Glucagon

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Glucagon glucagonreceptor

Glucagon is a peptide hormone, produced by alpha cells of the pancreas, that raises blood glucose levels. Its effect is opposite to that of insulin, which lowers blood glucose levels.

Glucagon Activation

Biochemical Structure and Synthesis

Glucagon is a 29-amino acid polypeptide. Its primary structure contains a single chain, and it is synthesized as a part of a larger molecule called preproglucagon in the pancreatic alpha cells. This preproglucagon is then cleaved and processed into the active form of glucagon.

Physiological Role

The primary role of glucagon is to maintain the body's glucose levels, counteracting the effect of insulin. Glucagon promotes glycogenolysis, the breakdown of glycogen stored in the liver into glucose, which is then released into the bloodstream. Additionally, it encourages gluconeogenesis, the production of glucose from non-carbohydrate sources.

Glucagon and Disease

Glucagon plays a role in the pathophysiology of diabetes mellitus. In type 1 diabetes, the loss of insulin production is often accompanied by a relative increase in glucagon, leading to excessive glucose production by the liver. In type 2 diabetes, glucagon levels may also be elevated, contributing to hyperglycemia. Researchers are investigating therapies that target glucagon receptors to manage glucose levels in diabetes.

Measurement and Clinical Significance

Glucagon levels in the blood can be measured and can provide important information about a person's glucose metabolism. Abnormally high levels of glucagon can be an indicator of a glucagonoma, a rare type of pancreatic neuroendocrine tumor.

See Also

• Insulin
• Pancreas
• Diabetes mellitus