SOMATOSTATIN: CHARACTERISTICS, FUNCTION AND DISEASES - BIOLOGY - 2025

The somatostatin is, regulating the endocrine system hormone protein. Its origin can be pancreatic, stomachic and intestinal. It is involved or acts in neurotransmission and cell proliferation, as well as in the inhibition of a significant number of secondary hormones.

Growth hormone inhibitory hormone (GHIH), as it is also known, plays an indirect role in controlling the level of sugar in the blood.

Structure of somatostatin. Taken and edited from Kdv2754, from Wikimedia Commons.

Somatostatin hormone has two active forms, one with 28 and the other with 14 amino acids. The distribution, abundance, or presence of these, will depend on the tissue where it is found.

For example, pancreatic tissue or the hypothalamus have only, or mainly, 14 amino acid forms. In intestinal tissue, for its part, its composition is mostly 28 amino acids.

Other nomenclatures

Besides somatostatin, this hormone is also known as growth inhibitory hormone (GHIH) and somatotropin release inhibitory factor (SRIF).

Other less used synonyms that are also valid when referring to somatostatin are: hormone inhibiting the release of somatotropin (SSRI) and hormone inhibiting growth hormone (GHRIH).

Discovery

The discovery of this hormone was made by Krulich et al. In 1968. While investigating the factor that released growth hormone, these researchers determined that extracts from the hypothalamus inhibited pituitary secretion.

The hypothalamus is a region of the diencephalon that controls the functions and activity of the nervous system and the pituitary.)

Later, Brazeau et al., In 1973, characterized it. In 1977 Pellieter et al. Discovered a human form of somatostatin (SST) in the hypothalamus.

Since then this hormone has been observed in almost all tissue and organ systems. It is present not only in humans but also in other mammals and vertebrates.

characteristics

Somatostatin is a protein hormone. It is classified and recognized as an inhibitory hormone, but it is better known as a growth hormone inhibitory neuropeptide.

This protein hormone consists of two active biological forms; SST -14 and SST-28. Both are formed from the same prehormone. Both forms are very common throughout the nervous system and largely in peripheral organs and tissues.

SST -14

Somatostatin composed of 14 amino acids. It has a disulfide bridge between two non-essential alpha-amino acids (cysteine) at positions 3 and 14, which gives it a stable cyclic structure.

Protein hormone, Somatostatin with 14 amino acids. Taken and edited from The original uploader was Mr Hyde at Czech Wikipedia., via Wikimedia Commons.

SST-28

Somatostatin with 28 amino acids. It contains a complete structure of the SST-14 form at the C-terminal end, and additionally, 14 amino acids at the N-terminal end.

Production

Somatostatin is produced in a wide variety of places in the body of humans and other vertebrates. The production of this protein hormone in the brain and digestive system has been extensively studied.

In the brain, these are produced mainly by neurons in the hypothalamus, from where the hormone somatostatin is released from the nerve endings of the hypothalamic-pituitary system.

The brainstem and hippocampus also exhibit somatostatin-secreting activity in the brain. Regarding the digestive system, it is known with certainty that it is produced in the duodenum, in the islets of Langerhans or pancreatic islets, and in the pyloric antrum.

Function

Somatostatin is a hormone whose main function is to inhibit. However, it can also act as a neurotransmitter or as a paracrine factor. Its action extends to many parts of the body such as:

-Hipothalamus: where it inhibits the production of anterohypophyseal pulsatile hormones.

- Anterior pituitary gland: where it inhibits the secretion of thyroid stimulating hormone and growth hormone, among others.

- Pancreas: somatostatin that works in the pancreas, is produced in the digestive system and inhibits the release of insulin and glucagon. It also fulfills the role of a paracrine factor, regulating the release or secretions in the pancreas.

- Central nervous system: it has a neurotransmitter function, where it inhibits the activity of other neurons.

- Gastric-intestinal system: in this complex area of ​​the body, somatostatin inhibits the secretion of gastrointestinal hormones, decreases muscle contractions (smooth muscle) and blood flow in the intestine. Another function is to act as a regulator of the releasing or secretory activity at multiple levels of the digestive tract (paracrine factor).

Somatotastatin-related diseases

Epilepsy

One of the hypotheses about the origin of epilepsies indicates that the selective loss of subpopulations of interneurons, which give rise to somatostatin and other proteins, is one of the causes of epileptic episodes.

Parkinson's

Parkinson's disease is a motor disorder that is related to the insufficiency of substances such as dopamine, produced by neurons.

Parkinson's patients suffering from dementia have been found to lack neurons with the hormone somatostatin.

Medical significance

Apart from its inhibitory, neurotransmitter and paracrine factor functions, somatostatin has multiple medical applications, among which are:

Antineoplastic

Antineoplastic drugs are substances that prevent the growth or development of cancer and / or tumor cells. Applications of somatostatin have been discovered for the treatment of different types of cancer such as breast and lung cancer, and tumors such as paragliomas and adenomas.

Medical diagnostics

Somatostatin is used for the diagnosis of various types of diseases. One of the most common tests is the somatostatin receptor scan.

This test is based on the fact that various types of tumors have a high affinity for somatostatin. It consists of injecting the patient through a venous injection of a molecule analogous to the hormone, labeled with a radioactive ion.

This marker reaches and binds to tumor cells at somatostatin receptors. A radiation detection can then show the location of tumors in the body.

This technique allows the detection, location, and monitoring of carcinoid, neuroendocrine and enteropancreatic tumors.

Treatments

Medical studies show advances in the use of somatostatin in the treatment of breast tumors and malignant lymphomas. They also use this hormone to inhibit gastrointestinal hormones whose concentrations are at very high levels in the presence of neuroendocrine tumors.

Acromegaly is a disease caused by injury to the pituitary. This disease is expressed in a functional cell tumor that releases or secretes growth hormone.

For its treatment, somatostatin analogs have been used to stabilize growth hormone and growth factor levels to slow tumor development.

References

1. Growth hormone-inhibiting hormone (GHIH). Recovered from pubchem.ncbi.nlm.nih.gov.
2. Somatostatin. Recovered from en.wikipedia.org.
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5. Somatostatin. Recovered from neuromics.com.
6. Somatostatin. Recovered from drugbank.ca.
7. ME Garcia Garcia, I. Garcia Morales, J. Matías Guiu, (2010). Experimental models in epilepsy. Neurology.
8. JA Lozano (2001). Parkinsonism and its treatment. Offarm