What is somatostatin's primary function?

Somatostatin's primary function is to inhibit the secretion of various hormones. This peptide hormone, produced primarily by the delta cells of the pancreas as well as in the hypothalamus and gastrointestinal tract, acts as a regulator in the endocrine system. It plays a critical role in modulating the effects of other hormones, including insulin and glucagon, thereby maintaining homeostasis.

Somatostatin exerts its inhibitory effects not only on pancreatic hormones but also affects the secretion of growth hormone from the pituitary gland and various gastrointestinal hormones such as gastrin and vasoactive intestinal peptide (VIP). By suppressing these hormone release processes, somatostatin helps control physiological functions related to growth, metabolism, and digestion.

The other options incorrectly assign functions not aligned with somatostatin's role. For example, somatostatin does not stimulate growth hormone secretion; rather, it inhibits it. Additionally, it does not enhance insulin release nor promote glucagon release, as its primary function is to reduce hormone secretion overall, thereby acting as a brake on various endocrine functions.