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Somatostatin
 
 
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Somatostatin (also known as growth hormone inhibiting hormone (GHIH) or somatotropin release-inhibiting factor (SRIF)) is a peptide hormone
Peptide hormone

Peptide hormones are a class of peptide that are secreted into the blood stream and have endocrine functions in living animals. Peptide hormones are increasingly being identified in plants with important roles in cell-to-cell communication and plant defence....
 that regulates the endocrine system
Endocrine system

The endocrine system is a system of small organs that involve the release of extracellular signaling molecules known as hormones. The endocrine system is instrumental in regulating metabolism, human development , and tissue and also plays a part in determining Mood ....
 and affects neurotransmission
Neurotransmission

Neurotransmission , also called synaptic transmission, is an electrical movement within synapses caused by a propagation of nerve impulses....
 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 acid
Amino acid

In chemistry, an amino acid is a molecule containing both amine and carboxyl functional groups. These molecules are particularly important in biochemistry, where this term refers to alpha-amino acids with the general formula H2NCHRCOOH, where R is an organic substituent....
s, the other of 28 amino acids.


tostatin is produced by neuroendocrine
Neuroendocrine

Neuroendocrine [IPA n??ro?'?nd?kr?n] cells are cells that release a hormone into the circulating blood in response to a neural stimulus. These hormones may be amines, neuropeptides, or specialized amino acids....
 neurons of the periventricular nucleus
Periventricular nucleus

The Periventricular nucleus is a composite structure of the hypothalamus.It should not be confused with the paraventricular nucleus....
 of the hypothalamus
Hypothalamus

The hypothalamus is a portion of the brain that contains a number of small nuclei with a variety of functions. One of the most important functions of the hypothalamus is to link the nervous system to the endocrine system via the pituitary gland ....
.






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Somatostatin (also known as growth hormone inhibiting hormone (GHIH) or somatotropin release-inhibiting factor (SRIF)) is a peptide hormone
Peptide hormone

Peptide hormones are a class of peptide that are secreted into the blood stream and have endocrine functions in living animals. Peptide hormones are increasingly being identified in plants with important roles in cell-to-cell communication and plant defence....
 that regulates the endocrine system
Endocrine system

The endocrine system is a system of small organs that involve the release of extracellular signaling molecules known as hormones. The endocrine system is instrumental in regulating metabolism, human development , and tissue and also plays a part in determining Mood ....
 and affects neurotransmission
Neurotransmission

Neurotransmission , also called synaptic transmission, is an electrical movement within synapses caused by a propagation of nerve impulses....
 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 acid
Amino acid

In chemistry, an amino acid is a molecule containing both amine and carboxyl functional groups. These molecules are particularly important in biochemistry, where this term refers to alpha-amino acids with the general formula H2NCHRCOOH, where R is an organic substituent....
s, the other of 28 amino acids.

Production


Digestive system


Somatostatin is secreted in several locations in the digestive system:
  • stomach
    Stomach

    In most mammals, the stomach is a hollow muscular organ of the gastrointestinal tract involved in the second phase of digestion, following mastication....
  • intestine
    Intestine

    In anatomy, the intestine is the segment of the Gastrointestinal tract extending from the stomach to the anus and, in humans and other mammals, consists of two segments, the small intestine and the large intestine....
  • delta cells of the pancreas
    Pancreas

    The pancreas is a gland Organ in the digestive system and endocrine system of vertebrates. It is both an endocrine gland , as well as an exocrine gland, secreting pancreatic juice containing Digestion enzymes that pass to the small intestine....


Brain

Somatostatin is produced by neuroendocrine
Neuroendocrine

Neuroendocrine [IPA n??ro?'?nd?kr?n] cells are cells that release a hormone into the circulating blood in response to a neural stimulus. These hormones may be amines, neuropeptides, or specialized amino acids....
 neurons of the periventricular nucleus
Periventricular nucleus

The Periventricular nucleus is a composite structure of the hypothalamus.It should not be confused with the paraventricular nucleus....
 of the hypothalamus
Hypothalamus

The hypothalamus is a portion of the brain that contains a number of small nuclei with a variety of functions. One of the most important functions of the hypothalamus is to link the nervous system to the endocrine system via the pituitary gland ....
. These neurons project to the median eminence
Median eminence

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 lies in the area roughly bounded on its posterolateral region by the cerebral peduncles, and on its anterolateral region...
, 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
Somatotrope

Somatotropes are cells in the anterior pituitary which produce growth hormone. These cells constitute 30-40% of anterior pituitary cells. They respond by releasing HGH in response to GHRH or are inhibited by GHIH , both received from the hypothalamus via the hypophyseal portal system vein and the secondary plexus....
 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 somatomedin
Somatomedin

Somatomedin is a group of hormones that is produced, when stimulated by somatotropin , to promote cell growth and division . In this way, they mediate the effect of somatotropin ....
s 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
Arcuate nucleus

The 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, Centrally-projecting neurons and Others....
, the hippocampus
Hippocampus

The hippocampus is a brain structure located inside the medial temporal lobe of the cerebral cortex, and therefore is part of the telencephalon ....
 and the brainstem nucleus of the solitary tract.

Actions

Control of Stomach Acid Sec
Somatostatin is classified as an inhibitory hormone, whose actions are spread to different parts of the body:

Anterior pituitary

In the anterior pituitary gland, the effects of somatostatin are:
  • Inhibit the release of growth hormone
    Growth hormone

    Growth hormone is a peptide hormone. It stimulates human development 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 cells within the lateral wings of the anterior pituitary gland....
     (GH) (thus opposing the effects of Growth Hormone-Releasing Hormone (GHRH))
  • Inhibit the release of thyroid-stimulating hormone
    Thyroid-stimulating hormone

    Thyroid-stimulating hormone is a peptide hormone synthesized and secreted by thyrotrope cells in the anterior pituitary gland which regulates the endocrine function of the thyroid gland....
     (TSH)


Gastrointestinal system

  • Somatostatin suppresses the release of gastrointestinal hormone
    Gastrointestinal hormone

    The gastrointestinal hormones constitute a group of hormones secreted by enteroendocrine cells in the stomach, pancreas, and small intestine that control various functions of the digestive organs....
    s
    • Gastrin
      Gastrin

      In humans, gastrin is a hormone that stimulates secretion of gastric acid by the parietal cells of the stomach and aids in gastric motility. It is released by G cells in the stomach, duodenum, and the pancreas....
    • Cholecystokinin
      Cholecystokinin

      Cholecystokinin is a peptide hormone of the gastrointestinal system responsible for stimulating the digestion of fat and protein. Cholecystokinin, previously called pancreozymin, is synthesised by I-cells in the mucosal epithelium of the small intestine and secreted in the duodenum, the first segment of the small intestine, and ca...
       (CCK)
    • Secretin
      Secretin

      Secretin is a peptide hormone produced in the S cells of the duodenum in the crypts of Lieberk?hn. Its primary effect is to regulate the pH of the duodenal contents via the control of gastric acid secretion and buffering with bicarbonate....
    • Motilin
      Motilin

      Motilin is a 22 amino acid polypeptide hormone which in humans is encoded by the MLN gene.Motilin secreted by M cells that are numerous in crypts of the small intestine, especially in the duodenum and jejunum....
    • Vasoactive intestinal peptide
      Vasoactive intestinal peptide

      Vasoactive intestinal peptide is a peptide hormone containing 28 amino acid residue s and is produced in many areas of the human body including the gut, pancreas and suprachiasmatic nuclei of the hypothalamus in the brain....
       (VIP)
    • Gastric inhibitory polypeptide (GIP)
    • Enteroglucagon
      Enteroglucagon

      Enteroglucagon is a peptide hormone derived from preproglucagon. It is a gastrointestinal hormone, secreted from mucosal cells primarily of the Colon and terminal ileum....
  • Lowers the rate of gastric emptying, and reduces smooth muscle contractions and blood flow within the intestine
  • Suppresses the release of pancreatic hormones
    • Inhibits the release of insulin
      Insulin

      Insulin is a hormone with extensive effects on both metabolism and several other body systems . Insulin causes most of the body's cells to take up glucose from the blood , storing it as glycogen in the liver and muscle, and stops use of fat as an energy source....
    • Inhibits the release of glucagon
      Glucagon

      Glucagon is an important hormone involved in carbohydrate metabolism. Produced by the pancreas, it is released when the glucose level in the blood is low , causing the liver to convert stored glycogen into glucose and release it into the bloodstream....
  • Suppresses the exocrine secretory action of pancreas
    Pancreas

    The pancreas is a gland Organ in the digestive system and endocrine system of vertebrates. It is both an endocrine gland , as well as an exocrine gland, secreting pancreatic juice containing Digestion enzymes that pass to the small intestine....
    .


Synthetic substitutes

Octreotide
Octreotide

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

Novartis International AG is a multinational corporation pharmaceutical company based in Basel, Switzerland that manufactures drugs such as clozapine , diclofenac , carbamazepine , valsartan , imatinib mesylate , ciclosporin , letrozole , methylphenidate , terbinafine , and others....
) is an octapeptide
Peptide

Peptides are short polymers formed from the linking, in a defined order, of a-amino acids. The link between one amino acid residue and the next is known as an amide chemical bond or a peptide bond....
 that mimics natural somatostatin pharmacologically, though is a more potent inhibitor of growth hormone
Growth hormone

Growth hormone is a peptide hormone. It stimulates human development 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 cells within the lateral wings of the anterior pituitary gland....
, glucagon, and insulin
Insulin

Insulin is a hormone with extensive effects on both metabolism and several other body systems . Insulin causes most of the body's cells to take up glucose from the blood , storing it as glycogen in the liver and muscle, and stops use of fat as an energy source....
 than the natural hormone and has a much longer half life (approximately 90 minutes, compared to 2-3 minutes for somatostatin). Since it is absorbed poorly from the gut, it is administered parenterally (subcutaneously, intramuscularly or intravenously). It is indicated for symptomatic treatment
Symptomatic treatment

Symptomatic treatment is any medicine therapy of a disease that only affects its symptoms, not its cause, i.e., its etiology. It is usually aimed at reducing the signs and symptoms for the comfort and well-being of the patient, but it also may be useful in reducing organic consequences and sequelae of these signs and symptoms of the disease....
 of carcinoid syndrome
Carcinoid syndrome

Carcinoid syndrome refers to the array of symptoms that occur secondary to carcinoid.Carcinoid tumors are discrete, yellow, well-circumscribed tumors that can occur anywhere along the gastrointestinal tract and in the lung....
 and acromegaly
Acromegaly

Acromegaly is a syndrome that results when the pituitary gland produces excess human growth hormone after epiphyseal plate closure. A number of disorders may affect the pituitary to create this circumstance, although most commonly it involves a GH producing tumor derived from a distinct type of cells and called pituitary adenoma....
.

Lanreotide
Lanreotide

Lanreotide is a medication used in the management of acromegaly and symptoms caused by neuroendocrine tumors, most notably carcinoid syndrome. It is a long-acting analog of somatostatin, like octreotide....
 (INN) is a medication used in the management of acromegaly and symptoms caused by neuroendocrine tumors, most notably carcinoid syndrome. It is a long-acting analogue of somatostatin, like octreotide.

[Lanreotide](as lanreotide acetate) is manufactured by Ipsen
Ipsen

Ipsen is a French pharmaceutical company headquartered in Paris, France. It primarily develops and markets medications used in oncology, endocrinology and the treatment of neuromuscular disorders....
, and marketed under the trade name Somatuline. It is available in several countries, including the United Kingdom, Australia and Canada, and was approved for sale in the United States by the Food and Drug Administration (FDA) on August 30, 2007.

Further reading