SSTR - Somatostatin Receptor | Elisa - Clia - Antibody - Protein

Background:

Somatostatin receptors (SSTRs) are a family of G protein-coupled receptors (GPCRs) that bind to the peptide hormone somatostatin. Somatostatin, also known as growth hormone-inhibiting hormone (GHIH), is a regulatory peptide involved in the inhibition of various physiological processes, including the secretion of growth hormone, insulin, glucagon, and other hormones. The primary ligands for SSTRs are somatostatin peptides, which include two active forms: somatostatin-14 (SST-14) and somatostatin-28 (SST-28). These peptides bind to SSTRs with varying affinities depending on the receptor subtype.In summary, somatostatin receptors play critical roles in regulating endocrine function, neurotransmission, and gastrointestinal physiology. Their dysregulation is implicated in various diseases, particularly neuroendocrine tumors. Therapeutic targeting of SSTRs using somatostatin analogs and radiolabeled ligands offers promising approaches for diagnosis and treatment across a range of clinical conditions.

Structural Features:

SSTRs consist of seven transmembrane domains, an extracellular N-terminus, and an intracellular C-terminus. They belong to the class A rhodopsin-like family of GPCRs.

Subtypes and Classification:

There are five known subtypes of SSTRs: SSTR1, SSTR2A, SSTR2B, SSTR3, and SSTR5. Each subtype exhibits distinct tissue distribution and signaling properties.

Physiological Functions:

1.   Endocrine Regulation: SSTRs play a crucial role in the regulation of hormone secretion from various endocrine glands, including the pituitary, pancreas, and gastrointestinal tract.

2.   Neurotransmission: Somatostatin acts as a neurotransmitter in the central nervous system, where it modulates neuronal activity, synaptic transmission, and neurotransmitter release.

3.   Gastrointestinal Function: SSTRs are involved in the regulation of gastrointestinal motility, secretion, and absorption.

4.   Immune System Modulation: Somatostatin and SSTRs play a role in immune system modulation, influencing immune cell function and cytokine production.

Clinical Implications:

1.   Neuroendocrine Tumors: SSTRs are highly expressed in neuroendocrine tumors (NETs), making them valuable diagnostic and therapeutic targets. Imaging techniques using radiolabeled somatostatin analogs allow for the localization and staging of NETs.

2.   Acromegaly: SSTR agonists are used in the treatment of acromegaly, a disorder characterized by excessive growth hormone secretion.

3.   Gastrointestinal Disorders: SSTR agonists are being investigated for the treatment of gastrointestinal disorders such as diarrhea-predominant irritable bowel syndrome (IBS-D) and refractory diarrhea associated with neuroendocrine tumors.

4.   Neurological Disorders: SSTRs have been implicated in neurological disorders such as epilepsy, Alzheimer's disease, and Parkinson's disease, although their exact role is still under investigation.

Therapeutic Potential:

1.   SSTR Agonists: Synthetic somatostatin analogs with increased stability and selectivity for specific SSTR subtypes are used therapeutically to inhibit hormone secretion and tumor growth in NETs and other conditions.

2.   Radiolabeled Ligands: Radiolabeled somatostatin analogs, such as ^68Ga-DOTATATE and ^177Lu-DOTATOC, are used in molecular imaging and targeted radionuclide therapy for NETs.

3.   SSTR Antagonists: SSTR antagonists are being explored as potential therapies for conditions where somatostatin signaling inhibition may be beneficial, such as refractory diarrhea.

4.   Combination Therapies: Combinations of SSTR agonists with other targeted therapies or cytotoxic agents are being investigated to enhance therapeutic efficacy in neuroendocrine tumors and other cancers.