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

In chickens, the kidney possesses a distinct cytosolic phosphoenolpyruvate carboxykinase activity which is not found in the liver. This activity is subject to long-term regulation by diet and changes in acid-base status. The activity is increased during starvation or metabolic acidosis. In addition, an unidentified component of some standard chicken diets results in altered activity. Using a specific cDNA probe the abundance of PEPCK mRNA has been determined in chicken kidney in vivo and in vitro. The abundance of PEPCK mRNA in chicken kidney increases during starvation and is rapidly decreased after refeeding carbohydrate. In isolated kidney tubules the abundance of the mRNA is increased after incubation with glucocorticoids, dibutyryl cAMP or hormones acting via changes in the concentration of cAMP (parathyroid hormone, epinephrine). Phorbol esters or hormones acting via calcium-dependent mechanisms were without effect. The results support the hypothesis that in the chicken the kidney is the major site of gluconeogenesis from substrates other than lactate and thus plays an important role in the maintenance of glucose homeostasis.
 ...
PMID:Hormonal and nutritional regulation of phosphoenolpyruvate carboxykinase mRNA levels in chicken kidney. 291 3

Ultrastructural changes of the parathyroid glands of starved mice were examined. The parathyroid glands of the starved mice showed a decrease in the volume of Golgi complexes and storage granules and an increase in the volume of lipid droplets, and contained more heterogeneously dense bodies and multivesicular bodies compared with that of the control mice. In addition, the volume of mitochondria, cisternae of granular endoplasmic reticulum and secretory granules and the number of prosecretory granules appeared to be decreased compared to those of the control mice. Myelin-like structures were observed in the parathyroid glands of the starved mice. The results of our study provide support for the hypothesis that starvation exerts an inhibitory influence not only on the synthesis but also on release of parathyroid hormone.
 ...
PMID:Effects of starvation on the ultrastructure of the mouse parathyroid gland. 396 23

Renal phosphate (Pi) wastage following 7 days of starvation was investigated in normal rats (HI-P) and others previously stabilized on a low phosphorus (LO-P)diet. In LO-P animals, Pi excretion increased after starvation, but was significantly less than in starved HI-P rats. After thyroparathyroidectomy, the increase in Pi excretion after parathyroid hormone (PTH) was significantly greater in nonacidotic starved HI-P rats than in LO-P animals. However, PTH elicited a 31-fold increase in Pi excretion in both of these groups. Starved LO-P and HI-P rats responded equivalently to dibutyryl cyclic AMP. The renal response to phosphate depletion normally promotes Pi conservation, but is attenuated markedly by 7 days of subsequent starvation. This results from at least partial restoration of phosphaturic responsiveness to PTH during starvation.
 ...
PMID:Interactions of starvation and selective phosphorus depletion on renal phosphate reabsorption. 628 63

Severe chronic undernutrition is associated with decreased bone turnover and significant bone loss. However, little is known about the short-term effects of nutritional deprivation on bone turnover. To investigate the effects of short-term fasting on bone metabolism and the contribution of acidosis to these changes, 14 healthy women ages 18-26 (mean, 21 +/- 2 (SD years) were randomized to potassium bicarbonate (KHCO3, 2 meq/kg/day in divided doses) to prevent acidosis or control (potassium chloride, 25 meq/day) during a complete 4-day fast. Bone turnover was assessed using specific markers of formation [osteocalcin (OC) and Type I procollagen carboxyl-terminal propeptide (PICP)] and resorption [pyridinoline (PYRX) and deoxypyridinoline (DPYRX)]. Serum bicarbonate levels fell significantly from 27.0 +/- 3.2 to 17.3 +/- 2.6 mmol/L (P < 0.01) in the control group and were decreased compared to patients receiving KHCO3 [17.3 +/- 2.6 vs. 23.4 +/- 2.4 mmol/L, (P < 0.001)]. Serum total and ionized calcium increased significantly in the control group [9.1 +/- 0.1 to 9.4 +/- 0.2 mg/dL (P < 0.01) and 1.20 +/- 0.03 to 1.23 +/- 0.03 mmol/L (P < 0.05), respectively], but not in patients receiving KHCO3. In addition, serum parathyroid hormone (PTH) levels decreased from 32 +/- 17 to 16 +/- 10 pg/mL (P < 0.05) and urinary calcium excretion increased [86 +/- 51 to 182 +/- 103 mg/day (P = 0.01)] in the control group, but not in patients receiving KHCO3. Serum osteocalcin (OC) and procollagen carboxyl-terminal propeptide (PICP) levels decreased significantly after 4 days of fasting from 9.1 +/- 3.4 to 5.5 +/- 4.2 ng/mL (P < 0.01) and 121 +/- 21 to 46 +/- 13 ng/mL (P = 0.0001) respectively in the patients receiving bicarbonate, and from 10.1 +/- 3.3 to 4.0 +/- 2.9 ng/mL (P < 0.01) and from 133 +/- 22 to 47 +/- 19 ng/mL (P < 0.001) respectively in the control group. The decrease in osteocalcin and PICP during fasting was comparable in both treatment groups. By contrast, urinary excretion of PYRX and DPYRX did not change significantly in either group with 4 days of fasting. These data are the first to demonstrate that markers of bone formation decline significantly with short-term fasting, independent of changes in acid-base status. By contrast, these data demonstrate a direct effect of acidosis in stimulating calcium release from bone during short-term fasting and suggest that acidosis may increase mineral dissolution independent of osteoclast activation and PTH in this experimental model of acute starvation.
 ...
PMID:Decreased bone formation and increased mineral dissolution during acute fasting in young women. 853 Jun 11

The parathyroid hormone (PTH) signaling pathways that effect changes in osteoblast gene expression also alter the organization of the cytoskeletal proteins. PTH regulates the expression of nucleoskeletal proteins, such as nuclear mitotic apparatus protein (NuMA) and topoisomerase II-alpha. NuMA is a structural component of the interphase nucleus and organizes the microtubules of the mitotic spindle during mitogenesis. We propose that PTH-induced alterations in osteoblast cytoarchitecture are accompanied by changes in osteoblast nuclear structure that contribute to changes in gene expression. We used immunofluorescence and confocal microscopy to determine the effect of PTH on the expression and nuclear distribution of NuMA in the rat osteosarcoma cell line, ROS 17/2.8. Cells were treated with PTH or vehicle, then fixed and stained with NuMA antibody. Optical sections of interphase naive cells revealed a diffuse distribution of NuMA, interspersed with speckles, in the central nuclear planes but not in nucleoli. During the metaphase and anaphase, NuMA localized at the mitotic spindle apparatus. The percentage of NuMA-immunopositive ROS 17/2.8 cells decreased with increasing confluence, but serum starvation did not attenuate NuMA expression. Cell density-dependent changes in cytoskeletal organization were observed in these cells. PTH treatment induced changes in cytoskeletal organization and increased the percentage of NuMA-immunopositive ROS 17/2.8 cells. These data suggest that PTH effects changes in osteoblast nuclear architecture by regulating NuMA, and that these alterations may be coupled to cytoskeletal organization.
 ...
PMID:Parathyroid hormone regulates the expression of the nuclear mitotic apparatus protein in the osteoblast-like cells, ROS 17/2.8. 955 30

We have recently demonstrated that the receptor for parathyroid hormone (PTH) and PTH-related peptide (PTHrP), PTHR, can be localized to the nucleus of cells within the liver, kidney, uterus, gut, and ovary of the rat. We set out to determine the localization of the PTHR in cultured osteoblast-like cells. MC3T3-E1, ROS 17/2.8, UMR106, and SaOS-2 cells were cultured in alpha-modified eagle medium containing 15% fetal calf serum under standard conditions. Untreated cells were grown on glass coverslips to 75-95% confluence and fixed in 1% paraformaldehyde. For experiments designed to examine cells synchronized by serum starvation, cells were grown on glass coverslips, starved of serum for 46 h, and then fixed at 2-h intervals for a total of 26 h after the addition of serum to the medium. Parallel sets of cells were pulsed with [3H]thymidine to track the DNA duplication interval. The PTHR was localized by immunocytochemistry using a primary antibody raised against a portion of the N-terminal extracellular domain of the PTHR. The results presented herein indicate that the PTHR attains a nuclear localization in each cell line examined. In UMR106 cells, PTHR immunoreactivity was restricted to the nucleolus. After cell synchronization, MC3T3-E1 cells double approximately 24 h after the addition of serum. Immunocytochemistry for the PTHR in these cells showed that the receptor staining is initially diffuse for the first 6 h, then becomes more perinuclear in distribution by 12-16 h. Nuclear localization of the receptor is achieved approximately 16-20 h after the addition of serum and remains there throughout the mitotic phase. Intense staining of mitotic and postmitotic cells was observed. No change in cell proliferation kinetics was observed in MC3T3-E1 cells cultured in the presence of 25 nM PTH(1-34). These data suggest an important role for the PTHR in the nucleus of MC3T3-E1 cells at the time of DNA synthesis and mitosis.
 ...
PMID:Nuclear localization of the type 1 parathyroid hormone/parathyroid hormone-related peptide receptor in MC3T3-E1 cells: association with serum-induced cell proliferation. 1070 93

The four types of experiments on milk secretion herein described really fall into one general class so far as the physiological effects produced are concerned. Starvation lowers the blood sugar and raises the osmotic pressure of the blood. The experiment using parathyroid hormone with or without starvation may have its effects interpreted as simply due to starvation since 1000 units of this hormone produced no visible effects on the blood calcium or milk constituents different from those of starvation. Since insulin produces a marked and rapid drop in blood sugar it too may be looked upon as a rapid starvation effect. It has some other important effects, however. Briggs et al. (21) have shown that potassium and phosphorus of the blood are decreased and Luck, Morrison, and Wilbur (22) indicate a reduction in the amino acids of the blood in insulin treatment. Phloridzin lowers the threshold for sugar retention with the consequence that in time it tends to lower the sugar of the blood to an even greater extent than that noted in starvation. It tends to depress the potassium, to increase the phosphorus content of the blood, and to cause the body to burn protein rather than carbohydrate, thus increasing nitrogen excretion. All of the experiments are characterized by a sharp reduction in the milk yield. Cary and Meigs (23) have studied like reductions in milk yield produced by varying the energy or protein of the diet. They conclude that such decrease in milk production may be interpreted as due to the direct effect of the starvation and the consequent reduction of the energy and protein available to milk secretion. The reduction in milk yield for the experiments herein described can undoubtedly be attributed to the same causes as those cited by Cary and Meigs. The experiment where Cow 47 was given a full ration and at the same time injected with large quantities of insulin is of particular interest in this connection. The ration was adequate and the cow ate well, yet her production declined to a fifth of her normal milk yield. Her chart shows that there was a slight reduction in her blood sugar when insulin was introduced into the blood stream. It seems furthermore likely that this sugar was not as available to milk secretion, since there appears to be more than a corresponding drop in the lactose content of the milk. The work of Luck et al. would seem to indicate that there should be a like drop in the amino acids of the blood. These two conditions would lead, according to the work of Cary and Meigs, to a reduction in the concentration of the nitrogen of the milk. Actually, in the experiment as it was performed, the nitrogen increased to a value about 40 per cent above normal. A somewhat similar conflict is noted in two of the other three insulin experiments where starvation accompanied insulin injection. To this extent it would seem that the factor deserving most emphasis in its immediate effect on milk yield is the energy available, and that the later and more secondary factor is the amino acid concentration of the blood. In the starvation experiments, the butter fat percentage of the milk rises rather uniformly with the duration of starvation. In the insulin experiments, however, the charts appear to show a marked reduction in this butter fat percentage immediately after the introduction of insulin. This is particularly noticed after the second and third injections. Since the dextrose of the blood tends to be reduced and made unavailable to the general physiological processes by the presence of the large excess of insulin, and since this reduction of the butter fat percentage is noted as an accompanying phenomenon, it would appear that the blood dextrose plays a part in the synthesis of milk fat as well as being the source of the milk lactose, possibly as a source of energy in converting body fat to butter fat. In this regard the results for the treatment of Cow 47 with phloridzin are of importance. As noted by others, the introduction of phloridzin causes a marked rise in the fat percentage of the milk. The lactose per cent is also higher than that noted in starvation. Since phloridzin, by lowering the threshold for the blood sugar, causes large quantities of it to be drained from the body through the urine, and therefore reduces the reserve supply, it follows that if the insulin hypotheses are correct we should expect an eventual lowering of the lactose and of the fat below the starvation level. During the last of the experiment this is what was actually observed. The effects of starvation and of insulin furnish concordant proof for the theory that the lactose of milk is derived from the sugar of the blood. The fact that the different constituents of the milk, the fat, the lactose, the nitrogen, and the ash, do not exactly parallel each other in their behavior throughout these experiments indicates that they have in all probability separate origin. This is particularly true of the butter fat percentage, which appears to have a rate of secretion which is more or less independent of the other constituents, and higher in amount. This result would fall in line with the conclusion of the writers in a previous paper in which it was indicated that the fat of the blood was very likely deposited in the udder as fat corresponding to body fat from which source it was metabolized into the fat of milk shortly before it was needed for milk secretion. The wide variation brought about in the constituents of the milk by the treatment all point to the conclusion that in milk secretion a balance is maintained between the osmotic pressure of the milk and of the blood. Thus when the sugar of the milk is reduced either through starvation or by insulin the ash constituents rise to compensate for this reduction and make the osmotic pressure of the milk similar to that of the blood. These results further appear to indicate that the salts and the sugars are more or less independent in their passage and metabolism into milk from the other constituents. These observations are therefore in line with those obtained by Jackson and Rothera (14) and by Davidson (15) in their brilliant experiments where they modified milk secretion by returning milk or milk sugars and salts to the udder. These experiments give direct proof for the conclusion that modifications of the blood of dairy cattle produce direct and predictable modification of the milk secreted.
 ...
PMID:ON THE MECHANISM OF MILK SECRETION : THE INFLUENCE OF INSULIN AND PHLORIDZIN. 1987 27

Glucocorticoids (GCs) are the final effector products of a neuroendocrine HPA/HPI axis governing energy balance and stress response in vertebrates. From a physiological point of view, basal GC levels are essential for intermediary metabolism and participate in the development and homeostasis of a wide range of body tissues, including the skeleton. Numerous mammalian studies have demonstrated that GC hormones exert a positive role during bone modeling and remodeling as they promote osteoblastogenesis to maintain the bone architecture. Although the pharmacological effect of the so-called stress hormones has been widely reported, the role of endogenous GCs on bone mineral metabolism as result of the endocrine stress response has been largely overlooked across vertebrates. In addition, stress responses are variable depending on the stressor (e.g., starvation, predation, and environmental change), life cycle events (e.g., migration and aging), and differ among vertebrate lineages, which react differently according to their biological, social and cognitive complexity (e.g., mineral demands, physical, and psychological stress). This review intends to summarize the endogenous GCs action on bone metabolism of mammals and fish under a variety of challenging circumstances. Particular emphasis will be given to the regulatory loop between GCs and the parathyroid hormone (PTH) family peptides, and other key regulators of mineral homeostasis and bone remodeling in vertebrates.
 ...
PMID:Stress, Glucocorticoids and Bone: A Review From Mammals and Fish. 3025 Apr 53