Exendin-3 (9-39) amide is a truncated form of the exendin-4 (48-86) amide peptide that acts as a potent competitive antagonist for the glucagon-like peptide 1 receptor (GLP-1R; Kd = 1.7 nM in CHL cells transfected with cloned human GLP-1).[1] It inhibits exendin-3-induced increases in cAMP levels in guinea pig pancreas cells (IC50 = 20 nM).[2] Exendin-3 (9-39) amide administration in the hypothalamus (10 and 100 µg, i.c.v.) reverses GLP-1 inhibition of feeding behavior in rats.[3]
References:
[1].Thorens, B., Porret, A., Bühler, L., et al.Cloning and functional expression of the human islet GLP-1 receptor. Demonstration that exendin-4 is an agonist and exendin-(9-39) an antagonist of the receptorDiabetes42(11)1678-1682(1993).
[2].Ruffman, J.-P., Singh, L., and Eng, J.Exendin-3, a novel peptide from Heloderma horridum venom, interacts with vasoactive intestinal peptide receptors and a newly described receptor on dispersed acini from guinea pig pancreas. Description of exendin-3(9-39) amide, a specific exendin receptor antagonistJ. Biol. Chem.266(5)2897-2908(1991).
[3].Turton, M.D., O'Shea, D., Gunn, I., et al.A role for glucagon-like peptide-1 in the central regulation of feedingNature379(6560)69-72(1996).