Biomaterial Database

Islet somatostatin--microvascular, paracrine, and pulsatile regulation. 1990

E Samols, and J I Stagner

VA Medical Center, Louisville, KY 40206.

The possible role of the D cell in the regulation of islet hormone secretion has been controversial for many years. It is known that the D cells characteristically reside in the islet mantle interspaced among A cells. We have shown by the anterograde and retrograde infusion of antibody directed against insulin, glucagon, or somatostatin into the isolated rat and dog pancreas that blood flow within the islet is from the B-cell core outward to the mantle. Despite the apparent randomness of the A and D cell in the mantle, our results indicate a further suborder of cellular perfusion in the mantle with the A cells perfused before the D cells. The D cells are last in line in terms of secretion. Thus the D cell is vascularly neutral and cannot directly effect A- or B-cell secretion through the intra-islet vasculature. Our results demonstrate that the B to A to D cellular order of perfusion is responsible for the regulation of islet hormone secretion, ie, insulin regulates the secretion of glucagon and glucagon (and probably insulin) regulate the secretion of somatostatin. Although each hormone is secreted as pulses, there does not appear to be a consistent phase relationship between insulin, glucagon, or somatostatin. The B to A to D cellular order of perfusion is responsible for net and integrated hormone secretion, but may not be the motive force of pulsatile secretion. Our studies have not documented a role for intra-islet mantle somatostatin. These results strongly suggest that the D cell is not a paracrine regulator of islet hormone secretion, but may be important in the regulation of exocrine function.

UI	MeSH Term	Description	Entries
D007515	Islets of Langerhans	Irregular microscopic structures consisting of cords of endocrine cells that are scattered throughout the PANCREAS among the exocrine acini. Each islet is surrounded by connective tissue fibers and penetrated by a network of capillaries. There are four major cell types. The most abundant beta cells (50-80%) secrete INSULIN. Alpha cells (5-20%) secrete GLUCAGON. PP cells (10-35%) secrete PANCREATIC POLYPEPTIDE. Delta cells (~5%) secrete SOMATOSTATIN.	Islands of Langerhans,Islet Cells,Nesidioblasts,Pancreas, Endocrine,Pancreatic Islets,Cell, Islet,Cells, Islet,Endocrine Pancreas,Islet Cell,Islet, Pancreatic,Islets, Pancreatic,Langerhans Islands,Langerhans Islets,Nesidioblast,Pancreatic Islet
D008833	Microcirculation	The circulation of the BLOOD through the MICROVASCULAR NETWORK.	Microvascular Blood Flow,Microvascular Circulation,Blood Flow, Microvascular,Circulation, Microvascular,Flow, Microvascular Blood,Microvascular Blood Flows,Microvascular Circulations
D010187	Pancreatic Hormones	Peptide hormones secreted into the blood by cells in the ISLETS OF LANGERHANS of the pancreas. The alpha cells secrete glucagon; the beta cells secrete insulin; the delta cells secrete somatostatin; and the PP cells secrete pancreatic polypeptide.	Hormones, Pancreatic
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D013004	Somatostatin	A 14-amino acid peptide named for its ability to inhibit pituitary GROWTH HORMONE release, also called somatotropin release-inhibiting factor. It is expressed in the central and peripheral nervous systems, the gut, and other organs. SRIF can also inhibit the release of THYROID-STIMULATING HORMONE; PROLACTIN; INSULIN; and GLUCAGON besides acting as a neurotransmitter and neuromodulator. In a number of species including humans, there is an additional form of somatostatin, SRIF-28 with a 14-amino acid extension at the N-terminal.	Cyclic Somatostatin,Somatostatin-14,Somatotropin Release-Inhibiting Hormone,SRIH-14,Somatofalk,Somatostatin, Cyclic,Somatotropin Release-Inhibiting Factor,Stilamin,Somatostatin 14,Somatotropin Release Inhibiting Factor,Somatotropin Release Inhibiting Hormone
D017481	Receptors, Somatostatin	Cell surface proteins that bind somatostatin and trigger intracellular changes which influence the behavior of cells. Somatostatin is a hypothalamic hormone, a pancreatic hormone, and a central and peripheral neurotransmitter. Activated somatostatin receptors on pituitary cells inhibit the release of growth hormone; those on endocrine and gastrointestinal cells regulate the absorption and utilization of nutrients; and those on neurons mediate somatostatin's role as a neurotransmitter.	Receptors, Somatotropin Release Inhibiting Hormone,Somatostatin Receptors,Receptors, SRIH,SRIH Receptors,Somatostatin Receptor,Receptor, Somatostatin
D017981	Receptors, Neurotransmitter	Cell surface receptors that bind signalling molecules released by neurons and convert these signals into intracellular changes influencing the behavior of cells. Neurotransmitter is used here in its most general sense, including not only messengers that act to regulate ion channels, but also those which act on second messenger systems and those which may act at a distance from their release sites. Included are receptors for neuromodulators, neuroregulators, neuromediators, and neurohumors, whether or not located at synapses.	Neurohumor Receptors,Neuromediator Receptors,Neuromodulator Receptors,Neuroregulator Receptors,Receptors, Neurohumor,Receptors, Synaptic,Synaptic Receptor,Synaptic Receptors,Neuromediator Receptor,Neuromodulator Receptor,Neuroregulator Receptor,Neurotransmitter Receptor,Receptors, Neuromediators,Receptors, Neuromodulators,Receptors, Neuroregulators,Receptors, Neurotransmitters,Neuromediators Receptors,Neuromodulators Receptors,Neuroregulators Receptors,Neurotransmitter Receptors,Neurotransmitters Receptors,Receptor, Neuromediator,Receptor, Neuromodulator,Receptor, Neuroregulator,Receptor, Neurotransmitter,Receptor, Synaptic,Receptors, Neuromediator,Receptors, Neuromodulator,Receptors, Neuroregulator