scholarly journals Effects of adrenalectomy before weaning in the genetically obese Zucker rat (fa/fa)

1986 ◽  
Vol 56 (1) ◽  
pp. 141-151 ◽  
Author(s):  
J. M. Fletcher
Keyword(s):  
Body Composition ◽  
Lipid Content ◽  
Plasma Concentrations ◽  
Liver Glycogen ◽  
Tyrosine Aminotransferase ◽  
Zucker Rats ◽  
Hepatic Glycogen ◽  
Phenotypic Differences ◽  
Reduced Body ◽  
Adrenalectomized Rats

1. Lean (Fa/?) and obese (fa/fa) Zucker rats were adrenalectomized or sham-operated at 19 d of age (3 d before weaning). Injection of corticosterone for 3 d after weaning (1.0 mg/d) was necessary to ensure survival of adrenalectomized fa/fa but not Fa/? rats. Intact and adrenalectomized fa/fa rats had a lower rectal temperature than Fa/? animals before and 3 d after adrenalectomy. The post-weaning survival of adrenalectomized fa/fa rats was enhanced by maintenance at an ambient temperature of 30° rather than 22°.2. Adrenalectomized and sham-operated rats were therefore kept at 30°, fed ad-lib. and killed at 34 d. Adrenalectomy had only small effects on the growth, body composition and appetite of Fa/? rats. The hyperphagia, greater lipid content, reduced protein content and hyperinsulinaemia of fa/fa rats were completely abolished by adrenalectomy.3. Intact fu/fa rats had higher liver glycogen contents and higher activities of the hepatic enzymes tyrosine aminotransferase (EC 2. 6. 1. 5) and acetyl CoA carboxylase (EC 6. 4. 1. 2) than intact Fa/? animals. Adrenalectomy abolished these phenotypic differences.4. Injection of adrenalectomized rats with 1.0 mg corticosterone-21-acetate daily from weaning to 34 d restored the abnormal body composition, hyperphagia, hyperinsulinaemia, higher hepatic glycogen and enzyme activities of fa/fa rats.5. In a second experiment adrenalectomized rats were injected with 1.0 mg corticosterone-21-acetate daily from weaning to 34 d and kept at 22°, fa/fu rats adrenalectomized and injected with corticosterone had a reduced body lipid content compared with intact fa/fa rats but still contained more lipid than intact or similarly treated Fa/? animals.6. In both experiments adrenalectomized Fa/? and fa/fa rats injected daily with corticosterone had the same plasma concentrations of this hormone when killed 3 h after the last injection at 34 d. It is concluded that corticosterone is required for expression of the abnormal appetite, hyperinsulinaemia and body composition of the fa/fa rat.

Resistance of hepatic glycogen to depletion in obese Zucker rats

1991 ◽  
Vol 69 (6) ◽  
pp. 841-845 ◽  
Author(s):  
Harry Koubi ◽  
Claude Duchamp ◽  
Alain Géloën ◽  
Alain Fréminet ◽  
Yves Minaire
Keyword(s):  
Cold Exposure ◽  
Liver Glycogen ◽  
Zucker Rats ◽  
Hepatic Glycogen ◽  
Glycogen Store ◽  
Obese Rats ◽  
Fasting And Refeeding ◽  
Obese Zucker Rats ◽  
Ad Libitum ◽  
Glycogen Stores

Glycogen stores (liver and carcass) have been studied in lean and obese Zucker rats. The animals were submitted to one of three feeding conditions: ad libitum, a 48-h fast, or a 48-h fast and food ad libitum for 24 h, and to two environmental conditions, either thermoneutrality or an acute cold exposure (2 days at 4–7 °C). After a 2-day fast at 25 °C, the liver glycogen store was reduced by 45 times in the lean rats, while it was decreased by only 3 times in the obese rats. Under these conditions, the liver glycogen store was 45 times higher in the obese than in the lean rats. After 2 days in the cold, liver glycogen store was 4.4 times higher in obese rats than in lean rats. After a 2-day fast in the cold, the liver glycogen store in the obese rats was 30 times higher than in the lean rats. In comparison to fasting at thermoneutrality, fasting in the cold did not lead to a further reduction in hepatic glycogen in obese Zucker rats. The differences observed in the mobilization of the hepatic glycogen store between obese and lean rats have not been found in the mobilization of the carcass glycogen store. Drastic conditions, such as a 2-day fast in the cold, did not exhaust the glycogen store in obese Zucker rats. The present observations point out that obese Zucker rats cannot mobilize the entire hepatic glycogen store, as seen in lean control rats. The role of this abnormality in the high hyperlipogenesis that maintains the obese state is still to be evaluated.Key words: glycogen, fasting and refeeding, cold exposure, obesity, liver.

Action of α-methyl-DL-tryptophan in vivo on catabolism of amino acids and their conversion to liver glycogen

1969 ◽  
Vol 47 (2) ◽  
pp. 179-184 ◽  
Author(s):  
M. Oravec ◽  
T. L. Sourkes
Keyword(s):  
Carbon Dioxide ◽  
Amino Acids ◽  
Body Temperature ◽  
Adrenal Glands ◽  
Liver Glycogen ◽  
Hepatic Glycogen ◽  
Stimulatory Action ◽  
Tryptophan Pyrrolase ◽  
Adrenalectomized Rats

AMTP (α-methyl-DL-tryptophan) stimulates the incorporation of (labeled) alanine, glutamate, leucine, isoleucine, histidine, threonine, tryptophan, pyruvate, and acetate into hepatic glycogen. Accompanying this phenomenon is an enhanced rate of oxidation of these substances to carbon dioxide, except for acetate whose oxidation is not influenced by AMTP. AMTP also causes an increased excretion of urea and a rise in body temperature. Presence of the adrenal glands is necessary for the stimulatory action of AMTP on the oxidation of alanine, glutamate, isoleucine, and pyruvate. AMTP-stimulated oxidation of leucine and threonine is only partially dependent upon the adrenal gland. The oxidation of histidine is increased to the same extent by AMTP in both intact and adrenalectomized rats. The ability of AMTP to increase the level of tryptophan pyrrolase activity and, thereby, to create an imbalance of the proportion of amino acids in the rat is implicated in the mechanism responsible for its glyconeogenic property and ability to increase catabolism of amino acids.

Effect of liver glycogen content on glucose production in running rats

1989 ◽  
Vol 66 (1) ◽  
pp. 318-322 ◽  
Author(s):  
J. Vissing ◽  
J. L. Wallace ◽  
H. Galbo
Keyword(s):  
Plasma Glucose ◽  
Glycogen Content ◽  
Hepatic Glucose Production ◽  
Plasma Concentrations ◽  
Glucose Production ◽  
Liver Glycogen ◽  
Treadmill Running ◽  
Hepatic Glycogen ◽  
Hepatic Glucose ◽  
Exercise Induced

The influence of supranormal compared with normal hepatic glycogen levels on hepatic glucose production (Ra) during exercise was investigated in chronically catheterized rats. Supranormal hepatic glycogen levels were obtained by a 24-h fast-24-h refeeding regimen. During treadmill running for 35 min at a speed of 21 m/min, Ra and plasma glucose increased more (P less than 0.05) and liver glucogen breakdown was larger in fasted-refed compared with control rats, although the stimuli for Ra were higher in control rats, the plasma concentrations of insulin and glucose being lower (P less than 0.05) in control compared with fasted-refed rats. Also, plasma concentrations of glucagon and both catecholamines tended to be higher and muscle glycogenolysis lower in control compared with fasted-refed rats. Lipid metabolism was similar in the two groups. The results indicate that hepatic glycogenolysis during exercise is directly related to hepatic glycogen content. The smaller endocrine glycogenolytic signal in face of higher plasma glucose concentrations in fasted-refed compared with control rats is indicative of metabolic feedback control of glucose mobilization during exercise. However, the higher exercise-induced increase in Ra, plasma glucose, and liver glycogen breakdown in fasted-refed compared with control rats indicates that metabolic feedback mechanisms are not able to accurately match Ra to the metabolic needs of working muscles.

Distribution of newly formed hepatic glycogen in adrenalectomized rats as observed by radioautography after injection of 3H-galactose

1984 ◽  
Vol 42 ◽  
pp. 228-229
Author(s):  
J. E. Michaels ◽  
J. T. Hung ◽  
E. L. Cardell ◽  
R. R. Cardell
Keyword(s):  
Glycogen Synthesis ◽  
Hepatic Glycogen ◽  
Electron Microscopic ◽  
Routine Procedures ◽  
Silver Grains ◽  
Synthetic Glucocorticoid ◽  
Adrenalectomized Rats

In order to study early events of glycogen synthesis, we have used adrenalectomized (ADX) rats fasted overnight and injected with the synthetic glucocorticoid dexamethasone (DEX) to stimulate glycogen synthesis. Rats were given DEX 0-5 hr prior to sacrifice and injected with 2 mCi 3H-galactose 1 hr prior to sacrifice. Liver was prepared for light (LM) and electron microscopic (EM) radioautography by routine procedures.The concentration of silver grains over hepatic cytoplasm was measured in LM radioautographs using a Zeiss Videoplan. The hepatocytes were categorized as unlabeled if no silver grains (gr) were present, lightly labeled (<10gr/100 μm2 cytoplasm) or intensely labeled (>10 gr/1002 μm cytoplasm). Although very few hepatocytes showed heavy labeling after 1 hr treatment with DEX, by 2 hr after DEX treatment 8% of the cells distributed throughout the lobule were intensely labeled.

Effect of Propolis-Supplemented Diet on Body Composition and Endocrine Function of Adipose Tissue

2020 ◽  
Vol 19 (2) ◽  
pp. 217-221
Author(s):  
Maria Jesús Lisbona-González ◽  
Candela Reyes-Botella ◽  
Esther Muñoz-Soto ◽  
Maria Victoria Olmedo-Gaya, ◽  
Jorge Moreno-Fernandez ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Body Composition ◽  
Adipose Tissue ◽  
Endocrine Function ◽  
Control Group ◽  
Albino Rats ◽  
Standard Diet ◽  
Reduced Body ◽  
Esterified Fatty Acids ◽  
Wistar Albino Rats

Adipose tissue is an endocrine organ and has central role in interaction with other organs or tissues while propolis can induce lipolysis. Therefore, the aim of this study is to provide detailed information about adipose tissue homeostasis modifications and body composition during propolis supplement consumption. Twenty male Wistar albino rats (8 weeks) were divided into two groups of 10 animals each and fed for 90 days with two different types of diets: standard for the control group (diet C) and standard diet + 2% propolis (diet P). Thyroid hormones did not show differences, while ghrelin and adiponectin decreased in the group that was fed propolis. Insulin, leptin, and non-esterified fatty acids also increased along with reduced body weight and fat, in addition to increased lean mass when propolis was in the diet. We conclude that propolis could decrease ghrelin and adiponectin but increase non-esterified fatty acids and insulin secretion, which improves body composition.

Modeling Studies of the Dynamic Control of Hepatic Glucose Balance

1975 ◽  
Vol 97 (3) ◽  
pp. 266-275
Author(s):  
R. N. Bergman ◽  
M. El Refai
Keyword(s):  
Central Nervous System ◽  
Dynamic Control ◽  
Plasma Concentrations ◽  
Glycogen Metabolism ◽  
Hepatic Glycogen ◽  
Simulation Studies ◽  
Biochemical Effects ◽  
Hepatic Glucose ◽  
Large Fluctuations ◽  
The Central Nervous System

The survival of mammals is dependent upon a relatively constant, adequate supply of glucose to the central nervous system, despite large fluctuations in the amount of food available. When food is abundant, the liver stores ingested carbohydrate as glycogen, and during fasts, the stored glycogen is released at a precisely regulated rate to maintain the blood glucose level. The rates of storage and release of carbohydrate by the liver are determined by the plasma concentrations of several bloodborne signals; most important are the concentrations of glucose, and the hormones insulin and glucagon. To understand the complex control relationships of these three signals as they affect the liver, their individual dynamic influences have been determined experimentally, and they have been integrated by means of a computer simulation of the pathways of hepatic glycogen metabolism. The simulation studies have led to specific hypotheses about the biochemical effects of glucose and insulin on the liver. The simulation studies have also led to the conclusion that glucose exerts a rapid moment-to-moment influence of glucose on the rate of uptake of glucose by the liver. Insulin, however, by exerting a slower influence on the sensitivity of the liver to glucose, is very effective in “optimizing” the amount of glycogen which the liver stores food during food intake. Thus, integrated experimental and simulation studies can lead to a view of a physiological regulating system which does not emerge from either approach used alone.

scholarly journals Glycogen synthesis in the perfused liver of adrenalectomized rats

1976 ◽  
Vol 156 (3) ◽  
pp. 585-592 ◽  
Author(s):  
P D Whitton ◽  
D A Hems
Keyword(s):  
Intact Animal ◽  
Glycogen Synthesis ◽  
Hepatic Metabolism ◽  
Hepatic Glycogen ◽  
Perfused Liver ◽  
Short Term ◽  
Glycogen Accumulation ◽  
Glycogen Deposition ◽  
Adrenalectomized Rats

1. A total loss of capacity for net glycogen synthesis was observed in experiments with the perfused liver of starved adrenalectomized rats. 2. This lesion was corrected by insulin or cortisol in vivo (over 2-5h), but not by any agent tested in perfusion. 3. The activity of glycogen synthetase a, and its increase during perfusion, in the presence of glucose plus glucogenic substrates, were proportional to the rate of net glycogen accumulation. 4. This complete inherent loss of capacity for glycogen synthesis after adrenalectomy is greater than any defect in hepatic metabolism yet reported in this situation, and is not explicable by a decrease in the rate of gluconegenesis (which supports glycogen synthesis in the liver of starved rats). The short-term (2-5h) stimulatory effect of glucocorticoids in the intact animal, on hepatic glycogen deposition, may be mediated partly through insulin action, although neither insulin or cortisol appear to act directly on the liver to stimulate glycogen synthesis.

Effects of Niacin and Vitamin C on Blood Sugar

1958 ◽  
Vol 192 (3) ◽  
pp. 511-513 ◽  
Author(s):  
G. N. Bera ◽  
J. Chowdhury
Keyword(s):  
Vitamin C ◽  
Blood Sugar ◽  
Blood Level ◽  
Subcutaneous Injection ◽  
Intramuscular Injection ◽  
Liver Glycogen ◽  
Simultaneous Administration ◽  
Diabetic Rabbits ◽  
Adrenalectomized Rats

Intramuscular injection of niacin in normal rats induces hyperglycemia which lasts approximately 1 hour. In adrenalectomized rats niacin produces a hypoglycemia. Subcutaneous injection of vitamin C lowers blood sugar in normal and diabetic rabbits, the effect being pronounced when the blood level of vitamin C is high. The simultaneous administration of niacin and vitamin C produced a pronounced hypoglycemia. The rise in blood sugar normally produced by niacin is nullified if vitamin C is injected simultaneously or shortly thereafter. In both normal and diabetic animals, vitamin C injections produce an increase in liver glycogen. The vitamin C content of liver is lower in normal than in alloxan diabetic animals.

Temporal patterns of tissue glycogen, glucose, and glycogen phosphorylase activity prior to hibernation in freeze-tolerant chorus frogs, Pseudacris triseriata

2008 ◽  
Vol 86 (10) ◽  
pp. 1095-1100 ◽  
Author(s):  
Steve C. Dinsmore ◽  
David L. Swanson
Keyword(s):  
Glycogen Phosphorylase ◽  
Threshold Level ◽  
Liver Glycogen ◽  
Critical Threshold ◽  
Hepatic Glycogen ◽  
Phosphorylase Activity ◽  
Continuous Increase ◽  
Glycogen Accumulation ◽  
Chorus Frogs ◽  
Glycogen Stores

Freezing survival may differ among winters in chorus frogs ( Pseudacris triseriata (Wied-Neuwied, 1838)), and low freezing survival is associated with low hepatic glycogen stores. The pattern of prehibernation liver glycogen accumulation in chorus frogs is unknown. Frogs might accumulate hepatic glycogen stores until a threshold level sufficient for winter survival is attained, after which frogs enter hibernation (critical threshold hypothesis). According to this model, frogs active late in the season should only be those with low hepatic glycogen stores. Alternatively, hepatic glycogen levels might continue to increase throughout the fall as long as frogs remain active (continuous increase hypothesis). We tested these hypotheses by measuring liver and leg muscle glycogen, glucose, and glycogen phosphorylase activities in chorus frogs throughout the fall prehibernation period in southeastern South Dakota. Hepatic glycogen levels were significantly related to date and increased throughout the fall period, consistent with the continuous increase hypothesis. This suggests that hepatic glycogen levels do not serve as a cue for entrance into hibernation. Liver phosphorylase activity did not vary significantly with progression of the fall season and activity was lower than in winter, suggesting that the winter increment of phosphorylase activity requires some stimulus during hibernation (e.g., low temperatures).

Food-deprivation affects seawater acclimation in tilapia: hormonal and metabolic changes

1996 ◽  
Vol 199 (11) ◽  
pp. 2467-2475 ◽  
Author(s):  
M Vijayan ◽  
J Morgan ◽  
T Sakamoto ◽  
E Grau ◽  
G Iwama
Keyword(s):  
Fresh Water ◽  
Food Deprivation ◽  
Sea Water ◽  
Plasma Concentrations ◽  
Essential Amino Acids ◽  
Nutritional State ◽  
Total Amino Acid ◽  
Hepatic Glycogen ◽  
Plasma Prolactin ◽  
Seawater Acclimation

We tested the hypothesis that nutritional state affects seawater acclimation by transferring either fed or food-deprived (2 weeks) male tilapia (Oreochromis mossambicus) from fresh water to full-strength sea water. Food-deprivation resulted in a significant increase in plasma concentrations of Na+, Cl-, cortisol, glucose, total amino acid, glutamate, serine and alanine, and in hepatic pyruvate kinase (PK) and lactate dehydrogenase (LDH) activities, whereas the prolactin-188 to prolactin-177 ratio (tPRL188:tPRL177) and plasma prolactin-188 (tPRL188), lactate, arginine and hepatic glycogen content and hepatic alanine aminotransferase (AlaAT) and 3-hydroxyacyl-Coenzyme A dehydrogenase (HOAD) activities were lower than in the fed group. Seawater transfer significantly increased the tPRL188:tPRL177 ratio and plasma concentrations of Na+, Cl-, K+, growth hormone (GH), glucose, aspartate, tyrosine, alanine, methionine, phenylalanine, leucine, isoleucine and valine levels as well as gill Na+/K+-ATPase activity and hepatic PK and LDH activities, whereas plasma tPRL177, tPRL188, glycine and lysine concentrations were significantly lower than in fish retained in fresh water. There was a significant interaction between nutritional state and salinity that affected the tPRL188:tPRL177 ratio and plasma concentrations of Cl-, GH, glucose, aspartate, tyrosine, serine, alanine, glycine, arginine and hepatic PK, LDH, AlaAT, aspartate aminotransferase, glutamate dehydrogenase and HOAD activities. These results, taken together, indicate that food-deprived fish did not regulate their plasma Cl- levels, despite an enhancement of plasma hormonal and metabolic responses in sea water. Our study also suggests the possibility that plasma prolactin and essential amino acids may be playing an important role in the seawater acclimation process in tilapia.

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