Supersensitivity of receptors

A prolonged decrease in the stimulation of the postsy-naptic receptors can result in a functional increase in receptor sensitivity. The best example of this is the denervation supersensitivity seen when a peripheral nerve is severed.7 In this situation, the lack of presynaptic neurotransmitter release results in a compensatory increase in postsynaptic receptor numbers on the muscle cell. Similarly, the loss of the endogenous neurotransmitter dopamine in neurodegenerative conditions such as Parkinson disease can result in supersensitivity of receptors for that neurotransmitter.14 This increased receptor sensitivity becomes problematic because administration of dopaminelike drugs can cause excessive or untoward responses (see Chapter 10).14... 

Kent TA, Wilber RD. Reserpine withdrawal psychosis the possible role of denervation supersensitivity of receptors. J Nerv Ment Dis 1982 170(8) 502. ... 

The decrease in circulating catecholamines due to prolonged clonidine administration mediates a supersensitivity of receptors. When clonidine therapy is abruptly withdrawn, catecholamine levels rebound, reflex activity overcompensates, and this, combined with the supersensitivity of receptors, produces an exaggerated response to stimulation and a dramatic increase in blood pressure. A hypertensive crisis may ensue within 12 to 24 hours after drug withdrawal. 

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