scholarly journals Recent advances in understanding the role of glucagon-like peptide 1

F1000Research ◽  
2020 ◽  
Vol 9 ◽  
pp. 239 ◽  
Author(s):  
Josh Reed ◽  
Stephen Bain ◽  
Venkateswarlu Kanamarlapudi

The discovery that glucagon-like peptide 1 (GLP-1) mediates a significant proportion of the incretin effect during the postprandial period and the subsequent observation that GLP-1 bioactivity is retained in type 2 diabetes (T2D) led to new therapeutic strategies being developed for T2D treatment based on GLP-1 action. Although owing to its short half-life exogenous GLP-1 has no use therapeutically, GLP-1 mimetics, which have a much longer half-life than native GLP-1, have proven to be effective for T2D treatment since they prolong the incretin effect in patients. These GLP-1 mimetics are a desirable therapeutic option for T2D since they do not provoke hypoglycaemia or weight gain and have simple modes of administration and monitoring. Additionally, over more recent years, GLP-1 action has been found to mediate systemic physiological beneficial effects and this has high clinical relevance due to the post-diagnosis complications of T2D. Indeed, recent studies have found that certain GLP-1 analogue therapies improve the cardiovascular outcomes for people with diabetes. Furthermore, GLP-1–based therapies may enable new therapeutic strategies for diseases that can also arise independently of the clinical manifestation of T2D, such as dementia and Parkinson’s disease. GLP-1 functions by binding to its receptor (GLP-1R), which expresses mainly in pancreatic islet beta cells. A better understanding of the mechanisms and signalling pathways by which acute and chronic GLP-1R activation alleviates disease phenotypes and induces desirable physiological responses during healthy conditions will likely lead to the development of new therapeutic GLP-1 mimetic–based therapies, which improve prognosis to a greater extent than current therapies for an array of diseases.

2002 ◽  
pp. 863-869 ◽  
Author(s):  
H Hui ◽  
L Farilla ◽  
P Merkel ◽  
R Perfetti

The incretin hormone glucagon-like peptide-1 (GLP-1) is capable of ameliorating glucose-dependent insulin secretion in subjects with diabetes. However, its very short half-life (1.5-5 min) in plasma represents a major limitation for its use in the clinical setting. The present study was designed to characterize the duration of the effect of GLP-1 in the Zucker diabetic fatty (ZDF) rat. ZDF rats were subjected to a 48 h infusion of human GLP-1 (30 pmol/kg per min), followed by an i.p. glucose tolerance test (IPGTT) (1 g/kg body weight), 2 h after removing the infusion pump. At 15 min from the beginning of the test, GLP-1-treated animals had lower plasma glucose levels (442+/-38 mg/dl) than saline-infused controls (583+/-63 mg/dl, P<0.01). This was reflected in the higher insulin levels attained in the GLP-1-treated animals (1999+/-163 vs 1250+/-51 pmol/l, GLP-1 vs saline respectively, P<0.01). Repetition of the IPGTT on day 3, 9 and 16 from the removal of the infusion pump revealed a surprising lasting 'memory' of the exposure to GLP-1. Indeed, the best insulin secretory response was observed approximately 1 week after discontinuation of the GLP-1 infusion, and lasted up to 3 weeks from the early exposure to GLP-1. Detection of fasting plasma levels of GLP-1 during the 3 weeks of the experiment showed a very rapid decline, consistent with the data reported by others. Our findings provide evidence for a long-lasting beneficial effect of GLP-1 that persists for weeks even when the circulating levels of GLP-1 are back to normal.


2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Enrique Z. Fisman ◽  
Alexander Tenenbaum

AbstractIncretin hormones are peptides released in the intestine in response to the presence of nutrients in its lumen. The main incretins are glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP). GLP-1 stimulates insulin secretion, inhibits glucagon secretion at pancreatic α cells and has also extrapancreatic influences as slowing of gastric emptying which increases the feeling of satiety. GIP is the main incretin hormone in healthy people, causative of most the incretin effects, but the insulin response after GIP secretion in type 2 diabetes mellitus (T2DM) is strongly reduced. Therefore, in the past GIP has been considered an unappealing therapeutic target for T2DM. This conception has been changing during recent years, since it has been reported that resistance to GIP can be reversed and its effectiveness restored by improving glycemic control. This fact paved the way for the development of a GIP receptor agonist-based therapy for T2DM, looking also for the possibility of finding a combined GLP-1/GIP receptor agonist. In this framework, the novel dual GIP and GLP-1 receptor agonist tirzepatide seems to be not just a new antidiabetic medication. Administered as a subcutaneous weekly injection, it is a manifold single pharmacological agent that has the ability to significantly lower glucose levels, as well as improve insulin sensitivity, reduce weight and amend dyslipidemia favorably modifying the lipid profile. Tirzepatide and additional dual GLP-1/GIP receptor agonists that could eventually be developed in the future seem to be a promising furthest advance for the management of several cardiometabolic settings. Obviously, it is too early to be overly hopeful since it is still necessary to determine the long-term effects of these compounds and properly verify the potential cardiovascular benefits. Anyway, we are currently facing a novel and very appealing therapeutic option.


2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
Matthias Ploug Larsen ◽  
Signe Sørensen Torekov

Background. The incretin effect is impaired in patients with type 2 diabetes. Aim. To assess the relation between the incretin hormone GLP-1 and the prediabetic subtypes: impaired fasting glucose (IFG), impaired glucose tolerance (IGT), and the combined IFG/IGT to investigate whether a low GLP-1 response may be a predictor of prediabetes in adults. Method. 298 articles were found using a broad search phrase on the PubMed database and after the assessment of titles and abstracts 19 articles were included. Results and Discussion. Studies assessing i-IFG/IFG and i-IGT/IGT found both increased, unaltered, and reduced GLP-1 levels. Studies assessing IFG/IGT found unaltered or reduced GLP-1 levels. When assessing the five studies with the largest sample size, it clearly suggests a decreased GLP-1 response in IFG/IGT subjects. Several other factors (BMI, glucagon, age, and nonesterified fatty acids (NEFA)), including medications (metformin), may also influence the secretion of GLP-1. Conclusion. This review suggests that the GLP-1 response is a variable in prediabetes possibly due to a varying GLP-1-secreting profile during the development and progression of type 2 diabetes or difference in the measurement technique. Longitudinal prospective studies are needed to assess whether a reduced GLP-1 response is a predictor of diabetes.


2012 ◽  
Vol 96 (3) ◽  
pp. 362-370 ◽  
Author(s):  
Zhenghong Cao ◽  
Ying Li ◽  
Lida Tang ◽  
Weiren Xu ◽  
Changxiao Liu ◽  
...  

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Mohammad Sarif Mohiuddin ◽  
Tatsuhito Himeno ◽  
Rieko Inoue ◽  
Emiri Miura-Yura ◽  
Yuichiro Yamada ◽  
...  

Objective. Diabetic polyneuropathy (DPN) is one of the most prevalent diabetic complications. We previously demonstrated that exendin-4 (Ex4), a glucagon-like peptide-1 receptor agonist (GLP-1RA), has beneficial effects in animal models of DPN. We hypothesized that GLP-1 signaling would protect neurons of the peripheral nervous system from oxidative insult in DPN. Here, the therapeutic potential of GLP-1RAs on DPN was investigated in depth using the cellular oxidative insult model applied to the dorsal root ganglion (DRG) neuronal cell line. Research Design and Methods. Immortalized DRG neuronal 50B11 cells were cultured with and without hydrogen peroxide in the presence or absence of Ex4 or GLP-1(7-37). Cytotoxicity and viability were determined using a lactate dehydrogenase assay and MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium inner salt), respectively. Antioxidant enzyme activity was evaluated using a superoxide dismutase assay. Alteration of neuronal characteristics of 50B11 cells induced by GLP-1RAs was evaluated with immunocytochemistry utilizing antibodies for transient receptor potential vanilloid subfamily member 1, substance P, and calcitonin gene-related peptide. Cell proliferation and apoptosis were also examined by ethynyl deoxyuridine incorporation assay and APOPercentage dye, respectively. The neurite projection ratio induced by treatment with GLP-1RAs was counted. Intracellular activation of adenylate cyclase/cyclic adenosine monophosphate (cAMP) signaling was also quantified after treatment with GLP-1RAs. Results. Neither Ex4 nor GLP-1(7-37) demonstrated cytotoxicity in the cells. An MTS assay revealed that GLP-1RAs amended impaired cell viability induced by oxidative insult in 50B11 cells. GLP-1RAs activated superoxide dismutase. GLP-1RAs induced no alteration of the distribution pattern in neuronal markers. Ex4 rescued the cells from oxidative insult-induced apoptosis. GLP-1RAs suppressed proliferation and promoted neurite projections. No GLP-1RAs induced an accumulation of cAMP. Conclusions. Our findings indicate that GLP-1RAs have neuroprotective potential which is achieved by their direct actions on DRG neurons. Beneficial effects of GLP-1RAs on DPN could be related to these direct actions on DRG neurons.


Drug Research ◽  
2019 ◽  
Vol 69 (09) ◽  
pp. 479-486
Author(s):  
Mitsuaki Takeuchi ◽  
Masayuki Okamoto ◽  
Miyuki Tamura ◽  
Takayo Murase ◽  
Nobuhide Watanabe

Abstract Background Long-acting glucagon-like peptide-1 receptor agonists (GLP-1 RAs) are widely used for treatment of type 2 diabetes (T2DM) in the United States, the European Union, and Japan. In our previous work, we designed and characterized a novel GLP-1 RA, SKL-18287. This RA consists of only natural L-amino acids, and is believed to exist in an oligomer form in systemic circulation. This unique feature may allow high biological stability and a long-lasting glucose lowering effect in T2DM treatment. In the present study, we investigated the pharmacokinetic properties of SKL-18287 in rats, monkeys, and mini-pigs. Tissue distributions of radioactivity were also studied in rats after subcutaneous administration of [3H]-SKL-18287. Methods Plasma concentrations of SKL-18287 were measured by LC-MS/MS after intravenous and subcutaneous administration of SKL-18287 in rats, monkeys, and mini-pigs. Pharmacokinetic parameters were then calculated and compared among these animal species. Tissue concentrations of radioactivity were determined by liquid scintillation counting following sample combustion, after subcutaneous administration of [3H]-SKL-18287 to rats. Results SKL-18287 showed an extended half-life of over 5 h, with good subcutaneous bioavailability, in all animal species. Prediction of the pharmacokinetic profiles of SKL-18287 in humans using an animal scale-up approach revealed an SKL-18287 half-life of 14.8 h. The radioactivity concentration in the pancreas, a target tissue of GLP-1RA, was relatively higher than in other tissues, until 12 h after [3H]-SKL-18287 administration. Conclusion SKL-18287 might be sufficient to maintain an effective concentration for a once-daily treatment for T2DM, and is a unique GLP-1 RA with a pancreas-selective feature.


1996 ◽  
Vol 271 (3) ◽  
pp. E458-E464 ◽  
Author(s):  
C. F. Deacon ◽  
L. Pridal ◽  
L. Klarskov ◽  
M. Olesen ◽  
J. J. Holst

Glucagon-like peptide 1 (GLP-1) metabolism was studied in halothane-anesthetized pigs (n = 7) using processing-independent (PI) and COOH-terminal (C) radioimmunoassays (RIA) and an enzyme-linked immunosorbent assay (ELISA) specific for biologically active GLP-1. Renal extraction of endogenous GLP-1 was detected by PI-RIA (33.1 +/- 13.3%) and C-RIA (16.0 +/- 6.3%) and by all assays during GLP-1 infusion (ELISA, 69.4 +/- 6.3%; PI-RIA, 32.6 +/- 7.3%; C-RIA, 43.7 +/- 3.4%), indicating substantial fragmentation. Hepatic and pulmonary degradation were undetectable under basal conditions, but exogenous GLP-1 elimination by the liver (43.6 +/- 8.9%) and lungs (10.1 +/- 3.2%) was measured by ELISA, suggesting primarily NH2-terminal degradation. Endogenous GLP-1 extraction by the hindleg was only detected by C-RIA (16.0 +/- 6.3%). During GLP-1 infusion, greater hindleg extraction was measured by ELISA (38.5 +/- 6.8%) and C-RIA (33.0 +/- 6.4%) than by PI-RIA (11.4 +/- 3.2%), indicating limited degradation at each terminus or more substantial COOH-terminal degradation. A shorter (P < 0.01) plasma half-life was revealed by ELISA (1.5 +/- 0.4 min) than by PI-RIA (4.5 +/- 0.6 min) or C-RIA (4.1 +/- 0.5 min). Metabolic clearance rates measured by PI-RIA (20.0 +/- 3.8 ml.min-1.kg-1) and C-RIA (15.5 +/- 1.6 ml.min-1.kg-1) were shorter (P < 0.01) than that measured by ELISA (106.8 +/- 14.7 ml.min-1.kg-1). Tissue-specific differential metabolism of GLP-1 occurs, and NH2-terminal degradation, rendering GLP-1 inactive, is particularly important in its clearance.


Sign in / Sign up

Export Citation Format

Share Document