Desensitisation is the loss of responsiveness to the continuing or increasing dose of a drug.
Receptor desensitisation occurs after prolonged or repeated exposure to a stimulus and often results in decreased responsiveness of that receptor for a stimulus. Receptor desensitisation also results in altered affinity for the ligand. Desensitisation may be accomplished byreceptor phosphorylation, uncoupling of receptor effector molecules and receptor internalisation as illustrated by the following example:
The graphic shows two types of receptor desensitisation in a cell culture with beta-adrenergic receptors. At t=0 isoprenaline (agonist)
In the late response phase (hours), the receptors are decreased too due to internalisation. Similarly as the second messenger, the receptor density can be restored by washing out the isoprenaline.