Dopaminergic receptors, specificity

Antipsychotic drugs block dopaminergic receptors, specifically the D2 receptors. Neuroleptic potency does not appear to correlate absolutely with the degree of receptor binding, so a secondary mechanism is also postulated. 

Neuroleptic drugs are used in the treatment of psychosis, such as schizophrenia they are generally antagonist ligands of dopamine at the central nervous system level. " Indications and therapeutic effects of the various families of neuroleptics result from two factors. The first one is the specifity of the ligand toward the different types of dopaminergic receptors, which are unequally distributed in the... 

Qll Other neuroleptic agents include phenothiazines, such as chlorpromazine, promazin and thioridazine, and thioxanthines, such as flupenthixol. The non-specific blockade of dopaminergic receptors afforded by these drugs leads to development of side effects, such as endocrine dysfunction and extrapyramidal motor symptoms. The unwanted antagonism of motor tracts results in extrapyramidal side effects, such as Parkinsonism and tardive dyskinesia. The latter is associated with involuntary movements of the face, limbs and trunk. Chronic neuroleptic therapy can inhibit the release of GABA. This in turn leads to changes in mobility. 

Over the usual concentration range of physiologically released, circulating epinephrine, B-receptor response (vasodilation) predominates In blood vessels of skeletal muscle and liver a-receptor (vasoconstriction). In blood vessels of other abdominal viscera. The renal and mesenteric vessels also contain specific dopaminergic receptors, activation of which causes dilatation, but their physiological significance has not been established. 

All typical APDs block (at least to some extent) 2 dopaminergic receptors and are not selective, meaning that they do not target specific brain regions. Sulpiride is a relative exception, since it is quite selective as a D2 blocker (although non-selective in its brain distribution). In that respect, sulpiride is often considered by clinicians as atypical in nature. The major dopaminergic pathways that are most relevant to schizophrenia are ... 

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