Plasma glucagon-like immunoreactivity (GLI) in dogs

Area of Science:

• Gastroenterology
• Endocrinology
• Metabolic Research

Background:

• Gut hormones play a crucial role in glucose homeostasis and insulin secretion.
• Glucagon-like immunoreactivity (GLI) is a key gut hormone involved in these processes.
• Understanding the characteristics of circulating GLI is essential for elucidating its physiological functions.

Purpose of the Study:

• To compare the molecular size and insulin-releasing activity of gut glucagon-like immunoreactivity (GLI) extracted from dog plasma with that extracted from the intestine.
• To determine if plasma-derived GLI retains the biological activity of its intestinal counterpart.

Main Methods:

• Plasma was collected from the portal vein of dogs following intestinal glucose administration and rapid pancreatic removal.
• Gut GLI was extracted from plasma using a modified Kenny's method.
• Molecular size was analyzed using gel filtration, and insulin-releasing activity was assessed by intrapancreatic infusion in dogs.

Main Results:

• Extractable GLI from dog plasma ranged from 4.30 to 25.74 ng.
• Gel filtration of plasma GLI revealed two peaks (Peak I and Peak II), consistent with intestinal GLI.
• Intrapancreatic infusion of Peak II plasma GLI significantly stimulated insulin release, similar to pancreatic glucagon.
• Peak I plasma GLI showed minimal insulin-releasing activity.

Conclusions:

• Gut GLI extracted from dog plasma exhibits identical molecular size distribution (elution pattern) on gel filtration as GLI extracted from the gut.
• Plasma-derived gut GLI possesses comparable insulin-releasing activity to intestinal GLI, particularly the Peak II fraction.
• These findings confirm that circulating GLI reflects the characteristics and biological activity of the GLI produced in the gut.