Identification of specific binding sites for glucagon-like peptide-1 on the posterior lobe of the rat pituitary
Abstract
Glucagon-like peptide-1 (GLP-1) immunoreactivity has been found in autonomic and neuroendocrine brain regions, whereas only limited data are available regarding the characterization and localization of brain GLP-1 receptors. In the present study, using quantitative in vitro autoradiography, a high density of specific binding sites for GLP-1 was characterized on sections of the posterior pituitary lobe of the rat. Low specific binding of radiolabeled GLP-1 was found in the anterior lobe and no specific binding in the intermediate lobe. To examine the specificity of GLP-1 binding sites, sections of the posterior lobe were incubated with radiolabeled GLP-1 in the presence of various peptides. Radiolabeled [Tyr39]exendin-4, a specific GLP-1 agonist, bound to these receptor sites with the same affinity as GLP-1, while glucagon and vasoactive intestinal peptide (VIP) were unable to displace 125I-GLP-1. Both unlabeled exendin-4 and GLP-1 inhibited this binding with equally high affinity. Using 125I-[Tyr39]exendin-4 as radiolabel, the concentration of biding sites was found to be 7.8 +/- 0.4 fmol/mg tissue. Further analysis of the binding data from experiments with tissue slices revealed the presence of high and low affinity binding si...Continue Reading
Citations
Interactions between gastric emptying and satiety, with special reference to glucagon-like peptide-1
Target-mediated pharmacokinetic and pharmacodynamic model of exendin-4 in rats, monkeys, and humans.
Related Concepts
Related Feeds
Cardiovascular Biology of GLP-1
Glucagon-like peptide 1 (GLP-1) plays a role in glucose metabolism, energy homeostasis, and inflammation suppression. GLP-1 receptor signaling has been shown to impact cardiovascular function. This feed focuses on the role of GLP-1 and GLP-1 receptor agonists on cardiovascular biology.