Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01275 (glucagon)
 26,492 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Specific binding sites for 125I-labeled insulin were detected in purified nuclei isolated from rat liver. Binding was rapid, reversible and directly proportional to the number of nuclei employed. Unlabeled native insulin, at concentrations as low as 1ng/ml, significantly inhibited the binding of labeled hormone, whereas unlabeled proinsulin and desoctapeptide insulin were less potent. In contrast, glucagon, thyrotropin, growth hormone (somatotropin), and prolactin were without effect. Under identical incubation conditions, 125I-labeled glucagon bound to liver plasma membranes 5- to 10-fold more strongly than did insulin; in contrast glucoagon did not bind to liver nuclei. These studies demonstrate the presence of specific binding sites for insulin in purified nuclei isolated from rat liver. In addition, they suggest that the nucleus may be an intracellular site of insulin action.
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PMID:Binding of insulin to isolated nuclei. 17 86

The effects of synthetic linear somatostatin on basal circulating levels on several pituitary and pancreatic hormones, and of glucose and free fatty acids (FFA) were studied in 6 normal men after an overnight fast. A priming intravenous infusion of 250 mug of somatostatin in 18 sec was followed by a constant infusion of 500 mug over a period of 60 min. A decrease in plasma values of GH, prolactin, TSH, insulin and glucagon and in blood glucose was observed during somatostatin infusion, while FFA levels increased progressively. Plasma IRI and blood glucose increased rapidly when the somatostatin infusion was stopped, while FFA decreased progressively; GH, prolactin, TSH and glucagon remained low as compared to basal levels for one hour after the end of the infusion, i.e. until the end of the experiment. A slight but significant increase of LH and ACTH was observed after the end of the infusion.
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PMID:Pituitary and extrapituitary effects of somatostatin in normal man. 18 9

Several procedures have been reported for the assay of corticotrophine-releasing factor (CRF), each having its advantages and disadvantages. This report deals with an in vitro assay of ACTH releasing activity utilizing pituitary incubation combined with ACTH radioimmunoassay. Rat half pituitary was preincubated in 2 ml Krebs Ringer bicarbonate buffer containing 0.2% glucose and 0.25 % BSA (KRBG-BSA) for 1.5 hr (45 min X 2). The medium was replaced by 1 ml KRBG-BSA and incubated for 30 min. Then the medium was again replaced by 1 ml KRBG-BSA or KRBG-BSA containing test materials and incubated for another 30 min. The amount of ACTH assayed by radioimmunoassay in the 2nd 30 min incubation was compared with in the 1st 30 min incubation and expressed as percentage. In ACTH radioimmunoassay, anti-ACTH serum was diluted to 1 : 1,500-3,000. The 125I-alpha 1-24ACTH-antibody system was not affected by lysine-vasopressin (LVP), arginine-vasopressin (AVP), rat's pituitary LH, GH and prolactin. Human 1-39ACTH was used as ACTH standard, and the dilution curve of incubation medium was paralleled with the standard curve. Repeatability of immunoassayable ACTH within-assay was 174 +/- 5.0 pg/tube (CV = 2.9%). A log dose-relationship was observed between the amounts of stalk median eminence extracts (SME ; NIAMDD) added to the incubation medium and its ACTH releasing activities. The sensitivity of this assay method was at least 0.1 SME or 10 mU of LVP and AVP. Using this method, it found that LVP, AVP, norepinephrine (100 ng/ml200 ng/ml) and 5-hydroxytryptophane (1 mug/ml) had ACTH releasing activities but LH-RH, TRH, glucagon, dopamine, phentolamine, propranolol, haloperidol, prostaglandin E1 and indomethacin did not affect the release of ACTH.
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PMID:[In vitro assay for ACTH-releasing activity using ACTH radioimmunoassay: ACTH releasing activities by various drugs (author's transl)]. 18 1

Obese Zucker rats were either pair-fed to their lean litter-mates or fed ad lib, to determine the effect of hyperphagia on serum hormone levels and tissue metabolism as indicated by enzyme activities and in vitro metabolite flux. Hyperphagia was shown to be non-essential for the elevation in serum insulin and suppression in serum growth hormone and prolactin in the genetically obese rat. It was also shown that the increased liver cell lipogenic rate was not dependent on hyperphagia in the obese rat and that adipose cell lipogenesis was not significantly altered in the pair-fed obese rat. The utilization of alanine for glucose synthesis in vitro was similar for both lean and obese rats, but its utilization for fatty acid synthesis was higher in the obese rat. Data is presented which suggest that the inhibitory effect of glucagon on liver lipogenesis is blunted in the obese rat.
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PMID:Serum hormone levels and tissue metabolism in pair-fed lean and obese Zucker rats. 19 81

Receptors for various hormones have been examined throughout the adult life span. In most of these studies receptor concentrations were found to decrease with increasing age, either during senescence or earlier in adulthood. In contrast, binding affinities did not change with age. Tissues and cells examined have included liver, brain, adipose tissue, skeletal muscle, prostate, fibroblasts, and lymphocytes. Receptors for steroids as well as membrane-active hormones such as insulin, glucagon, catecholamines, and prolactin were studied. Rats, mice, dogs, and humans have been employed. Changes in hormone receptor levels appear to constitute a common manifestation of the aging process, and offer interesting model systems in which to study the control of genetic expression during senescence.
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PMID:Hormone receptor changes during adulthood and senescence: significance for aging research. 21 48

The localization of various neuropeptides is described in the gut and in the hypothalamus in the rat. Evidence is given for the presence of material resembling corticotropin-like intermediate peptide in arcuate and periarcuate neurons, projecting to various hypothalamic nuclei, limbic areas and the thalamus. beta-Endorphin and glucagon decrease dopamine turnover in the median eminence, while secretin increases dopamine turnover and vasoactive intestinal polypeptide (VIP) has no effect. beta-Endorphin, VIP, secretin, and glucagon all produce discrete changes in norepinephrine turnover in various hypothalamic nuclei. Mainly increases of norepinephrine turnover were observed. These catecholamine turnover changes appear to cause changes in the secretion of prolactin and growth hormone. The results therefore indicate that gut hormones and opioid peptides may act directly on the hypothalamus on specific types of receptors to participate in the control of hypothalamic functions such as control of hormone secretion from the anterior pituitary and of food intake. It seems possible that gastrointestinal peptides released from the gastrointestinal tract into the circulation under certain circumstances could reach the hypothalamus and modulate its activity via the above-mentioned mechanisms. It may therefore be speculated that disturbances in gastrointestinal functions could lead to pathological changes in food intake via modulation of hypothalamic activity.
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PMID:Localization and possible function of peptidergic neurons and their interactions with central catecholamine neurons, and the central actions of gut hormones. 22 24

Variations in concentrations of growth hormone, insulin, glucagon, prolactin, adrenal corticoids, and thyroid hormones in blood plasma of ruminants as related to circadian rhythms, environmental factors and nutrition are reviewed. Rhythms in prolactin concentrations are related to light and temperature. Concentrations of prolactin in plasma are higher in warm environments and during longer photoperiods. There is episodic secretion of growth hormone in cattle with frequent peaks in plasma concentrations during 24 h. Marked increases in environmental temperature result in greater secretion of growth hormone for short times followed by a decline in plasma concentration with prolonged exposure. Extreme cold temperature also increases growth hormone concentrations in plasma. Secretion of thyroid hormones increases in cold and decreases in warm environments. Circadian rhythms are definite for plasma concentrations of adrenal corticoids in ruminants adjusted to their surroundings. Peaks occur late in dark periods, and lows occur during the end of light periods. Circadian patterns have not been consistent for secretion of insulin. Prolonged subjection to stresses such as noise, handling, and restraint can modify concentrations of prolactin, growth hormone, and adrenal corticoids. Changes in concentrations of insulin may occur if blood glucose is increased. After feeding, concentrations of growth hormone in plasma decrease and concentrations of insulin and glucagon increase. Relationships of these changes with metabolism are discussed.
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PMID:Relation of hormonal variations to nutritional studies and metabolism of ruminants. 35 Sep 15

The release of glucagon from pancreatic and extrapancreatic sources was studied in normal rats and in rats carrying transplants of a MtT-W-15 tumor which secretes large quantities of growth hormone and prolactin. The tumor-bearing rats had high serum levels of A cell immunoreactive glucagon (IRGa), total immunoreactive glucagon (IRGT) and immunoreactive insulin (IRI) and an increased total glucagon and insulin content of the pancreas. Pancreatic islets isolated from tumor-bearing rats secreted more glucagon under basal conditions but did not respond significantly to low glucose stimulation. However, they contained more insulin per islet and secreted more insulin under basal and stimulated conditions. The serum IRGa response to arginine infusion in vivo was lower in the tumor-bearing than in the normal rats. The introduction of a 5% glucose solution into the small intestine caused similar increases in the level of serum IRGT in the two groups of rats. Thus, the tumor increased the total pancreatic glucagon content and basal secretion, blunted the A cell response to stimulation, but did not significantly alter the secretion of glucagon by the intestine. We attribute these responses to tumor-induced hypersomatotropinism although we cannot rule out an effect of the large amounts of circulating prolactin.
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PMID:Glucagon secretion in rats bearing a growth hormone producing tumor (MtT-W-15). 36 50

Recently, evidence has been reported to suggest that human platelets like several other circulating blood cells may bind insulin. To examine whether human platelets contain specific insulin receptors, washed human platelets suspended in Hepes buffer were incubated at 24 degrees C with 125I-insulin in the presence and absence of unlabeled insulin and specific insulin binding was determined. Insulin binding by platelets increased progressively with time of incubation to reach a maximum at 3 h and was proportional to the number of platelets in the incubation mixture. Maximum insulin binding was observed at pH 8. Insulin degradation by platelets as assessed by TCA precipitability and reincubation studies was minimal. Scatchard analysis of the binding data and dissociation studies revealed evidence of negative cooperativity of the platelet insulin receptor. A high affinity dissociation constant of approximately equal to 3 X 10(9) M-1 was determined and the concentration of platelet insulin receptors was estimated as 25 binding sites/micron2 platelet surface area. Binding of 125I-insulin by platelets was inhibited by unlabeled porcine insulin and to a lesser extent by catfish insulin and porcine proinsulin but not by glucagon, prolactin, growth hormone, and thrombin. The findings indicate that human platelets contain specific insulin receptors. The significance of the platelet insulin receptor, particularly with respect to altered platelet function in diabetes mellitus, remains to be determined.
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PMID:Demonstration and partial characterization of insulin receptors in human platelets. 44 28

The effect of intravenous somatostatin on blood levels of metabolites and hormones has been examined in normal subjects who performed a 30-minute period of bicycle exercises at 70% maximal exercise capacity. The results have been compared with control studies in the same subjects. Measurements were made of blood levels of lactate, glucose, free fatty acids, glycerol, acetoacetate, 3-hydroxybutyrate, insulin, glucagon, growth hormone (hGH) and prolactin. Growth hormone and glucagon release were suppressed during exercise with somatostatin and there was a subsequent elevation during recovery. There was slight post-exercise depression of insulin, but no alteration of plasma prolactin secretion. Blood glucose was reduced during exercise with somatostatin and increased during recovery. The elevation of ketone bodies after exercise was greater in the investigation with somatostatin, but there were no significant changes in other metabolites. Somatostatin, although causing inhibition of hGH release, appeared to have no significant effect upon fatty acid mobilization during exercise.
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PMID:The effect of somatostatin on metabolic and hormonal changes during and after exercise. 47 77


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