glucagon


Also found in: Dictionary, Thesaurus, Medical, Acronyms, Wikipedia.
Related to glucagon: somatostatin, glucagon test

glucagon

(glo͞o`kəgŏn), hormonehormone,
secretory substance carried from one gland or organ of the body via the bloodstream to more or less specific tissues, where it exerts some influence upon the metabolism of the target tissue.
..... Click the link for more information.
 secreted by the α cells of the islets of Langerhans, specific groups of cells in the pancreaspancreas
, glandular organ that secretes digestive enzymes and hormones. In humans, the pancreas is a yellowish organ about 7 in. (17.8 cm) long and 1.5 in. (3.8 cm) wide. It lies beneath the stomach and is connected to the small intestine at the duodenum (see digestive system).
..... Click the link for more information.
. It tends to counteract the action of insulininsulin,
hormone secreted by the β cells of the islets of Langerhans, specific groups of cells in the pancreas. Insufficiency of insulin in the body results in diabetes. Insulin was one of the first products to be manufactured using genetic engineering.
..... Click the link for more information.
, i.e., it raises the concentration of glucose in the blood. Glucagon was first purified and crystallized in 1955; the amino acid sequence of this 29-amino acid polypeptide (see peptidepeptide,
organic compound composed of amino acids linked together chemically by peptide bonds. The peptide bond always involves a single covalent link between the α-carboxyl (oxygen-bearing carbon) of one amino acid and the amino nitrogen of a second amino acid.
..... Click the link for more information.
) was published in 1956–57. One of the most important actions of glucagon is the promotion of glycogenolysis, i.e., the degradation of glycogenglycogen
, starchlike polysaccharide (see carbohydrate) that is found in the liver and muscles of humans and the higher animals and in the cells of the lower animals. Chemically it is a highly branched condensation polymer of glucose; it is readily hydrolyzed to glucose.
..... Click the link for more information.
 to glucose, in the liver. Glucagon stimulates adenyl cyclase, the enzyme that catalyzes the conversion of adenosine triphosphateadenosine triphosphate
(ATP) , organic compound composed of adenine, the sugar ribose, and three phosphate groups. ATP serves as the major energy source within the cell to drive a number of biological processes such as photosynthesis, muscle contraction, and the synthesis of
..... Click the link for more information.
 to 3′5′-cyclic adenosine monophosphateadenosine monophosphate
(AMP) , organic compound composed of an adenine base, the sugar ribose, and one phosphate unit. AMP is one of the possible products of the hydrolysis of adenosine triphosphate (ATP) and is therefore important in the transfer of chemical energy during
..... Click the link for more information.
 (cyclic AMP).

Glucagon

The protein hormone secreted by the pancreas which is known to influence a wide variety of metabolic reactions. Glucagon, along with insulin and other hormones, plays a role in the complex and dynamic process of maintaining adequate supplies of sugar in the blood. Glucagon has often been called the hyperglycemic-glycogenolytic factor because it causes the breakdown of liver glycogen to sugar (a process known as glycogenolysis) and thereby increases the concentration of sugar in the bloodstream (a condition known as hyperglycemia). Glucagon may also be involved in the regulation of protein and fat metabolism, gastric acid secretion and gut motility, excretion of electrolytes (such as sodium, potassium and chloride) by the kidney, contractility of heart muscle, and release of insulin from the pancreas. Glucagon is used in human medicine chiefly in certain diabetic conditions when a dangerously low blood sugar must be rapidly raised. See Carbohydrate metabolism, Glycogen, Hormone, Insulin, Pancreas

glucagon

[′glü·kə‚gän]
(biochemistry)
The protein hormone secreted by α-cells of the pancreas which plays a role in carbohydrate metabolism. Also known as hyperglycemic factor; hyperglycemic glycogenolytic factor.
References in periodicals archive ?
We believe needle-free glucagon nasal powder could positively impact the lives of those who use insulin and expand the community of people who could take action in a severe hypoglycemia emergency," said Dr.
Chronic and transitional regulation of gluconeogenesis and glyconeogenesis by insulin and glucagon in neonatal calf hepatocytes.
Professor Stephen Bloom, Head of Division of Diabetes, Endocrinology and Metabolism at Imperial College London said: "The hormones glucagon and GLP-1 are both used by the body to control blood sugar and metabolism, so there is great interest in utilising them to find new treatments for obesity and type 2 diabetes.
A test run of an "artificial pancreas" that monitors blood sugar and delivers both insulin and a regulatory hormone called glucagon helped patients achieve near-normal blood sugar levels for more than 24 hours, according to a new study.
Decreased glucagon secretion that reduces hepatic glucose production, thus reducing insulin demand.
A new glucagon therapy that can be stored in solution form at room temperature and supplied in a convenient injection device could be an important advance for patients.
The findings demonstrate that insulin can become completely superfluous and its absence does not cause diabetes or any other abnormality when the actions of glucagon are suppressed.
I think there is definitely potential for the glucagon receptor antagonists in diabetes, but there is also a risk of hypoglycemia associated with them.
Glucagonoma are rare slow-growing tumours of the pancreatic alpha cells that cause hypersecretion of glucagon with an incidence estimated to be one in 20 million people per annum.
alpha]-Cells secrete glucagon in response to low blood glucose, glucagon stimulates liver to release glucose through glycogenolys is and gluconeogenesis and it also stimulates adipose tissue to release fatty acids through lipolysis; [beta]-cells produce insulin that stimulate muscle, liver and adipose cells to store glucose for later use by synthesizing glycogen, protein and fats (Figure 1), [delta]-cells secrete somatostatin that inhibits insulin and glucagon release from their islet cells [10, 11].
L-dopa, clonidine and glucagon tests were administered to 32, 21 and 12 patients and positive responses to the tests were detected in 11 (34.
Heptares is also developing programmes focused on Class B receptors involved in metabolic disease, including GLP1 and glucagon receptors (diabetes), and has the potential to apply its platform to other Class B GPCRs that have been clinically validated across multiple disease areas.