How do somatostatin analogues work in acromegaly?
The most extensively studied and used somatostatin analogue, octreotide, binds to the somatostatin receptor subtypes II and V, inhibiting GH secretion. Octreotide suppresses the serum GH level to less than 2.5 mcg/L in 65% of patients with acromegaly and normalizes circulating IGF-I levels in 70% of patients.
Is somatostatin used to treat acromegaly?
Acromegaly is a rare, chronic and severe disease. Drug therapy including somatostatin analogues (SAs), dopamine receptor agonists and growth hormone receptor antagonists (pegvisomant, PEG) are commonly used to treat patients who do not respond to surgery.
What is somatostatin analogs used for?
A somatostatin analogue is a man made (synthetic) version of somatostatin. It slows down the production of hormones, especially the growth hormone and serotonin. This helps to control the symptoms of carcinoid syndrome such as diarrhoea and flushing of the skin. It may also shrink the NET.
How does somatostatin inhibit HGH?
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 …
Why Octreotide is used in acromegaly?
Octreotide acts through four mechanisms to decrease abnormal GH secretion in acromegaly. First, octreotide suppresses GH secretion from the pituitary gland and from GH-secreting adenomas. Second, it decreases GH binding to hepatocytes. Third, it inhibits hepatic IFG-1 production and finally it controls tumour growth.
How do dopamine agonists treat acromegaly?
Dopamine agonists bind to the D2 receptor and suppress GH hypersecretion in some patients with acromegaly. Their clinical effectiveness is modest, although promising results have been obtained with two novel compounds, quinagolide and cabergoline, that possess long duration of action.
What is the mechanism of action of somatostatin analogues?
Mechanisms of action of Somatostatin synthetic Analogs (SSAs). (A). The antisecretory effects occur through the inhibition of the enzyme adenylyl cyclase (AC), the inhibition of voltage-dependent calcium channels and the stimulation of voltage-dependent potassium channels.
Is growth hormone stimulated by somatostatin?
Somatostatin dramatically stimulates growth hormone release from primate somatotrophs acting at low doses via somatostatin receptor 5 and cyclic AMP. J Neuroendocrinol.
What hormones does somatostatin inhibit?
Somatostatin from the hypothalamus inhibits the pituitary gland’s secretion of growth hormone and thyroid stimulating hormone. In addition, somatostatin is produced in the pancreas and inhibits the secretion of other pancreatic hormones such as insulin and glucagon.
How does octreotide inhibit HGH?
Octreotide can also be used in the treatment of acromegaly, a disorder of excessive growth hormone (GH). Octreotide, being a somatostatin analog, inhibits the release of GH from the pituitary gland through a process normally involved in negative feedback.