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Query: UNIPROT:P01275 (glucagon)
 26,492 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The influences of food deprivation and refeeding on glutathione (GSH) status, antioxidant enzyme activity and lipid peroxidation in response to an acute bout of exercise were investigated in the liver and skeletal muscles of male Sprague-Dawley rats randomly divided into three groups: starved for 48 h without refeeding; starved for 48 h and refed for 24 or 48 h. Half of each group of rats was exercised on a treadmill until exhaustion and killed immediately, whereas the other half group was killed at rest. Food-deprived rats had significantly lower liver GSH concentration and GSH:glutathione disulfide (GSSG) ratio. Malondialdehyde concentrations in the liver and skeletal muscle were both higher in the starved than in the refed rats (P < 0.05). Refed rats had significantly greater liver GSH level, gamma-glutamylcysteine synthetase and glucose 6-phosphate dehydrogenase activities and plasma insulin concentration than unfed rats. Exercised 24- and 48-h refed rats had 27% and 31 % lower liver GSH (P < 0.05), respectively, and a 21 % lower GSH:GSSG ratio (P < 0.05) than their rested counterparts. Plasma insulin concentrations were significantly lower, whereas glucagon concentrations were greater in the exercised than in the rested rats. Muscle GSH concentration was significantly lower in the food-deprived than in the refed rats (P < 0.05) but was unaffected by exercise. Exercised 24-h refed rats had significantly elevated muscle GSSG concentration compared with rested rats, along with a higher GSH peroxidase and a lower gamma-glutamyltranspeptidase activity (P < 0.05). These data indicate that both food deprivation-refeeding and exhaustive exercise influence liver and skeletal muscle glutathione status and that these changes may be controlled by hepatic glutathione synthesis and release due to hormonal stimulation.
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PMID:Alteration of glutathione and antioxidant status with exercise in unfed and refed rats. 868 45

Muscle atrophy and cachexia are associated with many human diseases. These catabolic states are often associated with the loss of glutathione (GSH), which is thought to contribute to the induction of oxidative stress within the muscle. Glutathione synthesis and secretary characteristics were studied in human skeletal muscle myoblasts and myotube-like cells derived from the myoblasts by growth factor restriction. Differentiation was associated with a shift in the sulfur amino acid precursor specificity for synthesis of GSH from cystine to cysteine, as well as loss in ability to use extracellular glutathione and activation of methionine use. The thiol drug N-acetylcysteine was also shown to be an effective precursor irrespective of the state of differentiation. Additionally, myoblasts and myotube cultures were shown to secrete GSH continually, but only the differentiated cells responded to stress hormones such as glucagon, vasopressin, and phenylephrine, by increased secretion of the tripeptide. The data suggest that the skeletal muscle cells may provide an important hormonally regulated extra-hepatic source of systemic GSH and also shed light on the mechanisms of accelerated turnover of GSH operating during strenuous muscle activity and trauma. The data may also provide biochemical rationales for the nutritional and/or pharmacological manipulation of GSH with sulfur amino acid precursors during the treatment of muscle-specific oxidative stress and atrophy.
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PMID:Differentiation-specific alterations to glutathione synthesis in and hormonally stimulated release from human skeletal muscle cells. 1182 Dec 57

Using isolated rat hepatocytes we have shown that glutathione (GSH) depletion by glutathione-S-transferase (GST)-catalyzed conjugation with 1-bromoheptane or phorone was accompanied by a significant elevation in ascorbate synthesis. Glycogenolysis was also stimulated without a significant rise in glucose synthesis. Furthermore, when glycogenolysis was stimulated in control hepatocytes by increasing intracellular cAMP levels (with glucagon or dibutyryl cAMP), cellular glucose levels, but not ascorbate levels, increased. These data suggest that GSH depletion can stimulate ascorbate synthesis independently of glucose synthesis and that hepatocytes can direct glycogenolysis towards ascorbate synthesis during GSH conjugation.
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PMID:Glycogenolysis is directed towards ascorbate synthesis by glutathione conjugation. 1504 60

A liver-selective glucocorticoid (GC) receptor antagonist (A-348441) was used to determine the effect of reduced hepatic GC signaling on hepatic glucose production. Fasted conscious dogs were studied in the presence (GRA, n = 6) or absence (CON, n = 6) of the intraduodenally administered GC receptor antagonist (100 mg/kg). All dogs were maintained on a pancreatic clamp and in a euglycemic state for 7 hours to ensure that any changes in glucose metabolism were the direct result of the effects of A-348441, which was given at the start of a 5-hour experimental period. In the GRA group, the arterial plasma insulin level was 4.6 +/- 0.7 and 4.8 +/- 0.6 microU/mL during the basal and the last 30 minutes of the experimental periods, respectively. In the CON group, it was 4.0 +/- 0.3 and 4.5 +/- 0.5 microU/mL in the 2 periods, respectively. The arterial plasma glucagon level was 49 +/- 4 and 46 +/- 3 pg/mL in the 2 periods in the GRA group, and 45 +/- 3 and 42 +/- 3 pg/mL in the CON group. Net hepatic glucose balance progressively decreased in the GRA group from 1.31 +/- 0.18 to 0.49 +/- 0.30 mg/kg per minute, whereas in the CON group, net hepatic glucose balance was 1.17 +/- 0.09 and 1.43 +/- 0.18 mg/kg per minute during the basal and last 30 minutes of the experimental periods, respectively. No significant change in net renal or gut glucose balance or nonhepatic glucose uptake was observed in either group. This study demonstrates that the GC receptor plays an important role in the regulation of basal hepatic glucose production and represents a significant potential therapeutic target.
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PMID:Selective antagonism of the hepatic glucocorticoid receptor reduces hepatic glucose production. 1691 47

Oxidative stress has been related to various diseases, gender and ageing, and has been measured by various markers. The authors developed a procedure to compute a global oxidative stress index (OXY-SCORE), reflecting both oxidative and antioxidant markers in healthy subjects. Its performance was tested in relation to age and gender and in coronary artery disease (CAD) patients. Eighty-two healthy subjects and 20 CAD patients were enrolled. Plasma free and total malondialdehyde (F- and T-MDA), glutathione disulphide/reduced form ratio (GSSG/GSH) and urine isoprostanes (iPF2alpha-III) levels were combined as oxidative damage markers (damage score). GSH, alpha- and gamma-tocopherol (TH) levels, and individual antioxidant capacity were combined as antioxidant defence indexes (protection score). The OXY-SCORE was computed by subtracting the protection score from the damage score. Among single parameters, T-MDA and iPF2alpha-III significantly correlated with age; only GSH and both tocopherols correlated with male gender in healthy subjects. The OXY-SCORE was positively associated with age (p=0.004) and male gender (p=0.03). As expected, the OXY-SCORE was higher in CAD with a very significant p-value (<0.0001), after adjusting for age, gender and smoking. Combining different markers can potentially provide a powerful index in the evaluation of oxidative stress related to age, gender and CAD status.
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PMID:Age- and gender-related oxidative status determined in healthy subjects by means of OXY-SCORE, a potential new comprehensive index. 1705 75

This study aimed to monitor the effect of a high (HD; 140% of energy requirements) versus a low diet (LD; 80% energy requirements) on oxidative status in goats during the peripartum period. Blood samples were taken from all goats at -2, -1, 0 (partum), +2 and +4 weeks from delivery. Blood samples were assayed for their content of reactive oxygen metabolites (ROMs), thiol (SH) groups, total antioxidant capacity (OXY) and for glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) activities. The observation that ROMs levels significantly increased during the peripartum period was accompanied by a decrease of GSH-Px activity at weeks 2 and 4 postpartum, which suggested that the goats might have experienced some degree of oxidative stress and lipid peroxidation. Overall, changes to the nutritional level of the diet had very little or no effect on redox homeostasis. The lack of any correlation between the biomarkers measured indicated that each oxidative stress marker responded differently, indicating that redox homeostasis was impaired in these dairy goats during the peripartum period.
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PMID:Effects of plane of nutrition on oxidative stress in goats during the peripartum period. 1923 Dec 60

Patients with long-standing diabetes commonly develop diabetic encephalopathy, which is characterized by cognitive impairment and dementia. Oxidative stress-induced neuronal cell apoptosis is a contributing factor. Glucagon-like peptide (GLP)-1 has recently become an attractive treatment modality for patients with diabetes. It also readily enters the brain, prevents neuronal cell apoptosis, and improves the cognitive impairment characteristic of Alzheimer's disease. Therefore, we investigated whether GLP-1 could protect against oxidative stress-induced neuronal cell apoptosis in pheochromocytoma (PC12) cells. PC12 cells were exposed to 1 mM methylglyoxal (MG) or MG plus 3.30 microg/ml GLP-1. Cell apoptosis, expression and phosphorylation of phosphatidylinositol-3 kinase/Akt/mammalian target of rapamycin/gamma-glutamylcysteine ligase catalytic subunit (GCLc), and redox balance were then determined. The data showed that MG induced PC12 apoptosis in accordance with the redox (glutathione (GSH) and GSH/glutathione disulfide [GSSG]) imbalance. GLP-1 protected against this MG-induced apoptosis, which corresponded to the phosphorylation of PI3K, Akt, and mTOR, as well as the upregulation of GCLc and the restoration of the redox imbalance. Inhibitors of PI3K (LY294002), Akt (Akt-I), and mTOR (rapamycin) reduced the GLP-1-induced GCLc upregulation and its protection against MG-induced PC12 apoptosis. The GLP-1-induced redox restoration was also attenuated by rapamycin. In conclusion, the neuroprotective effect of GLP-1 is due to an enhancement of PI3K/Akt/mTOR/GCLc/redox signaling.
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PMID:Glucagon-like peptide-1 (GLP-1) protects against methylglyoxal-induced PC12 cell apoptosis through the PI3K/Akt/mTOR/GCLc/redox signaling pathway. 1946 4

In the present study, the effects of dexamethasone on cadmium-induced toxicity were evaluated in isolated rat hepatocytes. Hepatocytes were cultured for 24 h in William's E medium containing fetal calf serum (10%), insulin (0.1 IU/ml), and glucagon (0.01 microM) in the absence or presence of 0.1 microM dexamethasone. Cadmium chloride, 5 or 10 microM, was added to the medium and the toxicity was evaluated for up to 48 h after treatment. Lactate dehydrogenase (LDH) release, the reduced and oxidized glutathione ratio (GSH/GSSG), protein-SH groups, and lipid peroxidation levels were evaluated. Cadmium induced a dose- and time-dependent LDH release in control hepatocytes at 24 h (Cd 10 microM 42%) while hepatocytes pretreated with dexamethasone showed lower necrosis (Cd 10 microM 12% at 24 h). GSH/GSSH ratio and protein-SH groups were higher while lipid peroxidation was lower in dexamethasone-treated hepatocytes as compared with untreated cells. In conclusion, cadmium toxicity was associated with an increase in intracellular oxidative stress responsible for accelerated cell death. The use of dexamethasone prevented cadmium damage, suggesting that the cytoprotective action of this hormone is related to its effect in preventing changes in thiols such as glutathione and protein-SH groups.
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PMID:Dexamethasone protects cultured rat hepatocytes against cadmium toxicity: involvement of cellular thiols. 1999 67

Our group recently proposed OXY-SCORE, a summary index of oxidative stress, computed by combining plasma free and total malondialdehyde (F- and T-MDA), glutathione in disulphide/reduced forms (GSSG/GSH), alpha- and gamma-tocopherol (TH), urine isoprostanes (iPF(2alpha)-III) levels, and plasma individual antioxidant capacity. Here, we describe the methods for the determination of the analytes and for the computation of the scores. We also report the results of two studies testing the performances of OXY-SCORE, and showing its value in assessing the oxidative status of cardiovascular patients and healthy subjects.
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PMID:OXY-SCORE: a global index to improve evaluation of oxidative stress by combining pro- and antioxidant markers. 2007 19

The present study was aimed to investigate the possible effects of beta-casomorphin-7, against hyperglycemia and free radical-mediated oxidative stress in streptozotocin-induced diabetic rats by assaying the blood glucose level and the activity of plasma enzymatic antioxidants, such as superoxide dismutase (SOD), catalase and glutathione peroxidase (GSH-Px). A significant increase in the levels of both blood glucose and oxidative stress with a predominant decrease in antioxidant status was observed in the diabetic rats when compared to control rats. After 15 days oral administration of beta-casomorphin-7 (7.5 x 10(-8) mol/day), the elevated blood glucose level was reduced. Oral administration of beta-CM-7 to diabetic rats showed an increase in the level of plasma insulin, the elevated plasma glucagon level was markedly reduced by the oral administration of beta-CM-7. Oral administration of beta-CM-7 to the diabetic group of rats also showed a significant elevation in the activity of SOD and catalase. Thus, the results of the present study suggest that beta-casomorphin-7 can protect rats from hyperglycemia and free radical-mediated oxidative stress in diabetic rats.
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PMID:Protective effect of beta-casomorphin-7 on type 1 diabetes rats induced with streptozotocin. 2068 84


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