What is the action of somatostatin in the endocrine system?

Somatostatin is a peptide hormone produced primarily by the delta cells of the pancreatic islets, as well as in the hypothalamus and gastrointestinal tract. Its main function within the endocrine system is to inhibit the secretion of various hormones, notably growth hormone (GH) and insulin.

By inhibiting growth hormone secretion, somatostatin regulates growth and metabolic processes, preventing excessive levels that could lead to conditions such as acromegaly or gigantism. Additionally, by also inhibiting insulin secretion, somatostatin can help regulate blood glucose levels, thereby playing a critical role in glucose metabolism.

In the broader context of hormone regulation, somatostatin serves as a key regulatory peptide that maintains balance in hormone secretion. This is particularly important in the context of the gastrointestinal tract, where it reduces gut motility and secretion of other digestive hormones, thereby moderating digestive processes.

The other options suggest actions that are not aligned with the known functions of somatostatin. For example, increasing hormone secretion or promoting releases contrasts with the inhibitory role that somatostatin serves, confirming that the correct answer focuses on its inhibitory functions in the endocrine system.