GLP-1-(9–36) amide reduces blood glucose in anesthetized pigs by a mechanism that does not involve insulin secretion

2002 ◽  
Vol 282 (4) ◽  
pp. E873-E879 ◽  
Author(s):  
Carolyn F. Deacon ◽  
Astrid Plamboeck ◽  
Søren Møller ◽  
Jens J. Holst
Keyword(s):  
Insulin Secretion ◽  
Therapeutic Potential ◽  
Intravenous Glucose ◽  
Dpp Iv ◽  
Glucagon Like Peptide ◽  
Glucagon Like Peptide 1 ◽  
Independent Effects ◽  
Insulinotropic Effect ◽  
Insulin Responses

Glucagon-like peptide 1 (GLP-1) is a potent anti-hyperglycemic hormone currently under investigation for its therapeutic potential. However, due to rapid degradation by dipeptidyl peptidase IV (DPP IV), which limits its metabolic stability and eliminates its insulinotropic activity, it has been impossible to assess its true efficacy in vivo. In chloralose-anesthetized pigs given valine-pyrrolidide (to block endogenous DPP IV activity), the independent effects of GLP-1-(7–36) amide on glucose and insulin responses to intravenous glucose were assessed, and the metabolite generated by DPP IV, GLP-1-(9–36) amide, was investigated for any ability to influence these responses. GLP-1-(7–36) amide enhanced insulin secretion ( P < 0.03 vs. vehicle), but GLP-1-(9–36) amide was without effect, either alone or when coinfused with GLP-1-(7–36) amide. In contrast, GLP-1-(9–36) amide did affect glucose responses ( P < 0.03). Glucose excursions were greater after saline (121 ± 17 mmol · l−1 · min) than after GLP-1-(9–36) amide (73 ± 19 mmol · l−1 · min; P < 0.05), GLP-1-(7–36) amide (62 ± 13 mmol · l−1 · min; P < 0.02) or GLP-1-(7–36) amide + GLP-1-(9–36) amide (50 ± 13 mmol · l−1 · min; P < 0.005). Glucose elimination rates were faster after GLP-1-(7–36) amide + (9–36) amide (10.3 ± 1.2%/min) than after GLP-1-(7–36) amide (7.0 ± 0.9%/min; P < 0.04), GLP-1-(9–36) amide (6.8 ± 1.0%/min; P < 0.03), or saline (5.4 ± 1.2%/min; P < 0.005). Glucagon concentrations were unaffected. These results demonstrate that GLP-1-(9–36) amide neither stimulates insulin secretion nor antagonizes the insulinotropic effect of GLP-1-(7–36) amide in vivo. Moreover, the metabolite itself possesses anti-hyperglycemic effects, supporting the hypothesis that selective DPP IV action is important in glucose homeostasis.

Sensory nerves contribute to insulin secretion by glucagon-like peptide-1 in mice

2004 ◽  
Vol 286 (2) ◽  
pp. R269-R272 ◽  
Author(s):  
Bo Ahrén
Keyword(s):  
Insulin Secretion ◽  
Direct Action ◽  
Insulin Response ◽  
Sensory Nerves ◽  
High Dose ◽  
Intravenous Glucose ◽  
Insulin Response To Glucose ◽  
Glucagon Like Peptide ◽  
Glucagon Like Peptide 1

It has been hypothesized that the potent insulinotropic action of the gut incretin hormone glucagon-like peptide-1 (GLP-1) is exerted not only through a direct action on the beta cells but may be partially dependent on sensory nerves. We therefore examined the influence of GLP-1 in mice rendered sensory denervated by neonatal administration of capsaicin performed at days 2 and 5 (50 mg/kg). Control mice were given vehicle. Results show that at 10-16 wk of age in control mice, intravenous GLP-1 at 0.1 or 10 nmol/kg augmented the insulin response to intravenous glucose (1 g/kg) in association with improved glucose elimination. In contrast, in capsaicin-pretreated mice, GLP-1 at 0.1 nmol/kg could not augment the insulin response to intravenous glucose and no effect on glucose elimination was observed. Nevertheless, at the high dose of 10 nmol/kg, GLP-1 augmented the insulin response to glucose in capsaicin-pretreated mice as efficiently as in control mice. The insulin response to GLP-1 from isolated islets was not affected by neonatal capsaicin, and, furthermore, the in vivo insulin response to glucose was augmented whereas that to arginine was not affected by capsaicin. It is concluded that GLP-1-induced insulin secretion at a low dose in mice is dependent on intact sensory nerves and therefore indirectly mediated and that this distinguishes GLP-1 from other examined insulin secretagogues.

scholarly journals Novel dipeptidyl peptidase IV resistant analogues of glucagon-like peptide-1(7-36)amide have preserved biological activities in vitro conferring improved glucose-lowering action in vivo

2003 ◽  
Vol 31 (3) ◽  
pp. 529-540 ◽  
Author(s):  
BD Green ◽  
VA Gault ◽  
MH Mooney ◽  
N Irwin ◽  
CJ Bailey ◽  
...  
Keyword(s):  
Type 2 Diabetes ◽  
Biological Activities ◽  
Dipeptidyl Peptidase ◽  
Dipeptidyl Peptidase Iv ◽  
Glucose Lowering ◽  
Dpp Iv ◽  
Glucagon Like Peptide ◽  
Glucagon Like Peptide 1

Although the incretin hormone glucagon-like peptide-1 (GLP-1) is a potent stimulator of insulin release, its rapid degradation in vivo by the enzyme dipeptidyl peptidase IV (DPP IV) greatly limits its potential for treatment of type 2 diabetes. Here, we report two novel Ala(8)-substituted analogues of GLP-1, (Abu(8))GLP-1 and (Val(8))GLP-1 which were completely resistant to inactivation by DPP IV or human plasma. (Abu(8))GLP-1 and (Val(8))GLP-1 exhibited moderate affinities (IC(50): 4.76 and 81.1 nM, respectively) for the human GLP-1 receptor compared with native GLP-1 (IC(50): 0.37 nM). (Abu(8))GLP-1 and (Val(8))GLP-1 dose-dependently stimulated cAMP in insulin-secreting BRIN BD11 cells with reduced potency compared with native GLP-1 (1.5- and 3.5-fold, respectively). Consistent with other mechanisms of action, the analogues showed similar, or in the case of (Val(8))GLP-1 slightly impaired insulin releasing activity in BRIN BD11 cells. Using adult obese (ob/ob) mice, (Abu(8))GLP-1 had similar glucose-lowering potency to native GLP-1 whereas the action of (Val(8))GLP-1 was enhanced by 37%. The in vivo insulin-releasing activities were similar. These data indicate that substitution of Ala(8) in GLP-1 with Abu or Val confers resistance to DPP IV inactivation and that (Val(8))GLP-1 is a particularly potent N-terminally modified GLP-1 analogue of possible use in type 2 diabetes.

Measurements of insulin responses as predictive markers of pancreatic β-cell mass in normal and β-cell-reduced lean and obese Göttingen minipigs in vivo

2006 ◽  
Vol 290 (4) ◽  
pp. E670-E677 ◽  
Author(s):  
Marianne O. Larsen ◽  
Bidda Rolin ◽  
Jeppe Sturis ◽  
Michael Wilken ◽  
Richard D. Carr ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Cell Mass ◽  
Insulin Response ◽  
Study Groups ◽  
Β Cell ◽  
Intravenous Glucose ◽  
Body Weights ◽  
In Vivo Tests ◽  
Insulin Responses

At present, the best available estimators of β-cell mass in humans are those based on measurement of insulin levels or appearance rates in the circulation. In several animal models, these estimators have been validated against β-cell mass in lean animals. However, as many diabetic humans are obese, a correlation between in vivo tests and β-cell mass must be evaluated over a range of body weights to include different levels of insulin sensitivity. For this purpose, obese ( n = 10) and lean ( n = 25) Göttingen minipigs were studied. β-Cell mass had been reduced ( n = 16 lean, n = 5 obese) with a combination of nicotinamide (67 mg/kg) and streptozotocin (125 mg/kg), acute insulin response (AIR) to intravenous glucose and/or arginine was tested, pulsatile insulin secretion was evaluated by deconvolution ( n = 30), and β-cell mass was determined histologically. AIR to 0.3 ( r2= 0.4502, P < 0.0001) or 0.6 g/kg glucose ( r2= 0.6806, P < 0.0001), 67 mg/kg arginine ( r2= 0.5730, P < 0.001), and maximum insulin concentration ( r2= 0.7726, P < 0.0001) were all correlated to β-cell mass when evaluated across study groups, and regression lines were not different between lean and obese groups except for AIR to 0.3 g/kg glucose. Baseline pulse mass was not significantly correlated to β-cell mass across the study groups ( r2= 0.1036, NS), whereas entrained pulse mass did show a correlation across groups ( r2= 0.4049, P < 0.001). This study supports the use of in vivo tests of insulin responses to evaluate β-cell mass over a range of body weights in the minipig. Extensive stimulation of insulin secretion by a combination of glucose and arginine seems to give the best correlation to β-cell mass.

scholarly journals Increased insulin clearance in mice with double deletion of glucagon-like peptide-1 and glucose-dependent insulinotropic polypeptide receptors

2018 ◽  
Vol 314 (5) ◽  
pp. R639-R646 ◽  
Author(s):  
Andrea Tura ◽  
Roberto Bizzotto ◽  
Yuchiro Yamada ◽  
Yutaka Seino ◽  
Giovanni Pacini ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Insulin Clearance ◽  
Second Phase ◽  
Incretin Hormones ◽  
Intravenous Glucose ◽  
C Peptide ◽  
Double Deletion ◽  
Glucagon Like Peptide ◽  
Glucagon Like Peptide 1 ◽  
First Phase Insulin Secretion

To establish whether incretin hormones affect insulin clearance, the aim of this study was to assess insulin clearance in mice with genetic deletion of receptors for both glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), so called double incretin receptor knockout mice (DIRKO). DIRKO ( n = 31) and wild-type (WT) C57BL6J mice ( n = 45) were intravenously injected with d-glucose (0.35 g/kg). Blood was sampled for 50 min and assayed for glucose, insulin, and C-peptide. Data were modeled to calculate insulin clearance; C-peptide kinetics was established after human C-peptide injection. Assessment of C-peptide kinetics revealed that C-peptide clearance was 1.66 ± 0.10 10−3 1/min. After intravenous glucose administration, insulin clearance during first phase insulin secretion was markedly higher in DIRKO than in WT mice (0.68 ± 0.06 10−3 l/min in DIRKO mice vs. 0.54 ± 0.03 10−3 1/min in WT mice, P = 0.02). In contrast, there was no difference between the two groups in insulin clearance during second phase insulin secretion ( P = 0.18). In conclusion, this study evaluated C-peptide kinetics in the mouse and exploited a mathematical model to estimate insulin clearance. Results showed that DIRKO mice have higher insulin clearance than WT mice, following intravenous injection of glucose. This suggests that incretin hormones reduce insulin clearance at physiological, nonstimulated levels.

scholarly journals Dual-acting peptide with prolonged glucagon-like peptide-1 receptor agonist and glucagon receptor antagonist activity for the treatment of type 2 diabetes

2007 ◽  
Vol 192 (2) ◽  
pp. 371-380 ◽  
Author(s):  
Thomas H Claus ◽  
Clark Q Pan ◽  
Joanne M Buxton ◽  
Ling Yang ◽  
Jennifer C Reynolds ◽  
...  
Keyword(s):  
Type 2 Diabetes ◽  
Insulin Secretion ◽  
Receptor Agonist ◽  
Antagonist Activity ◽  
Glucagon Receptor ◽  
Glucagon Receptor Antagonist ◽  
Glucagon Like Peptide ◽  
Glucagon Like Peptide 1

Type 2 diabetes is characterized by reduced insulin secretion from the pancreas and overproduction of glucose by the liver. Glucagon-like peptide-1 (GLP-1) promotes glucose-dependent insulin secretion from the pancreas, while glucagon promotes glucose output from the liver. Taking advantage of the homology between GLP-1 and glucagon, a GLP-1/glucagon hybrid peptide, dual-acting peptide for diabetes (DAPD), was identified with combined GLP-1 receptor agonist and glucagon receptor antagonist activity. To overcome its short plasma half-life DAPD was PEGylated, resulting in dramatically prolonged activity in vivo. PEGylated DAPD (PEG-DAPD) increases insulin and decreases glucose in a glucose tolerance test, evidence of GLP-1 receptor agonism. It also reduces blood glucose following a glucagon challenge and elevates fasting glucagon levels in mice, evidence of glucagon receptor antagonism. The PEG-DAPD effects on glucose tolerance are also observed in the presence of the GLP-1 antagonist peptide, exendin(9–39). An antidiabetic effect of PEG-DAPD is observed in db/db mice. Furthermore, PEGylation of DAPD eliminates the inhibition of gastrointestinal motility observed with GLP-1 and its analogues. Thus, PEG-DAPD has the potential to be developed as a novel dual-acting peptide to treat type 2 diabetes, with prolonged in vivo activity, and without the GI side-effects.

RANTES (CCL5) reduces glucose-dependent secretion of glucagon-like peptides 1 and 2 and impairs glucose-induced insulin secretion in mice

2014 ◽  
Vol 307 (3) ◽  
pp. G330-G337 ◽  
Author(s):  
Ramona Pais ◽  
Tamara Zietek ◽  
Hans Hauner ◽  
Hannelore Daniel ◽  
Thomas Skurk
Keyword(s):  
Insulin Secretion ◽  
Glucose Transporter ◽  
Cell Loss ◽  
Oral Glucose ◽  
Diabetes Therapy ◽  
Incretin Hormone ◽  
Glucagon Like Peptide ◽  
Glucagon Like Peptide 1

Type 2 diabetes is associated with elevated circulating levels of the chemokine RANTES and with decreased plasma levels of the incretin hormone glucagon-like peptide 1 (GLP-1). GLP-1 is a peptide secreted from intestinal L-cells upon nutrient ingestion. It enhances insulin secretion from pancreatic β-cells and protects from β-cell loss but also promotes satiety and weight loss. In search of chemokines that may reduce GLP-1 secretion we identified RANTES and show that it reduces glucose-stimulated GLP-1 secretion in the human enteroendocrine cell line NCI-H716, blocked by the antagonist Met-RANTES, and in vivo in mice. RANTES exposure to mouse intestinal tissues lowers transport function of the intestinal glucose transporter SGLT1, and administration in mice reduces plasma GLP-1 and GLP-2 levels after an oral glucose load and thereby impairs insulin secretion. These data show that RANTES is involved in altered secretion of glucagon-like peptide hormones most probably acting through SGLT1, and our study identifies the RANTES-receptor CCR1 as a potential target in diabetes therapy.

scholarly journals Insulin-independent effects of GLP-1 on canine liver glucose metabolism: duration of infusion and involvement of hepatoportal region

2004 ◽  
Vol 287 (1) ◽  
pp. E75-E81 ◽  
Author(s):  
D. Dardevet ◽  
M. C. Moore ◽  
D. Neal ◽  
C. A. DiCostanzo ◽  
W. Snead ◽  
...  
Keyword(s):  
Glucose Disposal ◽  
Control Group ◽  
Hepatic Glucose ◽  
Glucagon Like Peptide ◽  
Glucagon Like Peptide 1 ◽  
Independent Effects ◽  
Hepatic Glucose Uptake ◽  
Arteriovenous Difference

Whether glucagon-like peptide-1 (GLP-1) has insulin-independent effects on glucose disposal in vivo was assessed in conscious dogs by use of tracer and arteriovenous difference techniques. After a basal period, each experiment consisted of three periods (P1, P2, P3) during which somatostatin, glucagon, insulin, and glucose were infused. The control group (C) received saline in P1, P2, and P3, the PePe group received saline in P1 and GLP-1 (7.5 pmol·kg−1·min−1) peripherally (Pe; iv) in P2 and P3, and the PePo group received saline in P1 and GLP-1 peripherally (iv) (P2) and then into the portal vein (Po; P3). Glucose and insulin concentrations increased to two- and fourfold basal, respectively, and glucagon remained basal. GLP-1 levels increased similarly in the PePe and PePo groups during P2 (∼200 pM), whereas portal GLP-1 levels were significantly increased (3-fold) in PePo vs. PePe during P3. In all groups, net hepatic glucose uptake (NHGU) occurred during P1. During P2, NHGU increased slightly but not significantly in all groups. During P3, NHGU increased in PePe and PePo groups to a greater extent than in C, but no significant effect of the route of infusion of GLP-1 was demonstrated (16.61 ± 2.91 and 14.67 ± 2.09 vs. 4.22 ± 1.57 μmol·kg−1·min−1, respectively). In conclusion: GLP-1 increased glucose disposal in the liver independently of insulin secretion; its full action required long-term infusion. The route of infusion did not modify the hepatic response.

scholarly journals Actions of glucagon-like peptide-1 on KATP channel-dependent and -independent effects of glucose, sulphonylureas and nateglinide

2006 ◽  
Vol 190 (3) ◽  
pp. 889-896 ◽  
Author(s):  
Neville H McClenaghan ◽  
Peter R Flatt ◽  
Andrew J Ball
Keyword(s):  
Insulin Secretion ◽  
Protein Kinase ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Glucagon Like Peptide ◽  
Glucagon Like Peptide 1 ◽  
Channel Dependent ◽  
Releasing Effect ◽  
Independent Effects

This study examined the effects of glucagon-like peptide-1 (GLP-1) on insulin secretion alone and in combination with sulphonylureas or nateglinide, with particular attention to KATP channel-independent insulin secretion. In depolarised cells, GLP-1 significantly augmented glucose-induced KATP channel-independent insulin secretion in a glucose concentration-dependent manner. GLP-1 similarly augmented the KATP channel-independent insulin-releasing effects of tolbutamide, glibenclamide or nateglinide. Downregulation of protein kinase A (PKA)- or protein kinase C (PKC)-signalling pathways in culture revealed that the KATP channel-independent effects of sulphonylureas or nateglinide were critically dependent upon intact PKA and PKC signalling. In contrast, GLP-1 exhibited a reduced but still significant insulin-releasing effect following PKA and PKC downregulation, indicating that GLP-1 can modulate KATP channel-independent insulin secretion by protein kinase-dependent and -independent mechanisms. The synergistic insulin-releasing effects of combinatorial GLP-1 and sulphonylurea/nateglinide were lost following PKA- or PKC-desensitisation, despite GLP-1 retaining an insulin-releasing effect, demonstrating that GLP-1 can induce insulin release under conditions where sulphonylureas and nateglinide are no longer effective. Our results provide new insights into the mechanisms of action of GLP-1, and further highlight the promise of GLP-1 or similarly acting analogues alone or in combination with sulphonylureas or meglitinide drugs in type 2 diabetes therapy.

scholarly journals Disconnect between signalling potency and in vivo efficacy of pharmacokinetically optimised biased glucagon-like peptide-1 receptor agonists

2019 ◽  
Author(s):  
Maria Lucey ◽  
Philip Pickford ◽  
James Minnion ◽  
Jan Ungewiss ◽  
Katja Schoeneberg ◽  
...  
Keyword(s):  
Therapeutic Potential ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Receptor Trafficking ◽  
Appetite Suppression ◽  
Glucagon Like Peptide ◽  
Glucagon Like Peptide 1 ◽  
And Diffusion

AbstractObjectiveTo determine how pharmacokinetically advantageous acylation impacts on glucagon-like peptide-1 receptor (GLP-1R) signal bias, trafficking, anti-hyperglycaemic efficacy and appetite suppression.MethodsIn vitro signalling responses were measured using biochemical and biosensor assays. GLP-1 receptor trafficking was determined by confocal microscopy and diffusion-enhanced resonance energy transfer. Pharmacokinetics, glucoregulatory effects and appetite suppression were measured in acute, sub-chronic and chronic settings in mice.ResultsA C-terminally acylated ligand, exendin-phe1-C16, was identified with undetectable β-arrestin recruitment and GLP-1R internalisation. Depending on the cellular system used, this molecule was up to 1000-fold less potent than the comparator exendin-asp-3-C16 for cyclic AMP signalling, yet was considerably more effective in vivo, particularly for glucose regulation.ConclusionsC-terminal acylation of biased GLP-1R agonists increases their degree of signal bias in favour of cAMP production and improves their therapeutic potential.

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