Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P56851 (epididymal)
 11,273 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

5-Hydroxytryptamine (5-HT) inhibited the incorporation of 14C from 14C-labelled glucose, pyruvate, citrate and acetate into fatty acids but it did not inhibit the conversion of 14C from citrate and acetate into CO2, and the citrate conversion into glyceride-glycerol in epididymal and mesenteric adipose tissue from 24h-fasted rats. 5-HT stimulated the formation of lactate from glucose and pyruvate, and increased the ratio of lactate produced/pyruvate taken up. This ratio was similar to the NADH:NAD ratio. These results indicate that 5-HT inhibits fatty acid synthesis in rat white adipose tissue by mechanisms similar to those of the catecholamines.
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PMID:Inhibitory effect of 5-hydroxytryptamine on lipogenesis in rat adipose tissues. 4 10

The redox behaviour of the NAD(P) system and flavoproteins was registered by simultaneous fluorescence measurements in epididymal bull spermatozoa. The flavoprotein fluorescence signal can nearly exclusively be attributed to an NAD-linked enzyme, alpha-lipoamide dehydrogenase (Em7.4 = -286 mV). A comparison of intact with digitonin-permeabilized spermatozoa revealed that about 50% of the total NAD(P)H fluorescence signal was of mitochondrial origin. Under equilibrium conditions, the midpoint potentials of the NAD(P)H fluorescence signal of both compartments were almost identical (-300 mV). When lactate was present as substrate, 1 mM caffeine increased respiration oxidizing the NAD(P)H system in both mitochondria and cytosol. This indicates a close relationship of the two NAD pools in spermatozoa.
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PMID:Use of NAD(P)H and flavoprotein fluorescence signals to characterize the redox state of pyridine nucleotides in epididymal bull spermatozoa. 200 81

Enzyme activities related to fatty acid synthesis were determined in liver extracts of rats treated with thioacetamide (TAM) for 8 weeks. Lipogenesis and cholesterogenesis in vivo were evaluated both in liver and in epididymal adipose tissue. The enzymatic activities of ATP-citrate lyase, acetyl CoA carboxylase, fatty acid synthetase, glycerol kinase and NAD-kinase decrease progressively when TAM was chronically administered. However, in the same experimental conditions malic enzyme and other NADP-enzymes were noticeably increased. This increase can be related to an excess of NADPH production necessary for detoxification rather than for lipogenesis. The rate of in vivo incorporation of 3H2O into non-saponifiable fraction in liver showed an increase in the acute phase (1-3 days) of TAM-treatment. In the chronic phase of TAM intoxication this rate returned to values close to normality. The rate of in vivo incorporation of 3H2O to fatty acid fraction increased in the liver during the acute phase of TAM-treatment and showed a sharp decrease during the subacute and chronic phases of the intoxication. At the end of the 60-day period of TAM-treatment, the radioactivity incorporated into fatty acids was significantly lowered. These data showed that the alterations in hepatic lipogenesis observed during TAM administration are related to changes in the activities of lipogenic enzymes and probably are a consequence of alterations in plasma insulin concentration. Disturbances in lipid metabolism should play an important role in the pathogenesis of liver damage and its physiological significance could involve metabolic changes in proliferative and neoplastic liver diseases.
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PMID:Lipogenesis and cholesterogenesis de novo in liver and adipose tissue. Alterations of lipid metabolism by the effect of short- and long-term thioacetamide administration to rats. 264 16

Multiple forms of the soluble 17 beta-hydroxysteroid dehydrogenase of female rabbit liver were identified. NAD-dependent and NADP-dependent enzyme activities were separated by affinity chromatography on agarose-immobilized Procion Red HE3B, and three forms of the NADP-dependent enzyme activity were purified by chromatofocusing. These three enzyme forms are charge isomers and have no quaternary structure. The enzymes catalysed the C-17 oxidoreduction of oestrogens and androgens; with all enzyme forms the activity towards androgens was higher than that toward oestrogens. The enzymes also exhibited 3 alpha-hydroxysteroid dehydrogenase activity towards androgens of the 5 beta-androstane series. Comparison of the relative activities of the enzymes towards a number of oestrogen and androgen substrates revealed differences among the enzyme forms for both the oxidative and the reductive reactions. In particular, one enzyme form had a significantly lower Km for the 3 alpha-hydroxysteroid substrate and a higher 3 alpha-/17 beta-hydroxysteroid dehydrogenase activity ratio than the other two enzyme forms.
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PMID:A 17 beta-hydroxysteroid dehydrogenase of female rabbit liver cytosol. Purification and characterization of multiple forms of the enzyme. 298 68

Factors influencing the utilization of ketone bodies by mouse adipose tissue in vitro were studied. Epididymal fat pads can oxidize DL-Beta-hydroxybutyrate-3-(14)C and acetoacetate-3-(14)C to (14)CO(2) as well as convert these compounds to fatty acid-(14)C. An increased output of (14)CO(2) from Beta-hydroxybutyrate-3-(14)C was noted in response to glucose plus insulin, succinate, oxaloacetate, L-asparate, and L-malate. Fatty acid synthesis from Beta-hydroxybutyrate was enhanced by glucose plus insulin, L-aspartate, L-malate, oxaloacetate, and citrate. Nicotinamide stimulated the oxidation of Beta-hydroxybutyrate but not of acetoacetate to CO(2), and did not affect fatty acid synthesis from either ketone body. Nicotinamide increased NAD(+) and NADP(+) levels in epididymal fat pads without affecting the concentration of NADH and NADPH. "Superlipogenesis" caused by fasting the mice for 48 hr and re-feeding them for 24 hr sharply enhanced CO(2) output and lipogenesis from Beta-hydroxybutyrate. The activities of glucose-6-phosphate dehydrogenase, 6-phosphogluconic dehydrogenase, NADP-malic dehydrogenase, and citrate cleavage enzyme from mouse adipose tissue were increased during "superlipogenesis." Free fatty acid release by epididymal fat pads in vitro was slightly increased by Beta-hydroxybutyrate. The relationship of ketone body metabolism and lipogenesis in adipose tissue is discussed.
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PMID:Factors influencing the utilization of ketone bodies by mouse adipose tissue. 422 Nov 4

1. Attempts were made to define the role of phosphofructokinase in glycolytic control and the factors regulating the concentration of l-glycerol 3-phosphate in rat epididymal fat pads incubated in vitro. 2. Glycolysis rates were altered by anoxia or by additions of insulin, adrenaline or both to the incubation medium, and the changes in rate were related to changes in the steady-state concentrations of hexose phosphates, adenine nucleotides, l-glycerol 3-phosphate and citrate in the whole tissue. Measurements were also made of the lactate/pyruvate concentration ratio in the medium after incubation. 3. The mass-action ratios of phosphofructokinase, calculated from the whole-tissue concentrations of products and substrates, were less than 0.1% of the value of the ratio at pH7.4 at equilibrium. 4. Only in the presence of adrenaline could the observed stimulation of glycolytic flux be related to a possible activation of phosphofructokinase since, in this situation, the concentration of one substrate, fructose 6-phosphate, was not altered and the concentration of the other, ATP, was decreased. Increased glycolytic flux in the presence of insulin may be explained by an observed increase in the concentration of the substrate, fructose 6-phosphate. Under anaerobic conditions, glycolytic flux was decreased but this did not appear to be the result of inhibition of phosphofructokinase, since the concentrations of both substrates, fructose 6-phosphate and ATP, were decreased. The changes in glycolytic flux with insulin and anoxia may be secondary to changes in the rate of glucose uptake. 5. Changes in l-glycerol 3-phosphate concentration appear to be related both to changes in the concentration of dihydroxyacetone phosphate and to changes in the NADH/NAD(+) concentration ratio in the cytoplasm. They do not seem to be related directly to alterations in glycolytic rate.
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PMID:Regulation of glycolysis and L-glycerol 3-phosphate concentration in rat epididymal adipose tissue in vitro. Role of phosphofructokinase. 430 37

1. A method is described for extracting separately mitochondrial and extramitochondrial enzymes from fat-cells prepared by collagenase digestion from rat epididymal fat-pads. The following distribution of enzymes has been observed (with the total activities of the enzymes as units/mg of fat-cell DNA at 25 degrees C given in parenthesis). Exclusively mitochondrial enzymes: glutamate dehydrogenase (1.8), NAD-isocitrate dehydrogenase (0.5), citrate synthase (5.2), pyruvate carboxylase (3.0); exclusively extramitochondrial enzymes: glucose 6-phosphate dehydrogenase (5.8), 6-phosphogluconate dehydrogenase (5.2), NADP-malate dehydrogenase (11.0), ATP-citrate lyase (5.1); enzymes present in both mitochondrial and extramitochondrial compartments: NADP-isocitrate dehydrogenase (3.7), NAD-malate dehydrogenase (330), aconitate hydratase (1.1), carnitine acetyltransferase (0.4), acetyl-CoA synthetase (1.0), aspartate aminotransferase (1.7), alanine aminotransferase (6.1). The mean DNA content of eight preparations of fat-cells was 109mug/g dry weight of cells. 2. Mitochondria showing respiratory control ratios of 3-6 with pyruvate, about 3 with succinate and P/O ratios of approaching 3 and 2 respectively have been isolated from fat-cells. From studies of rates of oxygen uptake and of swelling in iso-osmotic solutions of ammonium salts, it is concluded that fat-cell mitochondria are permeable to the monocarboxylic acids, pyruvate and acetate; that in the presence of phosphate they are permeable to malate and succinate and to a lesser extent oxaloacetate but not fumarate; and that in the presence of both malate and phosphate they are permeable to citrate, isocitrate and 2-oxoglutarate. In addition, isolated fat-cell mitochondria have been found to oxidize acetyl l-carnitine and, slowly, l-glycerol 3-phosphate. 3. It is concluded that the major means of transport of acetyl units into the cytoplasm for fatty acid synthesis is as citrate. Extensive transport as glutamate, 2-oxoglutarate and isocitrate, as acetate and as acetyl l-carnitine appears to be ruled out by the low activities of mitochondrial aconitate hydratase, mitochondrial acetyl-CoA hydrolyase and carnitine acetyltransferase respectively. Pathways whereby oxaloacetate generated in the cytoplasm during fatty acid synthesis by ATP-citrate lyase may be returned to mitochondria for further citrate synthesis are discussed. 4. It is also concluded that fat-cells contain pathways that will allow the excess of reducing power formed in the cytoplasm when adipose tissue is incubated in glucose and insulin to be transferred to mitochondria as l-glycerol 3-phosphate or malate. When adipose tissue is incubated in pyruvate alone, reducing power for fatty acid, l-glycerol 3-phosphate and lactate formation may be transferred to the cytoplasm as citrate and malate.
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PMID:The intracellular localization of enzymes in white-adipose-tissue fat-cells and permeability properties of fat-cell mitochondria. Transfer of acetyl units and reducing power between mitochondria and cytoplasm. 439 82

The paper deals with a regulatory effect of the redox state of nicotinamide coenzymes on glyceroneogenesis in the epididymal fatty tissues involving incorporation of [2-14C] pyruvate into synthetized de novo blood glucose, glycerol and fatty acids of triacyglycerines. Large values of the NAD+/NADH and NADP+/NADPH ratios in cytoplasm and mitochondria promote a high rate of lipogenesis and glucose oxidation processes, which is pronounced in a more intense 14C incorporation into fatty acids than in triacylglycerol glycerols. A decrease in the NAD+/NADH ratio and an increase in the reducing ability of NAD-pairs under fasting intensify glyceroneogenesis in the fatty tissue. The incorporation of [14C] pyruvate into blood glucose in 3.6 times as high, the radioactivity of fatty acids lowers. Nicotinamide administered to animals after fastening inhibits glyceroneogenesis in the fatty tissue, lowering considerably the incorporation of [14C] pyruvate into triacylglycerol glycerol and blood glucose.
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PMID:[Study of the role of nicotinamide coenzymes in the regulation of glyceroneogenesis from pyruvate in rat epididymis fat tissue]. 621 12

The subcellular distribution of the enzymes primarily involved in the metabolism of ethanol and acetaldehyde were made in the rat testis and in the epididymis. The enzymes measured were alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH). They were NAD-dependent, temperature sensitive and displaying maximal activity in the presence of pyrophosphate buffer at pH 9.8. Both enzymes were readily measurable in the 10% (w/v) testicular and epididymal homogenates. The ADH activity was mainly localized in the nuclear and in the cytosolic fractions of the testis compared to the absence of measurable ADH activity in the epididymis. Testicular ALDH was measurable in all subcellular preparations, i.e. in the nuclear, in the mitochondrial, in the cytosolic and in the microsomal fractions. Maximal testicular ALDH activity was determined in both the nuclear and the cytosolic components compared to a lower microsomal ALDH activity. Determination of Km shows that cytosolic ALDH possesses the lowest apparent Km as contrasted with a high value for the mitochondrial ALDH. Testicular cytosolic ADH but not ALDH was noncompetitively inhibited by 3-methoxytyramine, histamine and d-amphetamine in vitro.
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PMID:Subcellular fractionation of alcohol and aldehyde dehydrogenase in the rat testicles. 703 79

GH, in the presence of glucocorticoid, produces a delayed increase in lipolysis in rat adipose tissue, but the biochemical mechanisms that account for this action have not been established. Other lipolytic agents rapidly activate adenylyl cyclase (AC) and the resulting production of cAMP initiates a chain of reactions that culminates in the activation of hormone-sensitive lipase. We compared responses of segments of rat epididymal fat or isolated adipocytes to 30 ng/ml GH and 0.1 microg/ml dexamethasone (Dex) with 0.1 ng/ml isoproterenol (ISO), which evoked a similar increase in lipolysis. All measurements were made during the fourth hour after the addition of GH+Dex or immediately after the addition of ISO to cells or tissues that had been preincubated for 3 h without hormone. Although no significant increases in cAMP were discernible in homogenates of GH+Dex-treated tissues, Rp-cAMPS (Rp-adenosine 3'5'-phosphothioate), a competitive inhibitor of cAMP, was equally effective in decreasing lipolysis induced by GH+Dex or ISO. The proportion of PKA that was present in the active form was determined by measuring the incorporation of 32P from [gamma-32P]ATP into kemptide in the absence and presence of saturating amounts of cAMP. GH+Dex and ISO produced similar increases in protein kinase A activity in tissue extracts. Treatment with GH+Dex did not change the total forskolin-stimulated AC present in either a crude membrane pellet sedimented at 16K x g or a less dense membrane pellet sedimented at 100K x g, but doubled the AC activity in the 16K pellet when assayed in the absence of forskolin. To evaluate possible effects on G proteins, pellets obtained from centrifugation of adipocyte homogenates at 16K x g and 100K x g were solubilized and subjected to PAGE and Western analysis. GH+Dex decreased Gi alpha2 by 44% (P < 0.02) in the 16K pellets and increased it by 52% (P < 0.01) in the 100K pellets. Gs alpha in the 16K pellet was unaffected by GH+Dex and was decreased (P < 0.05) in the 100K pellet. Sucrose density fractionation of the 16K pellets revealed a similar GH+Dex-dependent shift of Gi alpha2 to less dense fractions as determined by both Western analysis and [32P]NAD ribosylation catalyzed by pertussis toxin. No such changes were seen in the distribution of Gs alpha or 5'-nucleotidase. Colchicine (100 microM) blocked the GH+Dex-dependent shift of Gi alpha2 from the 16K to the 100K pellet and blocked the lipolytic effects of GH+Dex, but not those of ISO. We conclude that by modifying the relationship between AC and Gi alpha2, GH+Dex relieves some inhibition of cAMP production and consequently increases lipolysis.
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PMID:Growth hormone and dexamethasone stimulate lipolysis and activate adenylyl cyclase in rat adipocytes by selectively shifting Gi alpha2 to lower density membrane fractions. 1006 47


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