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PubMed2004

[Analogs of glucagon-like peptide-1 (GLP-1): an old concept as a new treatment of patients with diabetes mellitus type 2].

Upon ingestion of food, the incretin hormones glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) are synthesised and secreted by specialised gut cells. GLP-1 is also produced in the pancreatic islets and the central nervous system. Both incretins bind to specific G-protein-coupled receptors that are distributed throughout the body. Incretins potentiate meal-induced insulin production and secretion by the beta-cells and lower the blood glucose level in the presence of hyperglycaemia. GLP-1 and GIP stimulate beta-cell proliferation and differentiation, whereas GLP-1 only inhibits gastric emptying and glucagon secretion, reduces food intake and improves insulin sensitivity. Insulin-resistant and type-2 diabetic patients have an impaired incretin response to meal ingestion. However, the insulinotropic action of exogenous GLP-1, but not that of GIP, is preserved in these subjects. After parenteral administration, GLP-1 has an extremely short duration of action because it is rapidly degraded by the ubiquitous enzyme dipeptidyl peptidase IV (DPPIV). To prolong GLP-1 bioactivity, DPPIV-resistant GLP-1 analogues, DPPIV inhibitors and exenatide, a long-acting synthetic GLP-1 receptor agonist derived from the Gila monster hormone exendin-4, have been developed. Enhancement of incretin action seems a rational and promising option for the treatment of type-2 diabetes.

Diabetes Mellitus, Type 2↗
PubMed2004

Gateways to clinical trials.

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 Trials Knowledge Area of Prous Science Integrity, the drug discovery and development portal, http://integrity.prous.com. This issue focuses on the following selection of drugs: Abiraterone acetate, Ad5CMV-p53, adefovir dipivoxil, AE-941, ambrisentan, aripiprazole, atomoxetine hydrochloride, atrasentan; BCH-10618, bimatoprost, BMS-184476, BMS-275183, BMS-387032, botulinum toxin type B, BR-1, BR96-Doxorubicin; Capravirine, caspofungin acetate, cinacalcet hydrochloride; Darbepoetin alfa, desloratadine, dextrin sulfate, DJ-927, duloxetine hydrochloride; Elacridar, emtricitabine, eplerenone, ertapenem sodium, escitalopram oxalate, ESP-24217, etoricoxib, exenatide, ezetimibe; Ferumoxtran-10, fondaparinux sodium, fosamprenavir calcium; GS-7904L, GW-5634; HMN-214, human insulin; IC-14, imatinib mesylate, indiplon, insulin glargine, insulinotropin, iseganan hydrochloride; Lanthanum carbonate, L-Arginine hydrochloride, LEA29Y, lenalidomide, LE-SN38, lestaurtinib, L-MDAM, lometrexol, lopinavir, lopinavir/ritonavir; Magnesium sulfate, maraviroc, mepolizumab, metreleptin, milataxel, MNA-715, morphine hydrochloride; Nesiritide, neutrophil-inhibitory factor, NK-911; Olanzapine/fluoxetine hydrochloride, olmesartan medoxomil, omalizumab, ortataxel, oxycodone hydrochloride/ibuprofen; Panitumumab, patupilone, PC-515, PD-MAGE-3 Vaccine, peginterferon alfa-2a, peginterferon alfa-2b, peginterferon alfa-2b/ ribavirin, pemetrexed disodium, pimecrolimus, prasugrel, pregabalin, PRO-2000; Rosuvastatin calcium, RPR-113090; sabarubicin hydrochloride, safinamide mesilate, SB-715992, sitaxsentan sodium, soblidotin, synthadotin; Tadalafil, taltobulin, temsirolimus, tenofovir disoproxil fumarate, tenofovir disoproxil fumarate/emtricitabine, testosterone gel, tigecycline, tipranavir, tirapazamine, trabectedin, travoprost; UCN-01; Vardenafil hydrochloride hydrate; XB-947; Yttrium 90 (90Y) ibritumomab tiuxetan.

Clinical Trials as Topic↗
PubMed2004

Gateways to clinical trials.

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 Trials 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: (PE)HRG214, 1E10, 21-Aminoepothilone B; Ad.Egr.TNF.11D, Ad100-B7.1/HLA, adalimumab, adefovir dipivoxil, alefacept, alemtuzumab, AMD-070, anhydrovinblastine, aripiprazole, asimadoline, atrasentan, AVE-5883; Bimatoprost, BNP-7787, bosentan, botulinum toxin type B, BR-1; Canfosfamide hydrochloride, ciclesonide, curcumin, cypher; D0401, darbepoetin alfa, darifenacin hydrobromide, D-D4FC, dendritic cell-based vaccine, desloratadine, dextrin sulfate, dolastatin 10, drospirenone drospirenone/estradiol, DS-992, duloxetine hydrochloride, dutasteride; E-7010, efalizumab, eletriptan, EM-1421, enfuvirtide, entecavir, etoricoxib, everolimus, exenatide, ezetimibe; Favid, fidarestat, fingolimod hydrochloride, FK-352; Gefitinib, gemifloxacin mesilate, gepirone hydrochloride, gimatecan; HE-2000; Imatinib mesylate, indisulam, insulin detemir, irofulven, ISIS-5132; Lapatinib, levocetirizine, liraglutide, lumiracoxib; Metformin/Glyburide, methionine enkephalin, MK-0431, morphine hydrochloride, motexafin gadolinium, mycobacterium cell wall complex; Naturasone, neridronic acid, nesiritide; Oblimersen sodium, olanzapine/fluoxetine hydrochloride, omalizumab, oral insulin; Paclitaxel poliglumex, PC-515, PEG-filgrastim, peginterferon alfa-2a, peginterferon alfa-2b, peginterferon alfa-2b/ ribavirin, pegvisomant, pexelizumab, picoplatin, pramlintide acetate, prasterone, pregabalin; Quercetin; Ramelteon, ranirestat, RG228, rhGAD65, roflumilast, rubitecan; Sitaxsentan sodium, solifenacin succinate; Tadalafil, taxus, tipifarnib, tolevamer sodium, topixantrone hydrochloride; Valganciclovir hydrochloride, vardenafil hydrochloride hydrate, vildagliptin, voriconazole; XTL-001; Zoledronic acid monohydrate.

Databases, Factual↗
PubMedDate not supplied

[New strategy in type 2 diabetes tested in clinical trials. Glucagon-like peptide 1 (GLP-1) affects basic caused of the disease].

A novel therapy for type 2 diabetes is based on the gut hormone, glucagon-like peptide-1 (GLP-1). GLP-1 is released from the gut during a meal intake and stimulates insulin secretion. The hormone also inhibits glucagon secretion, delays gastric emptying and induces satiety. It has been shown to reduce circulating glucose both under fasting conditions and after meal intake in subjects with type 2 diabetes. A problem in developing this novel therapy is that GLP-1 is rapidly inactivated by the enzyme dipeptidyl peptidase-4 (DPP-4), which results in a short half-life of the hormone requiring continuous infusion. Two strategies have been developed to circumvent this drawback. One strategy is the use of DPP-4 resistant GLP-1 receptor agonists (exenatide and liraglutide) and another strategy is to inhibit DPP-4 activity (LAF237). Both these strategies have been successful in clinical studies.

Animals↗
PubMed2005

Gateways to clinical trials.

Gateways to Clinical Trials is a guide to the most recent clinical trials in current literature and congresses. The data in the following tables have been retrieved from the Clinical Trials Knowledge Area of Prous Science Integrity, the drug discovery and development portal, http://integrity.prous.com. This issue focuses on the following selection of drugs: Abiraterone acetate, acyline, adalimumab, adenosine triphosphate, AEE-788, AIDSVAX gp120 B/B, AK-602, alefacept, alemtuzumab, alendronic acid sodium salt, alicaforsen sodium, alprazolam, amdoxovir, AMG-162, aminolevulinic acid hydrochloride, aminolevulinic acid methyl ester, aminophylline hydrate, anakinra, anecortave acetate, anti-CTLA-4 MAb, APC-8015, aripiprazole, aspirin, atazanavir sulfate, atomoxetine hydrochloride, atorvastatin calcium, atrasentan, AVE-5883, AZD-2171; Betamethasone dipropionate, bevacizumab, bimatoprost, biphasic human insulin (prb), bortezomib, BR-A-657, BRL-55730, budesonide, busulfan; Calcipotriol, calcipotriol/betamethasone dipropionate, calcium folinate, capecitabine, capravirine, carmustine, caspofungin acetate, cefdinir, certolizumab pegol, CG-53135, chlorambucil, ciclesonide, ciclosporin, cisplatin, clofarabine, clopidogrel hydrogensulfate, clozapine, co-trimoxazole, CP-122721, creatine, CY-2301, cyclophosphamide, cypher, cytarabine, cytolin; D0401, darbepoetin alfa, darifenacin hydrobromide, DASB, desipramine hydrochloride, desloratadine, desvenlafaxine succinate, dexamethasone, didanosine, diquafosol tetrasodium, docetaxel, doxorubicin hydrochloride, drotrecogin alfa (activated), duloxetine hydrochloride, dutasteride; Ecallantide, efalizumab, efavirenz, eletriptan, emtricitabine, enfuvirtide, enoxaparin sodium, estramustine phosphate sodium, etanercept, ethinylestradiol, etonogestrel, etonogestrel/ethinylestradiol, etoposide, exenatide; Famciclovir, fampridine, febuxostat, filgrastim, fludarabine phosphate, fluocinolone acetonide, fluorouracil, fluticasone propionate, fluvastatin sodium, fondaparinux sodium; Gaboxadol, gamma-hydroxybutyrate sodium, gefitinib, gelclair, gemcitabine, gemfibrozil, glibenclamide, glyminox; Haloperidol, heparin sodium, HPV 16/HPV 18 vaccine, human insulin, human insulin; Icatibant, imatinib mesylate, indium 111 (111In) ibritumomab tiuxetan, infliximab, INKP-100, iodine (I131) tositumomab, IoGen, ipratropium bromide, ixabepilone; L-870810, lamivudine, lapatinib, laquinimod, latanoprost, levonorgestrel, licochalcone a, liposomal doxorubicin, lopinavir, lopinavir/ritonavir, lorazepam, lovastatin; Maraviroc, maribavir, matuzumab, MDL-100907, melphalan, methotrexate, methylprednisolone, mitomycin, mitoxantrone hydrochloride, MK-0431, MN-001, MRKAd5 HIV-1 gag/pol/nef, MRKAd5gag, MVA.HIVA, MVA-BN Nef, MVA-Muc1-IL-2, mycophenolate mofetil; Nelfinavir mesilate, nesiritide, NSC-330507; Olanzapine, olmesartan medoxomil, omalizumab, oral insulin, osanetant; PA-457, paclitaxel, paroxetine, paroxetine hydrochloride, PCK-3145, PEG-filgrastim, peginterferon alfa-2a, peginterferon alfa-2b, perillyl alcohol, pexelizumab, pimecrolimus, pitavastatin calcium, porfiromycin, prasterone, prasugrel, pravastatin sodium, prednisone, pregabalin, prinomastat, PRO-2000, propofol, prostate cancer vaccine; Rasagiline mesilate, rhBMP-2/ACS, rhBMP-2/BCP, rhC1, ribavirin, rilpivirine, ritonavir, rituximab, Ro-26-9228, rosuvastatin calcium, rosuvastatin sodium, rubitecan; Selodenoson, simvastatin, sirolimus, sitaxsentan sodium, sorafenib, SS(dsFv)-PE38, St. John's Wort extract, stavudine; Tacrolimus, tadalafil, tafenoquine succinate, talaglumetad, tanomastat, taxus, tegaserod maleate, telithromycin, tempol, tenofovir, tenofovir disoproxil fumarate, testosterone enanthate, TH-9507, thalidomide, tigecycline, timolol maleate, tiotropium bromide, tipifarnib, torcetrapib, trabectedin, travoprost, travoprost/timolol, treprostinil sodium; Valdecoxib, vardenafil hydrochloride hydrate, varenicline, VEGF-2 gene therapy, venlafaxine hydrochloride, vildagliptin, vincristine sulfate, voriconazole, VRX-496, VX-385; Warfarin sodium; Ximelagatran; Yttrium 90 (90Y) ibritumomab tiuxetan; Zanolimumab, zidovudine.

Clinical Trials as Topic↗
PubMed2005

Gateways to clinical trials.

Gateways to Clinical Trials is a guide to the most recent clinical trials in current literature and congresses. The data in the following tables have been retrieved from the Clinical Trials Knowledge Area of Prous Science Integrity, the drug discovery and development portal, http://integrity.prous.com. This issue focuses on the following selection of drugs: 3-AP, Adalimumab, adefovir dipivoxil, AeroDose albuterol inhaler, agalsidase alfa, alemtuzumab, aminolevulinic acid methyl ester, anidulafungin, anthrax vaccine, anti-CTLA-4 MAb, azimilide hydrochloride; Bevacizumab, BG-12, bimatoprost, bortezomib, bosentan, botulinum toxin type B; Caspofungin acetate, ceftobiprole, certolizumab pegol, CG-53135, cilansetron; Darbepoetin alfa, degarelix acetate, dimethylfumarate, duloxetine hydrochloride, dutasteride; Eicosapentaenoic acid/docosahexaenoic acid, eletriptan, entecavir, esomeprazole magnesium, exatecan mesilate, exenatide, ezetimibe; Falecalcitriol, fampridine, fondaparinux sodium, fontolizumab; Gefitinib, gepirone hydrochloride; Human insulin; IDEA-070, imatinib mesylate, iodine (I131) tositumomab; Lanthanum carbonate, lubiprostone; Mafosfamide cyclohexylamine salt, melatonin; NC-531, nemifitide ditriflutate, neridronic acid, nolatrexed dihydrochloride; Oral insulin; Palifermin, parecoxib sodium, PEG-filgrastim, peginterferon alfa-2a, peginterferon alfa-2b, plerixafor hydrochloride, posaconazole, pramlintide acetate, pregabalin, PT-141; Quercetin; Ranibizumab, renzapride hydrochloride, RSD-1235; Sabarubicin hydrochloride, semapimod hydrochloride, Semax, SHL-749; Tegaserod maleate, tenatoprazole, tetrodotoxin, tolevamer sodium, trabectedin, travoprost, travoprost/timolol; Valdecoxib, visilizumab, Xcellerated T cells, XP-828L; Zoledronic acid monohydrate.

Clinical Trials as Topic↗
PubMedDate not supplied

Gateways to clinical trials.

Gateways to Clinical Trials are a guide to the most recent clinical trials in current literature and congresses. The data in the following tables have been retrieved from the Clinical Trials Knowledge Area of Prous Science Integrity, the drug discovery and development portal, http://integrity.prous.com. This issue focuses on the following selection of drugs: (-)-Epigallocatechin gallate; ACP-103, Ad.Egr.TNF.11 D, adalimumab, AF-IL 12, AIDSVAX gp120 B/B, alefacept, alemtuzumab, a-Galactosylceramide, ALVAC vCP 1452, alvimopan hydrate, alvocidib hydrochloride, aminolevulinic acid hydrochloride, aminolevulinic acid methyl ester, anakinra, anidulafungin, antarelix, aprepitant, aripiprazole, arsenic sulfide, asoprisnil, atazanavir sulfate, atomoxetine hydrochloride; Bevacizumab, bimatoprost, BMS-184476, bortezomib, bosentan, botulinum toxin type B, BrachySil, brivudine; Caffeine, calcipotriol/betamethasone dipropionate, cannabidiol, capsaicin for injection, caspofungin acetate, CC-4047, cetuximab, CGP-36742, clofazimine, CpG-7909, Cypher; Darbepoetin alfa, dextromethorphan/quinidine sulfate, dimethylfumarate, dronabinol/cannabidiol, drotrecogin alfa (activated), duloxetine hydrochloride, dutasteride; Ecogramostim, efalizumab, eletriptan, emtricitabine, enfuvirtide, eplerenone, esomeprazole magnesium, estradiol acetate, eszopiclone, etoricoxib, exenatide, ezetimibe, ezetimibe/simvastatin; Fampridine, fondaparinux sodium, fosamprenavir calcium; Gefitinib, GPI-0100; hA 20, HTU-PA, human insulin, HuOKT 3 gamma 1(Ala 234-Ala 235), hyaluronic acid; Icatibant, imatinib mesylate, Indiplon, INKP-100, INKP-102, iodine (I131) tositumomab, istradefylline, IV gamma-globulin, ivabradine hydrochloride, ixabepilone; Lacosamide, landiolol, lanthanum carbonate, lasofoxifene tartrate, LB-80380, lenalidomide, lidocaine/tetracaine, linezolid, liposomal doxorubicin, liposomal vincristine sulfate, lopinavir, lopinavir/ritonavir, lumiracoxib, lurtotecan; Maribavir, morphine glucuronide, MVA-5 T 4; NBI-56418, NCX-4016, nesiritide, nicotine conjugate vaccine, NSC-330507; Oglufanide, omalizumab, oxipurinol; Palifermin, palonosetron hydrochloride, parecoxib sodium, PEG-filgrastim, peginterferon alfa-2a, peginterferon alfa-2b, peginterferon alfa-2b/ribavirin, PEGylated interferon alfacon-1, perospirone hydrochloride, pimecrolimus, pixantrone maleate, plerixafor hydrochloride, PowderJect lidocaine, pradefovir mesylate, prasterone, pregabalin, Prostvac VF, PT-141, PTC-124, pyridoxamine; QS-21, quercetin; R-126638, R-411, ralfinamide, rasagiline mesilate, rF-PSA, RG-2077, rhThrombin, rimonabant hydrochloride, rofecoxib, rosuvastatin calcium, rotigotine hydrochloride, rV-PSA; S-18886, S-303, seocalcitol, SGN-40, sitaxsentan sodium, SPP-301, St. John's Wort extract; Tadalafil, taxus, telithromycin, tenatoprazole, tenofovir disoproxil fumarate, testosterone MDTS, testosterone transdermal patch, tgAAC-09, TH-9507, thioacetazone, tipifarnib, TQ-1011, trabectedin, travoprost, trimethoprim; Valdecoxib, valganciclovir hydrochloride, valopicitabine, voriconazole; Xcellerated T cells.

Clinical Trials as Topic↗
PubMed2005

Gateways to clinical trials.

Gateways to Clinical Trials are a guide to the most recent clinical trials in current literature and congresses. The data in the following tables have been retrieved from the Clinical Trials Knowledge Area of Prous Science Integrity, the drug discovery and development portal, http://integrity. prous.com. This issue focuses on the following selection of drugs: 131I-chTNT; Abatacept, adalimumab, alemtuzumab, APC-8015, aprepitant, atazanavir sulfate, atomoxetine hydrochloride, azimilide hydrochloride; Bevacizumab, bortezomib, bosentan, buserelin; Caspofungin acetate, CC-4047, ChAGCD3, ciclesonide, clopidogrel, curcumin, Cypher; Dabigatran etexilate, dapoxetine hydrochloride, darbepoetin alfa, darusentan, denosumab, DMXB-Anabaseine, drospirenone, drospirenone/estradiol, duloxetine hydrochloride, dutasteride; Edodekin alfa, efaproxiral sodium, elaidic acid-cytarabine, erlotinib hydrochloride, ertapenem sodium, escitalopram oxalate, eszopiclone, etonogestrel/testosterone decanoate, exenatide; Fulvestrant; Gefitinib, glycine, GVS-111; Homoharringtonine; ICC-1132, imatinib mesylate, iodine (I131) tositumomab, i.v. gamma-globulin; Levetiracetam, levocetirizine, lintuzumab, liposomal nystatin, lumiracoxib, lurtotecan; Manitimus, mapatumumab, melatonin, micafungin sodium, mycophenolic acid sodium salt; Oblimersen sodium, OGX-011, olmesartan medoxomil, omalizumab, omapatrilat, oral insulin; Parathyroid hormone (human recombinant), pasireotide, peginterferon alfa-2a, peginterferon alfa-2b, peginterferon alfa-2b/ribavirin, phVEGF-A165, pimecrolimus, pitavastatin calcium, plerixafor hydrochloride, posaconazole, pramlintide acetate, prasterone, pregabalin, PT-141; Quercetin; Ranolazine, rosuvastatin calcium, rubitecan, rupatadine fumarate; Sardomozide, sunitinib malate; Tadalafil, talactoferrin alfa, tegaserod maleate, telithromycin, testosterone transdermal patch, TH-9507, tigecycline, tiotropium bromide, tipifarnib, tocilizumab, treprostinil sodium; Valdecoxib, vandetanib, vardenafil hydrochloride hydrate, voriconazole.

Clinical Trials as Topic↗
PubMed2006

Gateways to clinical trials.

Gateways to Clinical Trials are a guide to the most recent clinical trials in current literature and congresses. The data in the following tables have been retrieved from the Clinical Trials Knowledge Area of Prous Science Integrity, the drug discovery and development portal, http://integrity.prous.com This issue focuses on the following selection of drugs: A-007, A6, adalimumab, adenosine triphosphate, alefacept, alemtuzumab, AllerVax Ragweed, amphora, anakinra, angiotensin-(1-7), anidulafungin, apomine, aripiprazole, atomoxetine hydrochloride, avanafil; BAL-8557, becatecarin, bevacizumab, biphasic insulin aspart, BMS-188797, bortezomib, bosentan, botulinum toxin type B, brivudine; Calcipotriol/betamethasone dipropionate, caspofungin acetate, catumaxomab, certolizumab pegol, cetuximab, CG-0070, ciclesonide, cinacalcet hydrochloride, clindamycin phosphate/benzoyl peroxide, cryptophycin 52, Cypher; Dabigatran etexilate, darapladib, darbepoetin alfa, decitabine, deferasirox, desloratadine, dexanabinol, dextromethorphan/quinidine sulfate, DMF, drotrecogin alfa (activated), duloxetine hydrochloride; E-7010, edaravone, efalizumab, emtricitabine, entecavir, eplerenone, erlotinib hydrochloride, escitalopram oxalate, estradiol valerate/dienogest, eszopiclone, exenatide, ezetimibe; Fondaparinux sodium, fulvestrant; Gefitinib, gestodene, GYKI-16084; Hyaluronic acid, hydralazine hydrochloride/isosorbide dinitrate; Imatinib mesylate, indiplon, insulin glargine; Juzen-taiho-to; Lamivudine/zidovudine/abacavir sulfate, L-arginine hydrochloride, lasofoxifene tartrate, L-BLP-25, lenalidomide, levocetirizine, levodopa/carbidopa/entacapone, lexatumumab, lidocaine/prilocaine, lubiprostone, lumiracoxib; MAb-14.18, mitoquidone; Natalizumab, neridronic acid, neuradiab; Olpadronic acid sodium salt, omalizumab; p53-DC vaccine, parathyroid hormone (human recombinant), peginterferon alfa-2a, peginterferon alfa-2b, pemetrexed disodium, perifosine, pimecrolimus, prasterone, prasugrel, PRO-2000, Pseudostat; R24, rasburicase, RHAMM R3 peptide, rilonacept, rosuvastatin calcium, rotavirus vaccine, rufinamide; Sabarubicin hydrochloride, SHL-749, sirolimus-eluting stent, SLx-2101, sodium butyrate, sorafenib, SU-6668; TachoSil, tadalafil, taxus, tegaserod maleate, telbivudine, tenofovir disoproxil fumarate, teriparatide, tetramethylpyrazine, teverelix, tiotropium bromide, tipifarnib, tirapazamine, tolvaptan, TransvaxTM hepatitis C vaccine, treprostinil sodium; Valganciclovir hydrochloride, valsartan/amlodipine, vandetanib, vardenafil hydrochloride hydrate, vatalanib succinate, veglin, voriconazole; Yttrium 90 (90Y) ibritumomab tiuxetan; Zileuton, zotarolimus, zotarolimus-eluting stent.

Clinical Trials as Topic↗
PubMed1997

Novel signal transduction and peptide specificity of glucagon-like peptide receptor in 3T3-L1 adipocytes.

Glucagon-like peptide-1 (7-36) amide (GLP-1), in addition to its well known effect of enhancing glucose-mediated insulin release, has been shown to have insulinomimetic effects and to enhance insulin-mediated glucose uptake and lipid synthesis in 3T3-L1 adipocytes. To elucidate the mechanisms of GLP-1 action in these cells, we studied the signal transduction and peptide specificity of the GLP-1 response. In 3T3-L1 adipocytes, GLP-1 caused a decrease in intracellular cAMP levels which is the opposite to the response observed in pancreatic beta cells in response to the same peptide. In 3T3-L1 adipocytes, free intracellular calcium was not modified by GLP-1. Peptide specificity was examined to help determine if a different GLP receptor isoform was expressed in 3T3-L1 adipocytes vs. beta cells. Peptides with partial homology to GLP-1 such as GLP-2, GLP-1 (1-36), and glucagon all lowered cAMP levels in 3T3-L1 adipocytes. In addition, an antagonist of pancreatic GLP-1 receptor, exendin-4 (9-39), acted as an agonist to decrease cAMP levels in 3T3-L1 adipocytes as did exendin-4 (1-39), a known agonist for the pancreatic GLP-1 receptor. Binding studies using 125I-GLP-1 also suggest that pancreatic GLP-1 receptor isoform is not responsible for the effect of GLP-1 and related peptides in 3T3-L1 adipocytes. Based on these results, we propose that the major form of the GLP receptor in 3T3-L1 adipocytes is functionally different from the pancreatic GLP-1 receptor.

3T3 Cells↗
PubMed2002

Peptide conformational changes induced by tryptophan-phosphocholine interactions in a micelle.

Sodium dodecylsulfate (SDS) and dodecylphosphocholine (DPC) micelles are often used to mimic the membrane- or receptor-bound states of peptides in NMR studies. From the present examination of a 26-residue analog of exendin-4 (TrEX4) by NMR and CD in water, aqueous 30% trifluoroethanol (TFE), and bound to both SDS and DPC micelles, it is clear that these two lipid micelles can yield very different peptide structures. The Trp-cage fold (also observed in 30% TFE) is present when TrEX4 is bound to SDS micelles; however, tertiary structure is absent in the presence of DPC micelles. The loss of tertiary structure is attributed to an energetically favorable interaction (estimated as 2-3 kcal/mol) of the tryptophan side chain with the phosphocholine head groups. These dramatic structural differences suggest that care must be taken when using either SDS or DPC to mimic the membrane- or receptor-bound states.

Amino Acid Sequence↗
PubMed2006

Exendin-4, a glucagon-like protein-1 (GLP-1) receptor agonist, reverses hepatic steatosis in ob/ob mice.

Nonalcoholic fatty liver disease (NAFLD) represents a burgeoning problem in hepatology, and is associated with insulin resistance. Exendin-4 is a peptide agonist of the glucagon-like peptide (GLP) receptor that promotes insulin secretion. The aim of this study was to determine whether administration of Exendin-4 would reverse hepatic steatosis in ob/ob mice. Ob/ob mice, or their lean littermates, were treated with Exendin-4 [10 microg/kg or 20 microg/kg] for 60 days. Serum was collected for measurement of insulin, adiponectin, fasting glucose, lipids, and aminotransferase concentrations. Liver tissue was procured for histological examination, real-time RT-PCR analysis and assay for oxidative stress. Rat hepatocytes were isolated and treated with GLP-1. Ob/ob mice sustained a reduction in the net weight gained during Exendin-4 treatment. Serum glucose and hepatic steatosis was significantly reduced in Exendin-4 treated ob/ob mice. Exendin-4 improved insulin sensitivity in ob/ob mice, as calculated by the homeostasis model assessment. The measurement of thiobarbituric reactive substances as a marker of oxidative stress was significantly reduced in ob/ob-treated mice with Exendin-4. Finally, GLP-1-treated hepatocytes resulted in a significant increase in cAMP production as well as reduction in mRNA expression of stearoyl-CoA desaturase 1 and genes associated with fatty acid synthesis; the converse was true for genes associated with fatty acid oxidation. In conclusion, Exendin-4 appears to effectively reverse hepatic steatosis in ob/ob mice by improving insulin sensitivity. Our data suggest that GLP-1 proteins in liver have a novel direct effect on hepatocyte fat metabolism.

Adipose Tissue↗
PubMed2002

Exendin-4 differentiation of a human pancreatic duct cell line into endocrine cells: involvement of PDX-1 and HNF3beta transcription factors.

Exendin-4 (EX-4), a long acting agonist of GLP-1, induces an endocrine phenotype in Capan-1 cells. Under culture conditions which include serum, approximately 10% of the cells contain insulin and glucagon. When exposed to EX-4 (0.1 nM, up to 5 days), the number of cells containing insulin and glucagon increased to approximately 40%. Western blot analysis detected a progressive increase in protein levels of glucokinase and GLUT2 over 3 days of EX-4 treatment. We explored the sequence of activation of certain transcription factors known to be essential for the beta cell phenotype: PDX-1, Beta2/NeuroD, and hepatocyte nuclear factor 3beta (HNF3beta). Double immunostaining showed that PDX-1 coexisted with insulin and glucagon in EX-4-treated cells. Treatment caused an increase in PDX-1 protein levels by 24 h and induced its nuclear translocation. Beta2/NeuroD protein levels also increased progressively over 24 h. HNF3beta protein level increased twofold as early as 6 h after EX-4 treatment. EMSA results indicated that EX-4 caused a 12-fold increase in HNF3beta binding to PDX-1 promoter area II. Beta2/NeuroD protein levels progressively increased after 24 h treatment. Differentiation to insulin-producing cells was also seen when Capan-1 cells were transfected with pdx-1, with 80% of these cells expressing insulin 3 days after transfection. PDX-1 antisense totally inhibited such conversion. During the differentiation of duct cells to endocrine cells, cAMP levels (EX-4 is a ligand for the GLP-1, G-protein coupled receptor) and MAP kinase activity increased. Our results indicate that EX-4 activates adenylyl cyclase and MAP kinase which, in turn, may lead to activation of transcription factors necessary for an endocrine phenotype.

Cell Differentiation↗
PubMed2006

Major contributions of comparative endocrinology to the development and exploitation of the incretin concept.

An incretin is a factor released by the gut in response to nutrients that facilitates uptake of glucose by peripheral tissues. The incretin concept predates the discovery of insulin but it is now clear that incretins act by stimulating secretion of this hormone. As glucagon has insulin-releasing activity, it was speculated that intestinal glucagon-like immunoreactivity (enteroglucagon) was involved in the incretin effect but it was an achievement in the field of comparative endocrinology that led to the demonstration that the preproglucagon gene encodes the most potent incretin in the human. Characterization of cloned cDNAs encoding two preproglucagons from the Brockmann body of the anglerfish Lophius americanus demonstrated that the glucagon sequence is flanked by a 34 amino-acid-residue sequence with appreciable structural similarity to glucagon that was termed glucagon-like peptide (GLP). A 36 amino-acid-residue ortholog of anglerfish GLP was subsequently identified in human preproglucagon but this peptide had only weak insulin-releasing activity. However, alignment of GLP sequences from human and teleost fish showed that the human ortholog is extended from its N-terminus by a hexapeptide. Removal of this extension by an endogenous protease generates GLP-1-(7-36)amide, the potent and effective form of the incretin. More recently, comparative endocrinology has contributed to the exploitation of incretins as antidiabetic drugs. Exendin-4, a GLP-1 receptor agonist first isolated from the venom of the Gila monster Heloderma suspectum, is a clinically valuable, long-acting incretin and the skins of several species of frogs synthesize potent insulin-releasing peptides with therapeutic potential.

Amino Acid Sequence↗
PubMed2003

Glucagon-like peptide-1 decreases endogenous amyloid-beta peptide (Abeta) levels and protects hippocampal neurons from death induced by Abeta and iron.

Glucagon-like peptide-1(7-36)-amide (GLP-1) is an endogenous insulinotropic peptide that is secreted from the gastrointestinal tract in response to food. It enhances pancreatic islet beta-cell proliferation and glucose-dependent insulin secretion and lowers blood glucose and food intake in patients with type 2 diabetes mellitus. GLP-1 receptors, which are coupled to the cyclic AMP second messenger pathway, are expressed throughout the brains of rodents and humans. It was recently reported that GLP-1 and exendin-4, a naturally occurring, more stable analogue of GLP-1 that binds at the GLP-1 receptor, possess neurotrophic properties and can protect neurons against glutamate-induced apoptosis. We report here that GLP-1 can reduce the levels of amyloid-beta peptide (Abeta) in the brain in vivo and can reduce levels of amyloid precursor protein (APP) in cultured neuronal cells. Moreover, GLP-1 and exendin-4 protect cultured hippocampal neurons against death induced by Abeta and iron, an oxidative insult. Collectively, these data suggest that GLP-1 can modify APP processing and protect against oxidative injury, two actions that suggest a novel therapeutic target for intervention in Alzheimer's disease.

Alzheimer Disease↗
PubMed1997

Exendin-4 agonist and exendin(9-39)amide antagonist of the GLP-1(7-36)amide effects in liver and muscle.

The GLP-1 structurally related peptides exendin-4 and exendin(9-39)amide were found to act, in rat liver and skeletal muscle, as agonist and antagonist, respectively, of the GLP-1(7-36)amide effects on glucose metabolism. Thus, like GLP-1(7-36)amide, exendin-4 increased glycogen synthase a activity and glucose incorporation into glycogen in both tissues and also stimulated exogenous D-glucose utilization and oxidation in muscle. These effects of GLP-1(7-36)amide and exendin-4 were inhibited by exendin(9-39)amide. Our findings provide further support to the proposed use of GLP-1, or exendin-4, as a tool in the treatment of diabetes mellitus. Thus, in addition to the well-known insulinotropic action of the peptides, they act both in liver and in muscle in a manner most suitable for restoration of glucose homeostasis, with emphasis on their positive effects upon glycogen synthesis in the two tissues and on the stimulation of exogenous glucose catabolism in muscle.

Animals↗