Somatostatin

Information about Somatostatin


Somatostatin
Identifiers
Symbol	SST
Entrez	6750
HUGO	11329
OMIM	182450
RefSeq	NM_001048
UniProt	P61278
Other data
Locus	Chr. 3 q28

Somatostatin (also known as growth hormone inhibiting hormone (GHIH) or somatotropin release-inhibiting hormone (SRIF)) is a peptide hormone that regulates the endocrine system and affects neurotransmission and cell proliferation via interaction with G-protein-coupled somatostatin receptors and inhibition of the release of numerous secondary hormones.

Somatostatin has two active forms produced by alternative cleavage of a single preproprotein: one of 14 amino acids, the other of 28 amino acids.^[1]

Production

Digestive system

Somatostatin is secreted in several locations in the digestive system:

Brain

Somatostatin is produced by neuroendocrine neurons of the periventricular nucleus of the hypothalamus. These neurons project to the median eminence, where somatostatin is released from neurosecretory nerve endings into the hypothalamo-hypophysial portal circulation. These blood vessels carry somatostatin to the anterior pituitary gland, where somatostatin inhibits the secretion of growth hormone from somatotrope cells. The somatostatin neurons in the periventricular nucleus mediate negative feedback effects of growth hormone on its own release; the somatostatin neurons respond to high circulating concentrations of growth hormone and somatomedins by increasing the release of somatostatin, so reducing the rate of secretion of growth hormone.

Somatostatin is also produced by several other populations that project centrally - i.e. to other areas of the brain, and somatostatin receptors are expressed at many different sites in the brain. In particular, there are populations of somatostatin neurons in the arcuate nucleus, the hippocampus and the brainstem nucleus of the solitary tract.

Actions

D cell is visible at upper right, and somatostatinis represented by middle arrow pointing left

Somatostatin is classified as an inhibitory hormone,^[1] whose main actions are to:

Inhibit the release of growth hormone (GH)^[4] (thus opposing the effects of Growth Hormone-Releasing Hormone (GHRH))
Inhibit the release of thyroid-stimulating hormone (TSH)
Suppress the release of gastrointestinal hormones
Gastrin
Cholecystokinin (CCK)
Secretin
Motilin
Vasoactive intestinal peptide (VIP)
Gastric inhibitory polypeptide (GIP)
Enteroglucagon (GIP)
Lowers the rate of gastric emptying, and reduces smooth muscle contractions and blood flow within the intestine^[4]
Suppress the release of pancreatic hormones
Inhibit the release of insulin^[6]
Inhibit the release of glucagon^[6]
Suppress the exocrine secretory action of pancreas.

Synthetic substitutes

Octreotide (brand name Sandostatin, Novartis Pharmaceuticals) is an octopeptide that mimics natural somatostatin pharmacologically, though is a more potent inhibitor of growth hormone, glucagon, and insulin than the natural hormone.

References

1. ^ Physiology at MCG 5/5ch4/s5ch4_16
2. ^ Costanzo, LS. Board Review Series: Physiology 3rd Ed. Lippincott, Williams & Wilkins. 2003. p. 280.
3. ^
4. ^ [1]
5. ^
6. ^ Physiology at MCG 5/5ch4/s5ch4_17
7. ^

• • [ e] Endocrine system: hormones/endocrine glands (Peptide hormones, Steroid hormones)
Hypothalamic-pituitary	Hypothalamus: TRH, CRH , GnRH, GHRH, somatostatin, dopamine - Posterior pituitary: vasopressin, oxytocin - Anterior pituitary: α (FSH, LH, TSH), GH, prolactin, POMC (ACTH, MSH, endorphins, lipotropin)
Adrenal axis	Adrenal medulla: epinephrine, norepinephrine - Adrenal cortex: aldosterone, cortisol, DHEA
Thyroid axis	Thyroid: thyroid hormone (T₃ and T₄) - calcitonin - Parathyroid: PTH
Gonadal axis	Testis: testosterone, AMH, inhibin - Ovary: estradiol, progesterone, inhibin/activin, relaxin (pregnancy)
Other end. glands	Pancreas: glucagon, insulin, somatostatin - Pineal gland: melatonin
Non-end. glands	Placenta: hCG, HPL, estrogen, progesterone - Kidney: renin, EPO, calcitriol, prostaglandin - Heart atrium: ANP - Stomach: gastrin, ghrelin - Duodenum: CCK, GIP, secretin, motilin, VIP - Ileum: enteroglucagon - Adipose tissue: leptin, adiponectin, resistin - Thymus: Thymosin - Thymopoietin - Liver/other: Insulin-like growth factor (IGF-1, IGF-2)
Target-derived	NGF, BDNF, NT-3

• • [ e] Digestive system, physiology: gastrointestinal physiology
Enteric nervous system	Meissner's plexus - Auerbach's plexus
Exocrine	Chief cells (Pepsinogen) - Parietal cells (Gastric acid, Intrinsic factor) - Goblet cells (Mucus)
Endocrine/paracrine	G cells (gastrin), D cells (somatostatin) - ECL cells (Histamine) - enterogastrone: I cells (CCK), K cells (GIP), S cells (secretin)
Border	Brunner's glands - Paneth cells - Enterocytes
Fluids	Saliva - Bile - Intestinal juice - Gastric juice - Pancreatic juice
Processes	Swallowing - Vomiting - Peristalsis (Interstitial cell of Cajal) - Migrating motor complex - Borborygmus - Gastrocolic reflex - Segmentation contractions - Defecation

• • [ e] Peptides: neuropeptides
Hypothalamic	Somatostatin - CRH - GnRH - GHRH - Orexins - TRH - POMC (ACTH, MSH, Lipotropin)
Gastrointestinal hormones	Cholecystokinin - Gastric inhibitory polypeptide - Gastrin - Motilin - Secretin - Vasoactive intestinal peptide
Other hormones	Vasopressin - Calcitonin -
Other	Angiotensin - Bombesin/Neuromedin B - Calcitonin gene-related peptide - Carnosine - Delta sleep-inducing peptide - FMRFamide - Galanin - Gastrin releasing peptide - Kinins (Bradykinin, Tachykinins ) - Neuromedin (B, N, U) - Neuropeptide Y - Neurophysins - Neurotensin - Opioid peptide - Pancreatic polypeptide - Pituitary adenylate cyclase activating peptide

The Entrez Global Query Cross-Database Search System is a powerful federated search engine, or web portal that allows users to search many discrete health sciences databases at the National Center for Biotechnology Information (NCBI) website.
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Hugo is a male given name, a latinized form of the name Hugh, a German/Teutonic name meaning "Bright in Mind and Spirit".

Hugo is one of the most popular names in Europe ranking as high as #2 in France, #6 in Spain, and #7 in Belgium in 2006.
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The National Center for Biotechnology Information (NCBI) is part of the United States National Library of Medicine (NLM), a branch of the National Institutes of Health. The NCBI is located in Bethesda, Maryland and was founded in 1988.
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Swiss-Prot is a manually curated biological database of protein sequences. Swiss-Prot was created in 1986 by Amos Bairoch during his PhD and developed by the Swiss Institute of Bioinformatics and the European Bioinformatics Institute.
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locus (plural loci) is a fixed position on a chromosome, such as the position of a gene or a biomarker (genetic marker). A variant of the DNA sequence at a given locus is called an allele. The ordered list of loci known for a particular genome is called a genetic map.
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Peptide hormones are a class of peptides that are secreted into the blood stream and have endocrine functions in living animals.

Like other proteins, peptide hormones are synthesized from amino acids according to an mRNA template, which is itself synthesized from a DNA
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1. Pineal gland 2. Pituitary gland 3. Thyroid gland 4. Thymus 5. Adrenal gland 6. Pancreas 7. Ovary 8. Testes]]

The endocrine system
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Neurotransmission (latin: transmissio = passage, crossing; from transmitto = send, let through), also called synaptic transmission, is the transfer of signals between neurons.
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The term cell growth is used in two different ways in biology.

When used in the context of reproduction of living cells the phrase "cell growth" is shorthand for the idea of "growth in cell populations by means of cell reproduction.
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G protein-coupled receptors (GPCRs), also known as seven transmembrane receptors, 7TM receptors, heptahelical receptors, and G protein linked receptors (GPLR
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Identifiers
Symbol SSTR2

Entrez 6752
HUGO 11331
OMIM 182452

RefSeq NM_001050
UniProt P30874
Other data

Locus Chr. 17 q24

somatostatin receptor 4

Identifiers
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amino acid is a molecule that contains both amine and carboxyl functional groups. In biochemistry, this term refers to alpha-amino acids with the general formula H₂NCHRCOOH, where R is an organic substituent.
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In anatomy, the stomach is a bean-shaped hollow muscular organ of the gastrointestinal tract involved in the second phase of digestion, following mastication. The word stomach is derived from the Latin stomachus, which derives from the Greek word
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In anatomy, the intestine is the segment of the alimentary canal extending from the stomach to the anus and, in humans and other mammals, consists of two segments, the small intestine and the large intestine.
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Delta cells (δ-cells or D cells) are somatostatin producing cells.

They can be found in the stomach, intestine and the Islets of Langerhans in the pancreas.
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The pancreas is a gland organ in the digestive and endocrine systems of vertebrates<ref name="New Standard" />. It is both exocrine (secreting pancreatic juice containing digestive enzymes) and endocrine (producing several important hormones, including
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Neuroendocrine [IPA nʊəroʊˈɛndəkrɪn] cells are a specialized group of nerve cells (neurons) that produce hormones. These hormones may be amines, neuropeptides, or specialized amino acids.
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The Periventricular nucleus is a composite structure of the hypothalamus.

It should not be confused with the paraventricular nucleus.

External links

NeuroNames ancil-748

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The hypothalamus links the nervous system to the endocrine system via the pituitary gland (hypophysis). The hypothalamus, (from Greek ὑποθαλαμος = under the thalamus) is located below the thalamus, just above the brain stem.
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The median eminence is part of the inferior boundary for the hypothalamus part of the human brain. A small swelling on the tuber cinereum posterior to the infundibulum - atop the pituitary stalk - the median eminence
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The anterior pituitary (also called the adenohypophysis, from Greek adeno, "gland"; hypo, "under"; physis, "growth"; hence, glandular undergrowth) comprises the anterior lobe of the pituitary gland and is part of the endocrine system.
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Somatotropes are cells in the anterior pituitary which produce growth hormone. These cells constitute 40-50% of anterior pituitary cells. They respond by releasing HGH in response to GHRH (somatocrinin) or are inhibited by GHIH (somatostatin), both received from the hypothalamus
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Somatomedin is a hormone whose production is stimulated by somatotropin (STH) in order to promote cell growth and division.^[1]

They have similar biological effect to somatotropin or growth hormone.
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arcuate nucleus is an aggregation of neurons in the mediobasal hypothalamus, adjacent to the third ventricle and the median eminence. The arcuate nucleus includes several important populations of neurons, including:

Neuroendocrine neurons

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The hippocampus is a part of the forebrain, located in the medial temporal lobe. It forms a part of the limbic system and plays a part in memory and spatial navigation. Humans and other mammals have two hippocampi, one in each side of the brain.
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The solitary nucleus and tract are structures in the brainstem that carry and receive visceral sensation and taste from the facial (VII), glossopharyngeal (IX), vagus (X) cranial nerves, as well as the cranial part of the accessory nerve (XI).
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An Inhibitory Postsynaptic Potential (commonly abbreviated as IPSP) is the change in membrane voltage of a postsynaptic neuron which results from synaptic activation of inhibitory neurotransmitter receptors.
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Growth hormone (GH) or somatotropin (STH) is a protein hormone which stimulates growth and cell reproduction in humans and other animals. It is a 191-amino acid, single chain polypeptide hormone which is synthesized, stored, and secreted by the somatotroph
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Growth-hormone-releasing hormone (GHRH), also known as growth-hormone-releasing factor (GRF or GHRF) or somatocrinin, is a 44-amino acid peptide hormone produced in the arcuate nucleus of the hypothalamus.
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Thyroid-stimulating hormone (also known as TSH or thyrotropin) is a hormone synthesized and secreted by thyrotrope cells in the anterior pituitary gland which
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