Glucagonproducing

Glucagon-producing refers to cells and tissues capable of producing glucagon, a peptide hormone that raises blood glucose levels. The primary source is the alpha cells of the pancreatic islets (islets of Langerhans). A secondary, much smaller source exists in the gut from proglucagon-expressing enteroendocrine cells, though processing in these cells often yields other peptides such as GLP-1.

Biosynthesis and processing involve the GCG gene, which encodes proglucagon. In pancreatic alpha cells, proglucagon is cleaved by prohormone convertase 2 to produce glucagon. In intestinal L cells, proglucagon is cleaved by PC1/3 to yield GLP-1, GLP-2, and related peptides; glucagon itself is produced in smaller amounts in the gut.

Physiological role centers on maintaining glucose homeostasis. Glucagon acts on hepatocyte receptors to activate adenylate cyclase, increasing cAMP and promoting glycogenolysis and gluconeogenesis, thereby increasing hepatic glucose output during fasting. It also stimulates lipolysis and ketogenesis during prolonged fasting.

Regulation involves several signals. Glucagon secretion is stimulated by low blood glucose, elevated amino acids, and sympathetic activity; it is inhibited by high glucose, insulin, and somatostatin. In conditions such as type 2 diabetes or insulin deficiency, glucagon regulation can be impaired, contributing to hyperglycemia.

Clinical relevance includes cases of excess glucagon production, such as glucagon-secreting tumors (glucagonoma) that may cause weight loss and necrolytic migratory erythema. Conversely, glucagon is used clinically to treat severe hypoglycemia. Understanding glucagon-producing cells is important for metabolic regulation and diabetes management.