Glucagonostatic and Insulinotropic Action of Glucagonlike Peptide I-(7–36)-Amide

Ryoya Komatsu; Tatsuo Matsuyama; Mitsuyoshi Namba; Nobuaki Watanabe; Hidehiko Itoh; Norio Kono; Seiichiro Tarui

doi:10.2337/diab.38.7.902

Original Articles

Glucagonostatic and Insulinotropic Action of Glucagonlike Peptide I-(7–36)-Amide

Ryoya Komatsu,
Tatsuo Matsuyama,
Mitsuyoshi Namba,
Nobuaki Watanabe,
Hidehiko Itoh,
Norio Kono and
Seiichiro Tarui

The Second Department of Internal Medicine, Osaka University Medical School, and the Division of Clinical Laboratory, National Cardiovascular Center Hospital Osaka, Japan

Address correspondence and reprint requests to Ryoya Komatsu, MD, The Second Department of Internal Medicine, Osaka University Medical School, 1–1–50, Fukushima, Fukushima-ku, Osaka 553, Japan.

Diabetes 1989 Jul; 38(7): 902-905. https://doi.org/10.2337/diab.38.7.902

Abstract

We examined the effect of glucagonlike peptides (GLPs), which are cleaved from preproglucagon in the enteroglucagon cells, on rat endocrine pancreas with the isolated perfused system. GLP-I-(7–36)-amide, a truncated form of full-sequence GLP-I-(1–37), showed a potent inhibitory effect on glucagon secretion. This inhibitory effect of GLP-I-(7–36)-amide was demonstrated at concentrations of 0.25, 2.5, and 25 nM in 11.2 and 2.8 mM glucose. In contrast, insulin release was significantly stimulated by GLP-I-(7–36)-amide at its concentration from 0.025 to 25 nM in a high glucose concentration, whereas in a low glucose concentration, the stimulation was seen only at the highest concentration (25 nM). Neither GLP-I-(1–37) nor GLP-II showed any effect on glucagon and insulin release. Although several gastrointestinal hormones have been nominated as incretins, none of them may suppress the glucagon secretion. A truncated form of GLP-I, GLP-I-(7–36)-amide thus seems to be a unique incretin that exerts glucagonostatic action.