title: [3H]7-OH-DPAT is capable of labeling dopamine D2 as well as D3 receptors.
abstract: The binding of [3H](+)-7-hydroxy-2-(N,N-di-n-propylamino)tetralin ([3H]7-OH-DPAT) to dopamine D2 and D3 receptors expressed in Chinese hamster ovary (CHO) cells was investigated and compared with [3H]methylspiperone. [3H]7-OH-DPAT labeled the D3 receptor in the CHO cells in a guanine nucleotide-insensitive fashion and exhibited a Kd of about 0.5 nM. In the presence of MgCl2. [3H]7-OH-DPAT was also found to label the D2 receptor in CHO cells with high affinity (3.6 nM). The binding of [3H]7-OH-DPAT to the D2 receptor was sensitive to guanine nucleotides suggesting occupancy of a high affinity G protein-coupled state of the receptor. These results suggest that caution should be exercised when using [3H]7-OH-DPAT to label the dopamine D3 receptor in brain tissues.
authors.affiliation: Molecular Neuropharmacology Section, National Institute of Neurological Disorders & Stroke, National Institutes of Health, Bethesda, MD 20892.
authors.forename: A M
authors.initials: AM
authors.lastname: Gonzalez
authors.forename: D R
authors.initials: DR
authors.lastname: Sibley
mesh_terms: D000818:Animals; D001667:Binding, Competitive; D001921:Brain / Q000187:drug effects / Q000378:metabolism; D016466:CHO Cells / Q000187:drug effects / Q000378:metabolism; D006224:Cricetinae; D003412:Cricetulus; D018491:Dopamine Agonists / Q000378:metabolism / Q000494:pharmacology*; D006150:Guanine Nucleotides / Q000378:metabolism; D051381:Rats; D011954:Receptors, Dopamine / Q000187:drug effects / Q000378:metabolism*; D017448:Receptors, Dopamine D2 / Q000187:drug effects / Q000378:metabolism*; D050637:Receptors, Dopamine D3; D013134:Spiperone / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology; D013764:Tetrahydronaphthalenes / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D018491:Dopamine Agonists; C493595:Drd3 protein, rat; D006150:Guanine Nucleotides; D011954:Receptors, Dopamine; D017448:Receptors, Dopamine D2; D050637:Receptors, Dopamine D3; D013764:Tetrahydronaphthalenes; D013134:Spiperone; C039167:3-N-methylspiperone; C031349:7-hydroxy-2-N,N-dipropylaminotetralin