Dopamine receptors in human and calf brains, using [3H]apomorphine and an antipsychotic drug.
In order to develop a better dopamine receptor radioligand, [3H[apomorphine was prepared and tested for dopamine-like binding properties in both calf and human brain tissues. Specific binding of [3H]apomorphine was defined as that binding which occurred in the presence of 1 muM (-)-butaclamol (an inactive neuroleptic) minus that occurring in the presence of 1 muM (+)-butaclamol (active neuroleptic). The specific binding was saturable, the number of sites being double that of specific [3H]dopamine binding, and occurred primarily in dopamine-rich regions of postmortem human brains. The binding had a dissociation constant of 0.9 nM for human caudate (2 nM for calf caudate) and was blocked by dopamine and norepinephrine, but not by isoproterenol or (-)-propranolol, distinguishing it from a beta-adrenergic receptor. Since there was little desorption of [3H]apomorphine, the ligand permits extensive washing during routine assays for dopamine receptors, and facilitates biochemical purification of the receptor.
D000345:Affinity Labels; D000818:Animals; D001058:Apomorphine / Q000378:metabolism*; D001923:Brain Chemistry; D002417:Cattle; D002421:Caudate Nucleus / Q000032:analysis; D004298:Dopamine / Q000378:metabolism; D006220:Haloperidol / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D018377:Neurotransmitter Agents / Q000494:pharmacology; D009830:Olfactory Bulb / Q000032:analysis; D011433:Propranolol / Q000494:pharmacology; D011699:Putamen / Q000032:analysis; D011954:Receptors, Dopamine / Q000032:analysis* / Q000378:metabolism; D014149:Tranquilizing Agents / Q000494:pharmacology
D000345:Affinity Labels; D018377:Neurotransmitter Agents; D011954:Receptors, Dopamine; D014149:Tranquilizing Agents; D011433:Propranolol; D006220:Haloperidol; D001058:Apomorphine; D004298:Dopamine