Agonist

Definition

An agonist is any molecule which binds to a receptor on a cell, which then can potentially lead to subsequent changes in the cell’s functions. While agonists activate or trigger a process that follows their binding to a receptor, an antagonist inhibits these effects, and an inverse agonist results in opposite effects to those of the agonist. In pharmacology, this issue is pivotal, as certain medications can act as agonists of receptors, where they mimic the effects of a natural compound or ligand that normally binds to the same receptor. However, the synthetic compound can possibly lead to similar cellular changes without unwanted side effects or to compensate for a deficiency in the natural ligand. Indeed, receptors can be activated by endogenous agonists – a natural compound which binds to a receptor. In contrast, receptors can also be activated by exogenous agonists – synthetic medications or compounds which activate a receptor. An example of an endogenous agonist is...