingestion was measured on the first three occasions, and subsequent exercise capacity was measured on occasions four through six. No glycogen was resynthesized during the control trial. Liver glycogen resynthesis was evident after glucose (13 ± 8 g) and sucrose (25 ± 5 g) ingestion, both of which were different from control ( P < 0.01). No significant differences in muscle glycogen resynthesis were found among trials. A relationship between the CHO load (g) and change in liver glycogen content (g) was evident after 30, 90, 150, and 210 min of recovery ( r = 0.59–0.79, P< 0.05). Furthermore, a modest relationship existed between change in liver glycogen content (g) and subsequent exercise capacity ( r= 0.53, P < 0.05). However, no significant difference in mean exercise time was found (control: 35 ± 5, glucose: 40 ± 5, and sucrose: 46 ± 6 min). Therefore, 1 g/kg BM glucose or sucrose is sufficient to initiate postexercise liver glycogen resynthesis, which contributes to subsequent exercise capacity, but not muscle glycogen resynthesis.

scholarly journals Antidiabetic Effects of the Different Fractions of Ethanolic Extracts of Ocimum sanctum in Normal and Alloxan Induced Diabetic Rats

2009 ◽  
Vol 2 (1) ◽  
pp. 158-168 ◽  
Author(s):  
M. R. I. Khan ◽  
M. A. Islam ◽  
M. S. Hossain ◽  
M. Asadujjaman ◽  
M. I. I. Wahed ◽  
...  
Keyword(s):  
Blood Glucose ◽  
Glycogen Content ◽  
Fasting Blood Glucose ◽  
Liver Glycogen ◽  
Diabetic Rats ◽  
Ocimum Sanctum ◽  
Liver Glycogen Content ◽  
Glutamate Pyruvate ◽  
Serum Glutamate ◽  
Antidiabetic Effects

The antidiabetic effects of Ethyl acetate (Et-Ac), Petroleum-ether (Pet-ether), and Chloroform fractions from ethanolic extract of the leaves of Ocimum sanctum were investigated in normal and alloxan induced diabetic rats (AIDRs). The effect of these fractions (200 mg/kg body weight i.p) on fasting blood glucose (FBG), total cholesterol (TC), triglyceride (TG), serum glutamate oxaloacetate transaminases, serum glutamate pyruvate transaminases (SGOT, SGPT) level, and liver glycogen content were investigated in AIDRs and found significant effects. The most significant reduction of FBG level of around 80.19% was observed for Et-Ac fraction in AIDRs. A significant reduction (p< 0.01) in serum TC and TG level of 54.49% and 79.78% respectively was also found for Et-Ac fraction of O. sanctum. The hypoglycemic and hypolipidemic activities were comparable to metformin HCl (150 mg/kg). In severely diabetic rats, liver glycogen content was decreased by 50.60%. Administration of these fractions to the AIDRs resulted in the significant elevation of liver glycogen content. In diabetic rats, SGOT and SGPT levels were significantly elevated that were further reduced after intraperitoneal administration of these fractions. These results indicate that different fractions of O. sanctum have favorable effects in bringing down the severity of diabetes together with hepatoprotectivity. Keywords: Fasting blood glucose; Hypolipidemic; Serum glutamate oxaloacetate transaminases; Serum glutamate pyruvate transaminases; Hepatoprotectivity. © 2010 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved. DOI: 10.3329/jsr.v2i1.2769                 J. Sci. Res. 2 (1), 158-168 (2010) 

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