Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.3.9 (glucose-6-phosphatase)
3,081 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This study was performed to investigate the mechanism involved in a decrease in the serum glucose of golden hamsters infected with plerocercoids of Spirometra erinacei. The concentration of glucagon, the activity of glucose-6-phosphatase in the liver, and the in vivo incorporation of 2-deoxy-D-[1,2-3H]glucose into various organs increased in plerocercoid-infected hamsters compared with controls. Furthermore, the serum from the plerocercoid-infected hamsters enhanced the in vitro incorporation of [U-14C]glucose into adipose tissues, compared with control serum. The serum levels of immunoreactive insulin and somatomedin associated with nonsuppressible insulin-like activity in experimental animals, however, were not significantly different from those in controls. Therefore, we conclude that the decrease in serum glucose associated with plerocercoid infection is not the result of a decrease in gluconeogenesis, but the result of an increased utilization of glucose in the peripheral tissues.
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PMID:Carbohydrate metabolism in intact golden hamsters infected with plerocercoids of Spirometra erinacei (Cestoda: Diphyllobothriidae). 283 Jun 14

The aim of this study was to investigate the metabolic effects of short-term fasting in obese diabetic patients and to correlate the observed changes with the activity of hepatic key enzymes in an animal model of obesity-associated diabetes (ob/ob mice, C57BL/6J strain). In obese diabetic patients (ODP), a 72-h fast (causing slight change in body weight) decreased fasting glycemia by 3.82 +/- 0.79 mmoles/l and significantly improved glucose tolerance (OGTT) while reducing basal and stimulated insulinemia, whereas in obese non-diabetic patients (ONDP) only a small decrease in fasting glycemia (1.24 +/- 0.51 mmoles/l) occurred. This suggests that in ODP hyperphagia is a factor contributing to maintain hyperglycaemia and glucose intolerance (in the face of hyperinsulinaemia, indicating insulin resistance). In fed obese hyperglycaemic mice (OHM), which are a good model of the human obesity-associated diabetes, hepatic fructose-1,6-diphosphatase (F16Pase) and glucose-6-phosphatase (G6Pase), involved in glucose production, showed increased activity (+52 and +200 per cent, respectively) compared to control mice (CM), and the ratios of F16Pase and G6Pase to the opposing enzymes phosphofructokinase (PFK1) and glucokinase (GK), i.e. the F16Pase/PFK1 and G6Pase/GK ratios, were increased by 38 and 101 per cent, respectively, suggesting increase in gluconeogenesis and perhaps in glycogenolysis. In the 48-h fasted OHM, F16Pase activity was decreased (-30 per cent) compared to the fed animals, while the activity of G6Pase showed a smaller and statistically not significant change (-22 per cent). In contrast, in the CM a 48-h fasting was associated with a trend toward increased F16Pase (+22 per cent) and G6Pase (+173 per cent). However, since PFK1 and GK decreased to a similar extent in OHM and CM, the F16Pase/PFK1 and G6Pase/GK ratios, basally elevated in the OHM, did not change with fasting, whereas in the CM they showed a striking elevation (+71 and +274 per cent, respectively). The basally elevated F16Pase/PFK1 and G6Pase/GK ratios (functionally linked to glucose production) in the OHM may contribute to maintain hyperglycaemia; in these mice, the lack of further increase in the glucose production-related F16Pase/PFK1 and G6Pase/GK ratios (which occurs in CM) with fasting might allow that the interruption of the afflux of dietary carbohydrates ameliorates the glycaemic level. Similar mechanisms might occur also in the ODP.
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PMID:Metabolic effects of short-term fasting in obese hyperglycaemic humans and mice. 283 Nov 63

We aim to evaluate the effects of phenobarbital (PB) on the liver drug metabolism, NADPH production capacity and terminal gluconeogenic enzyme, glucose-6-phosphatase (G6Pase) activity in the diabetic state associated with genetic obesity in mice. The results showed that PB treatment increased the amount of liver total cytochrome P450 (cytP450), a drug metabolizing monooxygenase enzyme in genetically obese, hyperglycemic (ob/ob) mice 6-fold and the total activities of other monooxygenase enzymes NADPH cytP450 reductase and 7-ethoxyresorufin O-deethylase (ERDE) 2- and 6.5-fold, respectively. In addition, the regimen increased the liver total activities of two NADPH generating enzymes, 6-phosphogluconate dehydrogenase (6PGDH) and malic enzyme (ME) in obese mice suggesting that the regimen enhanced liver NADPH production capacity in the animals. The data further showed that PB treatment decreased the high hepatic G6Pase activity in obese mice. Both enhanced NADPH generating enzyme activities and lowered G6Pase activity may suppress hepatic glucose output. Since NADPH is required for drug oxidation reactions as a reducing cofactor, high NADPH generating capacity may facilitate liver drug metabolism in vivo. Although the diabetic state in obese mice differs somewhat from that seen in non-insulin dependent diabetic subjects (NIDDs), these findings provide some knowledge about the possible biochemical mechanisms whereby PB treatment normalizes drug metabolism and glycemic control in NIDDs, as has been noted in previous studies.
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PMID:Hepatic drug metabolism and the activities of NADPH generating enzymes and glucose-6-phosphatase in phenobarbital treated genetically obese (ob/ob) mice. 283 24

The ten-fold increase in glucose-6-phosphatase, previously reported, in 2S FAZA hepatoma cells exposed to dexamethasone, is completely blocked by low concentrations of insulin. At 3 x 10(-10) M insulin, the activity induced by 10(-6) M dexamethasone is reduced by half. The activity of intact microsomes, which reflects translocation of cytoplasmic glucose 6-phosphate into the endoplasmic reticulum, is induced by dexamethasone, but to a lesser extent than the hydrolase. Insulin also prevents this induction.
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PMID:Effect of insulin on the induction by dexamethasone of glucose-6-phosphohydrolase and translocase activities in cultured hepatoma cells. 283 6

In the presence of phenobarbital (PB) at 3 mM, hepatocytes isolated from adult rats by a collagenase-perfusion technique survived well on plastic dishes for at least 49 days after initiation of primary culture. PB at concentrations less than 3 mM was ineffective for the maintenance of hepatocytes, and the maintenance of them was attained only in the continuous presence of 3 mM PB. The hepatocytes surviving in the presence of 3 mM PB were morphologically indistinguishable from the hepatocytes after 1-day attachment period, except for the presence of prominent nucleoli in the former. Although both the albumin secretion and tyrosine aminotransferase (TAT) activities of the cells decreased gradually up to day 7 with time in culture, both were thereafter maintained at relatively high levels at least up to day 35 of primary culture. The addition of 10 microM dexamethasone caused a 3-5-fold induction in TAT activity, and the cells were capable of responding to the hormone in this manner at least up to day 28 of primary culture. Furthermore, the cells also had glucose-6-phosphatase activity, even though the level of this enzyme activity was relatively low as compared with that of TAT activity. Survival of hepatocytes in the presence of 3 mM PB was further enhanced by simultaneous addition of dexamethasone (10 microM) and insulin (10 micrograms/ml). The sensitivity of hepatocytes to 3'-methyl-4-dimethylaminoazobenzene (0.24 mM) was remarkably reduced by treatment with PB at 3 mM. PB treatment decreased efficiently the falling rate of total cytochrome P-450 content, but did not induce P-450PB, which is the specific form of cytochrome P-450 induced by PB, in primary cultured hepatocytes. On the other hand, 3-methylcholanthrene (MC, 10 microM) caused an increase of both contents of total cytochrome P-450 and P-450MC, which is the specific form of cytochrome P-450 induced by MC, in primary cultured hepatocytes. However, MC was ineffective for the maintenance of hepatocytes in primary culture. The possible biological actions of PB on primary cultured hepatocytes are discussed on the basis of the experimental data obtained.
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PMID:Long-term survival of functional hepatocytes from adult rat in the presence of phenobarbital in primary culture. 286 57

Salmon (Oncorhynchus kisutch) somatostatin (sSS; 4 or 8 ng/g body wt) or synthetic Gillichthys urotensin II (UII; 2 or 4 ng/g body wt) were injected intraperitoneally into juvenile freshwater coho salmon. Both sSS and UII caused a dose-dependent increase in plasma free fatty acids (FFA) which diminished with time. sSS induced an initial (1 hr) transient hyperglycemia. By contrast, UII tended to induce hypoglycemia, this effect being significant 5 hr after injection of the higher dose. Both sSS and UII depressed plasma insulin titers 1 hr after injection. By 3 hr, the sSS-associated insulin depression was no longer observed. UII treatment induced a hyperinsulinemia which was present 3 and 5 hr after peptide administration. Although no decreases in liver total lipid concentration or in mesenteric fat total tissue mass were observed, lipolytic enzyme activity within each depot was significantly enhanced by both peptides. Neither sSS nor UII altered 3H2O incorporation into fatty acids or neutral lipids. However, enhanced lipogenesis, particularly by UII, was indicated by increased NADPH production resulting from glucose-6-phosphate dehydrogenase activity. Both sSS and UII enhanced glucose mobilization, as indicated by decreased liver glycogen content and increased liver glucose-6-phosphatase activity. UII, but not sSS, stimulated glycogen synthetase activity. These results suggest that both sSS and UII stimulate hyperlipidemia by enhancing depot lipase activity and that although both factors are potentially gluconeogenetic, sSS seems to be glycogenolytic and hyperglycemic, whereas UII may channel glucose to FFA synthesis.
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PMID:Effects of somatostatin-25 and urotensin II on lipid and carbohydrate metabolism of coho salmon, Oncorhynchus kisutch. 288 97

Glucose transport and metabolism, and the effect of insulin thereon, was studied using suspensions of rat renal tubules enriched in the proximal component. [U-14C]Glucose oxidation is a saturable process (Km 3.1 +/- 0.2 mM; Vmax 14 +/- 0.2 mumole 14CO2 formed/g tissue protein per h). Glucose oxidation and [14C]lactate formation from glucose are inhibited in part by phlorizin and phloretin: the data suggest that the rate-limiting entry of glucose into the cell metabolic pool occurs by both the Na-glucose cotransport system (at the brush border) and the equilibrating, phloretin-sensitive system (at the basal-lateral membrane). Raising external glucose from 5 to 30 mM markedly increases aerobic and anaerobic lactate formation. Gluconeogenesis from lactate is not affected by variations of glucose concentrations. 24 h after streptozotocin administration, aerobic lactate formation is enhanced, as is the uptake of methyl alpha-D-glucoside by the tubules, while anaerobic glycolysis is depressed. Streptozotocin treatment (ST) increases both the Km and Vmax of glucose oxidation; gluconeogenesis and lactate oxidation are not affected. The effect of streptozotocin treatment on lactate formation are abolished by 1 mU/ml insulin. Streptozotocin treatment increases tissue hexokinase activity, decreases glucose-6-phosphatase, but has no significant effect on fructose-1,6-diphosphatase; phosphoenolpyruvate carboxykinase and pyruvate dehydrogenase. The data demonstrate fast streptozotocin-induced changes in cellular enzymes of carbohydrate metabolism. The enhancing effect of streptozotocin on methyl alpha-glucoside uptake is transient: 8 days after administration of the agent, no significant difference from controls is found. It is concluded that under the given experimental conditions insulin enhances the equilibrating glucose entry by the phloretin-sensitive pathway at the basal-lateral membrane, and transiently inhibits the Na-glucose cotransport system.
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PMID:Glucose transport and metabolism in rat renal proximal tubules: multicomponent effects of insulin. 293 29

The effect of fetal hypoglycemia and hypoinsulinemia on fetal rat hepatic glucose-6-phosphatase activity was studied. Fetal hypoglycemia and hypoinsulinemia were produced by inducing maternal hyperinsulinemia and hypoglycemia secondary to the exogenous administration of insulin via implantation of osmotically driven minipumps on day 15 of gestation into 15 experimental animals. 13 animals served as sham-operated controls. Cesarean sections were performed on day 20 or 21 of gestation under pentobarbital anesthesia. Liver glucose-6-phosphatase activity was increased in the hypoinsulinemic fetuses. In contrast, the hyperinsulinemic mothers had suppressed hepatic glucose-6-phosphatase activity. Hypoinsulinemia would appear to be the primary stimulus for enhanced fetal glucose-6-phosphatase in this model.
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PMID:Induction in utero of hepatic glucose-6-phosphatase by fetal hypoinsulinemia. 298 86

The activities and zonal distribution of key enzymes of carbohydrate metabolism were studied in livers of diabetic rats. 48 h after alloxan treatment the following alterations were observed, intermediate values being reached after 24 h: Blood glucose, acetoacetate and beta-hydroxybutyrate were increased to more than 500%; liver glycogen was reduced to about 10%. Portal vein insulin was reduced to below 10%, portal glucagon was increased to almost 200%. The glucogenic enzymes phosphoenolpyruvate carboxykinase and glucose-6-phosphatase were enhanced to 320% and 150%, respectively. The glycolytic enzymes glucokinase and pyruvate kinase L (differentiated from the M2 isoenzyme with a specific anti-L-antibody) were lowered to 50% and 75%, respectively. The citrate cycle enzyme succinate dehydrogenase remained unchanged. The normal periportal to perivenous gradient of phosphoenolpyruvate carboxykinase of about 3:1, as measured in microdissected tissue samples, was enhanced to about 4:1 with activities elevated to 230% and 190%, respectively, in the two zones. The normal periportal to perivenous gradient of pyruvate kinase L of about 1:1.7, as determined with the microdissection technique, was reduced to about 1:1.4 with levels lowered to 55% and 45%, respectively, in the two zones. The even zonal distribution of pyruvate kinase M2 remained unaltered.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Metabolic zonation in liver of diabetic rats. Zonal distribution of phosphoenolpyruvate carboxykinase, pyruvate kinase, glucose-6-phosphatase and succinate dehydrogenase. 298 84

The livers of streptozotocin-induced diabetic and fasted rats showed a decreased cholesterol synthesis measured by in vitro incorporation of [2-14C]acetate. A significant decrease of glucose-6-phosphate dehydrogenase (G-6-PD), 6-phosphogluconate dehydrogenase (6-PGD), and pyruvate kinase (PK) was also observed 7 days after administration of streptozotocin. These enzymatic activities were also low in livers of 72 hr fasted animals. An increase of glucose-6-phosphatase (G-6-Pase) was observed consistently in diabetic as well as in fasted rats. Suitable amounts of insulin and refeeding normalized the alterated enzymatic activities in diabetic and in fasted animals, respectively.
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PMID:Hexose monophosphate shunt and cholesterol synthesis in the diabetic and fasting states. 299 16


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