Glucagon Receptor Knockout Prevents Insulin-Deficient Type 1 Diabetes in Mice

  1. Roger H. Unger1,3
  1. 1Touchstone Center for Diabetes Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas
  2. 2Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York
  3. 3VA North Texas Health Care System, Dallas, Texas
  1. Corresponding author: Roger H. Unger, roger.unger{at}utsouthwestern.edu.

Abstract

OBJECTIVE To determine the role of glucagon action in the metabolic phenotype of untreated insulin deficiency.

RESEARCH DESIGN AND METHODS We compared pertinent clinical and metabolic parameters in glucagon receptor-null (Gcgr−/−) mice and wild-type (Gcgr+/+) controls after equivalent destruction of β-cells. We used a double dose of streptozotocin to maximize β-cell destruction.

RESULTS Gcgr+/+ mice became hyperglycemic (>500 mg/dL), hyperketonemic, polyuric, and cachectic and had to be killed after 6 weeks. Despite comparable β-cell destruction in Gcgr−/− mice, none of the foregoing clinical or laboratory manifestations of diabetes appeared. There was marked α-cell hyperplasia and hyperglucagonemia (∼1,200 pg/mL), but hepatic phosphorylated cAMP response element binding protein and phosphoenolpyruvate carboxykinase mRNA were profoundly reduced compared with Gcgr+/+ mice with diabetes—evidence that glucagon action had been effectively blocked. Fasting glucose levels and oral and intraperitoneal glucose tolerance tests were normal. Both fasting and nonfasting free fatty acid levels and nonfasting β-hydroxy butyrate levels were lower.

CONCLUSIONS We conclude that blocking glucagon action prevents the deadly metabolic and clinical derangements of type 1 diabetic mice.

Footnotes

  • Received April 1, 2010.
  • Accepted October 24, 2010.

Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered. See http://creativecommons.org/licenses/by-nc-nd/3.0/ for details.

| Table of Contents