Desensitization of receptors

Veratridine appears to act at a different part of pore channel from DDT or pyrethroids Act as agonists causing desensitization of receptor Inhibitor of GABA receptors... 

Desensitization of receptors Prolonged exposure to the catecholamines reduces the responsivity of these receptors, a phenomenon known as desensitization. Three mechanisms have been suggested to explain this phenomenon (1) sequestration of the receptors so that they are unavailable for interaction with the ligand (2) down-regulation, that is, a disappearance of the receptor either by destruction or decreased synthesis and (3) inability to couple to G-protein because the receptor has been phosphory-lated on the cytoplasmic side by either protein kinase A or p adrenergic receptor kinase (PARK). 

Morrison WJ, Shukla SD. Desensitization of receptor coupled activation of phosphoinositide specific pho )bolipaseC in platelets Evidence for distinct mechanisms for platelet activating factor and thrombin. Mol Pharmacol 1988 33 58-63... 

When a drug is given over time, the effects may decrease accordingly. This may be the consequence of, for example, desensitization of receptors or depletion of neurotransmitter stores. This effect is termed tolerance. If a drug is administered and produces a response that diminishes with subsequent doses, the effect is termed tachyphylaxis. This phenomenon is a rapid decrease in drug effect with subsequent dosing. 

When compared with the selective serotonin reuptake inhibitors (SSRIs), mirtazapine may show an earlier onset of action (although data are currently not well established). Mirtazapine has also been found to be efficacious in the treatment of elderly patients with depression. Mirtazapine has been shown to be effective in the treatment of panic disorder, social phobia, and post-traumatic stress disorder. In one study, mirtazapine combined with citalopram in obsessive-compulsive patients induced an earlier response when compared with citalopram plus placebo. It was suggested that antagonism of presynaptic a2-adrenergic receptors does not enhance serotonin neurotransmission directly, but rather disinhibits the norepinephrine activation of serotonergic neurons and thereby increases serotonergic neurotransmission by a mechanism that may not require a time-dependent desensitization of receptors. 

Tomhave ED, Richardson RM, Didsbury JR, Menard L, Snyderman R, Hydar A. Cross-desensitization of receptors for peptide chemoattractants characterization of a new form of leukocyte regulation. J Immunol 1994 153 3267-3275. 

One final remark should be made here regarding the concept of desensitization of receptors. From the sensor point of view, one would argue that... 

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