During fasting, what type of receptor assists in maintaining serum glucose levels in the liver?

During fasting, the liver plays a crucial role in maintaining serum glucose levels through various metabolic processes, one of which involves the action of hormones that utilize specific types of receptors. G protein-coupled receptors (GPCRs) are particularly important in this context because they mediate the effects of hormones like glucagon and epinephrine on liver cells.

When fasting, glucagon is released from the pancreas and binds to its GPCR on hepatocytes (liver cells). This interaction activates intracellular signaling pathways, predominantly through the activation of adenylate cyclase, which increases the levels of cyclic AMP (cAMP). The rise in cAMP levels activates protein kinase A (PKA), leading to downstream effects that promote gluconeogenesis (the generation of glucose from non-carbohydrate substrates) and glycogenolysis (the breakdown of glycogen into glucose). These processes help elevate blood glucose levels, ensuring that the body's energy needs are met during periods without food intake.

In summary, GPCRs are integral to the liver's response to fasting, mediating the effects of glucagon and other hormones to regulate glucose production and maintain serum glucose levels. This underscores the complexity and efficiency of hormonal control in metabolic processes during fasting.