Decrease In Glycogen Content Research Articles

A morphometric analysis of ischemic canine myocardium with and without reperfusion

Progressive morphological changes have been quantitated in ischemic and control regions of canine hearts previously assessed biochemically and physiologically. Muscle strips removed after a 5 or 10-min occlusion of the left circumflex artery were compared to those removed after reperfusion for 20 or 60 min following 10 min occlusion and to those removed immediately from normal and sham-operated dogs. Decreased glycogen content and decreased mitochondrial matrix were observed in fibers from ischemic regions as early as 5 min after ligation. Changes in the mitochondrial volume fraction were calculated by the point counting method and changes in the number of lipid droplets per unit area were determined. Mitochondrial volume fractions in ischemic regions were not significantly higher when compared to control regions of the same hearts, and were similar to the values measured for 10 and 70-min sham-operated dogs. We conclude that in early acute ischemia considerable variability in the different control groups emerges with extensive sampling and must be considered in interpreting ultrastructural changes.

Modulation by adrenalectomy and fasting of insulin effects in perfused hindlimb muscle.

Perfused hindlimb muscle from fed adrenalectomized rats accumulated more 2-deoxyglucose at submaximal concentrations of insulin in comparison to muscle from fed normal rats. However, in the fasted state, insulin-stimulated 2-deoxyglucose uptake was largely inhibited by adrenalectomy. Basal 2-deoxyglucose uptake did not differ between fed and fasted normal or adrenalectomized rats. The changes in insulin effects caused by adrenalectomy were due to altered hexose transport as shown by measurements of 3-O-methylglucose uptake and of intracellular free and phosphorylated 2-deoxyglucose. Muscles of fasted normal and fed or fasted adrenalectomized rats showed higher basal glycogen synthase --glucose-6-P/+glucose-6-P activity ratios than those of fed normal rats probably because of decreased glycogen content. However, muscles from fed or fasted adrenalectomized rats did not show any alterations in insulin effects on the activity ratio and half-maximal activation constant (A0.5) for glucose-6-P of glycogen synthase. Because of the dissociation of the effects of insulin on hexose transport and glycogen synthase in muscle of fasted adrenalectomized rats, it is concluded that the impairment in insulin-stimulated hexose transport in these animals is due to a defect lying beyond the interaction of insulin with its receptor.

Calcitonin increases calcium content and phosphorylase a activity in the hepatic particulate glycogen of rats.

The effect of calcitonin (CT) on hepatic glycogenolysis was investigated after a single subcutaneous administration of the hormone to intact rats. Administration of CT (porcine CT; 80 MRC mU/100 g BW) produced a significant decrease in glycogen content of the liver, and corresponding increases in phosphorylase a activity and calcium content of the particulate glycogen fraction in the liver. These alterations were observed with the dose of CT at physiological level. The removal of calcium by 1 mM EGTA treatment of the hepatic particulate glycogen caused a clear reduction in the increase in phosphorylase a activity produced by CT administration. Meanwhile, the enzyme activity in 1 mM EGTA-treated particulate glycogen of the liver in both control and CT (80 MRC mU/100 g BW)-treated rats was significantly enhanced by the addition of calcium ion (10 microM). Furthermore, a single intraperitoneal administration of calcium chloride (2.0 mg Ca/100 g BW) to intact rats produced a remarkable increase in phosphorylase a activity and calcium content of the hepatic glycogen particulate fraction. These results suggest that the promotion of hepatic glycogenolysis by CT administration may result from the increase in phosphorylase a activity mediated by cellular calcium.

Histochemistry of glycogen deposition in perinatal rat brain: importance of radial glial cells.

Changes in the glycogen content and patterns of deposition in the developing rat brain were studied using a light microscopic periodic acid-Schiff method on embryonic days (ED) 14, 16, 18, 20 and postnatal days (PD) 1, 3, 7, 12, 16 and 21. Regional and temporal differences were quantified with an automatic image analyser by estimation of stained material in subpial regions of cerebral cortex, thalamus, superior colliculus and medulla. The cellular localization of glycogen particles was investigated by electron microscopy on ED 18, ED 20 and PD 2. On ED 14 the first signs of glycogen storage were found in parts of the immature choroid plexus and in radial glial cells in the midbrain and medullary raphé. With advancing foetal age these structures retained their high capacity for glycogen storage but, in addition, an increasing number of radial fibres in most of the brain stem regions and in the cerebral cortex of older foetuses (ED 18-20) showed significant amounts of glycogen. The storage of glycogen in cerebral cortex was relatively low at all foetal age intervals studied. In new born animals the distribution of glycogen particles was similar to that found in the late foetal brain. A decrease of glycogen content commenced from PD 1 to 3 and reached the pattern of the adult brain between PD 7 and 21. Glycogen storage by radial glial cells in the developing rat brain might indicate their possible role as an energy source in perinatal carbohydrate metabolism.

Carbohydrate and amino acid metabolism during acute hypoxia in rats: blood and heart metabolites

1. Metabolic response of rats to acute hypoxia in vivo was studied by measuring glycogen store, blood and heart metabolites after a 30 min exposition to a 5% O2-95% N2 gas mixture. 2. The hypoxic test induced decrease of glycogen content of 47, 20 and 85% in the liver, muscle and heart, respectively. 3. Glucose, lactate, alanine and succinate were increased by 65, 310, 100 and 580% respectively in blood from control as compared with hypoxic animals. 4. Creatine-phosphate and ATP content in the heart was decreased by 92 and 45% respectively, whereas ADP and AMP did not change after hypoxia. 5. Hypoxia induced an increase of lactate (680%), pyruvate (105%), citrate (105%), succinate (152%), malate (544%) and alanine (273%), and a decrease of α-keto-glutarate (30%), glutamate (55%) and aspartate (55%) in the myocardium. 6. These data demonstrate the simultaneous utilization of carbohydrates and amino acids in response to oxygen deprivation in a strictly aerobic species. However ATP production arising from amino acid fermentation appears of minor quantitative importance compared with that of glycogenolysis and glycolysis. In the discussion, the possible role of these reactions is examined and the results of the present study are compared with those obtained in other organs and other species.

A stereological analysis of the effect of adriamycin on the ultrastructure of rat myocardial cells in culture

Adriamycin is an effective anti-cancer agent which produces a dose-dependent, irreversible cardiomyopathy of unknown etiology in a significant number of cancer patients. The effect of adriamycin on the ultrastructure of cultured mammalian myocardial cells was examined with light and electron microscope stereological analysis. Cell surface/cell volume, nuclear volume/cellular volume, and nuclear volume/sarcoplasmic volume ratios did not change after adriamycin treatment, showing that the cell volume and sarcoplasm volume were not altered. The nuclear surface area relative to both the nuclear volume and cellular volume was greater in adriamycin-treated cells, implying increased nuclear pleomorphism. The percent of myocardial sarcoplasm occupied by the mitochondria increased very significantly subsequent to adriamycin treatment. That the mitochondria increased in size was indicated by the unchanged mitochondrial surface/cell volume ratio and the decrease in the mitochondrial surface/volume ratio. A significant decrease in glycogen content after exposure to adriamycin as revealed by electron microscope stereological analysis was also observed with the light microscope. Subsequent to adriamycin treatment a small fraction of the cells died and detached from the plate.

The effect of isoproterenol and β-sympathomimetic drugs on human placental glycogen metabolism

Human placental glycogen metabolism is studied, in vitro, by means of three parameters: glycogen level, glycogen phosphorylase and glycogen synthase activities. No significant decrease of glycogen content is observed after incubation of placental fragments with 1 × 10 −4M isoproterenol or salbutamol. In placental homogenates, isoproterenol induces an increase of glycogen phosphorylase a activity and a simultaneous decrease of glycogen synthase a activity. This effect is time and dose-dependent, β sympathomimetic drugs (isoxsuprine, salbutamol) have only a slight action on the activity of both these placental enzymes.

Early corneal changes in vitamin A deficient rats

Corneas of retinol deficient rats maintained on low levels of retinoic acid in a conventional laboratory environment and corneas from retinol deficient rats receiving no retinoic acid or retinoic acid for 5 weeks and kept in a germ free environment have been examined for structural abnormalities before the onset of apparent xerophthalmia. All groups of deficient rats showed abnormally large numbers of exfoliating cells, increased density of keratofibrils throughout the epithelial layer, decreased glycogen content, deposits of electron dense particles in the basal lamina region and accumulation of electron dense bodies in the keratocytes. These changes probably occurred as a primary effect of vitamin A deficiency. However, the absence of neovascularization and inflammation of the corneal stroma in the germ free rats, suggests that these changes may be secondary, perhaps due to infection.

Effect of di-2-ethylhexyl phthalate (DEHP) on glycogen metabolism in rat liver

Effect of di-2-ethylhexyl phthalate (DEHP) on glycogen contents and certain enzymes of carbohydrate metabolism of rat liver was investigated. A significant decrease in glycogen content of unfasted and an increase in fasted animals was observed. Blood glucose tolerance was reduced and the rate of both glycogenesis and glycogenolysis, as judged by measuring glycogen contents after feeding labelled and unlabelled glucose, was also decreased. Activities of glucose-6-phosphate dehydrogenase, phosphorylase and glucose-6-phosphatase were significantly decreased while activities of fructose-1-6-diphosphate and aldolase remained unaltered. The present results suggest that DEHP affects both glycogenesis and glycogenolysis in rat liver.

Rat liver glycogen metabolism in the perinatal period

The correlation between blood glucose levels, the concentration of glycogen, the activities of glycogen sythase and phosphorylase and their respective kinases and phosphatases was examined in liver of rat fetuses between day 18 of gestation and one day after birth. Between day 18 and 21 there is a rapid increase in the concentration of glycogen and in the activity of synthase a and a much slower increase in the activity of phosphorylase a. The activity of the respective kinases increased rapidly during this period and reached maximun on day 21. The activity of synthase phosphatase and phosphorylase phosphatase increased after day 18, to reach a maximum on day 19 and 20, respectively, but decreased again towards day 21. The possibility that the changes in glycogen concentration and enzyme activities were related to an effect of glucose of AMP on the respective phosphatases was considered. It was found that the Km of phosphatase for glucose in the prenatal period was 5–7 mM, as in the adult. Since the level of blood glucose during this period was constant (2.8 mM), an effect of glucose on phosphatase activity seems unlikely. AMP concentration increased between day 18 and 21 from 6–15 nmol/g. In view of the low level of phosphorylase a activity during this period, the increase in AMP concentration is not considered to be important in the regulation of glycogen breakdown at this time. Immediately after birth blood glucose levels dropped to 5 mg/dl. This was accompanied by a rapid decrease in glycogen concentration and in the activity of glycogen synthase and a rise in phosphorylase activity. Blood glucose levels returned to the initial level within 1 h after birth, whereas the changes in glycogen concentration and enzyme activities continued for at least 3 h after birth. On day 22 all parameters examined had reached the level found in adult rat liver. It is suggested that the rapid changes observed immediately after birth are due to an effect of hypoglycemia mediated by hormones and cannot be ascribed to direct effects of metabolites on the enzyme systems involved.

Hepatic effects of xylidine isomers in rats

The effect of repeated (4 weeks) oral administration of 2,4-, 2,5- or 2,6-xylidine (at dose levels of 400–500 mg/kg/day) on the morphology and microsomal drug metabolising enzyme activity of the liver was studied in rats. All 3 isomers caused hepatomegaly which was considered to be due to proliferation of the smooth endoplasmic reticulum. Decreases in glycogen content and glucose-6-phosphatase activity were demonstrated histochemically. Biochemical investigations showed increases in microsomal protein and cytochrome P-450 content in rats dosed with 2,4- or 2,5-xylidine and in glucuronyltransferase activity in rats given 2,4-, 2,5- or 2,6-xylidine. Aniline hydroxylase activity was increased in all treated rats except males dosed with 2,6-xylidine. The results of the study indicate that all isomers of xylidine can be inducers of microsomal drug-metabolising enzyme activity, that they may be metabolised by oxidation and that the xylidine molecule may be eliminated as a conjugate with glucuronic acid.

Experimental evaluation of rigor mortis I. Histochemical analysis of rat skeletal muscle in the early post-mortem period

Histochemical investigation of rat skeletal muscle samples removed immediately post mortem from exercised rats gave the following results: 1. (1) Of the oxidoreductase enzymes studied, there was a slight increase in the activity of cytochrome oxidase. 2. (2) There was no change in the acid- and alkali-stable actomyosin ATPase activity. 3. (3) There was a notable decrease in glycogen concentration. In the case of strychnine intoxication: 1. (1) There was no change in oxidoreductase enzymes. 2. (2) There was an increase in the activity of alkali-stable ATPase in white fibres. 3. (3) The glycogen concentration notably decreased. There was no change in the activity of enzymes studied in those animals sacrificed by anoxia.

ATP Depletion, a Possible Role in the Pathogenesis of Hyperuricemia in Glycogen Storage Disease Type I

Other investigators have shown that fructose infusion in normal man and rats acutely depletes hepatic ATP and P(i) and increases the rate of uric acid formation by the degradation of preformed nucleotides. We postulated that a similar mechanism of ATP depletion might be present in patients with glucose-6-phosphatase deficiency (GSD-I) as a result of ATP consumption during glycogenolysis and resulting excess glycolysis. The postulate was tested by measurement of: (a) hepatic content of ATP, glycogen, phosphorylated sugars, and phosphorylase activities before and after increasing glycolysis by glucagon infusion and (b) plasma urate levels and urate excretion before and after therapy designed to maintain blood glucose levels above 70 mg/dl and thus prevent excess glycogenolysis and glycolysis. Glucagon infusion in seven patients with GSD-I caused a decrease in hepatic ATP from 2.25 +/- 0.09 to 0.73 +/- 0.06 mumol/g liver (P <0.01), within 5 min, persisting in one patient to 20 min (1.3 mumol/g). Three patients with GSD other than GSD-I (controls), and 10 normal rats, showed no change in ATP levels after glucagon infusion. Glucagon caused an increase in hepatic phosphorylase activity from 163 +/- 21 to 311 +/- 17 mumol/min per g protein (P <0.01), and a decrease in glycogen content from 8.96 +/- 0.51 to 6.68 +/- 0.38% weight (P <0.01). Hepatic content of phosphorylated hexoses measured in two patients, showed the following mean increases in response to glucagon; glucose-6-phosphate (from 0.25 to 0.98 mumol/g liver), fructose-6-phosphate (from 0.17 to 0.45 mumol/g liver), and fructose-1,6-diphosphate (from 0.09 to 1.28 mumol/g) within 5 min. These changes, except for glucose-6-phosphate, returned toward preinfusion levels within 20 min. Treatment consisted of continuous intragastric feedings of a high glucose dietary mixture. Such treatment increased blood glucose from a mean level of 62 (range 28-96) to 86 (range 71-143) mg/dl (P <0.02), decreased plasma glucagon from a mean of 190 (range 171-208) to 56 (range 30-70) pg/ml (P <0.01), but caused no significant change in insulin levels. Urate output measured in three patients showed an initial increase, coinciding with a decrease in plasma lactate and triglyceride levels, then decreased to normal within 3 days after treatment. Normalization of urate excretion was associated with normalization of serum uric acid. We suggest that the maintenance of blood glucose levels above 70 mg/dl is effective in reducing serum urate levels and that transient and recurrent depletion of hepatic ATP due to glycogenolysis is contributory in the genesis of hyperuricemia in untreated patients with GSD-I.

Oxidation of glucose-U-14C and synthesis of glycogen in different tissues of the garden snail,Cryptozona ligulata with reference to aestivation and starvation

The per cent decrease of glycogen content in all the tissues investigated is more in 20-days starved snails than the 4-months aestivated snails when compared to active snails. Recovery of administered glucose-U-14C in the respiratory CO2 is 42·27% in active snails, whereas it is 8·81% and 26·09% in aestivated and starved snails respectively. Maximal levels of incorporation of labelled glucose were found at 18 hr in all the tissues and the rate of incorporation was greatly elevated in the tissues of aestivated and starved snails. The causes for the difference in the rates of incorporation and the utilization of glycogen in active, aestivated and starved snails are discussed.

Histochemical and histoenzymatic changes in mouse liver in subacute benzene intoxication

The investigations were performed on mice. They were divided into a control group and 4 experimental groups. The experimental animals were administered intraperitoneally benzene 6 X every 24 h. The animals were decapitated 30 min. 4, 12 and 24 h after the last benzene administration. During the experiment, dyeing for neutral lipids and glycogen was carried out, and the activity of NADH2-r.t., SDH, G-6-Pase, ATP-ase and ACP was estimated. A decrease of glycogen content in liver cells, deviations in the amount of neutral lipids, reversible decrease of mitochondrial enzymes activity, and intensification of the processes of intracellular catabolism were found.

Centrally mediated hyperglycemia by 6-aminonicotinamide.

Some metabolic changes induced by the intraventricular administration of 6-aminonicotinamide (6-AN) were studied in mice. Five or ten microgram/animal of 6-AN produced a marked hyperglycemia, lowered glycogen content in the brain and liver, and reduced the adrenal epinephrine content. Adrenalectomy or hexamethonium prevented 6-AN-induced hyperglycemia and decrease of glycogen content in the liver but not in the brain. Decrease of adrenal epinephrine content induced by 6-AN was overcome by hexamethonium. Pretreatment with 6-AN (10 microgram/animal) markedly lowered the toxic action, but not the hypoglycemic action, of a large dose of insulin.

Morphological alterations and focal deficiency of the histochemical activity of acid and alkaline nucleases in rat liver after chronic administration of phenobarbital

Chronic oral administration of phenobarbital (up to 16 months) did not produce any neoplastic foci or nodules in the liver of male Wistar rats. Decrease of glycogen content and cytoplasmic alterations probably indicating S.E.R. hypertrophy were observed in the hepatocytes localized predominantly in the centrilobular areas of rats after chronic phenobarbital treatment. This treatment induced small foci of alkaline DNAse and RNAse deficient liver cells in the initial stages of the experiment. Acid DNAse and RNAse deficient zones increased in liver parenchyma since the third month of chronic administration of phenobarbital. At later stages of the experiment (7 to 16 months) they concerned in some cases more than 50% of liver parenchyma. The hyperbasophilia and the intensity of methylgreen-pyronin staining which, most probably, indicated the accumulation of nucleic acids also increased progressively with phenobarbital administration in similarly distributed irregular zones. These zones had predominant centrilobular localization. It was suggested that such zonal deficiency of acid nuclease activity might be involved in tumor-promoting action of phenobarbital when separately administered in rats after hepatocarcinogen treatment.

INSULIN DELAYS THE MORPHOLOGIC MATURATION OF FETAL RAT LUNG IN VITRO

Infants of diabetic mothers, who have increased circulating levels of insulin, are prone to an increased incidence of RDS. In order to evaluate the relationship between hyperinsulinism and lung maturation we have examined the influence of insulin on the morphologic development of fetal rat lung in organ culture. Ex-plants of 19 day gestation fetal lung were cultured in F12 medium, to which 1.0 u/ml insulin had been added, for 24 hours. Explants grown in F12 medium alone served as controls. After 24 hours the control cultures demonstrated evidence of continued maturation as evidenced by: larger alveolar spaces, less interstitial mesenchyme, decreased glycogen content, and increased numbers of lamellar bodies. Explants cultuted in medium containing insulin had the following features: very tall alveolar lining cells which were filled with glycogen and extended into the alveolar spaces, frequently obliterating them, more interstitial tissue and markedly fewer lamellar bodies than in the control cultures. The control cultures had 8.3±2.1 lamellar bodies per 10 alveolar lining cells, whereas the insulin treated cultures had 1.1±0.4 lamellar bodies per 10 lining cells.These observations indicate that insulin delays the appearance of lamellar bodies and increases the glycogen content of the alveolar lining cells in this culture system. Insulin may act by stimulating glycogen synthesis from glucose thereby diverting substrate away from phospholipid synthesis. Supported by USPHS grant no. HL 19752.

Effect of cyclic AMP on glycogen phosphorylase in Coprinus macrorhizus

Glycogen phosphorylase (1,4-α- d-glucan:orthophosphate α-glucosyltransferase, EC 2.4.1.1) activity was found in mycelial extracts of Coprinus macrorhizus concurrently with decrease of glycogen content in mycelial cells. Incubation of the enzyme sample with cyclic AMP and ATP leads to a 3-fold activation of the glycogen phosphorylase activity. Activation of the enzyme partially purified through Sepharose 6B required a cellular fraction containing cyclic AMP-dependent protein kinase.

Maternal-fetal carnitine relationship and neonatal ketosis in the rat.

The concentration of ketone bodies in plasma and of carnitine in various maternal, fetal, and neonatal tissues was examined during the developmental period in rats. Plasma ketone levels were low in the fetus, increased 10-fold during the first 24 h postpartom, and thereafter gradually declined such that normal values were found at the end of the suckling period. An almost identical profile was observed for liver carnitine concentrations in the baby rats. The converse was true for heart tissue, the carnitine content of which was low at birth and steadily increased to adult levels with the time of suckling. The primary source of carnitine in neonatal tissues, at least during the first 2 to 3 days postpartum, was shown to be the mother rat whose liver and milk carnitine content was very high at this time and fell as nursing continued. Experiments in which the fate of [14C]butyrobetaine, the immediate precursor of carnitine, was followed after injection into nursing mother rats indicated movement of carnitine from maternal liver leads to maternal plasma leads to milk leads to neonatal tissues. The above findings support the view expressed earlier that one prerequisite for the development of a high ketogenic profile in liver may be an elevation in the tissue carnitine concentration. Additional factors, however, are clearly involved as evidenced by the observation that in the fed state perfused livers from nursing mother rats synthesized ketone bodies from oleic acid at low rates compared with those seen after a 24 h fast, despite the fact that tissue carnitine levels were equally elevated in both groups. This paradox is likely related to the fact that in the fed state such livers also contained large quantities of glycogen, depletion of which through fasting was accompanied by marked acceleration of ketogenesis from oleate. The data indicate, therefore, that maximal ketogenic capacity of the liver requires for its induction an increase in carnitine coupled with a decrease in glycogen content of the tissue.