Receptor Selectivity
Definition
How far a compound acts on its intended receptor rather than on related ones. Selectivity is the difference between a GHRP that raises growth hormone alone and one that also moves cortisol and prolactin.
Terms used in this definition
Other entries this definition refers to.
What this means for research sourcing
Mechanistic terms like this describe how research compounds behave in vitro. See the mechanism overviews for compounds Volta stocks.
Related Terms in Pharmacology
Desensitization
A fall in receptor responsiveness under prolonged or repeated stimulation, achieved by internalising receptors or expressing fewer of them. It is one mechanism behind an effect that fades while exposure continues.
Tachyphylaxis
Response falling away rapidly over a few administrations rather than gradually, which separates it from slower desensitization. Reports of it appear with melanocortin agonists and with some growth hormone releasing peptides.
Downregulation
A reduction in the number of receptors a cell presents, in response to sustained stimulation. It is slower than desensitization and is the usual reason a protocol in the literature includes periods without administration.
Dose-Response Curve
A plot of effect against amount administered. A clean curve is among the stronger indications that an observed effect is real rather than noise, and the gap between the amount that first works and the amount that harms is the therapeutic window.
GLP-1 (Glucagon-Like Peptide-1)
An incretin released from the small intestine after a meal. It raises insulin secretion when glucose is high, suppresses glucagon, slows gastric emptying and signals fullness centrally. Its native half-life is about two minutes.
GLP-1 Receptor
The G protein-coupled receptor GLP-1 acts at, expressed in pancreatic islets, the stomach, the heart and several brain regions. The breadth of that expression is why agonists at it affect more than blood glucose.
GLP-1 Receptor Agonist
A compound that activates the GLP-1 receptor. Semaglutide and liraglutide are the approved examples, studied against glycaemic endpoints and against body weight, and the class is the reference point most newer metabolic peptides are compared with.
GIP (Glucose-Dependent Insulinotropic Polypeptide)
The second incretin, released from the upper small intestine, which also enhances glucose-dependent insulin secretion. It is a target of tirzepatide alongside GLP-1 and of retatrutide alongside GLP-1 and glucagon.