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

The fraction of 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase in the dephosphorylated (active) form in rat liver in vivo was measured after various experimental treatments of animals. Intraperitoneal injection of glucose (to raise serum insulin concentrations) into rats 4 h into the light phase (L-4) resulted in a transient (30 min) increase in the expressed (E)/total (T) activity ratio of HMG-CoA reductase without any change in total activity (obtained after complete dephosphorylation of the enzyme). Conversely, intravenous injection of guinea-pig anti-insulin serum into rats 4 h into the dark phase (D-4) significantly depressed the E/T ratio within 20 min. Intravenous injection of glucagon into normal rats at this time point did not affect the degree of phosphorylation of the enzyme, in spite of a 10-fold increase in hepatic cyclic AMP concentration induced by the hormone treatment. A 3-fold increase in the concentration of the cyclic nucleotide induced by adrenaline infusion was similarly ineffective in inducing any change in expressed or total activities of hepatic HMG-CoA reductase. However, when insulin secretion was inhibited, either by the induction of streptozotocin-diabetes or by simultaneous infusion of somatostatin, glucagon treatment was able to depress the expressed activity of HMG-CoA reductase (i.e. it increased the phosphorylation of the enzyme). Therefore insulin appears to have a dominant role in the regulation of the phosphorylation state of hepatic HMG-CoA reductase. In apparent corroboration of this suggestion, short-term 4 h food deprivation of animals before D-4 resulted in a marked decrease in the E/T activity ratio of reductase, which was not affected further by an additional 8 h starvation. By contrast, the total activity of the enzyme was not significantly affected by 4 h starvation, but was markedly diminished after 12 or 24 h starvation. Longer-term starvation also produced a chronic increase in the degree of phosphorylation of the enzyme. These results are discussed in relation to the role of reversible phosphorylation in the control of hepatic HMG-CoA reductase activity in vivo.
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PMID:Acute effects of starvation and treatment of rats with anti-insulin serum, glucagon and catecholamines on the state of phosphorylation of hepatic 3-hydroxy-3-methylglutaryl-CoA reductase in vivo. 288 48

The concentrations of secretin and somatostatin in plasma were measured in 10 healthy subjects during a 4-day fast. The fast induced increased concentrations of plasma secretin (from 1.2 +/- 0.5 to 9.5 +/- 2.3 pmol/l) and somatostatin (from 5.2 +/- 1.5 to 8.6 +/- 1.7 pmol/l). Gastric aspiration for 1 h suppressed the high concentrations of secretin by 46% and somatostatin by 27%. The intravenous infusion of glucose reduced the plasma secretin even further by 88%; the decrease in somatostatin was not statistically significant. The study shows that gastric aspiration and/or glucose infusion suppressed the high plasma concentration of secretin and that factors other than hyperchlorhydria must be involved in the hypersecretinemia seen during starvation. The elevated plasma somatostatin concentration seen during starvation may be a consequence of increased acid secretion.
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PMID:The relationship of secretin and somatostatin levels in plasma to glucose administration and acid secretion during fasting. 288 43

We examined the release of growth hormone-release inhibiting factor (somatostatin) from dispersed hypothalamic cells obtained from mature diabetic rodents and normal age-matched controls, in an attempt to demonstrate a possible hypothalamic defect which might underlie some of the reported abnormalities in somatotrophic function in diabetes mellitus. Insulinopoenic diabetes was induced by either streptozotocin or alloxan. Somatostatin release from cells from diabetic rats was diminished both basally and after stimulation by membrane depolarisation. Stimulated release was calcium dependent in cells from both normal and diabetic animals. The defect was present in both streptozotocin and alloxan induced diabetes. We also compared hypothalamic somatostatin release from cells obtained from obese hyperinsulinaemic C57 BL/Ks db/db diabetic mice and non diabetic lean litter mates (db/-). Despite longstanding marked hyperglycaemia, no significant alteration in somatostatin release was apparent. Likewise, starvation of rats for 5 days did not result in significant diminution of somatostatin release. These observations document a defect in hypothalamic somatostatin release in experimentally induced insulinopoenic diabetes, which is not apparent in the db/db mouse, suggesting that glucose per se is not responsible. Rather than the anticipated increase in hypothalamic somatostatin release in insulinopoenic diabetes, a reduction in release was observed. These observations are compatible with the hypothesis that increased hypothalamic somatostatin release is not responsible for abnormal growth hormone secretion in this model.
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PMID:Somatostatin release from dispersed hypothalamic cells: effects of diabetes. 289 19

Insulin, glucagon, and somatostatin concentrations were measured in 7 lean and 7 obese non-diabetic subjects over 7 days of fasting. In addition each subject was given a 75 g oral glucose tolerance test after fasts of 12 h and 7 days. In lean subjects complete food deprivation induced a significant decrease in the circulating levels of both insulin and somatostatin, while glucagon nearly doubled by 48 h and then remained constant for the duration of starvation. Refeeding with oral glucose suppressed the increased plasma glucagon, but insulin and somatostatin responses were enhanced in comparison with the prefast values, as assessed by the integrated areas of change. In obese subjects peripheral insulin and somatostatin levels were significantly lowered, but plasma glucagon level was unchanged at the end of the starvation period. In the same group glucose-induced insulin and somatostatin release were greater than in the fed state. Suppression of plasma glucagon by glucose appeared less complete in obese than in lean subjects. It is concluded that prolonged starvation enhances D-cell responsiveness to glucose in lean and obese subjects.
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PMID:Somatostatin response to glucose before and after prolonged fasting in lean and obese non-diabetic subjects. 290 Nov 33

Thioredoxin and thioredoxin reductase (NADPH-oxidized thioredoxin oxidoreductase, E.C. 1.6.4.5) have been proposed to be involved in several thiol-dependent reduction-oxidation reactions in cells. Both proteins have been immunohistochemically demonstrated in the periphery of the cytoplasm and in cytoplasmic granules of acinar and islet cells in mouse pancreas. In animals fed ad libitum, the staining for thioredoxin was more intense in the exocrine acinar cells than in the islet cells, whereas that for thioredoxin reductase was more intense in the endocrine than in the exocrine pancreas. In the islets of fed mice all endocrine cell types showed about the same staining intensity for thioredoxin, while thioredoxin reductase was greatly enriched in the somatostatin-containing D cells. Starvation overnight caused an increased staining for both proteins in the acinar cells as well as in the islets. Under conditions of starvation, thioredoxin reductase, in contrast to thioredoxin, appeared to increase preferentially in the islet B cells, as compared with the D cells. Cysteamine treatment reduced the staining for somatostatin and for thioredoxin reductase in the D cells without any obvious effect on the other pancreatic cells. The results are compatible with a role for thioredoxin and thioredoxin reductase in secretion.
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PMID:Immunohistochemical localization of thioredoxin and thioredoxin reductase in mouse exocrine and endocrine pancreas. 352 49

It has been previously demonstrated that glucagon increased plasma post-heparin lipolytic activity (PHLA) in normal rats, but this was not the case in alloxan diabetic rats. The present work was designed to determine if the administration of exogenous glucagon (0.2 mg i.v.) during suppression of endogenous hormone secretion with somatostatin modifies the plasma post-heparin lipolytic activity in normal rats and the action of such hormone upon monoglyceride hydrolase (MGH) activity. It was found that exogenous glucagon significatively increased PHLA and MGH activity in normal rats after 18-24 hours of starvation. However, both enzymatic activities were not influenced by exogenous glucagon when they were measured during somatostatin administration. Therefore it is believed that the enhancement of these activities observed when somatostatin was not simultaneously given was due to the insulin secretion that follows the glucagon injection.
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PMID:Glucagon action upon plasma post-heparin lipolytic and monoglyceride hydrolase activities. Studies involving administration of exogenous hormone during suppression of endogenous hormone secretion with somatostatin. 611 26

To delineate the hormonal mechanism of dietary-induced changes in sodium balance, the role of insulin and glucagon in natriuresis of fast was evaluated in obese subjects submitted to a total starvation and given either glucagon or somatostatin infusion on day 4 of fast. While large amounts of glucagon (1 mg over 6 h) stimulated concomitantly ketonaemia, ketonuria and renal sodium losses, the ten-times lower amounts of glucagon induced an increase in renal ketone body and sodium excretion without any significant change in ketonaemia. It was concluded, therefore, that elevated plasma glucagon level may enhance renal sodium loss in ketotic states, through a direct renal effect reducing tubular ketone body reabsorption, hence increased ketonuria and natriuresis. It appears nevertheless that decreased insulin secretion, rather than an increase in plasma glucagon level must be considered as a key hormonal factor responsible for natriuresis attending starvation. Indeed, the concomitant reduction in plasma glucagon and insulin levels, resulting from somatostatin infusion on day 4 of fast, was followed by significant increase in natriuresis. The latter observation supports several previous studies indicating that insulin stimulates sodium reabsorption by the kidney and that the reduction in insulin secretion may induce an increase in renal sodium excretion. It was concluded, therefore, that not only sodium intake but also the carbohydrate content of the diet should be reduced in an attempt to induce a negative sodium balance and to correct hypertension in obese subjects.
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PMID:Influence of insulin and glucagon on sodium balance in obese subjects during fasting and refeeding. 611 18

We have studied the effects of starvation and of obesity on somatostatin, insulin, and glucagon release from an isolated perfused organ system in fed and 3- and 5-day fasted Holtzman rats and in obese (fa/fa) and lean (Fa/?) Zucker rats. Fasting for 3 days significantly decreased basal (-71%) and amino acid-stimulated (-62%) somatostatin output. After 5 days of starvation, there was a significant increase over the 3-day level in somatostatin output stimulated by amino acid plus glucose (+540%) and by amino acids plus tolbutamide (+238%). Three and five days of starvation severely depressed insulin output while having no statistically significant effects on glucagon secretion. Somatostatin output from obese Zucker rats was significantly greater than that from lean controls in response to amino acids (41.2 +/- 13.2 vs. 16.3 +/- 10.3 ng/25 min, P less than 0.05). Insulin output was greatly increased from obese compared to lean Zucker rats, whereas there were no statistically significant differences in glucagon output. These data show that fasting decreases and obesity increases both somatostatin and insulin release. They suggest that altered stimulation by nutrients was primarily responsible for changes in somatostatin and insulin release observed in starving and obese rats.
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PMID:Effects of starvation and obesity on somatostatin, insulin, and glucagon release from an isolated perfused organ system. 611 33

The influence of food deprivation on the release of somatostatin and gastrin from the rat stomach was investigated using an isolated, vascularly perfused rat stomach preparation. Basal and acetylcholine-stimulated gastrin release were significantly lower after a 3 day starvation, whereas the inhibitory effect of acetylcholine and the stimulatory effect of glucagon on somatostatin secretion were not influenced by fasting. In dose-response studies, isoproterenol dose-dependently stimulated somatostatin secretion. The increases were similar in both groups fasted for 12 and 72 h. Gastrin release remained at basal levels. Bombesin dose-dependently increased gastrin secretion; this stimulatory effect on the G cell was significantly reduced after a 72-h starvation. Somatostatin secretion was only weakly stimulated by high concentration of bombesin revealing no effect of fasting. Somatostatin content of the nonperfused stomach declined from 57 +/- 4 pmol/stomach in fed controls to 36 +/- 3 pmol/stomach after a 72-h fast. Antral gastrin concentration decreased by 42% in a 3-day fasting period. It is concluded that rat gastric somatostatin release in vitro is--in contrast to gastrin--not altered by food deprivation while the somatostatin content in gastric tissue declined during fasting.
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PMID:Effect of food deprivation on rat gastric somatostatin and gastrin release. 612 Aug 79

The effect of 48-hour starvation on the somatostatin contents of the pancreas and gastrointestinal tract was studied in the guinea pig. Somatostatin contents were higher in various portions of the stomach and pancreas of fed guinea pigs than in fed rats and unchanged after 48-hour starvation, in spite of the decreased blood glucose level. These results suggest that somatostatin may not play the same physiological role in nutrient homeostasis of guinea pigs as it does in other species.
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PMID:Effect of starvation on somatostatin content of pancreas and gastrointestinal tract of the guinea pig. 612 97


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