somatostatin

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Somatostatin

A naturally occurring regulatory peptide that carries out numerous functions in the human body, including the inhibition of growth hormone secretion from the anterior pituitary gland. Somatostatin consists of 14 amino acids; two cysteine residues are joined by a disulfide bond so that the peptide forms a ring structure. A larger variant of this peptide, called somatostatin-28, is produced in some cells and has an additional 14 amino acids attached at the amino-terminal end of normal somatostatin (somatostatin-14).

Somatostatin acts primarily as a negative regulator of a variety of different cell types, blocking processes such as cell secretion, cell growth, and smooth muscle contraction. It is secreted from the hypothalamus into the portal circulation and travels to the anterior pituitary gland, where it inhibits the production and release of both growth hormone and thyroid-stimulating hormone. Many tissues other than the hypothalamus contain somatostatin, suggesting that this peptide has numerous roles.

Each of the functions of somatostatin is initiated by the binding of the peptide to one or more of five different cell-surface receptor proteins, thereby activating one or more intracellular G-proteins and initiating biochemical signaling pathways within the cell. See Signal transduction

Analogs of somatostatin have been synthesized that are smaller, more potent, longer-lasting, and more specific in their biological effects than natural somatostatin. Some of these analogs have become useful as drugs. See Endocrine system (vertebrate), Hormone, Neurosecretion, Pituitary gland

somatostatin

[¦sō·məd·ə′stat·ən]
(biochemistry)
A peptide secreted by the hypothalamus which acts primarily to inhibit the release of growth hormone from the anterior pituitary.
References in periodicals archive ?
This retrospective observational single-center study was designed to analyze the distribution and expression of somatostatin receptors (SSTRs) 1, 2A, 3, 4, and 5 in Cushing's disease and other pituitary adenomas (1) together with clinical aspects (2), such as age, gender, primary/recurrent disease, and hormone expression.
Somatostatin receptor 3 expression was evaluated in 232 pituitary adenoma samples.
Contradictory to these results, mRNA of SSTR3 and SSTR4 was the only detectable somatostatin receptors via RT-PCR in one case of pituitary Cushing's disease in a cohort by Nielsen et al.
These receptors provide a promising target for medical treatment of ACTH-producing adenomas with somatostatin analogs.
The neuropeptide somatostatin (SS) was isolated from ovine hypothalamus firstly.
Somatostatin multigene family consists of six homologous genes: SS1, SS2, SS3, SS4, SS5 and SS6 (Liu et al., 2010).
Distribution of somatostatin immunoreactive neurons and fibres in the central nervous system of a chondrostean, the Siberian sturgeon (Acipenser baeri).
Differential expression of two somatostatin genes during zebrafish embryonic development.
Somatostatin and Somatostatin Receptors in Neuroendocrine Tumors
Patel, "Somatostatin and its receptor family," Frontiers in Neuroendocrinology, vol.
Viollet, "Somatostatin, Alzheimer's disease and cognition: an old story coming of age?" Progress in Neurobiology, vol.
Watt et al., "Role of somatostatin receptor 1 and 5 on epidermal growth factor receptor mediated signaling," Biochimica et Biophysica Acta, vol.