Metabolic Effects of Glucagon

Glucagon is a catabolic hormone that promotes the maintenance of blood glucose levels. Its primary target is the liver.
1. Effects on carbohydrate metabolism: The IV administration of glucagon leads to an immediate rise in blood glucose. This results from an increase in the degradation of liver glycogen and an increase in hepatic gluconeogenesis.
2. Effects on lipid metabolism: The primary effect of glucagon on lipid metabolism is inhibition of FA synthesis through phosphorylation and subsequent inactivation of ACC by adenosine monophosphate (AMP)– activated protein kinase . The resulting decrease in malonyl CoA production removes the inhibition on long-chain FA β-oxidation . Glucagon also plays a role in lipolysis in adipocytes, but the major activators of hormone-sensitive lipase (via phosphorylation by protein kinase A) are the catecholamines. The free FA released are taken up by liver and oxidized to acetyl CoA, which is used in ketone body synthesis.
3. Effects on protein metabolism: Glucagon increases uptake by the liver of amino acids supplied by muscle, resulting in increased availability of carbon skeletons for gluconeogenesis. As a consequence, plasma levels of amino acids are decreased.

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