Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0038187 (starvation)
 24,951 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In order to study the effect of starvation on brown adipose tissue (BAT) type II 5'-monodeiodinating activity (5'MDI), type II 5'MDI was measured in vitro in the presence of 20 mM dithiothreitol, 1 mM propylthiouracil, 2 nM thyroxine (T4) and appropriate amounts of 600 X g infranatant of BAT from fed control or 3 day fasted mice, with or without daily T4 replacement (1.2 micrograms/100 g bw) during starvation. I- released from 125I-T4 was measured by ion-exchange column chromatography. Activity of BAT 5'MDI was markedly elevated in the 3 day fasted group (133 +/- 28 fmol I-/h per mg protein vs. 26 +/- 6.4; p less than 0.05). Kinetic studies using BAT infranatant suggested that fasting-induced activity is associated with a similar change in the Vmax, but no demonstrable change in apparent Km of T4 monodeiodination. T4 replacement during fasting, which normalized both serum T4 and T3 in fed and 3 day fasted groups, did not stop the increase of BAT 5'MDI in the fasted group (p less than 0.01). The data suggest that: (1) the fasting-induced increase in BAT 5'MDI is due mainly to the changes in capacity rather than the affinity of the enzyme, and (2) the fasting-induced increase in BAT 5'MDI is not mediated entirely through changes in serum thyroid hormone concentration.
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PMID:Induction of type II T4-5'-monodeiodinase activity in brown adipose tissue in fasted mice. 229 94

Dietary carbohydrate and thyroid hormone (T3) interact to regulate rat liver S14 gene expression. The molecular basis for this interaction was examined by analysis of hepatic mRNAS14 levels, S14 gene transcription, and chromatin structure. While starvation of euthyroid rats inhibited hepatic S14 gene transcription greater than or equal to 90%, sucrose administration induced mRNAS14 and S14 transcription to 82% of euthyroid-fed levels within 4 h. In contrast, administration of sucrose or T3 to starved hypothyroid animals restored S14 gene transcription to only 30% of euthyroid-fed values. Both T3 and sucrose were required to restore S14 run-on activity and mRNAS14 to euthyroid-fed levels within 4 h. Thus, T3 and sucrose interact synergistically and rapidly to induce S14 gene transcription. Analysis of S14 chromatin structure showed that starvation of hypothyroid rats inhibited the formation of three DNase I-hypersensitive sites flanking the 5'-end of the S14 gene (Hss-1 at -65 to -265 base pairs; Hss-2 at -1.2 kilobases and Hss-3 at -2.67 kilobases). The loss of these sites correlated with the repression of S14 gene transcription in starved hypothyroid rats. Whereas administration of sucrose to starved hypothyroid rats consistently induced the Hss-1 and Hss-2 sites, T3 consistently induced all three DNase I-hypersensitive sites. Yet, neither treatment alone induced S14 gene transcription to euthyroid levels. The combination of T3 and sucrose induced no additional change in S14 chromatin structure over that induced by T3 alone. Thus, regulation of S14 chromatin structure alone is not the sole mechanism by which these stimuli regulate S14 gene transcription. We speculate that the synergistic regulation of S14 gene transcription by T3 and dietary carbohydrate involves a complex interaction between factors which regulate the accessibility of putative cis-regulatory elements through changes in chromatin structure and the regulation of "transcription factors" which interact with these elements.
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PMID:Thyroid hormone and dietary carbohydrate interact to regulate rat liver S14 gene transcription and chromatin structure. 230 55

To elucidate the possible role of thyroid hormone in somatomedin-C (SmC)/insulin-like growth factor I regulation in diabetes mellitus and starvation, plasma SmC, liver SmC, and kidney SmC concentrations were measured in streptozotocin-induced (60 mg/kg) diabetic and starved (for 72 h) rats. Triiodothyronine (T3, 5.0 micrograms/kg every 24 h) was subcutaneously injected into diabetic rats for 7 days and into starved rats at 12, 36, and 60 h after starvation. Plasma T3, plasma SmC, liver SmC, and kidney SmC concentrations were significantly decreased in diabetic and starved rats. T3 administration restored plasma T3 levels to the normal value in diabetic and starved rats. Plasma SmC and kidney SmC concentrations were significantly increased in T3-treated starved rats, while they were not increased in T3-treated diabetic rats. These results suggest that thyroid hormone may have some role in SmC regulation during starvation, but may have no role in diabetes mellitus in the rat.
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PMID:Possible role of thyroid hormone in decreased somatomedin-C levels in diabetic and starved rats. 233 Nov 41

Thyroid hormone nuclear receptor molecules have been characterized as proteins of approximately 49,000 molecular weight existing in cells attached to chromatin and with 4000-8000 copies per nucleus. They bind T3 with Ka of 0.2 X 10(10) l/mol and show microheterogeneity on isoelectric focusing. Hormone responsiveness varies with receptor content in the nucleus and occupancy of receptor by T3. Recent investigations have shown that the receptors are part of the v-erbA related super family of nuclear hormone receptors. At least two types of T3 receptors (TR) exist, one coded by a gene on chromosome 3 (TR beta) and a second coded on chromosome 17 (hTR alpha). Receptors are low in the fetus and, in the adult, are dramatically reduced by starvation, illness and glucagon. Receptors function through binding of T3 or other hormone analogs to a domain in the carboxyl portion of the protein, and binding of the receptor-T3 complex through 'DNA-fingers' to specific response elements as enhancers and located in the 5'-flanking DNA of thyroid hormone responsive genes. Extensive studies on regulation of rat growth hormone have suggested binding of receptor or associated factors to several positions in the 5'-flanking DNA, and recent studies suggest that a crucial area may be a 15 bp segment between bases -179 and -164. Abnormal receptors are believed to be responsible for the syndrome of generalized resistance to thyroid hormone action, but it is yet unclear as to which form (or forms) of the receptor is abnormal in this syndrome.
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PMID:Thyroid hormone nuclear receptors and their role in the metabolic action of the hormone. 249 27

Two experiments were conducted to determine the effects of dehydroepiandrosterone (DHEA) on de novo fatty acid synthesis and oxygen consumption in BHE rats fed a 65% glucose diet. In Experiment 1, starved glucose-refed rats were injected ip with 120 mg of DHEA/kg body wt and hepatic de novo fatty acid synthesis was measured. DHEA-treated rats synthesized less fatty acid in response to starvation refeeding than nontreated rats. In Experiment 2, weanling rats were fed the glucose diet for 4 weeks. One-hundred twenty milligrams of DHEA/kg were injected daily for 3 weeks. Body weight gain, epididymal fat pad weight, and carcass lipid were less in the DHEA-treated rats than in the control rats. Mitochondrial respiration was less and liver size was greater in DHEA-treated rats compared with control rats. Whole body oxygen consumption was increased in DHEA-treated rats, suggesting that this steroid might be stimulating futile energy cycles involving lipid and protein turnover possibly through its effect on glucocorticoid and thyroid hormone function.
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PMID:Further studies on the effects of dehydroepiandrosterone on hepatic metabolism in BHE rats. 253 67

To elucidate the possible role of thyroid hormone in insulin secretion during starvation, we investigated the glucose-induced insulin release in T3-administered starved rats. The rats were fasted for 72 hr, and one-half of the starved rats were administered subcutaneous 3,5,3'-triiodothyronine (5.0 micrograms/kg) at 12, 36, and 60 hr. In an intravenous glucose (0.5 g/kg) infusion test, insulin response was significantly lower in starved rats than in fed controls. This decreased insulin was restored by T3 administration. These results suggest the thyroidal dependence of insulin response to glucose in short-term starvation.
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PMID:Thyroidal dependence of glucose-induced insulin secretion in starved rats. 268 3

A correlation between the Basal Metabolic Rate (BMR) and the level of rT3, and occasionally between BMR and T3 or T4 was found in 12 month fasting cockerels. The birds were fasted for 48 hrs and BMR was measured eight times (before fasting, at 6, 12, 24, 30, 36, and 48 hrs of fasting, and 4 hours after fasting). Blood samples for plasma collection were taken immediately after measuring the BMR. During starvation a decrease in BMR was observed. After refeeding BMR returned to the starting level. The decrease in BMR was accompanied by an increase in rT3 and T4 plasma levels. Between BMR and levels of T4 and rT3 negative coefficients of correlation were observed (r = -0.20 and r = -0.42, respectively). Contrary to this, the T3 level declined and was correlated with BMR (r = 0.62). After refeeding, the T3 level rapidly increased against the control value. Moreover, a high coefficient of correlation (r = -0.39) was found between the level of T3 and rT3. The data show that the reduction in plasma T3 level and increase in the rT3 one during starvation may be due to inhibition of deiodination of T4 to T3, since rT3 is a competitive inhibitor of this reaction. The presented results support the suggestion that in birds T3 is the metabolically active thyroid hormone, and rT3 antagonizes this effect.
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PMID:The relationship between basal metabolic rate (BMR) and concentrations of plasma thyroid hormones in fasting cockerels. 277 19

We investigated changes in the serum angiotensin-converting enzyme, as an index of thyroid hormone action, before, during and after fasting in 15 non-obese, hospitalized patients. Serum angiotensin-converting enzyme decreased significantly from 14.6 +/- 1.1 U/l before fasting to 13.2 +/- 1.1 U/l on the 5th day (P less than 0.05, N = 15) during fasting, and to 10.6 +/- 1.0 U/l on the 10th day (P less than 0.05, N = 8). The serum TSH and T3 levels decreased significantly to below the normal range, and the serum T4 level decreased gradually during fasting, whereas free T4 (Amerlex) changed slightly, but within normal range. Although re-feeding did not lead to any reduction in the serum TSH, T3, or T4 level, the serum angiotensin-converting enzyme further decreased to 8.7 +/- 0.9 U/l on the 5th day of re-feeding compared with that on the 10th day of fasting (P less than 0.01, N = 8). There was a delay in the re-elevation of serum angiotensin-converting enzyme following a rise in serum T3. No correlations were found between serum angiotensin-converting enzyme levels and thyroid hormone levels throughout the study period. It is concluded that a significant reduction in the serum angiotensin-converting enzyme level occurs under a 'low T3' state during acute starvation, although there is no clear association between serum angiotensin-converting enzyme and thyroid hormone levels.
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PMID:Changes in serum angiotensin-converting enzyme in acutely starved non-obese patients. A possible dissociation between angiotensin-converting enzyme and the thyroid state. 283 95

The effect of confinement and severe starvation on the plasma thyroxine (T4) and triiodothyronine (T3) concentrations was determined in emperor penguins (Aptenodytes forsteri). During their annual cycle, emperor penguins fast freely for periods of up to 4 months and may thus represent a unique subject to study endocrine adaptations to fasting. Plasma T4 concentrations progressively decreased following capture and confinement of naturally fasting penguins, and within 15-20 days stabilized at levels three times lower than in free-living penguins. A transient fourfold increase in plasma T3 concentration developed within the day following confinement in parallel with a rise in daily body mass loss. Both plasma T3 concentration and mass loss subsided to normal levels within 15 days. The decrease in plasma T4 concentration is in accordance with the well-known inhibitory effect of stress on thyroid function in birds and mammals, whereas the transient increase in plasma T3 concentration seems related to enhancement of energy expenditure as a consequence of restlessness. Starvation severe enough to exhaust fat stores and to activate protein catabolism induced a 6- and 5 to 10-fold fall in plasma T4 and T3, respectively. This is in marked contrast with maintenance of plasma thyroid levels during long-term natural fasting associated with protein sparing (R. Groscolas and J. Leloup (1986) Gen. Comp. Endocrinol. 63, 264-274). Surprisingly, there was a final reincrease in plasma T4 concentration in very lean penguins. These results suggest that the effect of starvation on plasma thyroid hormones seems to depend on how much protein catabolism is activated and demonstrate the acute sensitivity of thyroid hormone balance to stress in penguins.
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PMID:The effect of severe starvation and captivity stress on plasma thyroxine and triiodothyronine concentrations in an antarctic bird (emperor penguin). 292 Aug 94

Five-month-old lean and obese Zucker rats were fasted for up to 7 days (lean rats) or 28 days (obese rats), and serum total and free T4 and T3 concentrations, percent free T4 and T3 by equilibrium dialysis, and the binding of [125I] T4 to serum proteins by gel electrophoresis were measured. In the lean rats, a 4- or 7-day fast resulted in significant decreases in serum total and free T4 and T3 concentrations. There was a decrease in the percent free T3 after 7 days of starvation. In contrast, a 4- or 7-day fast did not alter any of these variables in the obese rats. However, after 14 or more days of starvation, serum total T4 and T3 concentrations increased, and the percent free T4 and T3 decreased, resulting in no change in the serum free T4 or T3 concentrations in the obese rats. The percent of [125I]T4 bound to serum thyronine-binding globulin increased and the percent bound to thyronine-binding prealbumin decreased with the duration of the fast in both the lean and obese rats. The increase in serum thyronine-binding globulin binding of T4 can explain the increase in serum total T4 and T3 concentrations, the decrease in percent free T4 and T3, and the normal free hormone concentration in the long term fasted obese rats. The findings in the lean rats appear to be due to a combination of the known central hypothyroidism that occurs during 4-7 days of fasting and the fasting-induced changes in T4 binding in serum. Changes in T4 and T3 binding in serum during fasting in the rat must be considered when the effects of fasting on serum concentrations of the thyroid hormones, thyroid hormone kinetics, and the peripheral action of the thyroid hormones are evaluated.
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PMID:Fasting induces the generation of serum thyronine-binding globulin in Zucker rats. 298 82


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