Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.3.3.1 (citrate synthase)
 4,488 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In the present study the effects of insulin, glucocorticoids and thyroid hormones on macrophage metabolism and function were investigated. The maximum activities of hexokinase, glucose-6-phosphate dehydrogenase, glutaminase and citrate synthase were determined in macrophages obtained from hormone-treated rats and those cultured for a period of 48 h in the presence of hormones. Macrophage phagocytosis was markedly inhibited by dexamethasone and thyroid hormones, remaining unchanged when insulin was added to the culture medium, however. The changes in the enzyme activities caused by hormone treatments of the rats were very similar to those found in culture. Insulin enhanced citrate synthase and hexokinase activities and diminished those of glutaminase and glucose-6-phosphate dehydrogenase. Dexamethasone had a similar effect except on glucose-6-phosphate dehydrogenase. The addition of thyroid hormones to the culture medium raised the activities of glutaminase and hexokinase and reduced that of citrate synthase. The results presented support the suggestion that the effects of insulin, glucocorticoids and thyroid hormones on immune and inflammatory responses could well be mediated through changes in macrophage metabolism.
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PMID:Effects of insulin, glucocorticoids and thyroid hormones on the activities of key enzymes of glycolysis, glutaminolysis, the pentose-phosphate pathway and the Krebs cycle in rat macrophages. 147 28

1. The effect of dexamethasone (30 micrograms day-1 100 g-1 body wt.) on the metabolism of glucose and glutamine was studied in the small intestine of rats after 9 days of treatment. 2. Dexamethasone treatment resulted in negative nitrogen balance (P less than 0.001), and produced increases in the concentrations of plasma glucose (22%, P less than 0.05), alanine (32%, P less than 0.001) and insulin (127%, P less than 0.001), but a decrease in the plasma concentration of glutamine (20%, P less than 0.05). 3. Portal-drained visceral blood flow increased by approximately 22% (P less than 0.001) in dexamethasone-treated rats, and was accompanied by a decrease in the arterio-venous concentration difference of glucose (43%, P less than 0.001) and an increase in that of lactate (22%, P less than 0.05), glutamine (35%, P less than 0.01), glutamate (33%, P less than 0.01) and alanine (21%, P less than 0.05). 4. Enterocytes isolated from dexamethasone-treated rats showed decreased and increased rates of glucose and glutamine utilization, respectively. 5. The maximal activities of hexokinase, 6-phosphofructokinase, citrate synthase and oxoglutarate dehydrogenase were decreased (30-64%, P less than 0.001) in intestinal mucosal scrapings of dexamethasone-treated rats, whereas the activity of glutaminase was increased (35%, P less than 0.001). 6. It is concluded that glucocorticoid administration decreases the rate of glucose utilization but increases that of glutamine (both in vivo and in vitro) by the epithelial cells of the small intestine. This may be caused by changes in the maximal activities of key enzymes in the pathways of glucose and glutamine metabolism in these cells.
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PMID:Effect of glucocorticoid treatment on glucose and glutamine metabolism by the small intestine of the rat. 340 28

The activities of three mitochondrial oxidative enzymes (citrate synthase, 3-ketoacid-CoA transferase, beta-hydroxyacyl-CoA dehydrogenase) and Na-K-ATPase were microassayed in isolated segments of the rat proximal convoluted tubule (PCT) and medullary thick ascending limb of the loop of Henle (mTAL). The effects of adrenalectomy (ADX) and ADX plus exogenous glucocorticoids were analyzed. The hormonal replacement was daily injections of dexamethasone (10 micrograms/100 g body weight/24 h) for 5 days. ADX lowered the activity of all oxidative enzymes studies in the mTAL, but not in the PCT and led to a decrease in Na-K-ATPase in both nephron segments. Dexamethasone restored the normal level of oxidative enzymes and Na-K-ATPase in the mTAL and of Na-K-ATPase in the PCT. We conclude that the activities of citrate synthase, 3-ketoacid-CoA transferase and beta-hydroxyacyl-CoA dehydrogenase and of Na-K-ATPase are coordinately regulated in the mTAL and that glucocorticoids are essential for the long-term regulation of these enzyme activities in this nephron segment. In contrast, the activities of mitochondrial oxidative enzymes are not influenced by glucocorticoids in the PCT. This study presents the first evidence for a cell-specific regulation by glucocorticoids of oxidative metabolism in the nephron of adult rat kidney.
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PMID:Effect of glucocorticoids on mitochondrial oxidative enzyme and Na-K-ATPase activities in the rat proximal tubule and thick ascending limb of Henle. 769 38

Glucocorticoids near term are known to upregulate many important enzyme systems prior to birth. Glutamate dehydrogenase (GDH) is a mitochondrial enzyme that catalyzes both the reversible conversion of ammonium nitrogen into organic nitrogen (glutamate production) and the oxidative deamination of glutamate resulting in 2-oxoglutarate. The activity of this enzyme is considered to be of major importance in the development of catabolic conditions leading to gluconeogenesis prior to birth. Ovine hepatic GDH mRNA expression and activity were determined in near-term (130 days of gestation, term 147 +/- 4 days) control and acutely dexamethasone-treated (0.07 mg(-1) hr(-1) for 26 hr) fetuses. Dexamethasone infusion had no effect on placental or fetal liver weights. Dexamethasone infusion for 26 hr significantly increased hepatic GDH mRNA expression. This increased GDH mRNA expression was accompanied by an increase in hepatic mitochondrial GDH activity, from 30.0 +/- 7.4 to 58.2 +/- 8.1 U GDH/U CS (citrate synthase), and there was a significant correlation between GDH mRNA expression and GDH activity. The generated ovine GDH sequence displayed significant similarity with published human, rat, and murine GDH sequence. These data are consistent with the in vivo studies that have shown a redirection of glutamine carbon away from net hepatic glutamate release and into the citric acid cycle through the forward reaction catalyzed by GDH, i.e., glutamate to oxoglutarate.
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PMID:Induction of glutamate dehydrogenase in the ovine fetal liver by dexamethasone infusion during late gestation. 1252 80