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)

1. Pancreatic islets exposed to 11 mM glucose exhibited complex variations of cytoplasmic Ca2+ concentration ([Ca2+]i) with slow (0.3-0.9 min-1) or fast (2-7 min-1) oscillations or with a mixed pattern. 2. Using digital imaging and confocal microscopy we demonstrated that the mixed pattern with slow and superimposed fast oscillations was due to separate cell populations with the respective responses. 3. In islets with mixed [Ca2+]i oscillations, exposure to the sarcoplasmic-endoplasmic reticulum Ca2+-ATPase inhibitors thapsigargin or 2,5-di-tert-butylhydroquinone (DTBHQ) resulted in a selective disappearance of the fast pattern and amplification of the slow pattern. 4. In addition, the protein kinase A inhibitor RP-cyclic adenosine 3',5'-monophosphorothioate sodium salt transformed the mixed [Ca2+]i oscillations into slow oscillations with larger amplitude. 5. Islets exhibiting only slow oscillations reacted to low concentrations of glucagon with induction of the fast or the mixed pattern. In this case the fast oscillations were also counteracted by DTBHQ. 6. The spontaneously occurring fast oscillations seemed to require the presence of cAMP-elevating glucagon, since they were more common in large islets and suppressed during culture. 7. Image analysis revealed [Ca2+]i spikes occurring irregularly in time and space within an islet. These spikes were preferentially observed together with fast [Ca2+]i oscillations, and they became more common after exposure to glucagon. 8. Both the slow and fast oscillations of [Ca2+]i in pancreatic islets rely on periodic entry of Ca2+. However, the fast oscillations also depend in some way on paracrine factors promoting mobilization of Ca2+ from intracellular stores. It is proposed that such a mobilization in different cells within a tightly coupled islet syncytium generates spikes which co-ordinate the regular bursts of action potentials underlying the fast oscillations.
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PMID:Origin of slow and fast oscillations of Ca2+ in mouse pancreatic islets. 950 10

We have designed and synthesized eight compounds 2-9 which incorporate various amino acid residues in positions 17, 18, and 21 of the glucagon molecule: 2, [Lys17]glucagon amide; 3, [Lys18]glucagon amide; 4, [Nle17,Lys18,Glu21]glucagon amide; 5, [Orn17,18, Glu21]glucagon amide; 6, [d-Arg17]glucagon; 7, [d-Arg18]glucagon; 8, [d-Phe17]glucagon; and 9, [d-Phe18]glucagon. Compared to glucagon (IC50 = 1.5 nM), analogues 2-9 were found to have binding affinity IC50 values (in nM) of 0.7, 4.1, 1.0, 2.0, 5.0, 25.0, 43.0, and 32.0, respectively. When these compounds were tested for their ability to stimulate adenylate cyclase (AC) activity, they were found to be full or partial agonists having maximum stimulation values of 100, 100, 100, 100, 87, 78, 94, and 100%, respectively. On the basis of the X-ray crystal structure of [Lys17,18,Glu21]glucagon amide reported here, the ability to form a salt bridge between Lys18 and Glu21 is probably key to their increased binding and second messenger activities. Among the eight analogues synthesized here, only analogue 4 preserves the ability to form a salt bridge between Lys18 and Glu21. However, since these modifications are minor they do not seem to change the amphiphilic character of the C-terminus, allowing these analogues to reach 78-100% stimulation in the adenylate cyclase assay. Biological data from analogues 6-9 supports the idea that position 18 of glucagon may influence binding only, while position 17 may influence both receptor recognition and transduction.
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PMID:Structure-function studies on positions 17, 18, and 21 replacement analogues of glucagon: the importance of charged residues and salt bridges in glucagon biological activity. 966 60

Interactions between two classes of receptors have been observed in several cell lines and preparations. The aim of this work was to assess the impact of simultaneous stimulation of endothelial muscarinic and alpha2-adrenergic receptors (alpha2-AR) on vascular reactivity. Rabbit middle cerebral arteries were isolated and changes in isometric tension were recorded in the presence of indomethacin. Inhibition of nitric oxide (NO) synthase with Nomega-nitro-L-arginine (L-NOARG, 100 micromol l(-1)) revealed alpha-AR-dependent contractions. Pre-addition of acetylcholine (ACH, 1 micromol l(-1)) augmented oxymetazoline (OXY, 10 micromol l(-1), alpha2-AR agonist)-, but decreased phenylephrine (PE, 10 micromol(-1), alpha1-AR agonist)-induced contraction (P<0.05). The effects of ACH were endothelium-dependent. Vessels were precontracted with 40 mmol l(-1) KCl-physiological salt solution (PSS) in the absence of L-NOARG, or PE or OXY in the presence of L-NOARG. In the presence of high external K+ or PE, ACH induced a potent relaxation (P<0.05). In the presence of OXY, however, ACH mediated contraction (P<0.05). After pertussis toxin (PTX, inactivator of Galpha(i/o) proteins) pre-treatment, alpha2-AR-dependent contractions were abolished. Forty mmol l(-1) KCl-PSS induced contraction was not altered by PTX whereas ACH-induced relaxation was augmented (P<0.05). To investigate if endothelin-1 (ET-1) intervened in the endothelium-dependent contractile response to ACH in the presence of OXY-dependent tone, vessels were incubated in the presence of BQ123 (1 micromol l(-1)), an ETA receptor antagonist. OXY-mediated tone was not affected by BQ123; however, ACH-induced contraction was reversed to a relaxation (P<0.05). These data indicate that activation of endothelial alpha2-AR triggers an endothelium-dependent, ET-1 mediated, contraction to ACH. This suggests that activation of alpha2-AR affects muscarinic receptor/G protein coupling leading to an opposite biological effect.
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PMID:Functional cross-talk between endothelial muscarinic and alpha2-adrenergic receptors in rabbit cerebral arteries. 986 46

Peripheral administration of large doses of lithium chloride (LiCl) to rats causes a spectrum of effects that are consistent with visceral illness. LiCl reduces food intake, decreases salt ingestion after sodium depletion, induces pica, and produces robust conditioned taste aversions. Because some of the effects of peripheral LiCl are mimicked by centrally administered glucagon-like peptide-1 (7-36) amide (GLP-1), we hypothesized that this peptide is involved in the neural pathways by which LiCl causes visceral illness. To test this hypothesis, we pretreated rats with a selective and potent GLP-1 receptor antagonist given directly into the third ventricle via an indwelling cannula before administration of peripheral LiCl. The GLP-1 receptor antagonist completely blocked the effect of LiCl to reduce food intake, induce pica, and produce a conditioned taste aversion. The same dose of GLP-1 receptor antagonist did not reverse the LiCl-induced reduction in NaCl intake. The data indicate a role for GLP-1 receptors in the CNS pathway that mediates some of the effects of visceral illness.
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PMID:The role of CNS glucagon-like peptide-1 (7-36) amide receptors in mediating the visceral illness effects of lithium chloride. 1066 51

To elucidate the role of intermediate filament proteins in endocrine cells, we investigated the expression and subcellular distribution of GFAP in mouse islets of Langerhans. For this purpose, combined immunocytochemical and biochemical analysis with a panel of antibodies was carried out to identify GFAP-immunoreactive cells in mouse endocrine pancreas. Cell fractionation into NP-40-soluble and detergent/high salt-insoluble components was performed to assess whether GFAP was located in the cytosolic and/or cytoskeletal compartments of immunoreactive cells. Immunoelectron microscopic analysis was carried out to determine the subcellular distribution of the protein. Peripheral islet cells were stained with anti-GFAP antiserum. These cells were identified as glucagon-secreting cells by immunocytochemical staining of consecutive sections with anti-somatostatin, anti-GFAP, and anti-glucagon antisera. Western blotting analysis of both NP-40-soluble and detergent/high-salt insoluble fractions of isolated islets of Langerhans allowed detection of GFAP in both cytosolic and cytoskeletal compartments. Interestingly, however, the former location was highly predominant. In addition, immunoelectron microscopy localized GFAP associated with the periphery of secretory granules. On the basis of these results, an intriguing role for GFAP in secretory events should be strongly suspected.(J Histochem Cytochem 48:1233-1242, 2000)
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PMID:GFAP is expressed as a major soluble pool associated with glucagon secretory granules in A-cells of mouse pancreas. 1095 Aug 80

Effects of repeated daily intracerebroventricular injections of 1 microg of glucagon-like peptide-1 (7-36) amide (tGLP-1) on feeding and drinking behaviour, as well as neurohypophysial hormone secretion, was investigated in rats drinking tap water or 2% saline for 6 days. In euhydrated rats, tGLP-1 decreased moderately food and water consumption without a marked reduction of body weight. In salt-loaded rats, tGLP-1 considerably inhibited saline intake. On the other hand, food consumption and body weight changes were similar in vehicle- and tGLP-1-treated rats drinking 2% saline. Osmotic stimulation resulted in the augmented release of both neurohypophysial hormones. tGLP-1 did not alter plasma vasopressin and oxytocin concentrations either in euhydrated or osmotically stimulated rats. It is concluded that tGLP-1 may modify feeding and drinking behaviour under conditions of normal or disturbed water-electrolyte balance in the rat.
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PMID:Effects of tGLP-1 on feeding behaviour and neurohypophysial function under chronic osmotic stimulation. 1253 13

Injury and critical illness are characterised by hyperglycaemia, high free fatty acids and high net protein catabolism, due partly to suppression of insulin secretion in the shock phase and insulin resistance in the flow phase of injury, accompanied by high levels of cytokines and the catabolic hormones cortisol, glucagon and catecholamines. Pre-operative carbohydrate loading reduces post-operative insulin resistance and its consequences. Insulin has been shown to reduce the catabolic response as well as controlling hyperglycaemia. In contrast to its sodium retaining properties in normal, obese and diabetic subjects, insulin-glucose-potassium therapy may induce a sodium diuresis in catabolic patients with salt and water overload and in patients with congestive heart failure in whom haemodynamic improvement has also been observed. Diabetic patients with myocardial infarction and cardiac surgery also benefit from insulin treatment. Recent studies have described positive effects on clinical outcome in critical illness. Whether this is due simply to maintenance of euglycaemia or to the other effects of insulin remains to be determined.
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PMID:Insulin revisited. 1255 44

Glucagon-like peptide-1 (7-36) amide (tGLP-1) has been shown to modify the secretory function of the rat hypothalamo-neurohypophysial complex (HNC). However, mechanisms underlying this action are still unclear. Using explants containing the HNC obtained from euhydrated rats, possible interactions of tGLP-1 with angiotensin II (Ang II), forskolin-induced cAMP synthesis or calcium ions were investigated. In addition, explants taken from rats given 2% saline were used in order to examine whether chronic osmotic stimulation affects tGLP-1 action on vasopressin and oxytocin neurons. tGLP-1 did not modify Ang II- or forskolin-evoked hormone release. Incubation of the HNC in calcium-free medium inhibited the tGLP-1-dependent vasopressin/oxytocin secretion. Prolonged salt loading in vivo completely changed the neurohypophysial response to tGLP-1 in vitro; it did not only abolish the stimulatory effect of tGLP-1 on basal hormone release, but reduced K(+)-stimulated vasopressin/oxytocin secretion. Consequently, the neurohypophysial response to tGLP-1 may depend on the functional status of the HNC and on the presence of calcium ions, but not cAMP.
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PMID:Mechanisms involved in glucagon-like peptide-1 (7-36) amide action on the rat hypothalamo-neurohypophysial system. 1262 33

Glucagon, a 29-residue peptide hormone, plays an important role in glucose homeostasis and in diabetes mellitus. Several glucagon antagonists and agonists have been developed, but limited structural information is available to clarify the basis of their biological activity. The solution structure of the potent glucagon antagonist, [desHis1, desPhe6, Glu9]glucagon amide, was determined by homonuclear 2D NMR spectroscopy at pH 6.0 and 37 degrees C in perdeuterated dodecylphosphocholine micelles. The overall backbone root-mean-square deviation (rmsd) for the structured portion (residues 7-29, glucagon numbering) of the micelle-bound 27-residue peptide is 1.36 A for the 15 lowest-energy structures, after restrained molecular dynamics simulation. The structure consists of four regions (segment backbone rmsd in A): an unstructured N-terminal segment between residues 2 and 5 (1.68), an irregular helix between residues 7 and 14 (0.79), a hinge region between residues 15 and 18 (0.54), and a well-defined alpha-helix between residues 19 and 29 (0.33). The two helices form an L-shaped structure with an angle of about 90 degrees between the helix axes. There is an extended hydrophobic cluster, which runs along the inner surface of the L-structure and incorporates the side chains of the hydrophobic residues of each of the amphipathic helices. The outer surface contains the hydrophilic side chains, with two salt bridges (D15-R18 and R17-D21) implied from close approach of the charged groups. This result is the first clear indication of an overall tertiary fold for a glucagon analogue in the micelle-bound state. The relationship of the two helical structural elements may have important implications for the biological activity of the glucagon antagonist.
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PMID:NMR solution structure of the glucagon antagonist [desHis1, desPhe6, Glu9]glucagon amide in the presence of perdeuterated dodecylphosphocholine micelles. 1262 48

Gateways to Clinical Trials is a guide to the most recent clinical trials in current literature and congresses. The data in the following tables has been retrieved from the Clinical Studies Knowledge Area of Prous Science Integrity(R), the drug discovery and development portal, http://integrity.prous.com. This issue focuses on the following selection of drugs: ABI-007, adalimumab, adefovir dipivoxil, alefacept, alemtuzumab, 3-AP, AP-12009, APC-8015, L-Arginine hydrochloride, aripiprazole, arundic acid, avasimibe; Bevacizumab, bivatuzumab, BMS-181176, BMS-184476, BMS-188797, bortezomib, bosentan, botulinum toxin type B, BQ-123, BRL-55730, bryostatin 1; CEP-1347, cetuximab, cinacalcet hydrochloride, CP-461, CpG-7909; D-003, dabuzalgron hydrochloride, darbepoetin alfa, desloratadine, desoxyepothilone B, dexmethylphenidate hydrochloride, DHA-paclitaxel, diflomotecan, DN-101, DP-b99, drotrecogin alfa (activated), duloxetine hydrochloride, duramycin; Eculizumab, Efalizumab, EKB-569, elcometrine, enfuvirtide, eplerenone, erlotinib hydrochloride, ertapenem sodium, eszopiclone, everolimus, exatecan mesilate, ezetimibe; Fenretinide, fosamprenavir calcium, frovatriptan; GD2L-KLH conjugate vaccine, gefitinib, glufosfamide, GTI-2040; Hexyl insulin M2, human insulin, hydroquinone, gamma-Hydroxybutyrate sodium; IL-4(38-37)-PE38KDEL, imatinib mesylate, indisulam, inhaled insulin, ixabepilone; KRN-5500; LY-544344; MDX-210, melatonin, mepolizumab, motexafin gadolinium; Natalizumab, NSC-330507, NSC-683864; 1-Octanol, omalizumab, ortataxel; Pagoclone, peginterferon alfa-2a, peginterferon alfa-2b, pemetrexed disodium, phenoxodiol, pimecrolimus, plevitrexed, polyphenon E, pramlintide acetate, prasterone, pregabalin, PX-12; QS-21; Ragaglitazar, ranelic acid distrontium salt, RDP-58, recombinant glucagon-like peptide-1 (7-36) amide, repinotan hydrochloride, rhEndostatin, rh-Lactoferrin, (R)-roscovitine; S-8184, semaxanib, sitafloxacin hydrate, sitaxsentan sodium, sorafenib, synthadotin; Tadalafil, tesmilifene hydrochloride, theratope, tipifarnib, tirapazamine, topixantrone hydrochloride, trabectedin, traxoprodil, Tri-Luma; Valdecoxib, valganciclovir hydrochloride, vinflunine; Ximelagatran; Ziconotide.
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PMID:Gateways to clinical trials. 1514 27


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