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PubMed1984

Effects of various oils and of starvation on the lipid metabolism in brain.

In this study the effects of the dietary fat sources, viz., Dalda, mustard oil and groundnut oil in the brain lipid metabolism during starvation has been investigated. To find out this, these oils were fed to albino rats for 8 weeks followed by 3 and 5 days of starvation. Total as well as galactolipids of brain were not affected by dietary oils and starvation, whereas phospholipids of brain were significantly increased by fasting irrespective of the dietary fats. On the other hand, cholesterol was found to be increased in the groups fed with Dalda and groundnut oil and to be significantly decreased during fasting experiments. Incorporation of (1-14C)acetate into lipid of the brain slices of rats fed different experimental diets than followed by starvation revealed that the uptake of radioactivity was higher in the group fed with groundnut oil, followed by Dalda. Low uptake was observed in the group fed with mustard oil.

Animals↗
PubMed1993

The effect of starvation on the diurnal variation of amylase secretion from rat parotid glands.

The purpose of this study was to investigate the effect of starvation on the cellular function of rat parotid glands in relation to the diurnal variation of amylase secretion from the tissue. Salivary amylase secreted from the glands of rats starved for 24 h showed diurnal variation, with two peaks at 13 and 21 h. The peak at 21 h was more notable than that in fed rats, because of the accumulation of a large amount of amylase in the tissue due to starvation. Maximal binding (Bmax) values of [3H]dihydroalprenolol in the parotid membrane of starved rats also showed diurnal variation, with marked peak at 13 and 21 h. However, phosphorylation of nuclear non-histone proteins in starved rat parotid glands showed diurnal variation, with peaks at 17 and 1 h. This phasing was delayed by 4 h in comparison to that of fed rats, suggesting that the delay of diurnal variation of amylase secretion commences at least a few days after the beginning of starvation. These results indicate that changes in salivary amylase secreted from parotid glands of rats starved for 24 h coupled with those in the number of beta-adrenoceptors in the tissue show the same diurnal variation as observed in fed rats. Starvation of rats for 24 h does not appear to influence the response of parotid gland cells to stimuli.

Amylases↗
PubMed1987

The role of plasma secretin during starvation in dogs.

Plasma secretin levels were measured during a 72-hour starvation period in dogs. Plasma secretin rose significantly and insulin levels fell significantly during starvation. Intravenous glucose loading at the end of the 72-hour starvation period suppressed plasma secretin and free fatty acid levels with a concomitant rise of glucose and insulin levels. These findings suggest that secretin might be regulated by plasma glucose and insulin levels and might play a role in lipolysis during starvation.

Animals↗
PubMed1991

Possible role of adrenergic mechanism in starvation-induced reduction in circulating thyroxine and triiodothyronine in rats.

To elucidate the possible role of adrenergic mechanism in thyroid hormone metabolism during starvation, serum thyrotropin (TSH), thyroxine (T4), and 3,5,3'-triiodothyronine (T3) levels and conversion of T4 to T3 in perfused liver were investigated in fasting (60 h) and fed rats. Propranolol (0.5 mg/kg), yohimbine (0.3 mg/kg) or phentolamine (5.0 mg/kg) was subcutaneously injected to the rat every 12 h. Serum levels of TSH, T4, and T3 were significantly lower in fasting rats than in fed rats. Although propranolol, yohimbine, and phentolamine administration did not significantly alter circulating TSH, T4 and T3 levels in fed rats, phentolamine partly inhibited the starvation-induced reduction in circulating TSH, T4, and T3. Thyroxine uptake and T3 production in perfused liver were significantly lower in fasting rats than in fed rats. Phentolamine treatment did not alter the T4 uptake and T3 production in perfused liver of fasting rats. These results suggest that alpha-adrenergic mechanism may have some role in starvation-induced reduction in circulating T4 and T3, and that phentolamine partly inhibited this phenomenon probably through the inhibitory effect on reduction in circulating TSH during starvation.

Animals↗
PubMed2006

Amino acid starvation induced autophagic cell death in PC-12 cells: evidence for activation of caspase-3 but not calpain-1.

While the apoptotic and necrotic cell death pathways have been well studied, there lacks a comprehensive understanding of the molecular events involving autophagic cell death. We examined the potential roles of the apoptosis-linked caspase-3 and the necrosis/apoptosis-linked calpain-1 after autophagy induction under prolonged amino acid (AA) starvation conditions in PC-12 cells. Autophagy induction was observed as early as three hours following amino acid withdrawal. Cell death, measured by lactate dehydrogenase (LDH) and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays occurred within 24 h following starvation and was accompanied by an upregulation in caspase-3 activity but not calpain-1. The cell death that occurred following AA starvation was significantly alleviated by treatment with the autophagy inhibitor 3-methyl adenine but not with the broad spectrum caspase inhibitors. Thus, this study demonstrates that 3-methyladenine-sensitive autophagic cell death due to AA starvation in PC-12 cells is mechanistically and biochemically similar to, yet distinct from, classic caspase dependent apoptosis.

Amino Acids↗
PubMed2003

Effect of starvation on lipid metabolism and stability of DHA content of lipids in horse mackerel (Trachurus japonicus) tissues.

For the purpose of characterizing the effect of starvation on 22:6n-3 (DHA) content in marine fish tissues, horse mackerel (Trachurus japonicus) were reared in a tank containing filtered, sterilized seawater under nonfeeding conditions for 107 d (survival rate of the fish was 96.51%). The crude total lipids (TL) of ordinary dorsal muscle, dorsal skin, and viscera of the starved individuals were separated into classes on silicic acid columns, and the constituents of the TL were quantified by gravimetric recovery from column chromatography. The TL, initially > 85% TAG in dorsal muscle, and even more in skin lipids, decreased dramatically within the first 44 d of starvation, and then decreased more gradually during the remainder of the test period, whereas the visceral TL decreased more slowly. The percentages of both saturated and monoenoic FA in the muscle TL also decreased somewhat, but those of DHA increased significantly in muscle during the test periods. Decreases in PE and PC initially were much smaller than TAG, but DHA levels remained high in both PE and PC. These findings indicate that all of the FA in the depot lipids of horse mackerel tissues are easily metabolized for energy production during starvation, but DHA in muscle lipids of the starved fish was maintained at a consistently high level, indicating that starvation did not affect DHA stability in phospholipids. The findings suggest that preservation of DHA in cell membrane lipid PE and PC is necessary for self-protection functions in starving fish.

Animals↗
PubMed1976

Effect of starvation of the distribution of free and membrane-bound ribosomes in rat liver and on the content of phospholipid and glycogen in purified ribosomes.

The distribution of free and membrane-bound ribosomes in liver in response to starvation has not been clearly defined. An investigation has been made of the effects of starvation on the content of DNA, RNA, protein, phospholipid and glycogen in rat liver, on the distribution of free and membrane-bound ribosomes, and on the content of phospholipid and glycogen in free and bound ribosome fractions. The results indicate that starvation can produce up to a 50% reduction in hepatic ribosomes without altering either the fraction of rRNA relative to the total RNA or the distribution of free and membrane-bound ribosomes. In addition, the degree of contamination of isolated ribosomes with membranous material does not fluctuate with changes in the nutritional status of the animal. The results suggest that the relative capacities for protein synthesis among the two ribosome compartments are maintained during the early stages of starvation. Further, co-sedimentation with glycogen is not responsible for the presence of membranous materials in purified ribosomes.

Animals↗
PubMed1992

Effect of starvation on glycogen and glucose metabolism in different areas of the rat brain.

We have studied the changes in concentration of glycogen, glucose and the bisphosphorylated sugars, glucose 1,6-P2 and fructose 2,6-P2, in several rat brain regions during 72 h of starvation. The animals were killed by focused microwave irradiation. The activities of glycogen metabolizing enzymes in the different areas were measured. A large decrease in glycogen and glucose concentration was observed in all areas. The concentrations of bisphosphorylated sugars changed, suggesting that an increase in glycolysis could take place at the beginning of starvation, with blood glucose as a major energy source. Differences in metabolite concentration before starvation disappeared after 72 h. The activities of glycogen synthase, glycogen phosphorylase and glycogen phosphorylase kinase were similar in all areas, and they did not change during starvation.

Animals↗
PubMed1987

The increase in zincaemia provoked by starvation does not influence the intestinal absorption of zinc.

Serum zinc, measured in obese patients undergoing two weeks of therapeutic starvation (0 kcal, water ad libitum) increased significantly during the starvation period (+48% at day 10) and returned to prestarvation values after refeeding with a 500 kcal diet. Intestinal absorption of zinc was investigated by an oral zinc tolerance test (with 75 mg of zinc acetate) on the second and the tenth day of starvation. No significant differences were observed between the first and the second test. In our experimental conditions 10 days of starvation failed to induce a loss of zinc exceeding 0.75% of the total body stores. It is concluded that the concentration of zinc in blood per se does not regulate intestinal absorption in the absence of a significant change in zinc requirements.

Adolescent↗
PubMed1992

Regulation of rat erythrocyte L-glutamine, L-glutamate and L-lysine uptake by short term starvation.

1. The kinetic parameters (Km, Vmax and Kd) of L-glutamine, L-glutamate and L-lysine uptake by isolated red blood cells in fed and 24 hr starved rats have been determined. 2. L-Lysine and L-glutamine uptake was best fitted by a two transport component: a saturable component and a diffusion one. 3. Starvation brought about important decreases in the Km and Vmax for both L-lysine and L-glutamine uptake. 4. The Kd for L-glutamine showed a significant increase whereas that corresponding to L-lysine did not change by starvation. 5. L-Glutamate uptake adjusted to diffusion kinetics, with a Kd which did not change due to starvation. 6. It is concluded that the amino acid uptake showed specific regulation by starvation. 7. The mechanism involved is not dependent on protein synthesis--given the unnucleated nature of mammal red cells. 8. The magnitude of the changes observed in the uptake kinetic parameters may account for the extent of the blood amino acid pool changes as those produced in vivo over physiological limits.

Animals↗
PubMed1978

Effect of starvation on hypothalamic-pituitary-thyroid function in the rat.

Total starvation in the rat for 2 days did not alter the hypothalamic content of thyrotropin-releasing hormone (TRH), but did decrease both pituitary TSH content and serum TSH concentration. Five days starvation resulted in a significant decrease in serum TSH and a slightly enhanced serum TSH response to exogenous TRH, suggesting that the pituitary retains its sensitivity to TRH. Fasting for 5 days resulted in a decreased 1 and 4th, but an increased 24th thyroid 131I uptake. Other starvation-induced abnormalities of intrathyroid 131I metabolism were a consistent increase in the percent of organified 131I present as MIT and DIT and a decreased percent 131I labeled T4 AND T3. These alterations in the intrathyroid metabolism of 131I in the starved rat probably reflect both a decrease in serum TSH concentration and a decrease in urinary and fecal loss of administered 131I. The serum total and free T4 and total and free T3 concentrations were decreased following 2 and 5 days of starvation.

Animals↗
PubMed1986

Regulation of myofibrillar protein degradation in rat skeletal muscle during brief and prolonged starvation.

Myofibrillar protein breakdown during brief and prolonged starvation was assessed in perfused rat skeletal muscle from 8-week-old fat-fed rats that conserve skeletal muscle protein during starvation and survive for 12 to 15 days and age-matched chow-fed rats that do not conserve protein and survive only five to six days. Following the inhibition of protein synthesis with cycloheximide, myofibrillar proteolysis was assessed by measuring the release of 3-methylhistidine from the perfused rat hindquarter while simultaneous measurement of total protein breakdown was assessed by measuring tyrosine release. Myofibrillar proteolysis progressed through three distinct phases during starvation: an early phase occurring within 24 hours in which proteolysis increased in all rats, a middle phase, which took three to five days to develop and during which proteolysis decreased and was present only in fat-fed rats, and a late phase in which proteolysis again increased. Total protein breakdown (ie, tyrosine release) changed little in phase I, decreased in phase II, and increased in phase III. The release of 3-methylhistidine from the perfused hindquarter reflected changes in muscle and urine of intact rats suggesting that data obtained with the perfused hindquarter reflected the in vivo situation. Insulin, amino acids, high concentrations of glucose, indomethacin, or epinephrine as well as adrenalectomy failed to attenuate the increase in 3-methylhistidine release from the perfused hindquarter during brief and late starvation. Free fatty acids and ketone bodies were also without effect in vitro. Refeeding fasting rats for four hours decreased myofibrillar proteolysis.(ABSTRACT TRUNCATED AT 250 WORDS)

3-Hydroxybutyric Acid↗
PubMed1988

Metabolic response to starvation at late gestation in chronically ethanol-treated and pair-fed undernourished rats.

To study the role of undernourishment in the negative effects of ethanol during pregnancy and to determine whether maternal ethanol intake modifies metabolic response to starvation at late gestation, female rats receiving ethanol in their drinking water before and during pregnancy (ethanol group) were compared with animals that received the same amount of solid diet as the ethanol group rats (pair-fed group) and with normal rats fed ad libitum (control group). All animals were killed on the 21st day of gestation, either in the fed state or after 24-hours fasting. The body weight of ethanol rats was lower than that of controls but higher than that of pair-fed rats. When compared with controls, ethanol and pair-fed rats had reduced fetal body weights, whereas fetal body length was reduced only in the former. In the fed state, blood glucose concentration was lower in the ethanol and pair-fed rats and fetuses than in controls. Twenty-four-hour starvation caused a reduction in this parameter only in control and ethanol mothers. In the fed state, maternal liver glycogen concentration was lower in ethanol and higher in pair-fed mothers than in controls. Blood beta-hydroxybutyrate levels were higher in ethanol-treated mothers than in the others, and 24-hour starvation increased this parameter in ethanol and control rats to a greater extent than in the pair-fed ones. Liver triacylglyceride concentration was higher in ethanol-treated mothers than in the other two groups, and starvation caused this concentration to increase in ethanol and control groups but not in the pair-fed group.(ABSTRACT TRUNCATED AT 250 WORDS)

Alcoholism↗
PubMed1983

Effect of short-term starvation stress on the age-related changes in hepatic SDH activity of the indian murrel, Channa punctatus.

Judging from correlation analysis it is evident that the fed control male and female murrels of the oldest classes have significantly higher SDH (EC 1.3.99.1) activity than the youngest classes of respective sexes. This is true for starved groups also. Starvation for 3 days led to an increase in hepatic enzyme activity over fed controls in three oldest groups (3+-, 4+- and 5+-yr classes) of female. This trend of raised activity was maintained in the same groups even in 7 days of starvation. On the other hand, in the male fish, 3 days of starvation caused an increase in hepatic enzyme activity over that in fed control fishes of all year classes barring those of 0+-yr class. Seven days of starvation failed to produce a significant change in enzyme activity in almost all age classes except in the 5+-yr class where the activity still remained at a higher level over that of fed controls.

Age Factors↗
PubMed1982

Some physiological and biochemical features of starvation and refeeding in small wild rodents (Microtinae).

Blood glucose and leucocytes and liver glycogen and lipids were investigated in Cl. rutilus and Cl. rufocanus fasted for 0, 6, 12, 18 and 22 hr. It was observed: 1. In both species blood glucose content drops (1.3-1.5 times) by 6 hr, slowly rises by 12 hr and then progressively and strongly declines up to the end of starvation (36% and 27% of control for Cl. rutilus and Cl. rufocanus respectively). 2. Liver glycogen was depleted by 6 hr of fasting while lipids accumulate in liver during starvation in a large quantity (3.4-3.6 times at the end). 3. White blood cells content in fasted animals decreases. At one end of starvation it equals 23% and 16% of control for Cl. rutilus and Cl. rufocanus, respectively. 4. Hypoglycemia in Microtinae during starvation is pronounced compared with that in Muridae. Leucopenia and accumulation of lot of lipids in liver are new phenomena for fasting. 5. After refeeding hyperglycemia develops, the liver accumulates large quantities of glycogen. Recovery of all indexes slow. Complete normalization does not occur by 16 hr of refeeding.

Animals↗
PubMed1988

Long-term starvation in Xenopus laevis Daudin--II. Effects on several organs.

1. The effect of starvation for 12 months on organo-somatic indices, glycogen, protein and water contents of several organs and the Na+/K+ ratio in muscle was studied in the South African clawed toad Xenopus laevis Daudin. 2. The liver- and ovary-somatic index were reduced by 30 and 70% of the initial value after 12 months. Fat bodies had disappeared after approximately 6 months of starvation. The indices of heart and kidney were not changed. 3. Glycogen concentration of the liver, ovaries and muscle were depleted nearly totally during the first half of the experimental time, whereas glycogen in the kidney seemed to be unaffected. 4. Protein concentration increased in the liver, decreased in the muscle and remained constant in the kidney. 5. Starvation caused an increase of the water concentration of the whole animal and different organs, especially at the end of the experiment. 6. The Na+/K+ ratio of the muscle increased significantly after 6 months of starvation and reached a maximum after 10 months.

Animals↗
PubMed1986

Starvation-induced microautophagic vacuoles in rat myocardial cells.

During prolonged starvation the heart atrophies and loses protein mass. Debate lingers over the basic mechanisms in the production of negative cardiac protein balance during starvation. The extent to which cardiac proteolysis takes place within the lysosomal vacuolar system is unknown. The present communication examines the starvation-induced changes within the lysosomal system of rat myocardial cells, as studied by means of conventional electron-microscopic techniques. Special attention has been paid to the occurrence of microautophagic vacuoles. It is concluded that during prolonged starvation microautophagic vacuoles appear in rat myocardial cells, suggesting the induction of a microautophagic pathway of lysosomal proteolysis.

Animals↗
PubMed2006

Characterization and variations of organic parameters in teleost fish endolymph during day-night cycle, starvation and stress conditions.

The aim of the present work was to examine the modifications of the organic composition of fish endolymph under environmental conditions (day-night cycle, starvation and Cl2-stress) known to modify otolith growth. Endolymph electrophoretic patterns were compared. An antibody raised against the trout otolith organic matrix allowed examining the variations of organic matrix precursors in the endolymph under the above conditions. Western blot analysis showed bands around 60-80 kDa. A 50% decrease of immunolabelling was observed during the night whereas increases were seen after starvation (factor 3) or stress (factor 2) suggesting that these variations could be related to the organic matrix deposit. A factor retarding in vitro CaCO3 crystallization (FRC) was shown to co-precipitate with endolymph proteins and its apparent molecular mass (determined by measuring the activity after electro elution of gel electrophoresis) was estimated around 20 kDa. The FRC activity was stable during day-night cycle whereas it decreased by 70% and nearly 100% under starvation and stress respectively. These results suggest that the FRC, although retarding in vitro crystallization, plays a major role in the process of otolith calcification and that the decreases measured after starvation and stress are responsible for the decreases of the otolith growth. The variations of these two parameters (precursors and FRC) could contribute for the changes in the microstructure of the otolith.

Animals↗