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At least 433 records · Page 24Linked to original sources

PubMed1999

Effect of prolonged moderate and severe energy restriction and refeeding on plasma leptin concentrations in obese women.

BACKGROUND: Plasma leptin in humans is subject to both long- and short-term regulation; it correlates with indexes of body fat that can only change slowly. However, short-term fasting causes large and rapid decreases. OBJECTIVE: We tested the interactions between energy intake and fat loss on plasma leptin during prolonged moderate and severe energy restriction, with a view to understanding mechanisms of control. DESIGN: Postabsorptive leptin was measured with an enzyme-linked immunosorbent assay specific for the human peptide in 21 obese women aged 41 +/- 3 y (weight: 102 +/- 4 kg; 48 +/- 1% body fat) after 1 wk of a weight-maintaining diet and then weekly for 4 wk during a total fast (group 1); a 1.9-MJ/d all-protein, very-low-energy diet (VLED) (group 2); or a low-energy, balanced-deficit diet (BDD) providing 50% of maintenance energy (group 3). In groups 1 and 2, leptin was also measured after 1 wk of refeeding with a diet equivalent to the BDD. RESULTS: Mean leptin decreased markedly by up to 66% (P < 0.001) at week 1 of energy restriction and then gradually thereafter. The change in leptin per kilogram fat mass correlated with that in glucose concentrations [r = 0.538 (P = 0.012) at week 1 and r = 0.447 (P = 0.042) at week 4] but not with that in fat mass. During refeeding postfasting, leptin increased (P = 0.008), despite an ongoing loss of fat mass and correlated positively with changes in resting energy expenditure. At times with comparable cumulative energy restriction and fat loss between diets, the percentage change in leptin paralleled that in glucose. CONCLUSIONS: In obesity, changes in energy intake over days to weeks are a primary modulator of plasma leptin concentrations that are related to the change in glycemia and are able to override the regulatory influence of fat mass.

Adult↗

PubMed1979

Interaction of glucocorticoid and insulin in the responses of rats to starvation-refeeding.

Experiments designed to determine whether the role of glucocorticoid (GC) in the induction of the enzyme overshoot response to starvation-refeeding was direct or permissive through insulin were conducted. Intact, adrenalectomized (ADX), and streptozotocin (STREP) treated rats with or without insulin and/or GC replacements were starved for 48 hours and refed a 65% glucose diet for 48 hours. The typical enzyme overshoot response to starvation-refeeding was observed in the intact rats, ADX rats given GC, STREP rats given insulin and ADX-STREP rats given glucocorticoid plus insulin. No overshoot was observed if glucocorticoid was absent whereas a modest increase in enzyme activity could be observed in insulin deficient rats treated with GC.

Adrenal Glands↗

PubMed1981

Effect of prolonged experimental protein malnutrition and of refeeding on growth, adipose tissue development and body composition in rats.

The effect of experimental protein malnutrition and of subsequent refeeding at various ages on growth, adipose tissue development, body composition and serum triiodothyronine (T3) concentration were studied in weanling, male Sprague-Dawley rats fed isoenergetic diets containing 22% casein (controls) or 8% casein (PM-3) from 3 until 33 weeks of age. In addition, groups of control rats were switched to the 8% casein diet at 7 weeks of age (PM-7), and groups of PM-3 rats were refed the control diet from 7 (RF-7) or 11 (RF-11) weeks of age. At 33 weeks of age, PM-3 rats were 56% and PM-7 rats 82% the weight of controls, while RF-7 rats were 84% and RF-11 77% the weight of controls, respectively. Carcass fat and energy content corresponded to body weight in all groups. The weights of the epididymal fat pads of control rats did not increase after 24 weeks of age. The epididymal fat pad weights of all other groups remained smaller than those of controls, but continued to increase throughout the study. Epididymal adipocyte numbers did not change after 11 weeks of age in control rats or after 17 weeks of age in PM-7 and RF-7 rats, but continued to increase throughout the 33 weeks in the PM-3 and RF-11 rats. Adipocyte size increased with age in all groups but remained smaller throughout in PM-3 rats. Serum T3 concentrations were greatest in the PM-3 rats, intermediate in the PM-7 rats and became normalized in both RF groups by 33 weeks of age. These studies confirm that the postweaning protein deprivation impairs the growth of lean tissues and indicate that its primary effect on adipose tissue is a decrease in adipocyte proliferation and/or differentiation which may not recover with refeeding.

Adipose Tissue↗

PubMed1982

Effects of diet composition and adrenalectomy on the lipogenic responses of rats to starvation-refeeding.

The interacting effects of diet and glucocorticoid (GC) on the tritium incorporation into lipid and glucose-6-phosphate dehydrogenase activity in starved-refed rats was studied. Male Sprague-Dawley rats were intact, adrenalectomized (ADX), or ADX and given GC and fed either ad libitum or not fed for 48 hours amd refed either a 65% glucose diet, 65% sucrose diet, 65% starch diet, 65% protein diet or a 40% fat diet. No diet differences in rates of 3HOH incorporation into total lipids were observed in ad libitum-fed rats. ADX lowered lipogenesis and this effect was diet dependent. Sucrose-fed, glucose-fed and protein-fed ADX rats had lower rates of lipogenesis than their intact controls. Starvation-refeeding increased lipogenesis in all groups of intact rats except those fed the 40% fat diet. The magnitude of the response was diet dependent. Sucrose-fed rats had greater responses than fat-fed rats. The diet effect was dependent on the presence of the adrenals and GC. Thus, the large increase in liver lipid associated with starvation-refeeding is contingent on the composition of the diet and the presence of the adrenals.

Adrenalectomy↗

PubMed1986

Effects of food restriction and starvation-refeeding on volatile fatty acid concentrations in the rat.

Adult male rats were fed either ad libitum or at levels of 19 or 15 g of nonpurified diet per rat daily or subjected to 48 h of starvation followed by 24 h of refeeding. Concentrations of total and individual volatile fatty acids (VFA) in cecal contents were higher in rats fed ad libitum than in those restricted to 19 or 15 g/d. Only butyrate concentration was lower in rats given 15 g/d than in those given 19 g/d. In starved animals all cecal VFA declined within 24 h of food removal, but the greatest change was in butyrate, which fell to less than 12% of the initial value. Acetate and propionate fell further after 48 h, but their concentrations were restored to control values within 24 h of refeeding while butyrate remained depressed by 50%. Cecal pH was closely related to total VFA concentration, although the highest degree of correlation was with butyrate. Hepatic portal venous plasma VFA concentrations generally reflected those in cecal digesta except that the proportion of butyrate was relatively lower in this blood vessel than in cecal contents. Under all conditions acetate was the only VFA found in arterial plasma and in the fully fed state was lower than in hepatic portal venous plasma. Food restriction and starvation did not alter arterial concentrations, indicating abolition of net uptake. We conclude that all VFA are affected by availability of fermentable material to the large bowel microflora but that the disproportionate changes in butyrate may reflect preferential use of this acid by cells of the large bowel wall.

Animals↗

PubMed1988

Rat transthyretin: effects of acute short-term food deprivation and refeeding on serum and cerebrospinal fluid concentration and on hepatic mRNA level.

To gain some insight into the nutritional factors that affect the blood level of transthyretin (TTR) and its metabolism, we have investigated the response of rat TTR to 1, 2 and 3 d of fasting and to 24 h of fasting followed by refeeding. The observed changes were compared to the level of TTR in cerebrospinal fluid (CSF) and to the amount of circulating thyroid hormones. Dot hybridization of a hepatic mRNA-cDNA probe specific for TTR was used to measure the relative level of TTR mRNA. Serum TTR decreased significantly after fasting and the decrease was proportional to the duration of the treatment. When rats were fasted for 24 h and then refed, serum TTR levels remained low after 2 d of refeeding. The dot hybridization results suggested that reduced liver synthesis was not the only mechanism that could explain this long-lasting effect of fasting. The TTR level in CSF was not influenced by fasting. In addition to the high sensitivity of serum TTR to food deprivation, the study also showed two distinct influences of fasting on the thyroid hormones: a primary effect that probably results in an inhibition of the conversion of thyroxine (T4) to triiodothyronine (T3) and a decreased T4-bound fraction, probably as a result of decreased serum level of TTR.

Animals↗

PubMed1988

Differential effects of adrenalectomy and starvation-refeeding on hepatic lipogenic responses to dehydroepiandrosterone and glucocorticoid in BHE and Sprague-Dawley rats.

The interaction of rat strain and glucocorticoid status on the dehydroepiandrosterone (DHEA)-mediated decrease in response to starvation-refeeding was studied. DHEA treatment of intact starved-refed Sprague-Dawley rats resulted in significantly lower hepatic lipid and glucose-6-phosphate dehydrogenase activity than observed in non-DHEA-treated rats. When Sprague-Dawley rats were adrenalectomized (ADX), the response to DHEA treatment was potentiated. If glucocorticoid was replaced, there was some amelioration of the DHEA effect in the ADX rats. Responses to DHEA in BHE rats subjected to the above paradigms were different. The responses of starved-refed BHE rats to DHEA were more pronounced and it appeared that glucocorticoid replacement was not as effective in overcoming DHEA in these rats. Thus, it appears that the comparative inhibition of the glucocorticoid-mediated response to starvation-refeeding by DHEA is strain dependent.

Adrenalectomy↗

PubMed1990

Effects of fasting and refeeding on the level of uncoupling protein mRNA in rat brown adipose tissue: evidence for diet-induced and cold-induced responses.

Brown adipose tissue (BAT) is characterized by the existence of a unique mitochondrial protein (uncoupling protein or UCP) that uncouples oxidative phosphorylation and thus allows heat production. Its role in thermogenesis has been emphasized in recent years in response to cold stress (nonshivering thermogenesis, NST) as well as to hyperphagia (diet-induced thermogenesis, DIT). The present work was a first attempt to determine whether varying nutritional conditions could affect UCP gene expression. Total RNA was isolated from interscapular BAT and hybridized with a cDNA probe for UCP. Changes in UCP mRNA level were studied in rats fasted and refed for various periods at 23 or 28 degrees C. A 2 d fast at 23 degrees C reduced UCP mRNA level, whereas refeeding increased it. A prolonged starvation (53 h) induced an unexpected rise in UCP mRNA, which was associated with a fall in body temperature. Increasing the ambient temperature to thermoneutrality (28 degrees C) suppressed the fall in body temperature as well as the rise in UCP mRNA, which could then be characterized as a cold-induced response. Under the same environmental conditions (28 degrees C), refeeding still triggered a sharp, though transient, increase in UCP mRNA, showing that DIT was dissociated from NST.

Adipose Tissue, Brown↗

PubMed1991

Age and protein restriction followed by balanced refeeding affect pancreatic digestive enzyme outputs and turnover times in rats.

Outputs and turnover times of trypsinogen 2, chymotrypsinogen 1, lipase and amylase were determined in pancreatic juice of growing male Wistar rats at various times during protein restriction (5% protein) followed by balanced refeeding (20% protein). In control rats fed a 20% protein diet, trypsinogen 2, chymotrypsinogen 1 and amylase outputs increased progressively with age, those of lipase remained constant and the turnover times of the four hydrolases were shortened. With time, protein restriction induced the most rapid decrease in trypsinogen 2 output, followed by that of amylase, then by those of trypsinogen 1 and lipase. Compared with controls, protein restriction enhanced specific radioactivity in total proteins and each hydrolase and diminished the enzyme turnover times at the beginning of the experiment. Refeeding returned each hydrolase output to control values, but the turnover times remained shortened to the end of experiment. Pancreatic lobules were isolated from control and protein-depleted rat pancreata after 23 d of dietary treatment. After a pulse of [3H]leucine, lobules were incubated in Krebs-Ringer-bicarbonate-HEPES. Basal and stimulated (50 pmol cholecystokinin/L) secretions of total proteins, amylase and radioactive proteins were measured. Protein restriction resulted in a lower response of acinar cells to cholecystokinin. The reduced ability of cholecystokinin to stimulate secretion may be attributable to a lower number and/or to the reduced affinity of cholecystokinin receptors in acinar cells. Therefore, the observed output and turnover changes during protein restriction could be partly due to an impairment of cholecystokinin efficiency.

Aging↗

PubMed1998

Feeding a low energy diet and refeeding a control diet affect glycolysis differently in the slow- and fast-twitch muscles of adult male Wistar rats.

Muscle glycogen concentrations in underfed (HYPO) and refed rats (RE) in an earlier study did not correlate with fatigue. We hypothesized that underfeeding slowed glycolysis in the slow-twitch soleus, but not in the fast-twitch extensor digitorum longus (EDL). Thirty adult male Wistar rats were randomly assigned to receive one of two isovolemic and micronutrient-complete liquid diets, a control (CN) energy-complete diet for 10 d or a diet 80% lower in energy (HYPO) for 7 d producing a 20% loss of initial weight. Rats were refed an energy-complete diet for 1 or 4 d (RE1, RE4). Rats were then anesthetized, and the soleus and EDL muscles of the hindlimbs were isolated and electrically stimulated in situ. The pre- and postfatigued muscles were freeze-clamped, lyophilized and stored at -70 degreesC until assayed for specific glycolytic and Krebs cycle metabolites. The HYPO diet caused significantly slower glycolysis in the stimulated soleus but not the EDL compared with the CN diet as supported by the following: 1) a lower fructose-1,6-bisphosphate (F-1,6-P2)/fructose-6-phosphate (F-6-P) ratio; 2) a greater glucose-6-phosphate (G-6-P)/lactate ratio; 3) a lower lactate/glycogen ratio; and 4) lower lactate concentration. Four days of refeeding normalized the F-1,6-P2/F-6-P ratio, but did not improve the lactate/glycogen or the G-6-P/lactate ratios. We conclude that undernutrition compromises glycolysis only in slow-twitch muscles and that 4 d of refeeding restores phosphofructokinase activity.

Analysis of Variance↗

PubMed1999

Food deprivation and refeeding influence growth, nutrient retention and functional recovery of rats.

The objective of this work was to determine the effects of starvation and refeeding on growth, nutritional recovery and intestinal repair in starved rats. Male Wistar rats, weighing 200 g, were starved for 3 d, then refed a soy-based diet for another 3 d. Normally fed rats were given the same diet and used as controls. The variables assessed were as follows: body weight gain and nitrogen retention during recovery after starvation; muscle glutamine concentration; tissue protein content; gut mucosa and liver glutathione levels; intestinal permeability to ovalbumin, lactulose and mannitol; and intestinal tissue apoptosis. Starvation was associated with lower muscle glutamine levels and intestinal mucosa impairment, including a lower content of mucosal protein, a higher level of oxidized glutathione, enhanced permeability to macromolecules and greater numbers of apoptotic cells. Refeeding for 3 d resulted in rapid repair of gut atrophy and normalization of not only intestinal permeability but also of the majority of metabolic markers assessed in other tissues. In conclusion, with the use of severely starved rats, we have established a reversible experimental animal model of malnutrition that might prove useful in comparing the effectiveness of different enteral diets.

Analysis of Variance↗

PubMed2000

Lipoprotein lipase activity and mRNA are up-regulated by refeeding in adipose tissue and cardiac muscle of sheep.

Previous studies in rodents have shown that the lipoprotein lipase (LPL) regulation is complex and often opposite in adipose tissue (AT) and muscle in response to the same nutritional treatment. However, neither LPL responses nor the molecular mechanisms involved in the nutritional regulation have been studied in both AT and muscle of ruminant species. To explore this, we measured the LPL activity and mRNA levels in perirenal AT and cardiac muscle (CM) of control, 7-d-underfed or 14-d-refed ewes. Underfeeding decreased (P < 0.01) LPL activity both in AT (-59%) and CM (-31%), and these activities were restored (P < 0.01) by refeeding (AT, +248%; CM, +34%). Variations of LPL mRNA level measured by real-time reverse transcription-polymerase chain reaction or by Northern blot followed variations of LPL activity: underfeeding decreased AT- and CM-LPL mRNA levels (-58 and -53%, respectively), and refeeding restored (P < 0.01) them in CM (+117%) and increased them over the baseline in AT (+640%). Quantification of either 3.4- or 3.8-kb LPL mRNA levels revealed a predominant (P < 0.001) expression of the 3.4-kb mRNA in AT (60%) and of the 3.8-kb mRNA in CM (56%), without any preferential regulation of one of these mRNA species by the nutritional status. This work reveals a tissue-specific expression pattern of the ovine LPL gene and a pretranslational nutritional regulation of its expression, which is achieved in the same direction in perirenal AT and CM. The different regulation of CM-LPL between ewes and rats probably arises from peculiarities of ruminant species for nutrient digestion and absorption and liver lipogenesis.

3' Untranslated Regions↗

PubMed2003

Expression of DNase I in rat parotid gland and small intestine is regulated by starvation and refeeding.

DNase I in rats is mainly expressed in the parotid gland and the small intestine and functions as a digestive enzyme. Male Wistar rats were deprived of food for 48 h, refed with nonpurified diet for 2 h and killed at 0, 0.33, 0.67, 1, 2, 6 or 12 h. The activity and mRNA of DNase I in the parotid gland and the small intestine were determined. We found that in rats that were not fed for 48 h there was accumulation of DNase I in the parotid gland but not in the small intestine. In the parotid gland, refeeding decreased DNase I activity (P < 0.05), perhaps due to an increase in secretion. The increase in DNase I mRNA probably resulted from the need for protein synthesis. However, in the small intestine, both the enzyme activity and the amount of mRNA were up-regulated by refeeding (P < 0.05). Exposing rats to food in a sealed transparent flask also caused a 2.5-fold increase in DNase I mRNA within 30 min in the parotid gland. These data suggested that the expression of rat parotid DNase I is up-regulated by feeding and that mastication is not essential for the regulation.

Animals↗

PubMed2004

Improvement of nutritional status as assessed by multifrequency BIA during 15 weeks of refeeding in adolescent girls with anorexia nervosa.

In patients with anorexia nervosa (AN), an assessment of changes in body composition and nutritional status is crucial for adequate nutritional management during refeeding therapies. Phase-sensitive multifrequency bioelectrical impedance analysis (BIA) is an inexpensive and noninvasive technique with which to determine nutritional status and body composition. We investigated 21 female adolescents with AN (initial BMI 15.5 +/- 1.1 kg/m(2)) 4 times between wk 3 and 15 of inpatient refeeding and 19 normal-weight, age-matched female controls. From wk 3 to 15, BMI, fat mass, body cell mass (BCM), total body water (TBW), intracellular water (ICW) but not extracellular mass (ECM), and extracellular water (ECW) increased significantly. Reactance (Xc), phase angle (PhA), and the ECM/BCM index as parameters of nutritional status improved significantly in patients and no longer differed from controls in wk 15, although the BMI of patients was significantly lower than those of controls. Changes in the ECM/BCM index were due to accretion of BCM, which was associated with an increase of ICW. Multifrequency phase-sensitive BIA seems to be a promising tool for the assessment of changes in nutritional status and body composition in patients with AN. An individually determined and controlled hyperenergetic diet as part of a multidimensional, interdisciplinary treatment program for eating disorders seems to quickly improve the nutritional status of AN patients.

Adolescent↗

PubMed1986

Effect of starvation and refeeding on autophagy and heterophagy in rat liver.

Increase in the density of liver lysosomes after leupeptin administration was marked in starved rats but only slight in starved-refed rats. The levels of several intracellular enzymes in the liver lysosome fraction purified from leupeptin-treated rats were about 10 to 30 times more in starved rats than in refed rats. However, there was no difference between the intralysosomal levels of endocytosed FITC-labeled asialofetuin in starved and refed rats, indicating that refeeding after starvation markedly suppressed autophagy but not heterophagy in vivo. Immunohistochemical studies with cathepsin B and asialofetuin Fab'-peroxidase conjugates showed that refeeding after starvation markedly altered the cellular distribution of cathepsin B in the liver, resulting in a linear arrangement of the enzyme only on the periphery of hepatocytes. In contrast, endocytosed asialofetuin was found only in the periphery of hepatocytes of both starved and starved-refed rats. These results indicate that autophagy and heterophagy are regulated by different mechanisms in vivo.

Animals↗

PubMed1999

The effect of feed deprivation and subsequent refeeding on the bone characteristics of aged hens.

In an attempt to improve skeletal integrity of older caged laying hens, birds were held without feed for 4 to 8 d and then refed. Feed deprivation caused an immediate loss in breaking force of the tibia (P < 0.05). Although bone strength increased during subsequent refeeding, values did not return to prefast levels (P < 0.05). Feed withdrawal did cause a reduction in modulus of elasticity of the tibia (P < 0.05), which is a potential benefit for bones that are more resilient to damage; this characteristic was maintained through 30 d of feeding. Histological examination of the tibia hinted at some bone remodelling during refeeding following withdrawal, although the magnitude of these changes was of limited biological significance. These data suggest that simple feed withdrawal for 4 or 8 d is insufficient to bring about a meaningful improvement in skeletal integrity of the older caged laying hen.

Aging↗

PubMed1989

Rapid versus gradual refeeding in acute gastroenteritis in childhood: energy intake and weight gain.

Fifty-two children aged 6-46 months (mean 19 months), hospitalized for acute gastroenteritis (GE), were randomized after oral rehydration to receive 7 days of either traditional gradual refeeding (GR) or rapid refeeding (RR), the latter consisting of a full-strength lactose-limited diet, including lactase-treated whole milk. The study focused on the effect of a high energy intake, excluding possible negative effects of lactose. Both dietary regimens were well tolerated, the only difference in the clinical symptoms between the two regimens being a higher stool frequency within the RR group (p less than 0.02). The total energy intake, as well as energy derived from fat and protein, was significantly higher in the RR than in the GR group (p less than 0.0001). The mean daily energy intake of the latter group never reached recommended daily allowance (RDA) levels, while that of the RR group did on day 5. Moreover, during the whole period of dietary regimen, the RR group exceeded the RDA protein requirements (mean intake ranged 175-252%), while the GR group did not reach this RDA level until day 4. Milk was a major source of energy in the RR group, providing 47-59% of the daily energy intake. The short- and long-term weight gains in the RR group were only a little higher than those of the GR group, the difference being insignificant.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗

PubMed1996

Effect of weight loss and refeeding diet composition on anaerobic performance in wrestlers.

Collegiate wrestlers (N = 12) consumed a formula, hypoenergy diet (18 kcal.kg-1, 60% carbohydrate) without dehydration for 72 h. For the next 5 h, the athletes were fed either a 75% (HC) or a 47% (MC) carbohydrate formula diet of 21 kcal.kg-1. Each wrestler performed three anaerobic arm ergometer performance tests (TEST1, before weight loss; TEST2, after weight loss; TEST3, after refeeding). Blood withdrawn just before and after each test was analyzed for pH, bicarbonate, base excess, glucose, and lactate. Both groups had a similar significant reduction in total work done during TEST2 (92.4% of TEST1). Work done in TEST3 by HC was 99.1% of TEST1 while MC did 91.5% of their initial work (P = 0.1). Peak power was unaffected by the treatment. Plasma lactate significantly increased during the performance test from 1.72 to 21.91 mmol.l-1 as did plasma glucose from 4.88 to 5.25 mmol.l-1 when groups and trials were collapsed. Lactate accumulation was diminished during TEST2 compared with the other tests. Although the exercise bout reduced pH, bicarbonate, and base excess, there was no difference in the effect by group. In conclusion, weight loss by energy restriction significantly reduced anaerobic performance of wrestlers. Those on a high carbohydrate refeeding diet tended to recover their performance while those on a moderate carbohydrate diet did not. The changes in performance were not explained by the acid/base parameters measured.

Adult↗