Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01275 (glucagon)
 26,492 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Metabolic changes during the first 24 hours of starvation were studied in rats previously adapted for 3 weeks during the postweaning growth period to a low-protein diet using lactalbumin as a dietary protein source. Previous adaptation to a high-quality, low-protein diet reduced the effects of early starvation on the loss of body and liver weight. In rats fed a low-protein diet (6% lactalbumin, LP rats), free triiodothyronine (T3) concentration remained higher than in control rats (13% lactalbumin, C rats) throughout the experiment (+38%, 24 hours), and the plasma insulin concentration, which was lower than in C rats during the first 6 hours (-56%), was not different thereafter. Plasma insulin to glucagon molar ratio was lower (-54%) and liver cyclic adenosine monophosphate (cAMP) concentration was higher (+28%) in LP than in C rats in the fed state, but these were not different at 24 hours of starvation. Plasma glucose concentration was slightly lower in LP than in C rats (-15%) in the fed state, but it was not different in both groups during starvation. Whereas they were unchanged in the fed state, plasma lactate concentration was lower (-57%) and free fatty acid and total ketone body concentrations were higher (+38% and +183%, respectively) in LP than in C rats at 24 hours of starvation.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Metabolic changes during early starvation in rats fed a low-protein diet in the postweaning growth period. 161 90

Cultured rat hepatocytes were preincubated with glucagon or a cyclic AMP analogue for up to 24 h and lipid synthesis and secretion were determined during the next 2 h. Glucagon or cyclic AMP did not change the incorporation of choline or glycerol into phosphatidylcholine, or choline into sphingomyelin, in the cells after 0-12 h of preincubation. After 12 h these incorporations were increased. Incorporations into hepatic lysophosphatidylcholine were decreased after preincubation with glucagon or cyclic AMP for 0-12 h, but by 24 h they increased. There was no change in the lysophosphatidylcholine in the medium after preincubation with glucagon or cyclic AMP for up to 6 h, but increases occurred after preincubation from 12 to 24 h. The secretion of triacylglycerol was decreased after preincubation for 0-1 h, but it returned to control values after 4 h. After preincubation for 18-24 h the incorporation of glycerol into secreted triacylglycerol was increased. The results are discussed in relation to the control of lipid metabolism in starvation and diabetes.
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PMID:Biphasic effects of glucagon and cyclic AMP on the synthesis and secretion of lipids by rat hepatocytes. 165 86

Cyclic AMP phosphodiesterase was measured in liver homogenates and microdissected periportal and perivenous liver tissue from rats in different dietary states under different conditions of substrate saturation and effector stimulation. A radiochemical microtest, more sensitive by 2-3 orders of magnitude than the usual assay, was established for the determination of the activity in liver samples corresponding to 200-800 ng dry weight. At saturating cyclic AMP concentrations (46 microM) phosphodiesterase was homogeneously distributed within the liver acinus of fed rats. Starvation for 48 h led to a decrease in the overall activity and to a heterogenous distribution with slightly higher activities in the perivenous zone. At physiological cyclic AMP concentrations (1.8 microM) phosphodiesterase showed a flat zonal gradient in livers of fed rats with higher levels in the periportal zone; after 48 h starvation it was homogeneously distributed. In the presence of cyclic GMP (2 microM) the basal activity at physiological substrate concentrations was stimulated to a greater extent in the perivenous zone. This led to a homogeneous activity distribution in the fed state and to a heterogenous pattern with a slight perivenous maximum in the fasted state. Thus there was no or only a small zonal heterogeneity of signal transmitting enzymes such as cyclic AMP phosphodiesterase and glucagon-stimulated adenylate cyclase (Zierz and Jungermann 1984). This similar signal transducing capacity in the periportal and the perivenous area will contribute to maintain the zonation of signal input due to the hormone concentration gradients across the liver acinus.
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PMID:Distribution of cyclic AMP phosphodiesterase in microdissected periportal and perivenous rat liver tissue with different dietary states. 171 30

In summary, the vitamin pantothenic acid is an integral part of the acylation carriers, CoA and acyl carrier protein (ACP). The vitamin is readily available from diverse dietary sources, a fact which is underscored by the difficulty encountered in attempting to induce pantothenate deficiency. Although pantothenic acid deficiency has not been linked with any particular disease, deficiency of the vitamin results in generalized malaise clinically. In view of the fact that pantothenate is required for the synthesis of CoA, it is surprising that tissue CoA levels are not altered in pantothenate deficiency. This suggests that the cell is equipped to conserve its pantothenate content, possibly by a recycling mechanism for utilizing pantothenate obtained from degradation of pantothenate-containing molecules. Although the steps involved in the conversion of pantothenate to CoA have been characterized, much remains to be done to understand the regulation of CoA synthesis. In particular, in view of what is known about the in vitro regulation of pantothenate kinase, it is surprising that the enzyme is active in vivo, since factors that are known to inhibit the enzyme are present in excess of the concentrations known to inhibit the enzyme. Thus, other physiological regulatory factors (which are largely unknown) must counteract the effects of these inhibitors, since the pantothenate-to-CoA conversion is operative in vivo. Another step in the biosynthetic pathway that may be rate limiting is the conversion of 4'-phosphopantetheine (4'-PP) to dephospho-CoA, a step catalyzed by 4'-phosphopantetheine adenylyl-transferase. In mammalian systems, this step may occur in the mitochondria or in the cytosol. The teleological significance of these two pathways remains to be established, particularly since mitochondria are capable of transporting CoA from the cytosol. Altered homeostasis of CoA has been observed in diverse disease states including starvation, diabetes, alcoholism, Reye syndrome (RS), medium-chain acyl CoA dehydrogenase deficiency, vitamin B12 deficiency, and certain tumors. Hormones, such as glucocorticoids, insulin, and glucagon, as well as drugs, such as clofibrate, also affect tissue CoA levels. It is not known whether the abnormal metabolism observed in these conditions is the result of altered CoA metabolism or whether CoA levels change in response to hormonal or nonhormonal perturbations brought about in these conditions. In other words, a cause-effect relation remains to be elucidated. It is also not known whether the altered CoA metabolism (be it cause or result of abnormal metabolism) can be implicated in the manifestations of a disease. Besides CoA, pantothenic acid is also an integral part of the ACP molecule.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Pantothenic acid in health and disease. 174 61

1. Plasma levels of insulin, glucagon, and glucagon-like peptide (Glp) were all reduced by starvation of salmon and cod. In the salmon the drop in Glp was larger than in insulin and glucagon. 2. After starvation the activity of hexokinase (EC 2.7.1.1) was increased in salmon liver, but decreased in cod liver. The salmon hepatic hexokinase activity was inversely correlated with the Glp/insulin ratio. 3. Activities of hepatic glycogen phosphorylase (EC 2.4.1.1) and phosphofructokinase (EC 2.7.1.11) were increased in starved as compared to fed salmon. In cod, starvation resulted in decreased or unchanged activity of phosphorylase. This discrepancy may be related to different degrees of environmental and handling stress. 4. Intraperitoneal injection of human insulin in salmon gave increased hepatic phosphorylase and hexokinase activities and reduced plasma levels of glucagon, Glp and endogenous fish insulin at sampling after 30 hr. 5. No differences in hepatic hexokinase activities or plasma hormone levels were observed between cod fed low and high carbohydrate diets. Apparently, regulation of glucose phosphorylation by dietary carbohydrate does not occur.
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PMID:Insulin and glucagon family peptides in relation to activities of hepatic hexokinase and other enzymes in fed and starved Atlantic salmon (Salmo salar) and cod (Gadus morhua). 181 75

The effect of insulin on the properties of liver carnitine palmitoyltransferase I (CPT I) was assessed in conscious starved rats with the euglycemic hyperinsulinemic clamp. A 24-hour clamp was necessary to fully reverse the effect of starvation on liver malonyl-CoA concentration, CPT I maximal activity, and apparent km and Ki for malonyl-CoA. Since glucagon was not decreased during the clamp, insulin is the major factor involved in the regulation of CPT I.
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PMID:Effect of insulin on the properties of liver carnitine palmitoyltransferase in the starved rat: assessment by the euglycemic hyperinsulinemic clamp. 186 36

Hormonal modulation of hepatic plasma membrane lactate transport was studied in primary cultures of isolated hepatocytes from fed rats to examine the mechanism for the known enhancement of lactate transport in starvation and diabetes. Total cellular lactate entry was increased by 14% in the presence of dexamethasone; this was accounted for by an approximately 40% increase in the carrier-mediated component of entry with no effect on diffusion. A trend of similar magnitude was evident with glucagon. The effects of dexamethasone and glucagon on lactate transport constitute an additional potential mechanism for enhancement of gluconeogenesis by these hormones.
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PMID:Hormonal modulation of hepatic plasma membrane lactate transport in cultured rat hepatocytes. 208 71

Food intake, plasma glucose, insulin (I) and glucagon (G), hepatic glycogen and fructose 2,6-bisphosphate (F-2, 6-P2) and liver glucokinase, glucose 6-phosphatase (G6-Pase), 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (6-PF-2 kinase/F-2, 6-P2ase), pyruvate kinase (PK-L) and phosphoenolpyruvate carboxykinase (PEPCK) activities were measured in 2 and 22-month-old rats before 3 d starvation and after 2, 4, 6, 24 and 48 h refeeding a high carbohydrate (HC, 74% w/w) diet. Expressed per 100 g of body weight, the food intake of old rats was 55% lower than that of young rats and the amount of carbohydrate absorbed hourly during the first 6 h of refeeding was 2.4-fold higher in young than in old rats. During the first 6 h of refeeding plasma glucose increased 2-fold and returned to normal values after 24 h in young rats, while plasma glucose did not change during refeeding in old rats. In young rats [I] fell by 85% after starvation and returned to normal values 2 h after refeeding. [I] was higher in old than in young rats; it decreased by 40% after starvation and returned to the basal value 4 h after refeeding. No marked changes were observed in plasma [G] in both groups. No difference was observed in hepatic glycogen in the two groups, while F-2, 6-P2 was higher in old than in young rats. In young rats, the opposite changes in liver glucokinase and G6-Pase activities occurring after starvation and during refeeding were
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PMID:Age-dependent glycolysis and gluconeogenesis enzyme activities in starved-refed rats. 208 82

The increased activity of pyruvate dehydrogenase (PDH) kinase induced in hearts of rats by starvation for 48 h was maintained following preparation of cardiac myocytes, and it was also maintained, though at a decreased level, after 25 h of culture in medium 199. This loss of PDH kinase activity was not prevented by n-octanoate, dibutyryl cyclic AMP or glucagon. The PDH kinase activity of myocytes from fed rats was increased to that of starved rats after 25 h of culture with n-octanoate, dibutyryl cyclic AMP or both agents together.
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PMID:Longer-term regulation of pyruvate dehydrogenase kinase in cultured rat cardiac myocytes. 215 9

Hepatic fatty acid synthase is regulated by nutritional state. Starvation decreases and refeeding increases the activity of avian fatty acid synthase, principally by regulating transcription of the gene (Back, B. W., Goldman, M. J., Fisch, J.E., Ochs, R.A., and Goodridge, A.G. (1986) J. Biol. Chem. 261, 4190-4197). In chick embryo hepatocytes in culture, the stimulatory effect of feeding on fatty acid synthase activity is mimicked by adding triiodothyronine and insulin; the inhibitory effect of starvation is mimicked by adding glucagon or cyclic AMP. We now show that triiodothyronine alone stimulates transcription of fatty acid synthase by 4- to 6-fold, about the same as the increase in fatty acid synthase mRNA. When added alone, insulin has little or no effect on transcription, mRNA level, or enzyme activity. In combination with triiodothyronine, however, insulin amplifies the response to triiodothyronine by about 2-fold, leading to an overall increase of about 10-fold. Insulin-like growth factor 1 (IGF-1) has the same effect as insulin, no effect by itself, and amplification of the stimulation by triiodothyronine. A maximally effective dose of insulin has no effect in the presence of a maximally effective dose of IGF-1, suggesting regulation by a common pathway. It takes much less IGF-1 than insulin to achieve a given effect, suggesting that both insulin and IGF-1 may act through IGF-1 receptors. Plasma levels of IGF-1 are decreased by starvation and increased by feeding (reviewed by Froesch, E.R., and Zapf, J. (1985) Diabetologia 28, 485-493). Thus, IGF-1 may play a physiological role in the regulation of hepatic fatty acid synthase during transitions between the starved and fed states, roles previously assigned primarily to insulin and glucagon. IGF-1 regulates transcription of the fatty acid synthase gene. Insulin and IGF-1 also have similar effects on activity, mRNA abundance, and transcription of the malic enzyme gene. Glucagon or dibutyryl cyclic AMP inhibit fatty acid synthase activity and mRNA level in hepatocytes in culture by 70-80% and 60%, respectively, but have no effect on transcription of the fatty acid synthase gene, suggesting a post-transcriptional mode of regulation for cyclic AMP.
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PMID:Triiodothyronine stimulates transcription of the fatty acid synthase gene in chick embryo hepatocytes in culture. Insulin and insulin-like growth factor amplify that effect. 217 Apr 11


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