Presence and characterization of glucagon-like peptide-1(7-36) amide receptors in solubilized membranes of rat adipose tissue.

Abstract

Specific binding of [125I]glucagon-like peptide-1(7-36)amide ([125I]GLP-1(7-36)amide) to solubilized rat adipose tissue membranes was found to be dependent on temperature, time, and membrane protein concentration and readily dissociated. GLP-1(1-36)amide, GLP-2, or glucagon (10(-6) M) did not compete with [125I]GLP-1(7-36)amide binding. Half-maximal binding was achieved with 8 x 10(-10) M unlabeled GLP-1(7-36)amide, and the Scatchard plot revealed the presence of high and low affinity binding sites with Kd values of approximately 0.6 and 20 nM, respectively. The binding capacity of [125I]GLP-1(7-36)amide was about 3 times higher than that of [125I]glucagon, while the high affinity Kd and the half-maximal binding of the two peptides were similar. The presence and abundance of GLP-1(7-36)amide receptors in fat tissue together with the previous findings that the peptide stimulates glycerol and cAMP production in rat adipocytes and stimulates fatty acid synthesis in explants of rat adipose tissue open the possibility that this insulinotropic intestinal peptide may also be involved in the regulation of lipid metabolism in health and disease.

The expression of GLP‐1 receptor mRNA and protein allows the effect of GLP‐1 on glucose metabolism in the human hypothalamus and brainstem

“…These results are comparable with those obtained in membrane fractions from rat brain (Calvo et al . 1995) and rat adipose tissue (Valverde et al . 1993).…”

Glucagon-like peptide-1: a potent regulator of food intake in humans

“…Furthermore, GLP-1 receptors have been found in the endocrine pancreas,24 adipose tissue,25and stomach 2627 Moreover, nerves containing GLP-1 have been identified in the brain 28…”

Inositolphosphoglycans possibly mediate the effects of glucagon-like peptide-1(7-36)amide on rat liver and adipose tissue

“…7,8 Also, GLP-1 was shown to stimulate basal and/or insulin-induced glucose transport in rat adipocytes 8,17 and 3T3-L1 cells, 35 and to increase glycogen synthesis in rat fat pieces. 8 By [ 125 I]GLP-1 binding studies, speci®c GLP-1 receptors were found in solubilized membranes of rat 13 and human adipose tissue, 12 and by PCR and Southern blot analysis, using the pancreatic GLP-1 receptor cDNA probe, the presence of mRNA for this receptor in rat epididymal fat and 3T3-L1 adipocytes was detected. 11 The exact structure of the GLP-1 receptors in this tissue, and in liver, remain to be elucidated, however.…”