BINDING OF [H-3]-LABELED PERGOLIDE MESYLATE TO DOPAMINE RECEPTORS OF MAMMALIAN BRAINS

  • 1 January 1980
    • journal article
    • research article
    • Vol. 30  (2) , 195-210
Abstract
The ergoline dopamine agonist, [3H]pergolide [(8.beta.)-8-[(methythio)methyl]-6-propylergoline methanesulfonic acid], 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, lergotrile and 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 .mu.M (+)butaclamol. Saturable binding of [3H)pergolide was observed in particulate fractions 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.