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)

Both vasoactive intestinal peptide (VIP) and glucagon rapidly elevated cyclic AMP levels in embryonic chick retinal pigment epithelium (RPE), in culture as well as in freshly dissected tissue. In cultured cells, the half-maximal activities of VIP and glucagon were 5 X 10(-8) M and 3 X 10(-8) M, respectively. After 3 min of reaction, VIP elevated intracellular cyclic AMP by 100-fold; elevation with glucagon was up to 10-fold. Both neuropeptides stimulated adenylate cyclase activity in RPE membranes. Glucagon showed a half-maximal activity of 1 X 10(-8) M. VIP remained more effective than glucagon in stimulating adenylate cyclase activity, but the dose-response curve was shifted to a higher concentration range when compared to that of the VIP-elevated intracellular cyclic AMP.
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PMID:Elevation of intracellular cyclic AMP and stimulation of adenylate cyclase activity by vasoactive intestinal peptide and glucagon in the retinal pigment epithelium. 609 40

1. The effects of secretin, glucagon, cholecystokinin-pancreozymin (CCK-PZ), gastric inhibitory peptide (GIP), vasoactive intestinal peptide (VIP), somatostatin, neurotensin and enkephalin on basal, pentagastrin- and histamine-stimulated gastric acid secretion were investigated in the conscious fistula rat. 2. Glucagon and GIP were ineffective inhibitors of basal and pentagastrin-stimulated secretion. CCK-PZ stimulated acid secretion at a low dose level but at higher doses it inhibited both pentagastrin- and histamine-induced secretions. VIP was ineffective at low doses and at high doses its action was complicated by reflux of stimulated pancreatic and intestinal secretions into the stomach. Met-enkephalin inhibited histamine- but not pentagastrin-stimulated secretion. Neurotensin inhibited the response to pentagastrin but had no effect on histamine-stimulated secretion. Secretin and somatostatin were potent inhibitors of basal and pentagastrin-stimulated acid secretion with little or no effect on the response to histamine. 3. At doses completely inhibitory to pentagastrin-stimulated secretion secretin and somatostatin did not block the mobilization of gastric mucosal histamine by pentagastrin, although somatostatin caused partial competitive inhibition at lower doses of pentagastrin. Thus secretin and somatostatin inhibited pentagastrin-induced secretion neither by blocking gastric mucosal histamine mobilization nor by abolishing the direct action of histamine on the parietal cell -- findings which are inconsistent with the proposed role of histamine as the mediator of the action of gastrin on the parietal cell.
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PMID:Effects of various gastrointestinal peptides on parietal cells and endocrine cells in the oxyntic mucosa of rat stomach. 610 65

Fifteen male Holstein X Frisian calves, weighing 65 +/- 3 kg and fed a milk replacer twice daily were fitted with a return cannula loop, chronically implanted at 10 days of age in the pancreatic duct, were used. In six successive experiments we have observed the influence of an intravenous infusion of secretin, cholecystokinin pancreozymin (CCK-PZ), vasoactive intestinal peptide (VIP), glucagon, gastrin and somatostatin on pancreatic juice flow rate, and on the excretion of proteins, calcium, inorganic phosphorus, zinc and amylase activity of pancreatic juice. In two other experiments, we have studied the interaction of secretin (or CCK-PZ) with somatostatin (SRIF). Each experiment was performed 5 h after calves feeding and no milk was given to the animals during the time of sampling. Our results indicate that the endocrine regulation of the exocrine pancreas in young calves is similar to that described in other mammals. Secretin and CCK-PZ increased significantly excretion of water, calcium, magnesium, inorganic phosphorus, zinc, proteins and amylase activity. Somatostatin and glucagon inhibited effects observed with two precedent hormones. Gastrin increased pancreatic juice flow rate but excretion of protein and amylase activity do not varied significantly. VIP showed no significant effect on pancreatic excretion of water, minerals, proteins and amylase activity. However, our animals seem to be characterized by a more intense excretion of proteins and amylase in the pancreatic juice following secretin than after CCK-PZ infusion.
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PMID:The endocrine regulation of exocrine pancreas in preruminant milk-fed calves. 610 15

The properties of the specific receptors for vasoactive intestinal peptide (VIP) in rat liver plasma membranes have been studied by using 125I-VIP as a tracer. The binding of the peptide was a reversible, saturable and specific process, as well as time and temperature dependent. Peptide inactivation was also dependent on time and temperature and remained relatively low in the standard conditions used, as it happened in the inactivation of the binding sites. The binding data were compatible with the existence of two classes of VIP receptors: a high affinity (Kd = 4.2 x 10(-10) M) and low binding capacity (1.5 pmol VIP/mg protein) class and another one of low affinity (Kd = 1.7 x 10(-7) M) and high binding capacity (38.6 pmol VIP/mg protein). The specificity of the binding sites of VIP was established from the fact that binding of 125I-VIP was inhibited by native VIP and by 60-fold higher concentrations of secretin but not by the parent hormone glucagon, by insulin or somatostatin at concentrations as high as 10(-6) M.
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PMID:Properties of vasoactive intestinal peptide-receptor interaction in rat liver membranes. 611 23

The effects of pirenzepine on the plasma concentrations of gut hormones in the fasting and postprandial states were studied in six healthy subjects. On separate days and in random order, 10 mg pirenzepine, in 2 ml of solvent, or 2 ml saline (0.15 mol/l) were given intravenously 30 min before a standard normal breakfast (2220 kJ). Pirenzepine was not found to affect basal or postprandial levels of insulin, glucagon, gastric inhibitory peptide (GIP), neurotensin, vasoactive intestinal peptide (VIP) or somatostatin. The basal concentration of pancreatic polypeptide (PP) was lowered (p less than 0.05) and the postprandial elevation reduced, though not significantly. While the basal concentration of motilin was also suppressed (p less than 0.05), the postprandial elevation remained unchanged following pirenzepine. The release of enteroglucagon was reduced significantly in the basal and postprandial states (p less than 0.05 and p less than 0.025 respectively). The postprandial gastrin response was prolonged slightly, but insignificantly, by pirenzepine. It is concluded that pirenzepine does not exert any major or unexpected actions on the hormonal control of digestion.
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PMID:The effect of pirenzepine on meal-stimulated gastrointestinal hormones. 611 82

We have previously shown that stimulation of the preganglionic cervical sympathetic trunk leads to an acute increase in tyrosine hydroxylase (TyrOHase) activity in the rat superior cervical ganglion. This increase appears to be mediated in part by acetylcholine and in part by a second neurotransmitter. As a first step in an attempt to determine the identity of this noncholinergic transmitter, we have examined the ability of a number of neuropeptides to increase ganglionic TyrOHase activity in vitro. Secretin and vasoactive intestinal peptide (VIP) both stimulated TyrOHase activity, whereas angiotensin II, bombesin, bradykinin, cholecystokinin octapeptide, glucagon, insulin, luteinizing hormone-releasing hormone, [D-Ala(2), Met(5)]enkephalinamide, motilin, neurotensin, somatostatin, and substance P produced no effects. Secretin produced a significant increase in TyrOHase activity at 1 nM and a maximal elevation at 0.1 muM. VIP produced a significant increase at 0.1 muM and a near maximal effect at 10 muM. Although secretin was about 2 orders of magnitude more potent than VIP, it produced a significantly smaller maximal increase in enzyme activity. Incubation of ganglia with both secretin (10 muM) and VIP (10 muM) produced an increase in TyrOHase activity that was not significantly different from that produced by VIP alone. The stimulatory effects of secretin and VIP were reversible within minutes after removal of the peptides. Neither incubation of intact ganglia with the cholinergic antagonists hexamethonium and atropine nor prior decentralization of ganglia altered the response to the peptides. Thus, the data demonstrate that secretin and VIP acutely increase TyrOHase activity in the superior cervical ganglion and suggest that they produce this effect by acting directly on ganglionic neurons. It remains to be determined whether secretin or VIP or a related peptide is released during preganglionic nerve firing and whether one or more of these peptides is responsible for the noncholinergic elevation of TyrOHase activity produced by preganglionic nerve stimulation.
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PMID:Secretin and vasoactive intestinal peptide acutely increase tyrosine 3-monooxygenase in the rat superior cervical ganglion. 613 May 26

Preliminary observations have indicated the existence of characteristic spectra of gastroenteropancreatic (GEP) neurohormonal peptides in endocrine tumors arising in foregut, midgut, and hindgut derivatives. In order to further explore this feature of GEP endocrine neoplasms, islet cell tumors from 14 patients were studied, as were endocrine tumors of the stomach, duodenum, and upper jejunum from 6, 5, and 2 patients, respectively. All tumors were examined immunohistochemically with antisera raised against islet hormones [insulin, somatostatin, glucagon, pancreatic polypeptide (PP)], peptides of the gastrin family [gastrin, cholecystokinin (CCK)], peptides of the secretin family [secretin, vasoactive intestinal peptide (VIP)], and substance P, neurotensin, leu-enkephalin, beta-endorphin, motilin, calcitonin, and ACTH. In addition, an ultrastructural investigation was made. Whenever possible, the immunohistochemical observations were correlated with the clinical manifestations and with the results of radioimmunochemical determination of GEP neurohormones in the blood. The pattern of immunoreactive neurohormonal peptides and the clinical picture were those to be expected in endocrine tumors arising in foregut derivatives. Some principles are proposed for the classification of GEP endocrine tumors on the basis of their histopathologic growth pattern, their spectrum of neurohormonal peptides, and their clinical manifestations.
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PMID:Neurohormonal peptides in endocrine tumors of the pancreas, stomach, and upper small intestine: I. An immunohistochemical study of 27 cases. 613 99

We have examined the ability of a number of neuropeptides to increase tyrosine hydroxylase (TH) activity in the superior cervical ganglion in vitro. Secretin and vasoactive intestinal peptide (VIP) both increased TH activity, whereas angiotensin II, bombesin, bradykinin, cholecystokinin octapeptide, insulin, luteinizing hormone-releasing hormone, [D-Ala2, Met5]enkephalinamide, motilin, neurotensin, somatostatin, and substance P produced no effects. Secretin and VIP increased TH activity with an EC50 of 5 nM and 0.5 microM, respectively. The effects of these peptides were not altered by prior decentralization of the ganglia, by addition of hexamethonium (3 mM) and atropine (6 microM), or by lowering the concentration of calcium in the medium to 0.1 mM. Addition of carbachol (3 microM) potentiated the effects of both secretin and VIP on TH activity. Several gastrointestinal peptides with structural similarities to secretin and VIP were examined for their ability to increase TH activity. Glucagon, gastric inhibitory peptide and human pancreatic tumor growth hormone-releasing factor produced no effect at a concentration of 10 microM, while PHI increased enzyme activity.
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PMID:Acute stimulation of ganglionic tyrosine hydroxylase activity by secretin, VIP and PHI. 614 16

We studied the actions of substance P, bombesin, vasoactive intestinal peptide (VIP), and the octapeptide of cholecystokinin (CCK-8-S) on the release of somatostatin, insulin, and glucagon from the isolated perfused pancreatico-duodenal canine preparation. Substance P at concentrations ranging from 0.2-5.0 nM stimulated the secretion of somatostatin, insulin, and glucagon in a dose-dependent manner. However, the responses evoked by substance P were modified by the prevailing glucose level; higher somatostatin and insulin and lower glucagon responses were obtained at the high glucose concentration of 8.3 mM rather than at the low glucose concentration of 2.8 mM. At a glucose concentration of 5.5 mM, somatostatin release was above the prestimulation level in response to 1 nM substance P (89 +/- 15%; P less than 0.01), VIP (49 +/- 7%; P less than 0.01), or CCK-8-S (99 +/- 21%; P less than 0.01); bombesin was without effect (16 +/- 14; P = NS). Insulin release was enhanced by substance P (150 +/- 45%; P less than 0.05), bombesin (162 +/- 56%; P less than 0.05), VIP (44 +/- 5%; P less than 0.01), and CCK-8-S (190 +/- 17%; P less than 0.001). Furthermore, a significant release of glucagon was evoked by 1 nM substance P (501 +/- 158%; P less than 0.05), bombesin (30 +/- 10%; P less than 0.05), VIP (43 +/- 8%; P less than 0.01), or CCK-8-S (140 +/- 19%; P less than 0.001).
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PMID:Effects of substance P and other peptides on the release of somatostatin, insulin, and glucagon in vitro. 615 61

The use of protein A- and IgG-conjugated colloidal gold staining methods for the immuno-localisation of peptide hormones and neurotransmitters at light- and electron microscope level are described and discussed. Bright-field and dark-ground illumination modes have been used to visualise the gold-labelled antigenic sites at the light microscope level. Immunogold staining procedures at the ultrastructural level using region-specific antisera have been adopted to localise specific molecular forms of peptides including gastrin (G17 and G34), glucagon and pro-glucagon, insulin and pro-insulin, in normal tissue and in tumours of the gastroenteropancreatic system. Similar methods have been used to demonstrate the heterogeneity of p-type nerves in the enteric nervous system. Vasoactive intestinal polypeptide (VIP) has been localised to granular sites (mean +/- S.D. granule diameter = 98 +/- 19 nm) in nerve terminals of the enteric plexuses and in tumour cells of diarrhoeogenic VIP-producing neoplasias (mean +/- S.D. granule diameter = 126 +/- 37 nm) using immunogold procedures applied to ultraviolet-cured ultrathin sections. Co-localisation of amines and peptides in carotid body type I cells and in chromaffin cells of normal adrenal medulla and phaeochromocytomas has also been demonstrated. Advantages of the immunogold procedures over alternative immunocytochemical techniques are discussed.
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PMID:Immunogold staining procedure for the localisation of regulatory peptides. 618 90


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