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Query: UMLS:C0038187 (starvation)
 24,951 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. The effects of dietary modification, including starvation, and of corticotropin injection on the activities of acyl-CoA synthetase, glycerol phosphate acyltransferase, dihydroxyacetone phosphate acyltransferase, phosphatidate phosphohydrolase, diacylglycerol acyltransferase and lipoprotein lipase were measured in adipose tissue. 2. Lipoprotein lipase activities in heart were increased and those in adipose tissue were decreased when rats were fed on diets enriched with corn oil or beef tallow rather than with sucrose or starch. The lipoprotein lipase activity was lower in the adipose tissue of rats fed on the sucrose rather than on the starch diet. 3. Rats fed on the beef tallow diet had slightly higher activities of the total glycerol phosphate acyltransferase in adipose tissue than did rats fed on the sucrose or starch diet. The diacylglycerol acyltransferase and the mitochondrial glycerol phosphate acyltransferase activities were higher for the rats fed on the tallow diet than for those fed on the corn-oil diet. 4. Starvation significantly decreased the activities of lipoprotein lipase (after 24 and 48 h), acyl-CoA synthetase (after 24 h) and of the mitochondrial glycerol phosphate acyltransferase and the N-ethylmaleimide-insensitive dihydroxyacetone phosphate acyltransferase (after 48 h) in adipose tissue. The activities of the microsomal glycerol phosphate acyltransferase, diacylglycerol acyltransferase and the soluble phosphatidate phosphohydrolase were not significantly changed after 24 or 48 h of starvation. 5. The activities of lipoprotein lipase and phosphatidate phosphohydrolase in adipose tissue were decreased 15 min after corticotropin was injected into rats during November to December. No statistically significant differences were found when these experiments were performed during March to September. These differences may be related to the seasonal variation in acute lipolytic responses. 6. These results are discussed in relation to the control of triacylglycerol synthesis and lipoprotein metabolism.
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PMID:The activities of lipoprotein lipase and of enzymes involved in triacylglycerol synthesis in rat adipose tissue. Effects of starvation, dietary modification and of corticotropin injection. 628 Jun 82

Obesity was induced in male Sprague-Dawley rats by overfeeding a cafeteria-style diet. The obesity was characterized by both adipocyte hypertrophy and hyperplasia. Body weight was then reduced by starvation to match that of control animals that had been fed ordinary Purina Chow. The previously obese rats were then refed to match the same body weight as controls, or given the same amount of Purina Chow as consumed by the controls. This resulted in a remaining moderate obesity, now due only to adipocyte hyperplasia with normal fat cell size. The previously obese rats needed less energy to keep their body weight equal to controls, and they spontaneously ate less than controls. They were, however, less food efficient because they did not accumulate as much energy in fat and protein depots during the period of refeeding as the controls did, and consequently must have transformed more energy into heat. This is in sharp contrast to nonobese animals subjected to a similar experimental procedure. Lipogenic enzymes and lipoprotein lipase activity in adipose tissue as well as plasma insulin concentrations were elevated in overfed rats but normalized during refeeding of Chow after fasting.
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PMID:Refeeding after fasting in the rat: effects of dietary-induced obesity on energy balance regulation. 633 94

The basal rate of lipolysis and basal lipoprotein lipase activity were determined in vitro in subcutaneous adipose tissue obtained from eight healthy non-obese subjects, ten obese subjects before and during one week's starvation, nine untreated non-insulin dependent diabetics and seven treated non-insulin dependent diabetics whose disease had been under metabolic control for at least three months. There was a negative correlation between the rate of lipolysis and activity of lipoprotein lipase in untreated diabetes mellitus and during starvation (r from -0.87 to -0.81). Under these two conditions the rate of lipolysis is increased and the lipoprotein lipase activity is decreased. There was no correlation between lipolysis and lipoprotein lipase in non-obese subjects, non-starving obese subjects and treated diabetic patients (r from 0.11 to 0.36). Thus, during starvation and in untreated diabetes, there is a strong reciprocal relationship between basal lipolytic activity and basal lipoprotein lipase activity in human adipose tissue which is not found under normal conditions or in obesity and well-controlled diabetes. It is concluded that a negative connection between lipolysis and lipoprotein lipase in human adipose tissue may be of physiological importance for the regulation of the energy balance in conditions such as untreated non-insulin dependent diabetes and starvation where adipose tissue lipids are the major source of energy.
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PMID:The relationship between the basal lipolytic and lipoprotein lipase activities in human adipose tissue. 634 23

Rats were given daily injections of protamine-zinc insulin (PZI) that increased food intake and body weight. Termination of insulin treatment resulted in transient hypophagia and weight loss. Simultaneously with the weight loss, plasma levels of glycerol, free fatty acids, glucose, and ketones increased, whereas adipose tissue lipoprotein lipase activity and liver glycogen decreased. These changes in food intake and metabolism after termination of PZI treatment were accentuated in streptozotocin-diabetic rats. Two antilipolytic drugs (nicotinic acid and 3,5-dimethylpyrazole) blocked the elevation in plasma glycerol while having no effect on food intake. A 1-day fast after termination of insulin treatment equalized insulin-treated and control groups for plasma glycerol and ketones and reversed group differences in free fatty acids; the elevation in plasma glucose persisted despite starvation. Following starvation, previously PZI-treated rats ate less than controls on refeeding. The results show that enhanced lipolysis does not invariably accompany hypophagia during excess weight loss and suggest that a disturbance in carbohydrate metabolism or an increase in hepatic fatty acid oxidation may underlie this decrease in food intake.
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PMID:Metabolic concomitants of hypophagia during recovery from insulin-induced obesity in rats. 635 32

Fasting in normal rats produced a fall in hepatic triglyceride lipase (H-TGL) activity as well as lipoprotein lipase (LPL) activities of adipose tissue and psoas minor muscle. On the other hand, LPL activities of heart and diaphragm were not decreased by fasting; the former, in fact, was increased significantly. Changes in tissue specific lipase activity caused by withdrawal of insulin from insulin-treated diabetic animals paralleled in direction the changes induced by starvation of normal rats. Furthermore, it was shown in the present paper that the tissue specific lipase activity of diabetic rats became stuck in the starve phase of the starve-feed cycle regardless of dietary intake. The changes of the tissue specific lipase activities, especially of liver, adipose tissue and heart, appeared to coincide with those of plasma insulin levels. These results strongly suggest that the tissue specific lipase system is under hormonal regulation by insulin. Streptozotocin diabetes produced hypertriglyceridemia. The possible mechanism of the hypertriglyceridemia in diabetic animals was discussed in connection with the role of the tissue specific lipase system in the serum triglyceride metabolism.
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PMID:The effects of streptozotocin diabetes on tissue specific lipase activities in the rat. 638 14

Muscles of genetically-obese animals exhibit decreased binding of and metabolic responses to insulin. Muscle protein catabolism was investigated by measuring the activity of alkaline, myofibril-bound protease in male (ob/ob) mice, fed ad libitum, or fasted for 5 d. Enzyme activity in the isolated myobrillar fraction was determined by the degradation of 14C-globin. Compared to the lean siblings, protease activity in the obese mice was 2.0, 1.5 and 1.3-fold higher in gastrocnemius, diaphragm and soleus muscle respectively, but without change in heart. The higher protease activity in gastrocnemius, diaphragm and soleus was associated with a parallel decrease in the weight and protein mass of the muscles. The muscles of obese mice also showed a 3 to 4-fold increase in triglyceride and a 2-fold increase in glycogen content. After 5-d starvation, the activity of protease rose in the gastrocnemius of obese mice only 1.5 fold, while it increased as much as 4 and 2 fold in gastrocnemius and diaphragm, respectively, in the lean mice. There was no significant change in heart enzyme activity. After 5-d starvation, serum insulin in obese mice fell markedly but remained still higher than that in ad libitum fed lean mice. Insulin-dependent serum metabolites, as well as adipose tissue lipoprotein lipase and hepatic enzymes related to lipogenesis and gluconeogenesis were consequently much less affected in obese mice and the prevalence of adequate insulin supply appeared to be the cause for lack of significant effect on muscle protease activity in fasting obese mice. It is suggested, therefore, that the induction of myofibrillar protease in obesity is linked to the decrease in cellular responsiveness to insulin and may also be interrelated with the intracellular metabolic adjustments to the enhanced muscle lipid availability.
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PMID:Increased protease activity in muscles of obese- (ob/ob) mice. 676 Dec 89

Lipoprotein lipase (EC 3.1.1.34) extracted from adipose tissue of glucose-fed rats with 5 mM-sodium barbital, pH 7.5, containing 20% (v/v) glycerol and 0.1% (v/v) Triton X-100, was partially purified by affinity chromatography on heparin linked to Sepharose 4B. Sodium dodecyl sulphate/polyacrylamide-gel electrophoresis of the partially purified enzyme preparation revealed the presence of two major Coomassie-staining bands (mol.wts. 62 000 and 56 000) as well as a number of minor bands. Treatment of partially purified enzyme with [1,3-3H]di-isopropyl fluorophosphate resulted in the incorporation of radiolabel into the band of mol.wt. 56 000, but not into the band of mol.wt. 62 000. Both the amount of the 56 000-mol.wt. polypeptide and the incorporation of [1,3-3H]di-isopropyl fluorophosphate into this band were greatly reduced in the enzyme preparations isolated from adipose tissue of 48 h-starved rats. whereas the amount of the 62 000-mol.wt. polypeptide was unaffected by starvation. Purification of lipoprotein lipase from adipose tissue of glucose-fed rats was also carried out using affinity chromatography on Sepharose 4B linked to heparin with low affinity for antithrombin-III. This procedure resulted in the presence of a single band of mol.wt. 56 000 on sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. These results suggest that the polypeptide of mol.wt. 56 000 corresponds to the subunit of lipoprotein lipase, whereas the 62 000-mol.wt. polypeptide probably represents antithrombin-III.
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PMID:Purification and characterization of rat adipose tissue lipoprotein lipase. 716 5

1. During the first two thirds of gestation, coinciding with a minimal accretion by the conceptus, the mother is in an anabolic state which is supported by her hyperphagia and the more efficient conservation of exogenous nutrients when she eats. During this phase maternal fat deposits are accumulated thanks to the enhancement in adipose tissue lipogenic and glycerologenic activity. In contrast, in the latter part of gestation, the rapid fetal growth is sustained by the intense transfer of nutrients from maternal circulation. 2. Glucose is quantitatively the most abundant of the several substrates that cross the placenta and despite increased maternal gluconeogenesis this transfer is responsible for the maternal tendency to hypoglycemia. This causes a switch to a net catabolic state which is especially evident in the net breakdown of fat depots. 3. Enhanced release of adipose tissue lipolytic products, free fatty acids (FFA) and glycerol, facilitates the liver synthesis of triglycerides and their later release into circulation associated to very low-density lipoprotein (VLDL). Glycerol is also used as an important gluconeogenic substrate and FFAs are broken down through beta-oxidation for ketone body synthesis. Flow through these pathways becomes increased when food is withheld and this actively contributes to the availability of fuels to the fetus which becomes partially preserved from maternal metabolic insult. Increased liver production of VLDL-triglycerides and decreased extrahepatic lipoprotein lipase contribute to exaggerated maternal hypertriglyceridemia which, besides being a floating metabolic reserve for emergency conditions such as starvation, constitutes an essential substrate for milk synthesis around parturition in preparation for lactation. 4. While the maternal anabolic tendencies found during the first two-thirds of gestation seem to be facilitated by hyperinsulinemia in the presence of a normal responsiveness to the hormone, it is proposed that most of the metabolic changes taking place during the last third of gestation seem to be caused by the insulin-resistant state which is consistently present at this stage, since its reversion caused by sustained exaggerated hyperinsulinemia also reverts several of these metabolic adaptations.
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PMID:Carbohydrate-lipid interactions during gestation and their control by insulin. 754 70

We previously showed that fatty liver was easily induced in suncus by starvation and that the plasma level of apolipoprotein B (apo B) was very low. There are three possible explanations for the low level of apo B in the animals: low synthetic rate, low secretion rate, and rapid catabolism in the circulation of apo B. We measured post-heparin lipolytic activity (lipoprotein lipase activity), which plays a key role in the catabolism of apo B-containing lipoprotein, VLDL, and found no difference between rats and suncus. We also investigated the hepatic synthetic rate of apo B by liver perfusion studies. Newly synthesized apo B in the suncus liver was detected by immunoprecipitation and found to amount to 12.5% of that in rats. The secretion rate of VLDL in suncus, which was estimated by intravenous injection of Triton WR1339, was 13.8% of that in rats. These two results suggest that there is no major defect in the secretory process. We separated Golgi apparatus from rat and suncus livers, and found much fewer lipoprotein particles in suncus than in rat Golgi apparatus. This evidence suggests that there is no defect in the lipolytic process or hepatic secretory process of apo B-containing lipoprotein, VLDL, but there may be a defect in the assembly process of VLDL and/or in the synthetic process of apo B in suncus. Such a defect may be one of the reasons for starvation-induced fatty liver in suncus.
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PMID:Defect in assembly process of very-low-density lipoprotein in suncus liver: an animal model of fatty liver. 759 40

To evaluate the effects of strain, gender and fasting in the regulation of lipoprotein lipase (LPL) and hepatic lipase (HL) activities were measured in tissues of male and female Wistar and Sprague-Dawley rats after feeding or a 24-h starvation period. It is noteworthy that an effect of gender on LPL activity was observed in Wistar, but not in Sprague-Dawley rats, not only in the basal (fed) activity in several tissues, such as white and brown adipose tissues, heart, and brain, but also in response to fasting which affected LPL activity in brown adipose tissue, heat and lung of female but not of male Wistar rats. By contrast, HL activity in liver, plasma and adrenals of Sprague-Dawley rats was higher in females than in males. No effect of gender on HL activity was observed in Wistar rats. Our results indicate that differences exist between Wistar and Sprague-Dawley rats in the regulation of both LPL and HL. Some of the contradictory results found in the literature may be explained by the differences between rat strains and gender, as well as differences in the nutritional status of the animals.
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PMID:Lipoprotein lipase and hepatic lipase in Wistar and Sprague-Dawley rat tissues. Differences in the effects of gender and fasting. 801 63


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