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

Two experiments, one using 0+ the other 1+ rainbow trout, were conducted to investigate the effect of prolonged starvation on plasma growth hormone levels. The results from both experiments were essentially the same. As expected, starvation resulted in cessation of growth and in a lower coefficient of condition, whereas fed fish continued to grow and remained in good condition. Starvation had relatively little effect on the plasma cortisol level; in one experiment levels were elevated temporarily in starved fish, although by the end of the experiment there was no longer any difference between starved and fed fish, and in the other experiment plasma cortisol levels remained very low throughout the course of the experiment in both starved and fed fish. In contrast, in both experiments starvation had a pronounced effect on the plasma growth hormone level, which rose steadily during both experiments, such that it was six times higher after 1 month of starvation in 0+ fish, and five times higher after 6 weeks of starvation in 1+ fish. Thus, paradoxically, fed fish had very low plasma growth hormone levels and grew rapidly, whereas starved fish had elevated plasma growth hormone levels but did not grow. In both experiments a strong negative correlation was observed between the plasma growth hormone level and the coefficient of condition of the fish. The results are discussed with regard to the well-established metabolic changes that occur during starvation, and it is suggested that a major role of growth hormone during starvation is to aid in the mobilisation of fatty acids and glycerol from adipose stores.
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PMID:The effect of starvation on growth and plasma growth hormone concentrations of rainbow trout, Oncorhynchus mykiss. 187 76

The purpose of this study was to examine the influence of an eight day starvation period on semen characteristics and some endocrine parameters of young bulls. The experiments were performed with 18 bulls in two trials showing the following set-up: pre-treatment period (7 or 20 days), starvation period (8 days), realimentation period (3 days) and control period (64 days). During the pre-treatment period and the control period the bulls obtained a well-balanced food-ration, during the period of starvation only 2 kg straw daily. During the starvation period the bulls lost 6% of their bodyweight. No influence on general health could be noticed. The concentrations of testosterone, LH, bovine growth hormone, insulin and insulin-like growth factor decreased significantly during or after the period of starvation. There was no clear influence in volume, sperm density and total number of sperm due to the metabolic stress during the hunger period. The initial progressive motility of sperm was not affected. The percentage of morphological abnormal spermatozoa increased 45-55 days after the hunger period. Simultaneously the semen freezability was decreased. An influence on the acrosomal morphology of frozen/thawed spermatozoa could not be obtained. The concentration of fructose, citric acid and glycerylphosphorylcholine (GPC) of the seminal plasma was insignificantly influenced during the period of starvation. The realimentation caused a stimulating effect on the secretion mainly of GPC.
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PMID:[Effects of a metabolic endurance test developed for the constitution examination of young bulls on spermatologic and endocrine parameters]. 207 62

The aim of the study was to observe the effect of longer fasting of dairy cows during lactation on the insulin and thyroxine levels in blood serum. The test was performed at the Research Institute of Animal Production, Nitra. The blood samples for determination of the hormone levels were collected in the morning from the vena jugularis of four fasted 4-5-year-old dairy cows of the Black Pied breed during lactation with an average daily performance of 16.91. The blood was collected on the first, fifth, sixth, seventh, eight and ninth day (fasting) and then on the fifteenth and twenty first day of the test (feeding). The insulin level in the blood serum of fasted dairy cows was more or less balanced till the seventh day of fasting, and ranged from 4.33 to 4.91 microU.ml-1. On the last two days of fasting, the insulin level increased up to 7.11 microU.ml-1 on the 9th day of fasting. The insulin level was significantly higher during feeding than during starvation. The thyroxine level was statistically significantly lower in fasted dairy cows. Increasing insulin level at the last two collections of the fasting period was probably closely connected with the shifting of the endocrine balance from dominant position of insulin to the dominance of the growth hormone and glucocorticoids. A comparatively high effect on the increase of the insulin level was exerted during that time also by the increasing amounts of non-esterifed fatty acids. Starvation significantly reduced the levels of the studied hormones in dairy cows during lactation.
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PMID:[Insulin and thyroxine levels in dairy cows during lactation and after a 9-day fast]. 210 Apr 23

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

In order to determine the central or peripheral origin of the starvation-induced modifications of growth hormone (GH) and thyroid-stimulating hormone (TSH) secretions, the effects of starvation were studied in freely moving male rats with hypothalamo-hypophyseal disconnection. Five days after the disconnection GH secretion exhibited lower maximal values and higher trough levels and ultradian pulsatile secretion was lost as compared to controls. TSH levels were also decreased. The lesion did not modify pituitary somatostatin (SRIF) receptors as assessed by 125I-Tyr-O-D-Trp-8-SRIF binding or inhibition of adenylate cyclase activity. On the other hand, the growth hormone releasing factor (GRF) capacity to stimulate adenylate cyclase was strongly reduced by the lesion without modification of the affinity. Exposure to 72 h food deprivation decreased GH pulses and TSH levels in control rats but did not modify GH secretory profiles or TSH levels of lesioned rats. Plasma glucose and insulin levels were equally decreased after fasting in control and lesioned rats. Altogether, our results demonstrate that starvation-induced modifications of GH and TSH secretions are of central origin while glucose and insulin changes are peripherally triggered. They suggest that the hypothalamus is the only source of SRIF implicated in this effect.
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PMID:Involvement of central somatostatin in the alteration of GH secretion in starved rats. 257 76

Exercise is associated with a marked increase in glucose uptake by muscle, which is initially supported by breakdown of hepatic glycogen and subsequently by increased gluconeogenesis. If hepatic glucose production is inadequate, hypoglycemia results. During exercise there is decreased plasma insulin and increased catecholamines, glucagon, cortisol, and growth hormone, which contribute to but are not essential for the increased hepatic output of glucose. Although insulin concentrations fall, insulin sensitivity is increased. However, the augmented glucose uptake by muscle is due to other factors. The symptoms of exhaustion during exercise are not due to hypoglycemia, and prevention of hypoglycemia may not prolong the time of exercise to exhaustion. During severe caloric restriction, hepatic glucose production decreases and free fatty acids and ketone bodies become important sources of calories. Although under these circumstances hepatic gluconeogenesis is usually sufficient to prevent hypoglycemia, with very severe caloric restriction hypoglycemia can result. With starvation, insulin concentrations fall while growth hormone and glucagon increase. Frequently the usual symptoms of hypoglycemia are absent in individuals with hypoglycemia from severe caloric restriction. Hypoglycemia from severe caloric restriction has not been totally restricted to underdeveloped areas of the world. In such patients no endocrine abnormalities have been found, and hypoglycemia has persisted despite administration of large amounts of carbohydrate. Pregnancy and lactation could predispose to hypoglycemia in the face of inadequate caloric intake.
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PMID:Exercise and deficient carbohydrate storage and intake as causes of hypoglycemia. 264 24

A recombinant plasmid carrying a bovine growth hormone gene fused with the regulatory and signal regions of the alkaline phosphatase gene of E. coli was constructed. The bovine growth hormone gene expression as well as protein partial processing and secretion into the periplasm have been shown to take place under phosphate starvation, i.e. conditions of alkaline phosphatase derepression.
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PMID:[Biosynthesis and secretion of bovine growth hormone in Escherichia coli under the control of the secretory vector containing a promoter and signal region of the alkaline phosphatase gene]. 267 71

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

Studies in man have shown that the episodic release of growth hormone (GH) is infrequent and erratic, and unlike that in the rat does not appear to have discernible ultradian periodicities. However, these observations in nonfasted subjects may be invalid since mixed nutrients have unpredictable effects on GH release. Moreover, in the fed state basal GH levels are frequently undetectable, thus rendering the identification of low amplitude pulses unreliable. Accordingly, the 24-h pulsatile pattern of GH secretion obtained from repetitive venous sampling in six normal adult male subjects was examined during a control fed day and during the first and fifth days of a 5-d fast. The GH data were analyzed using two distinct methods: a discrete pulse detection algorithm (Cluster analysis) and Fourier expansion time-series, which allows fixed periodicities of secretory activity to be resolved. The 5-d fast resulted in a significant increase in discrete GH pulse frequency (5.8 +/- 0.7 vs. 9.9 +/- 0.7 pulses/24 h, P = 0.028), 24 h integrated GH concentration (2.82 +/- 0.50 vs. 8.75 +/- 0.82 micrograms.min/ml; P = 0.0002), and maximal pulse amplitude (5.9 +/- 1.1 vs. 12.3 +/- 1.6 ng/ml, P less than 0.005). While multiple low-amplitude sinusoidal periodicities were present on the control fed day, time-series analysis revealed enhancement of circadian and ultradian cycles on the first and fifth days of fasting. Concomitantly, fasting resulted in a decline (day 1 vs. day 5) in serum concentrations of somatomedin C (1.31 +/- 0.22 vs. 0.77 +/- 0.18 U/ml) and glucose (4.9 +/- 0.2 vs. 3.2 +/- 0.2 mmol/liter), and a marked rise in free fatty acid (0.43 +/- 0.12 vs. 1.55 +/- 0.35 mmol/liter) and acetoacetate (35 +/- 6 vs. 507 +/- 80 nmol/liter). We conclude that the acute nutritional status is an important determinant of spontaneous pulsatile GH secretion in man. Fast-induced enhancement of GH release is achieved through combined frequency (discrete pulses) and amplitude (sinusoidal periodicities) modulation. Such alterations in somatotropic hormone release may play an important role in substrate homeostasis during starvation.
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PMID:Fasting enhances growth hormone secretion and amplifies the complex rhythms of growth hormone secretion in man. 312 26

The morphologic features of the anterior pituitary gland were studied by immunohistologic methods in 12 patients who had died of complications of anorexia nervosa, 4 patients who had died while on a "crash diet", 13 patients who had died of organic disease associated with inanition, and 5 age- and sex-matched control subjects who had been involved in sudden fatal accidents. All known pituitary hormones were found to be present. Abnormalities noted in both the patients with anorexia and those with organic inanition included relative hypogranulation of adrenocorticotropic and, to a lesser extent, growth hormone cells. These changes are of unknown importance but are likely the result of starvation in that they were not observed in patients on a "crash diet" or in control patients. We conclude that no specific or etiologic abnormalities are present in the pituitary glands of subjects with anorexia nervosa and that the altered secretion of adenohypophyseal hormones often noted in patients with this disorder cannot be attributed to a primary pituitary disorder.
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PMID:Anorexia nervosa: an immunohistochemical study of the pituitary gland. 333 38


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