Dopamine D4 receptor in human peripheral blood lymphocytes: a radioligand binding assay study.
The expression of dopamine D4 receptor was investigated in human peripheral blood lymphocytes with a radioligand binding assay technique, using [3H]clozapine as radioligand. [3H]Clozapine was specifically bound to human peripheral blood lymphocytes. The binding was time-, temperature-, and concentration-dependent and of high affinity, with a dissociation constant (K(d)) value of 0.34 +/- 0.02 nM and a maximum density of binding sites (B(max)) value of 27 +/- 1.4 fmol/10(6) cells. The pharmacological profile of [3H]clozapine binding to human peripheral blood lymphocytes was similar to that found in Chinese hamster ovary (CHO) cells transfected with the D4 clone (D4.2 variant). The above results are consistent with molecular biology studies demonstrating the expression of a dopamine D4 receptor in immune cells and in human peripheral blood lymphocytes. The availability of a rapid and sensitive radioligand binding assay technique for the dopamine D4 receptor in human peripheral blood lymphocytes may contribute to better define the role of this dopamine receptor subtype in neurological and psychiatric disorders.
Ricci
A
A
Dipartimento di Scienze Cardiovascolari e Respiratorie, Università La Sapienza, Rome, Italy.
Bronzetti
E
E
Felici
L
L
Tayebati
S K
SK
Amenta
F
F
D000328:Adult; D000818:Animals; D016466:CHO Cells; D003024:Clozapine / Q000494:pharmacology*; D006224:Cricetinae; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D008214:Lymphocytes / Q000378:metabolism*; D008297:Male; D011869:Radioligand Assay; D017448:Receptors, Dopamine D2 / Q000187:drug effects* / Q000378:metabolism*; D050638:Receptors, Dopamine D4
C493599:DRD4 protein, human; D017448:Receptors, Dopamine D2; D050638:Receptors, Dopamine D4; D003024:Clozapine