Receptors: Functional Assays
Measurement of biological effect resulting from interaction with the receptor; Measurement of receptor signaling
Psychoactive drugs generally exert their effects by binding to a specific recognition site, whether that is associated with a receptor, a transporter, or an enzyme, and thereby alter the function of that receptor, enzyme, or transporter. However, receptors are the predominant targets for psychoactive drugs (Grigoriadis et al. 2009), and these may be either G-protein-coupled receptors (GPCRs) or, to a lesser extent, ion channels (the latter being either ligand or voltage gated).
Although the actual effect produced by drugs affecting GPCRs and ion channels is very different, their mechanisms of action follow similar principles. Hence, a drug acting at a GPCR or ion channel may block the effect of an endogenous agonist (i.e., acts as an antagonist), mimic the effect of the endogenous activator (i.e., acts as an agonist), or inhibit spontaneous...