What substance inhibits the secretion of glucagon?

Insulin and somatostatin are the substances that inhibit the secretion of glucagon. Insulin, produced by the pancreatic beta cells, plays a pivotal role in glucose homeostasis. When blood glucose levels rise, insulin is released not only to promote glucose uptake by tissues but also to suppress the secretion of glucagon from the alpha cells of the pancreas. This helps to prevent further release of glucose into the bloodstream, maintaining tighter control over blood sugar levels.

Somatostatin, which is produced by D cells in the pancreatic islets, further enhances this inhibitory effect on glucagon secretion. Somatostatin acts as a paracrine regulator, inhibiting both insulin and glucagon secretion, thereby playing a crucial role in balancing the actions of these two hormones.

The understanding of these interactions is fundamental, as the balance between insulin and glucagon is crucial to maintaining metabolic homeostasis in the body. In contrast, other options do not play a direct role in inhibiting glucagon secretion.