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Review

99mTc-Hydrazinonicotinamide-aminohexanoic acid-Lys40-exendin-4

Kam Leung  1
In: Molecular Imaging and Contrast Agent Database (MICAD) [Internet]. Bethesda (MD): National Center for Biotechnology Information (US); 2004.
[updated ].
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Review

99mTc-Hydrazinonicotinamide-aminohexanoic acid-Lys40-exendin-4

Kam Leung.
Free Books & Documents

Excerpt

Glucagon-like peptide-1 (GLP-1, 30 amino acids) is secreted from enteroendocrine cells of the distal small intestine in response to food ingestion (1). GLP-1 plays an important role in glucose metabolism and homeostasis. It inhibits gastric emptying, glucagon secretion, and glucose production (2). In addition, it induces insulin release from the pancreatic β-cells as well as their proliferation. The GLP-1 receptor has been identified in normal tissues such as the pancreas, stomach, brain, and lung, and it has been shown to be highly overexpressed in human insulinomas and gastrinomas (3). In insulinomas, GLP-1 receptor density is considerably greater, and the GLP-1 receptor is more frequently observed than somatostatin receptors.

Exendin-4 is a GLP-1 analog with 39 amino acids isolated from the venom of the Gila monster (Heloderma suspectum) (4). Exendin-4 and GLP-1 share a 53% amino acid sequence homology. Exendin-4 is a more potent and longer-lasting GLP-1 receptor agonist than GLP-1. Exendin-4 is resistant to cleavage by dipeptidyl peptidase IV, whereas the first two N-terminal amino acids of GLP-1 are rapidly cleaved. Exenatide, a synthetic version of exendin-4, is the first GLP-1 mimetic recently approved by the United States Food and Drug Administration (FDA) for use in select patients with type 2 diabetes (5). 99mTc-Hydrazinonicotinamide-aminohexanoic acid-Lys40-exendin-4 ([Lys40(Ahx-HYNIC-99mTc)NH2]-exendin-4) is being developed for single-photon emission computed tomography (SPECT) imaging of the GLP-1 receptor (6).

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References

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