scholarly journals Impact of Incretin Hormone Receptors on Insulin-Independent Glucose Disposal in Model Experiments in Mice

2021 ◽  
Vol 12 ◽  
Author(s):  
Tina Ovlund ◽  
Giovanni Pacini ◽  
Bo Ahrén
Keyword(s):  
Insulin Secretion ◽  
Knockout Mice ◽  
Hormone Receptors ◽  
Elimination Rate ◽  
Glucose Disposal ◽  
Oral Glucose ◽  
Potential Contribution ◽  
Large Contribution ◽  
Intravenous Glucose ◽  
Incretin Hormone

A large contribution to glucose elimination from the circulation is achieved by insulin-independent processes. We have previously shown that the two incretin hormones, glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) increase this process and, therefore, seem to contribute to glucose disposal both through this effect and through the classical incretin effect resulting in enhanced insulin levels. We have now explored in more detail the potential contribution by incretin hormone receptors to insulin-independent processes for glucose elimination. To that end, we have performed intravenous glucose tests (0.35g/kg) in C57BL/6J mice and analyzed glucose elimination rate and glucose effectiveness (i.e., insulin-independent glucose disposal, SG) in wildtype mice and in mice with genetic deletion of GIP receptors or GLP-1 receptors. We performed studies with or without complete blockade of insulin secretion by the drug diazoxide (25 mg/kg). The mice were anesthetized with a novel fentanyl citrate/fluanisone formulation, called Fluafent, together with midazolam. Initially we demonstrated that glucose and insulin data after intravenous and oral glucose were not different using this anesthesia compared to the previously commonly used combination of HypnormR and midazolam. The results show that SG was reduced in GLP-1 receptor knockout mice, whereas there was no difference between GIP receptor knockout mice and wildtype mice, and this was evident both under normal conditions and after complete inhibition of insulin secretion. The study therefore indicates that insulin-independent glucose elimination requires active GLP-1 receptors and thus that the two incretin hormone receptor types show dissociated relevance for this process.

scholarly journals PACAP stimulates insulin secretion but inhibits insulin sensitivity in mice

1998 ◽  
Vol 274 (5) ◽  
pp. E834-E842 ◽  
Author(s):  
Karin Filipsson ◽  
Giovanni Pacini ◽  
Anton J. W. Scheurink ◽  
Bo Ahrén
Keyword(s):  
Insulin Secretion ◽  
Insulin Sensitivity ◽  
Elimination Rate ◽  
Insulin Response ◽  
Area Under The Curve ◽  
Glucose Disposal ◽  
Sensitivity Index ◽  
Maximal Effect ◽  
Intravenous Glucose

Although pituitary adenylate cyclase-activating polypeptide (PACAP) stimulates insulin secretion, its net influence on glucose homeostasis in vivo has not been established. We therefore examined the action of PACAP-27 and PACAP-38 on insulin secretion, insulin sensitivity, and glucose disposal as derived from the minimal model of glucose disappearance during an intravenous glucose tolerance test in anesthetized mice. PACAP-27 and PACAP-38 markedly and equipotently potentiated glucose-stimulated insulin secretion, with a half-maximal effect at 33 pmol/kg. After PACAP-27 or PACAP-38 (1.3 nmol/kg), the acute (1–5 min) insulin response was 3.8 ± 0.4 nmol/l (PACAP-27) and 3.3 ± 0.3 nmol/l (PACAP-38), respectively, vs. 1.4 ± 0.1 nmol/l after glucose alone ( P < 0.001), and the total area under the curve for insulin (AUCinsulin) was potentiated by 60% ( P < 0.001). In contrast, PACAP-27 and PACAP-38 reduced the insulin sensitivity index (SI) [0.23 ± 0.04 10−4min−1/(pmol/l) for PACAP-27 and 0.29 ± 0.06 10−4min−1/(pmol/l) for PACAP-38 vs. 0.46 ± 0.02 10−4min−1/(pmol/l) for controls ( P < 0.01)]. Furthermore, PACAP-27 or PACAP-38 did not affect glucose elimination determined as glucose half-time or the glucose elimination rate after glucose injection or the area under the curve for glucose. Moreover, glucose effectiveness and the global disposition index (AUCinsulin times SI) were not affected by PACAP-27 or PACAP-38. Finally, when given together with glucose, PACAP-27 did not alter plasma glucagon or norepinephrine levels but significantly increased plasma epinephrine levels. We conclude that PACAP, besides its marked stimulation of insulin secretion, also inhibits insulin sensitivity in mice, the latter possibly explained by increased epinephrine. This complex action explains why the peptide does not enhance glucose disposal.

The effect of melatonin on incretin hormones – results from experimental and randomized clinical studies

2021 ◽  
Author(s):  
Esben Stistrup Lauritzen ◽  
Julie Støy ◽  
Cecilie Bæch-Laursen ◽  
Niels Grarup ◽  
Niels Jessen ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Glucose Homeostasis ◽  
Tolerance Test ◽  
University Hospital ◽  
Oral Glucose ◽  
Incretin Hormones ◽  
Intravenous Glucose ◽  
In Situ Study

Abstract Context Glucose homeostasis is under circadian control through both endocrine and intracellular mechanisms with several lines of evidence suggesting that melatonin affects glucose homeostasis. Objective To evaluate the acute in-vivo and in-situ effects of melatonin on secretion of the incretin hormones, GLP-1 and GIP, and their impact on β-cell insulin secretion. Design A human randomized, double-blinded, placebo-controlled crossover study combined with a confirmatory in-situ study of perfused rat intestines. Setting Aarhus University Hospital. Methods: Fifteen healthy male participants were examined 2 x 2 times: An oral glucose tolerance test (OGTT) was performed on day one and an isoglycemic intravenous glucose infusion replicating the blood glucose profile of the OGTT day was performed on day two. These pairs of study days were repeated on treatment with melatonin and placebo, respectively. For the in-situ study, six rat intestines and four rat pancreases were perfused arterially with perfusion buffer ± melatonin. The intestines were concomitantly perfused with glucose through the luminal compartment. Results In humans, melatonin treatment resulted in reduced GIP secretion compared with placebo (ANOVA p=0.003), an effect also observed in the perfused rat intestines (ANOVA p=0.003) in which GLP-1 secretion also was impaired by arterial melatonin infusion (ANOVA p&lt;0.001). Despite a decrease in GIP levels, the in-vivo glucose-stimulated insulin secretion was unaffected by melatonin (p=0.78). Conclusion Melatonin reduced GIP secretion during an oral glucose challenge in healthy young men but did not affect insulin secretion. Reduced GIP secretion was confirmed in an in-situ model of the rat intestine.

scholarly journals Insulin secretion-independent effects of GLP-1 on canine liver glucose metabolism do not involve portal vein GLP-1 receptors

2005 ◽  
Vol 289 (5) ◽  
pp. G806-G814 ◽  
Author(s):  
Dominique Dardevet ◽  
Mary Courtney Moore ◽  
Catherine A. DiCostanzo ◽  
Ben Farmer ◽  
Doss W. Neal ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Portal Vein ◽  
Glucose Disposal ◽  
Control Group ◽  
Oral Glucose ◽  
Oral Glucose Tolerance Testing ◽  
Hyperglycemic Clamp ◽  
Independent Effects ◽  
Hepatic Portal

Whether glucagon-like peptide (GLP)-1 requires the hepatic portal vein to elicit its insulin secretion-independent effects on glucose disposal in vivo was assessed in conscious dogs using tracer and arteriovenous difference techniques. In study 1, six conscious overnight-fasted dogs underwent oral glucose tolerance testing (OGTT) to determine target GLP-1 concentrations during clamp studies. Peak arterial and portal values during OGTT ranged from 23 to 65 pM and from 46 to 113 pM, respectively. In study 2, we conducted hyperinsulinemic-hyperglycemic clamp experiments consisting of three periods (P1, P2, and P3) during which somatostatin, glucagon, insulin and glucose were infused. The control group received saline, the PePe group received GLP-1 (1 pmol·kg−1·min−1) peripherally, the PePo group received GLP-1 (1 pmol·kg−1·min−1) peripherally (P2) and then intraportally (P3), and the PeHa group received GLP-1 (1 pmol·kg−1·min−1) peripherally (P2) and then through the hepatic artery (P3) to increase the hepatic GLP-1 load to the same extent as in P3 in the PePo group ( n = 8 dogs/group). Arterial GLP-1 levels increased similarly in all groups during P2 (∼50 pM), whereas portal GLP-1 levels were significantly increased (2-fold) in the PePo vs. PePe and PeHa groups during P3. During P2, net hepatic glucose uptake (NHGU) increased slightly but not significantly (vs. P1) in all groups. During P3, GLP-1 increased NHGU in the PePo and PeHa groups more than in the control and PePe groups (change of 10.8 ± 1.3 and 10.6 ± 1.0 vs. 5.7 ± 1.0 and 5.4 ± 0.8 μmol·kg−1·min−1, respectively, P < 0.05). In conclusion, physiological GLP-1 levels increase glucose disposal in the liver, and this effect does not involve GLP-1 receptors located in the portal vein.

scholarly journals β-cell knockout of SENP1 reduces responses to incretins and worsens oral glucose tolerance in high fat diet-fed mice

2021 ◽  
Author(s):  
Haopeng Lin ◽  
Nancy Smith ◽  
Aliya F Spigelman ◽  
Kunimasa Suzuki ◽  
Mourad Ferdaoussi ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Glucose Tolerance ◽  
Knockout Mice ◽  
High Fat Diet ◽  
Glucagon Secretion ◽  
Oral Glucose ◽  
Oral Glucose Tolerance ◽  
High Fat ◽  
Β Cell ◽  
Islet Mass

SUMOylation reduces oxidative stress and preserves islet mass at the expense of robust insulin secretion. To investigate a role for the deSUMOylating enzyme <u>sen</u>trin-specific <u>p</u>rotease <u>1</u> (SENP1) following metabolic stress, we put pancreas/gut-specific SENP1 knockout mice (pSENP1-KO) on a high fat diet (HFD). Male pSENP1-KO mice were more glucose intolerant following HFD than littermate controls, but only in response to oral glucose. A similar phenotype was observed in females. Plasma glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like-peptide 1 (GLP-1) responses were identical in pSENP1-KO and -WT littermates, including the HFD-induced upregulation of GIP responses. Islet mass was not different, but insulin secretion and β-cell exocytotic responses to the GLP-1 receptor agonist Exendin-4 (Ex4) and GIP were impaired in islets lacking SENP1. Glucagon secretion from pSENP1-KO islets was also reduced, so we generated β-cell-specific SENP1 knockout mice (βSENP1-KO). These phenocopied the pSENP1-KO mice with selective impairment in oral glucose tolerance following HFD, preserved islet mass expansion, and impaired β-cell exocytosis and insulin secretion to Ex4 and GIP without changes in cAMP or Ca<sup>2+</sup> levels. Thus, β-cell SENP1 limits oral glucose intolerance following HFD by ensuring robust insulin secretion at a point downstream of incretin signaling.

scholarly journals Measurement of selective effect of insulin on glucose disposal from labeled glucose oral test minimal model

2005 ◽  
Vol 289 (5) ◽  
pp. E909-E914 ◽  
Author(s):  
Chiara Dalla Man ◽  
Andrea Caumo ◽  
Rita Basu ◽  
Robert Rizza ◽  
Gianna Toffolo ◽  
...  
Keyword(s):  
Minimal Model ◽  
Glucose Production ◽  
Tolerance Test ◽  
Intravenous Glucose Tolerance Test ◽  
Glucose Disposal ◽  
Oral Glucose ◽  
Intravenous Glucose ◽  
Selective Effect ◽  
Clamp Technique ◽  
Model Independent

The oral glucose minimal model (OMM) measures insulin sensitivity (SI) and the glucose rate of appearance (Ra) of ingested glucose in the presence of physiological changes of insulin and glucose concentrations. However, SI of OMM measures the overall effect of insulin on glucose utilization and glucose production. In this study we show that, by adding a tracer to the oral dose, e.g., of a meal, and by using the labeled version of OMM, OMM* to interpret the data, one can measure the selective effect of insulin on glucose disposal, [Formula: see text]. Eighty-eight individuals underwent both a triple-tracer meal with the tracer-to-tracee clamp technique, providing a model-independent reference of the Ra of ingested glucose ([Formula: see text]) and an insulin-modified labeled intravenous glucose tolerance test (IVGTT*). We show that OMM* provides not only a reliable means of tracing the Ra of ingested glucose (Ra meal) but also accurately measures [Formula: see text]. We do so by comparing OMM* Ra meal with the model-independent [Formula: see text] provided by the tracer-to-tracee clamp technique, while OMM* [Formula: see text] is compared with both [Formula: see text], obtained by using as known input [Formula: see text], and with [Formula: see text] measured during IVGTT*.

scholarly journals The Incretin Effect in Female Mice With Double Deletion of GLP-1 and GIP Receptors

2019 ◽  
Vol 4 (2) ◽  
Author(s):  
Bo Ahrén ◽  
Yuichiro Yamada ◽  
Yutaka Seino
Keyword(s):  
Insulin Secretion ◽  
Beta Cell ◽  
Beta Cell Function ◽  
Cell Function ◽  
Insulin Response ◽  
Oral Glucose ◽  
Incretin Effect ◽  
Intravenous Glucose ◽  
C Peptide ◽  
Female Mice

Abstract To establish the contribution of glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) for the incretin effect after oral glucose, studies were undertaken in female mice with genetic deletion of receptors for GIP and GLP-1 (double incretin receptor knockout [DIRKO] mice) and their wild-type (WT) counterparts. Insulin secretion was explored after oral glucose (doses ranging from 0 to 100 mg), after intravenous glucose (doses ranging from 0 to 0.75 g/kg), and after oral and intravenous glucose at matching circulating glucose. DIRKO mice had glucose intolerance after oral glucose challenges in association with impaired beta-cell function. Suprabasal area under the curve for C-peptide (AUCC-peptide) correlated linearly with suprabasal AUCglucose both in WT (r = 0.942, P = .017) and DIRKO mice (r = 0.972, P = .006). The slope of this regression was lower in DIRKO than in WT mice (0.012 ± 0.006 vs 0.031 ± 0.006 nmol C-peptide/mmol glucose, P = .042). In contrast, there was no difference in the insulin response to intravenous glucose between WT and DIRKO mice. Furthermore, oral and intravenous glucose administration at matching glucose levels showed that the augmentation of insulin secretion after oral glucose (the incretin effect) in WT mice (11.8 ± 2.3 nmol/L min) was entirely absent in DIRKO mice (3.3 ± 1.2 nmol/L min). We conclude that GIP and GLP-1 are required for normal glucose tolerance and beta-cell function after oral glucose in mice, that they are the sole incretin hormones after oral glucose at higher dose levels, and that they contribute by 65% to insulin secretion after oral glucose.

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 Gastric inhibitory polypeptide is the major insulinotropic factor in K(ATP) null mice

2004 ◽  
pp. 407-412 ◽  
Author(s):  
K Tsukiyama ◽  
Y Yamada ◽  
K Miyawaki ◽  
A Hamasaki ◽  
K Nagashima ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Knockout Mice ◽  
Insulin Response ◽  
Gastric Inhibitory Polypeptide ◽  
Tolerance Test ◽  
Insulin Tolerance Test ◽  
Oral Glucose ◽  
Double Knockout ◽  
Insulin Tolerance ◽  
Deficient Mice

OBJECTIVE: ATP-sensitive K(+) (K(ATP)) channels in pancreatic beta-cells are crucial in the regulation of glucose-induced insulin secretion. Recently, K(ATP) channel-deficient mice were generated by genetic disruption of Kir6.2, the pore-forming component of K(ATP) channels, but the mice still showed a significant insulin response after oral glucose loading in vivo. Gastric inhibitory polypeptide (GIP) is a physiological incretin that stimulates insulin release upon ingestion of nutrients. To determine if GIP is the insulinotropic factor in insulin secretion in K(ATP) channel-deficient mice, we generated double-knockout Kir6.2 and GIP receptor null mice and compared them with Kir6.2 knockout mice. METHODS: Double-knockout mice were generated by intercrossing Kir6.2-knockout mice with GIP receptor-knockout mice. An oral glucose tolerance test, insulin tolerance test and batch incubation study of pancreatic islets were performed on double-knockout mice and Kir6.2-knockout mice. RESULTS: Fasting glucose and insulin levels were similar in both groups. After oral glucose loading, blood glucose levels of double-knockout mice became elevated compared with Kir6.2-knockout mice, especially at 15 min (345+/-10 mg/dl vs 294+/-20 mg/dl, P<0.05) and 30 min (453+/-20 mg/dl vs 381+/-26 mg/dl, P<0.05). The insulin response was almost completely lost in double-knockout mice, although insulin secretion from isolated islets was stimulated by another incretin, glucagon-like peptide-1 in the double-knockout mice. Double-knockout mice and Kir6.2-knockout mice were similarly insulin sensitive as assessed by the insulin tolerance test. CONCLUSION: GIP is the major insulinotropic factor in the secretion of insulin in response to glucose load in K(ATP) channel-deficient mice.

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