Abstract

Introduction: Radiolabeled Exendin-4, a synthetic glucagon-like peptide-1 (GLP-1) analog, is used as a tracer for diagnostic purposes of beta-cells and in experimental animal research. Exendin-4 can be radiolabeled with Ga-68, I-111 n or (99)mTc and used for positron emission tomography (PET) and single-photon emission computed tomography (SPECT) imaging to diagnose insulinomas, visualization of pancreatic beta-cell mass and transplanted Islets of Langerhans. In humans, Exendin-4 is widely used as a therapeutic agent for treatment of type 2 diabetes (T2D). The compound, which is administered subcutaneously (SC) may cause nausea, vomiting and a minor increase in the heart rate (HR). However, possible side-effects on cardiovascular functions after intravenous (IV) administration have not been reported. This study describes the Exendin-4 dose at which cardiovascular side-effects occur in pigs and cynomolgus monkeys. The IV effect of the tracer on insulin secretion is also investigated in pigs.Methods: Seven clinically healthy littermate pigs (40 days old) were used; three of them were made diabetic by streptozotocin (STZ). All pigs underwent PET imaging under general anesthesia to examine the glucagon-like peptide-1 receptor (GLP-1R) in beta-cells with radiolabeled Exendin-4. A baseline tracer dose IV [Ga-68]Exendin-4 (0.025 +/- 0.010 mu g/kg) followed by a competition dose IV [Ga-68]Exendin-4 (3.98 +/- 133 mu g/kg) 60 min later were administered. Blood samples were taken and analyzed for insulin secretion by using ELISA. Cardiovascular and respiratory variables were monitored throughout the experiment.Results: Immediately after administration of the high dose [Ga-68]Exendin-4 the HR rose from 122 14 to 227 +/- 40 bpm (p < 0.01) and from 100 +/- 5 to 181 +/- 13 bpm (p < 0.01) in healthy non -diabetic and diabetes-induced pigs, respectively. The tachycardia was observed for >2 h and one healthy non-diabetic pig suffered cardiac arrest 3 h after the IV [Ga-68]Exendin-4. Arrhythmia was detected by listening to the heart with a stethoscope up to 4 days after the [Ga-68]Exendin-4 injection. In all animals, no effect on the cardiovascular system was registered after the low dose of IV [Ga-68]Exendin-4. Insulin secretion increased (p < 0.05) when IV [Ga-68]Exendin-4 was given in dosages >= 0.14 mu g/kg.Conclusions: Intravenous administration of mu g/kg [Ga-68]Exendin-4 resulted in severe tachycardia and arrhythmias in healthy non -diabetic and diabetes-induced pigs, and the insulin secretion was stimulated in healthy non diabetic animals when >= 0.14 mu g/kg [Ga-68]Exendin-4 was given. (C) 2016 Elsevier Inc. All rights reserved.

Keywords

Exenatide; Adverse-effects; Tachycardia; Arrhythmias; Swine; Imaging; PET; Monkeys

Published in

Nuclear Medicine and Biology
2016, Volume: 43, number: 7, pages: 397-402
Publisher: ELSEVIER SCIENCE INC

SLU Authors

• Rydén, Anneli

  • Department of Clinical Sciences, Swedish University of Agricultural Sciences
    

• Nyman, Görel

  • Department of Clinical Sciences, Swedish University of Agricultural Sciences
    

• Nalin, Lovisa

  • Department of Clinical Sciences, Swedish University of Agricultural Sciences
    

• Andréasson, Susanne

  • Department of Clinical Sciences, Swedish University of Agricultural Sciences
    

• Jensen Waern, Marianne

  • Department of Clinical Sciences, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Clinical Science


Publication identifier

DOI: https://doi.org/10.1016/j.nucmedbio.2016.04.002

Permanent link to this page (URI)

https://res.slu.se/id/publ/83099