Binding of [3H]pergolide mesylate to dopamine receptors of mammalian brains.

The ergoline dopamine agonist, [3H]pergolide, binds with pharmacological specificity to particulate fractions of rat and calf brains. Dopamine agonists (apomorphine, 5,6-dihydroxy-2-dimethylaminotetralin, 6.7-dihydroxy-2-methylaminotetralin, lergotrileand bromocriptine) and dopamine antagonists (haloperidol and (+)butaclamol but not its pharmacologically inactive isomer, (-)butaclamol) were potent inhibitors, while monoamines (dopamine, norepinephrine, epinephrine and serotonin) were weaker inhibitors of [3H]pergolide binding. Olfactory tubercle was the only brain region other than striatum which exhibited significant [3H]pergolide binding displaceable by 1 microM (+)butaclamol. Saturable of calf and rat striatum with dissociation constants, kd values, of 1.2 to 3.1 nM. The number of binding sites was enriched in crude synaptosomal fractions. The relationship of [3H]pergolide binding to the binding of other dopaminergic ligands is discussed.