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

1. The lipoprotein lipase activity of white adipose tissue from a variety of sites, muscular tissue from the heart, limb and diaphragm and lung tissue was determined in samples from nine mammalian and one avian species. 2. The effect of 24 hr starvation on these activities was studied in five of the mammalian and the avian species.
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PMID:The distribution of lipoprotein lipase (clearing factor lipase) activity in the adiposal, muscular and lung tissues of ten animal species. 31 28

Mammalian pregnancy is characterized by progressive hyperinsulinaemia, raised plasma lipids and increased vulnerability to ketosis after food deprivation. The present investigations were performed to assess the role of two placental steroids, oestradiol and progesterone, in the development of these changes, since plasma titres of these hormones progressively increase during human gestation. In both human subjects and adult female rats it was demonstrated that these two steroids, separately or in combination, augment plasma insulin concentration in vivo, cause hypertrophy of pancreatic islets and promote exaggerated secretion of insulin, but not glucagon, by pancreatic islets in vitro. Hypertriglyceridaemia induced by oestrogen alone or combined with progesterone was associated with increased splanchnic production of triglyceride as well as altered tissue lipoprotein lipase (EC 3.1.1.34) and circulating apoproteins that influence activity of this enzyme. The combined regimen also increased hepatic glycogen storage and suppressed gluconeogenesis in vivo in the rat while accelerating the onset of ketosis during starvation in human subjects and in the animal model. Oestradiol and progesterone appear to effect metabolic changes in nonpregnant animals and human subjects that simulate maternal adaptations to advancing gestation, including altered endocrine pancreatic function, triglyceride metabolism and metabolic fuel storage and mobilization.
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PMID:The influence of hormonal changes of pregnancy on maternal metabolism. 37 20

When male rats of between 6 and 13 days of age were starved for 6 h the lipoprotein lipase activity of the epididymal and subcutaneous white adipose tissue did not decline as it did in adults and in animals aged 14-30 days. The lipoprotein lipase activity in the hearts of animals from 6 days of age increased in response to starvation as it did in adults. The relationship of these changes to changes in circulating hormone levels during development was considered.
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PMID:The effect of short-term starvation on the lipoprotein lipase activity of adipose tissue and cardiac muscle during postnatal development of the rat. 39 57

The lipoprotein lipase activity of rat epididymal adipose tissue falls on starvation and increases on refeeding. Studies with fat cells isolated from this tissue have shown that increases in the activity of the enzyme occur under appropriate incubation conditions in vitro. The present study compares the responses of cells isolated from the adipose tissue of fed and 48-h starved rats. Fat cells from rats starved for 48 h display a lower initial lipoprotein lipase activity than cells from fed rats. When cells from rats in both nutritional states are incubated in a suitable medium at 25 degrees C, there is a progressive increase in the medium lipoprotein lipase activity. The absolute increase in the total activity of the incubation system during incubations of cells from 48-h starved rats is significantly less than during incubations of cells from fed rats. However, when expressed as a percentage of the initial cell activity, the rises in total activity are similar in the two nutritional states. Cycloheximide has no significant effect on the increase in activity of lipoprotein lipase that occurs with cells from 48-h starved rats. However, it does partially block the increase in activity seen with cells from fed rats and in a manner similar to that previously reported for cells from 24-h starved rats. The significance of the results is discussed in relation to previous studies with both intact adipose tissue and isolated fat cells.
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PMID:The effect of nutritional state on the lipoprotein lipase activity of isolated fat cells. 69 38

The hydrolysis of lipoprotein triglycerides is catalyzed by lipoprotein lipase (LPL), an enzyme found in many tissues. We have examined tissue LPL activity (LPLA) in rats with experimentally-induced hyperthyroidism. In younger, lighter rats, hyperthyroidism was accompanied by a decrease in LPL in adipose tissue whereas heart and diaphragm muscle LPL activities were increased. These changes are consistent with the hypothesis that the hypercatabolism and increased beta-adrenergic activity of hyperthyroidism result in characteristic changes in tissue LPLA. In older, heavier hyperthyroid animals, however, adipose tissue LPLA was increased and heart and diaphragmatic LPLA were similar to control activities. Propranolol feeding abolished the thyroxine-induced increase in adipose tissue LPLA. In euthyroid animals of similar size the response of muscle LPLA to short-term starvation was also attenuated. These changes in tissue LPLA may provide a mechanism for shunting triglyceride fatty acids away from adipose tissue for utilization by muscle in the hyperthyroid state. During growth and aging, these adaptations are modified.
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PMID:Tissue lipoprotein lipase in the hyperthyroid rat. Effect of growth and aging. 84 80

A new method was used for selective measurement of lipoprotein lipase and hepatic lipase in human postheparin plasma. Hepatic lipase was assayed in 1.0 M NaCl withour addition of serum, and the activity of lipoprotein lipase was determined in 0.1 M NaCl after immunoprecipitation of hepatic lipase with specific antiserum. The activity of both these enzymes and the total lipolytic activity were measured in plasma samples taken during a 4-h infusion of heparin. Each of the activities was related to basal serum triglyceride concentration and to the fractional removal constant (K) of Intralipid in 13 obese subjects before and after prolonged fasting. During a normal isocaloric diet the lipolytic activities showed a biphasic response to heparin infusion in all subjects. A peak activity was reached within 30 minutes ("early response") and thereafter the lipase activities decreased to a constant level maintained during the rest of the heparin infusion ("late response"). The early response of lipoprotein lipase showed a significant inverse correlation with the basal serum triglyceride level (r = -0.85) and a significant positive correlation with the fractional removal rate of Intralipid (r = 0.84). The late response of lipoprotein lipase was not related to either of these parameters. The early response of hepatic lipase was not correlated with basal triglyceride concentration or Intralipid removal, whereas the late response of this enzyme showed a significant negative correlation with the removal rate of Intralipid (r = -0.82). After fasting for several days the acute response of all lipolytic activities to heparin was markedly decreased or totally abolished, but the magnitude of the late response was similar to that seen in the fed state. The fractional removal rate of Intralipid was slightly increased by starvation. All correlations between postheparin plasma lipases and serum triglyceride concentration and removal disappeared in fasting subjects. It is concluded that the rapidly releasable lipoprotein lipase probably reflects the activity of the tissue enzyme(s) which is responsible for the primary removal of very low density lipoprotein (VLDL) triglycerides and chylomicrons. It is probable that this component of the postheparin plasma lipolytic activity is derived from the endothelial lipoprotein lipase pool. This enzyme plays a key role in the efflux of plasma triglycerides under normal conditions, and it is thus one determinant of plasma triglyceride level. Prolonged fasting obviously changes the triglyceride removal sites and mechanism but does not impair the removal efficiency.
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PMID:Effect of fasting on two postheparin plasma triglyceride lipases and triglyceride removal in obese subjects. 120 62

Addition of serum to incubated adipose tissue resulted in excess of free fatty acids and/or glycerol released. It was propranolol-resistant and in many but not all experiments greater after using serum of fasting (FS) rats than that of fed rats (CS). The increment of free fatty acids and/or glycerol released due to the presence of FS was not potentiated by theophylline; however the effect of both CS and FS was potentiated by heparin. The postheparin serum lacked the property of CS or FS. By the interaction with serum, adipose tissue could be substituted by lipoprotein lipase isolated either from this tissue or from bovine milk. It is suggested that the difference between CS and FS might be caused by a qualitative alteration of the lipoprotein pattern resulting in easier availability of serum lipids to the extraadipose tissues during starvation.
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PMID:Enhanced lipolysis during interaction of serum and adipose tissue: its mechanism and effect of starvation. 123 48

In contrast to the complete absence of lipoprotein lipase (LPL) mRNA in adult rat liver, fetal and neonatal rat liver contain substantial amounts of LPL mRNA, which is translated in active LPL protein as can be deduced from the presence of LPL activity in this organ. At this neonatal stage, both the relative abundance of LPL mRNA and LPL activity increased with starvation. During the suckling period, LPL mRNA and LPL activity gradually decreased until both parameters were undetectable. While the administration of L-thyroxine or hydrocortisone enhanced the disappearance of LPL mRNA, induced hypothyroidism delayed its disappearance. In adult animals induced hypothyroidism could not reactivate LPL mRNA production in the liver. The data presented suggest that liver LPL production responds to changes in the nutritional state and becomes extinguished during development, in a fashion reminiscent to the extinction of alpha-fetoprotein. This extinction of LPL gene expression is influenced by hormonal factors.
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PMID:Neonatal extinction of liver lipoprotein lipase expression. 162 43

During the first half of gestation in the rat, maternal net body weight increases rapidly, whereas in the second half of gestation, the mass of maternal structures declines, coincident with the rate of maternal fat accumulation. Enhanced maternal food intake, extrahepatic tissue lipoprotein lipase (LPL) activity, and adipose tissue lipogenesis are responsible for the progressive accumulation of maternal fat. However, during late gestation, decreased fat synthesis in maternal adipose tissue, enhanced lipolytic activity, and decreased LPL activity deplete maternal fat depots. These changes, plus enhanced endogenous production of triglyceride-rich lipoproteins, are also responsible for maternal hypertriglyceridemia. This condition benefits the offspring in two ways: 1) enhanced LPL activity in maternal liver when fasting increases triglyceride consumption for ketone body synthesis, giving the basis for accelerated starvation; and 2) induction of LPL activity in the mammary gland before parturition diverts maternal circulating triglycerides to milk synthesis in preparation for lactation. The magnitude of the maternal-fetal glucose transfer was higher than that of any of the other substrates studied, including alanine, and despite actions to spare glucose, this transfer causes maternal hypoglycemia, which is especially intense in the fasting condition. This increases sympathoadrenal activity in the mother, which may contribute to her active gluconeogenesis. Glycerol was a more efficient glucose precursor than alanine and pyruvate, and whereas glycerol placental transfer is very small, it is proposed that the fetus benefits from this product of adipose tissue lipolysis when it is previously converted into glucose.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Intermediary metabolism in pregnancy. First theme of the Freinkel era. 174 73

Oxidation in vivo of [14C]triolein to 14CO2 was significantly lower in obese (fa/fa) Zucker rats as compared with their lean (+/?) controls. In response to a 24 h starvation period, both lean and obese rats showed an enhanced rate of [14C]triolein oxidation. There were, however, no changes in the rate of intestinal absorption of [14C]triolein between the lean and obese animals. Conversely, the total tissular [14C]lipid accumulation was significantly higher in white adipose tissue, carcass and plasma in the obese animals, whereas that of brown adipose tissue was lower. This was associated with a marked hyperinsulinaemia and hypertriglyceridaemia in the fa/fa animals. Starvation dramatically decreased [14C]lipid accumulation in white adipose tissue of the lean Zucker rats, but had no effect in the obese rats. The lipogenic rate of the obese rats was significantly higher than that of lean rats in liver, white adipose tissue, skeletal muscle and carcass. Lipoprotein lipase activity (per g of tissue) was significantly lower in both white and brown adipose tissue of obese versus lean rats; however, total activity was higher in both tissues. Starvation significantly lowered perigenital-adipose-tissue lipoprotein lipase activity in the lean groups, and had no effect in the obese ones. These results demonstrate that the tissue capacity of exogenous lipid uptake is involved, but cannot be the only factor influencing the maintenance of obesity in these animals. Thus, in the adult fa/fa rat, the large increase in obesity is not solely dependent on a deviation of energy-producing substrate metabolism towards the storage of lipids in white fat. Other factors, such as a low rate of oxidation, a high lipogenic rate and decreased brown-adipose-tissue activity are involved in the perseverance of the obesity syndrome.
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PMID:Lipid metabolism in the obese Zucker rat. Disposal of an oral [14C]triolein load and lipoprotein lipase activity. 201 94


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