Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0011849 (diabetes)
 277,896 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The activity of enzymes with a regulatory function in the pathways of glycolysis, gluconeogenesis, NADPH generation and fatty acid synthesis was measured in the placenta and liver of rats. Compared with the liver, a high activity of pyruvate kinase was found in the placenta, indicating a high glycolytic potential; a small capacity for gluconeogenesis was also present and a moderate to low activity of enzymes associated with lipogenesis. The activity of all placental enzymes fell from day 15 to 20 of gestation irrespective of the pathway they represented. The pattern of decline continued when the gestation was prolonged up to day 26 by the administration of chorionic gonadotropin. The rates of activity disappearance over 11 days of gestation differed for each enzyme, with half-lives ranging from 2.7 days for NADP-malate dehydrogenase to 7 days for glucose-6-phosphate dehydrogenase. In contrast, the activity of hepatic enzymes either remained unchanged or showed individual adaptation to the advancing pregnancy. The regression in placental metabolic capacity after day 15 of gestation was also evident by the decrease in glucose uptake and its channelling to lactate, CO2, glycerol and fatty acids. In addition, placental ageing was associated with triglyceride accumulation, mainly due to the decrease in free fatty acid oxidation. Treatment of pregnant rats with several hormones, while markedly affecting the hepatic enzyme activities, failed to induce appreciable changes in the corresponding placental enzymes. This was illustrated in the case of triiodothyronine treatment. Similarly, insulin deficiency induced by streptozotocin failed to elicit adaptive changes in placental enzyme activities typical of diabetes like those occurring in the maternal liver; some converse responses in the placenta were attributed to hyperglycaemia. On the other hand, responses in some fetal liver enzymes were suggestive of fetal hyperinsulinaemia. These observations indicate that placental enzymes are not susceptible to endocrine regulation and imply that placental metabolism is largely independent of the physiopathological alterations affecting the maternal organism. The gradual activity decreases with gestation suggest that the enzyme complement of the placenta, once developed, is designed to last through its limited lifespan without continuous replenishment. Within this context, no mechanism seems to operate to ind1ce the adaptive synthesis of individual enzymes, and the age of the placenta appears to be the primary factor determining its enzyme activity and metabolic performance.
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PMID:Regulation of placental enzymes of the carbohydrate and lipid metabolic pathways. 3 55

The role of preserved beta-cell function in preventing ketoacidosis in type I insulin-dependent diabetes was assessed in eight patients with and seven patients without residual beta-cell function as determined from C-peptide concentrations. After 12 hours of insulin fatty-acid, and glycerol concentrations were all significantly higher in patients without beta-cell function than in those with residual secretion. Mean blood glucose concentrations reached 17.2 +/- SE of mean 1.3 mmol/l (310 +/- 23 mg/100 ml) in the first group compared with 8.8 +/- 1.4 mmol/l (159 +/- 25 mg/100 ml) in the second (P less than 0.01), while 3-hydroxybutyrate concentrations rose to 5.5 +/- mmol/l (57 +/- 5 mg/100 ml) and 1.4 +/- 0.3 mmol/l (15 +/- 3 mg/100 ml) in the two groups respectively (P less than 0.01). Individual mean C-peptide concentrations showed a significant inverse correlation with the final blood glucose values (r = -0.91; P less than 0.02). These findings strongly suggest that even minimal residual insulin secretion is important for metabolic wellbeing in diabetes and may prevent the development of severe ketoacidosis when insulin delivery is inadequate.
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PMID:Role of residual insulin secretion in protecting against ketoacidosis in insulin-dependent diabetes. 11 78

The lipolytic effect of norepinephrine (NE) in adipose tissue in vitro was studied before and after exercise in non-fasted rats with severe, untreated streptozotocin diabetes. It was observed that: 1. NE in increasing concentrations stimulated glycerol release in vitro to an equal extent from the adipose tissue of nondiabetic and diabetic rats. However, the re-esterification of free fatty acids (FFA) in adipose tissue in vitro was decreased by NE in diabetic rats as compared to normal rats. 2. During exercise NE further decreased the re-esterification of FFA in vitro in adipose tissue of diabetic rats. 3. Exercise did not change NE-induced glycerol release in vitro in the adipose tissue of diabetic rats. 4. In diabetic animals the increase in plasma glycerol and FFA during exercise was correlated inversely with the NE-induced release of glycerol and FFA from the adipose tissue of the same animals after exercise. The lipolytic effect of NE is not significantly different in adipose tissue of diabetic and nondiabetic rats. By decreasing the re-esterification of FFA in vitro, NE is probably responsible for the observed increase in the release of FFA in vivo, a likely energy source in severely diabetic animals.
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PMID:Influence of norepinephrine and exercise on lipolysis in adipose tissue of diabetic rats. 12 5

Metabolic and hormonal changes produced by muscular exercise were studied in rats with mild streptozotocin diabetes. In both diabetic and control animals the mean blood glucose increased and liver glycogen decreased during exercise. The postexercise blood glucose level correlated with the liver glycogen content in diabetic rats. A decrease of blood glucose occurred in some diabetic animals, and these also showed a decrease of liver glycogen to very low levels during exercise. During exercise the rise of plasma glycerol was higher in diabetic than in control animals, but changes in circulating free fatty acids, acetone bodies, insulin, corticosterone, lactate, and acid-base equilibrium were similar in the two groups. The results indicate that the only abnormal metabolic response to exercise in rats with mild diabetes is a slight increase of lipid mobilization.
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PMID:Metabolic and hormonal effects of exercise in mild streptozotocin diabetes. 13 Jun 72

The effect of hormone administration on the activity of lipoprotein lipase in the lung was studied in the rat. The following hormones were administered: dexamethasone, L-thyroxine, estradiol-17beta and progesterone. In addition, lung lipoprotein lipase activity was studied in diabetic and lactating rats. Lipoprotein lipase activity was measured in dried, defatted preparations of rat lung using double labeled ([14C]palmitate, [3H]glycerol) chylomicron triacylglycerol as substrate. Dexamethasone administration caused a rise of 70% in the level of activity of lipoprotein lipase in acetone powders of lung and a 100% increase in the amount of enzyme released during heparin infusion into isolated, perfused lungs. Enzyme activity was higher in lungs of females than of male rats; however; the level of activity was unaffected by estrogen or progesterone administration to either male or ovariectomized rats. Diabetes, hyperthyroidism or lactation did not change lipoprotein lipase activity in the lung. The constant presence of lipoprotein lipase activity in the lung suggests that this organ is able to maintain a steady supply of triacylglycerol-fatty acids under a variety of physiological and pathological conditions. Stimulation of enzyme activity by dexamethasone could lead to increased uptake of triacylglycerol-fatty acids by the lung and may thus be a contributing factor to corticosteroid-induced enhanced surfactant synthesis.
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PMID:Lipoprotein lipase in rat lung. Effect of dexamethasone. 13 65

1. Injection of L-tryptophan (750 mg/kg body wt.) led to pronounced hypoglycaemia in fed and 48 h-starved rats. 2. The hypoglycaemic effect is blocked by pretreament with p-chlorophenylalanine, compound MK-486 [Carbidopa: L-alpha-(3,4-dihydroxybenzyl)-alpha-hydrazinopropionic acid monohydrate] or methysergide, and potentiated by pargyline. 3. 5-Hydroxy-L-tryptophan is more potent and induces a more rapid hypoglycaemia than does tryptophan. Other tryptophan metabolites were not associated with hypoglycaemia. 4. Adrenalectomy increases, and acute experimental diabetes strongly decreases, the sensitivity of rats to tryptophan induction of hypoglycaemia. Diabetic animals were also insensitive to 5-hydroxytryptophan. 5. Metabolite concentration changes in the livers from tryptophan-treated 48h-starved and diabetic animals were consistent with a rapid inhibition of gluconeogenesis. This did not correlate with the hypoglycaemic response. 6. Tryptophan treatment was associated with a significant increase in the plasma [beta-hydroxybutyrate]/[acetoacetate] ratio; there were no changes in the plasma concentrations of urea, triacyglycerol, non-esterified fatty acids and glycerol. 7. These observations suggest that the hypoglycaemic action of tryptophan is mediated through formation of intracellular 5-hydroxytryptamine, and is unrelated to the inhibition of gluconeogenesis. It is unlikely that this increased synthesis of 5-hydroxytryptamine involves directly either the adrenal glands or the central nervous system.
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PMID:Tryptophan and the control of plasma glucose concentrations in the rat. 14 76

Concentrations of serum cholesterol, triglyceride, and free glycerol were neasured, and serum lipoprotein electrophoresis was performed in normal dogs and in dogs with hypothyroidism, diabetes mellitus, and acute pancreatitis. Twelve privately owned dogs and 20 Basset Hounds from a research colony served as normal subjects. Privately owned had higher serum lipid concentrations than did research dogs. On electrophorisis of normal dog serum, lipoprotein bands were detected at the beta, pre-beta, alpha-2, and alpha-1 positions. Hypercholesterolemia was associated with increased intensity of the alpha-2-lipoprotein band, and hypertriglyceridemia occurred with increased lipoprotein at the origin, or the beta or pre-beta positions. Hypothyroid dogs had normal lipid values and lipoprotein electrophoretic patterns, hypercholesterolemia with increased intensity of the alpha-2-lipoprotein band, or hypercholesterolemia and hypertiglyceridemia with prominent beta-, pre-beta, and alpha-2-lipoprotein electrophoretic patterns were changed to near-normal values after levothyroxine administration. Diabetic dogs had increased serum cholesterol and triglyceride content and a predominance of lower density lipoproteins, as detected by electrophoresis. Insulin therapy caused the lipid concentrations to decrease and the electrophoretic pattern to revert to near normal. Dogs with acute pancreatitis had moderately increased serum lipid content and electrophoretic patterns characterized by increased intensity of the beta-lipoprotein band and by altered migration of alpha-1-lipoproteins.
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PMID:Lipids and lipoproteins in normal dogs and in dogs with secondary hyperlipoproteinemia. 16 57

The sensitivity of alpha- and beta-adrenergic receptors, and the antilipolytic actions of prostaglandin E1 or insulin on adipose tissue of obese diabetic and non-diabetic subjects have been studied. Accumulation of cyclic AMP in adipose tissue and release of glycerol in response to several catecholamines (adrenaline, noradrenaline and isoprenaline) in the presence or absence of an alpha-adrenergic blocker (phentolamine) have been used to assess catecholamine receptor sensitivity. No differences in beta-receptor activity were observed between diabetics and non-diabetics, either on glycerol release or accumulation of cyclic AMP; alpha-receptor activity was also similar, except for significantly less accumulation of cyclic AMP in diabetic tissue incubated with noradrenaline and phentolamine (p less than 0.01). The antilipolytic action of prostaglandin E1 (at concentrations of 30 fM to 30 pM) on lipolysis (stimulated submaximally with isoprenaline, 10(-7) M) was similar in diabetic and control groups. The antilipolytic action of insulin (from 10(-10) to 10(-6) M) on lipolysis was also similar between the groups. It is concluded that neither disorders of the catecholamine receptor nor of the antiliolytic actions of prostaglandin E1 or insulin are responsible for the abnormalities of fatty acid metabolism in adult diabetes.
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PMID:Catecholamine receptor sensitivity and the regulation of lipolysis in adult diabetes. 18 98

1. The development of glycerolkinase before and after birth was investigated in liver and kidney of rat and hamster. In rat liver, enzyme activity increased very slowly before birth and rapidly thereafter, reaching adult values at the 6th day of postnatal life. In hamster liver, glycerolkinase was considerably elevated already in utero, increased dramatically within the 1st day of postnatal life and reached adult values at the end of the 1st week. The development of hepatic glycerolkinase was compared with that of hepatic phosphoenolpyruvate carboxykinase of rat and hamster up to the 20th day of postnatal life. The different time-courses of the levels of these two enzymes before and after birth as well as the known kinetics of serum insulin, glucagon and corticosterone during that time suggested that none of these hormones is involved in the perinatal development of hepatic glycerolkinase activity. In contrast to liver, kidney glycerolkinase activity in both, rat and hamster, showed a delayed increase during the first week of postnatal life followed by a more pronounced elevation to adult values within the following 2 weeks. 2. When liver and kidney glycerolkinase activity was investigated during starvation (+/- refeeding), in alloxan diabetes(+/- insulin) and after adrenalectomy (+/- cortisol) no significant change in enzyme activity per g tissue could be detected either in liver or in kidney. However, total hepatic glycerolkinase activity was diminished during starvation as a consequence of decreasing liver weight. 3. Incorporation of U-[14C]-glycerol into CO2, lipids and glucose + glycogen by rat liver and kidney cortex slices was studied under the above gluconeogenetic conditions. Despite unchanged glycerolkinase activity in both organs, gluconeogenesis from glycerol was enhanced during starvation and in chronic alloxan diabetes, and could be reversed by refeeding and insulin replacement, respectively. 4. Feeding 20% of linolic acid to normal, alloxan-diabetic or adrenalectomized rats resulted in a significant increase in glycerolkinase activity in liver but not in kidney. 5. From the present findings it is suggested that the first step of gluconeogenesis from glycerol in liver and kidney is not influenced by glucagon, insulin and glucocorticoids, which are generally believed to regulate the rate of gluconeogenesis from non-glycerol precursors, but probably by the change in blood glycerol concentration.
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PMID:Glycerolkinase--a regulatory enzyme of gluconeogenesis? 18 91

Subcutaneous adipose tissue was obtained from 9 patients with untreated diabetes mellitus and from 13 obese nondiabetics. After incubation with isoprenaline or noradrenaline, glycerol release and tissue cyclic AMP (cAMP) were determined. Basal glycerol release was twice as rapid from the diabetic adipose tissue. With isoprenaline, the cAMP concentration and the glycerol production was significantly higher in the diabetic adipose tissue. Noradrenaline did not increase glycerol production or cAMP concentration in the diabetic adipose tissue. Subcutaneous adipose tissue was also removed from the diabetics after antidiabetic treatment. Basal lipolysis was significantly reduced and noradrenaline significantly increased both glycerol release and cAMP production. With isoprenaline, cAMP production and glycerol release were significantly less after antidiabetic treatment than in the untreated state. The data provide evidence for increased alpha- as well as beta-adrenergic receptor sensitivity in human subcutaneous adipose tissue of untreated diabetic patients.
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PMID:Abnormalities in the adrenergic control and the rate of lipolysis in isolated human subcutaneous adipose tissue in diabetes mellitus. 18 19


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