It is a hormone produced by many different tissues, but it is found mainly in the nervous and digestive systems.
Somatostatin is also known as SS, SST, or SOM. This growth hormone-inhibiting hormone affects several areas of the body by hindering the secretion of other hormones.
Learning about the role of this hormone will help you better understand the complexities of the endocrine system and how they affect your overall health.
The primary function of somatostatin is to prevent the production of other hormones and stop the unnatural rapid reproduction of cells, such as those that may occur in tumors. The hormone also acts as a neurotransmitter and has a role in the gastrointestinal tract.
Somatostatin affects several areas of the body. The hypothalamus regulates the secretion of hormones from the pituitary gland, including growth hormone and thyroid-stimulating hormone.
In the pancreas, somatostatin inhibits the secretion of pancreatic hormones, including glucagon and insulin. Finally, in the gastrointestinal tract, the hormone reduces gastric secretion and the emission of gastrointestinal hormones, such as secretin and gastrin.
Possible problems with the somatostatin inhibitor
Because it is an inhibitor, somatostatin is essential in balancing hormone levels in the body and stopping the effects of excessive production of certain hormones.
That means that somatostatin levels that are too low can cause problems associated with elevated levels of other hormones. Growth hormone, in particular, can be problematic. However, this is a condition rarely reported.
In contrast, some patients will struggle with excessive somatostatin levels when they have a specific type of endocrine tumor called somatostatinoma.
This tumor produces the hormone independently. The extreme suppression of hormones normally inhibited by somatostatin, such as insulin, can cause significant health problems.
If you find that your somatostatin levels are not where they should be, you need the help of an endocrinologist to identify the cause of this problem. If you have a somatostatinoma, you may need to remove the tumor to stop the overproduction of somatostatin.
Interestingly, the chemically altered versions of somatostatin are currently used as a medical therapy to control the secretion of the hormone in patients with certain endocrine conditions.
The synthetic hormone can also slow the growth of some tumors and treat gastrointestinal diseases.
Schedule an appointment with an endocrinologist before starting somatostatin treatment for a related condition or if you have questions about your somatostatin levels.
Receptors and mechanism of action
Five stomomatatin receptors, all of which are members of the superfamily of G protein-coupled receptors, have been identified and characterized.
Each of the receptors activates different signaling mechanisms within the cells, although all inhibit adenylyl cyclase. Four of the five receivers do not differentiate SS-14 from SS-28.
Somatostatin acts endocrine and paracrine to affect its target cells. The majority of circulating somatostatin appears to come from the pancreas and the gastrointestinal tract.
If one had to summarize the effects of somatostatin in one sentence, it would be: “Somatostatin inhibits the secretion of many other hormones.”
Effects on the pituitary gland:
Somatostatin was named for its effect of inhibiting the secretion of the growth hormone of the pituitary gland. Experimentally, all known stimuli for the secretion of growth hormones are suppressed by administering somatostatin.
In addition, animals treated with antisera to somatostatin show high concentrations of growth hormone in the blood, as do animals that are genetically modified to alter their somatostatin gene.
Ultimately, the secretion of growth hormone is controlled by the interaction of somatostatin and growth hormone-releasing hormone, both secreted by hypothalamic neurons.
Effects on the pancreas:
The cells inside the pancreatic islets secrete insulin, glucagon, and somatostatin. Somatostatin appears to act primarily in paracrine to inhibit the secretion of both insulin and glucagon.
It also has the effect of suppressing exocrine pancreatic secretions by inhibiting the enzymatic secretion stimulated by cholecystokinin and the secretion of bicarbonate produced by secretin.
Effects on the gastrointestinal tract:
Somatostatin is secreted by cells disseminated in the GI epithelium and by neurons in the enteric nervous system.
It has been shown to inhibit the secretion of many other GI hormones, including gastrin, cholecystokinin, secretin, and vasoactive intestinal peptide.
In addition to the direct effects of inhibiting the secretion of other GI hormones, somatostatin has a variety of other inhibitory effects in the GI tract, which may reflect its impact on other hormones, plus some additional direct effects.
Somatostatin suppresses the secretion of gastric acid and pepsin, decreases the rate of gastric emptying, and reduces smooth muscle contractions and blood flow within the intestine. Collectively, these activities seem to have the general effect of decreasing the rate of nutrient absorption.
Effects on the nervous system:
Somatostatin is often called neuromodulatory activity within the central nervous system and appears to have various complex effects on neuronal transmission.
The injection of somatostatin into the brain of rodents leads to such things as increased arousal and decreased sleep, and deterioration of some motor responses.