Figure 4.

Schematic representation of feedback regulation between the liver and the islet α‐cells. Glucagon is produced in islet α‐cells and the binding of glucagon‐to‐glucagon receptors in the liver increases the intracellular cyclic adenosine monophosphate level, which leads to an increase in hepatic glucose production and amino acid catabolism. Blockade of glucagon action results in an increase in the serum amino acid levels, and consequently promotes α‐cell proliferation. cAMP, cyclic adenosine monophosphate; GLP‐1, glucagon‐like peptide 1; GLP‐2, glucagon‐like peptide 2; GNAS, guanine nucleotide binding protein, alpha stimulating; GRPP, glicentin‐related pancreatic polypeptide; IP, intervening peptide.