MICROANATOMY

Detailed explanation-1: -Somatostatin (SST) potently inhibits insulin and glucagon release from pancreatic islets. Five distinct membrane receptors (SSTR1-5) for SST are known, and at least two (SSTR2 and SSTR5) have been proposed to regulate pancreatic endocrine function.

Detailed explanation-2: -Results: A tonic inhibitory role of somatostatin was demonstrated with infusion of somatostatin receptor antagonists, which significantly increased glucagon secretion at low and high glucose, whereas insulin secretion was only increased at high glucose levels.

Detailed explanation-3: -These results show that somatostatin lowers blood glucose concentrations as a secondary effect of inhibition of glucagon secretion.

Detailed explanation-4: -The most potent regulator of glucagon secretion is circulating glucose. Hypoglycemia stimulates the pancreatic alpha cell to release glucagon and hyperglycemia inhibits glucagon secretion (Fig.