Are striatal dopamine D4 receptors increased in schizophrenia?
The density of dopamine D2-like receptors was determined using [3H]emonapride binding in putamen tissue taken postmortem from schizophrenic subjects and matched controls. A 72% increase in number of these receptors was identified in the schizophrenics, although three patients not receiving antipsychotic drug treatment before death exhibited receptor densities in the control range. Displacement of 1 nM [3H]emonapride binding by raclopride was used to define the contribution of the D4 subtype of dopamine receptors to total [3H]emonapride binding. No evidence was obtained for the presence of D4 receptors in putamen tissue from either control or schizophrenic subjects, indicating that the increase in D2-like receptor density in schizophrenia is due not to an increase in number of D4 sites in the disease, but to an up-regulation of D2 or D3 receptors probably induced by chronic treatment with antipsychotic drugs.
Reynolds
G P
GP
Department of Biomedical Science, University of Sheffield, England, U.K.
Mason
S L
SL
D000368:Aged; D000818:Animals; D014150:Antipsychotic Agents / Q000494:pharmacology; D001549:Benzamides / Q000378:metabolism; D001667:Binding, Competitive; D003342:Corpus Striatum / Q000378:metabolism* / Q000473:pathology; D065127:Dopamine D2 Receptor Antagonists; D006801:Humans; D007700:Kinetics; D011759:Pyrrolidines / Q000378:metabolism; D020891:Raclopride; D011954:Receptors, Dopamine / Q000032:analysis / Q000378:metabolism*; D050638:Receptors, Dopamine D4; D012016:Reference Values; D012457:Salicylamides / Q000494:pharmacology; D012559:Schizophrenia / Q000378:metabolism* / Q000473:pathology
D014150:Antipsychotic Agents; D001549:Benzamides; C493599:DRD4 protein, human; D065127:Dopamine D2 Receptor Antagonists; D011759:Pyrrolidines; D011954:Receptors, Dopamine; D012457:Salicylamides; D050638:Receptors, Dopamine D4; D020891:Raclopride; C030265:nemonapride