Dopamine receptor affinities in vitro and neurochemical effects in vivo of pergolide and its metabolites.

Pergolide (LY127809, CAS 66104-23-2), pergolide sulfone and pergolide sulfoxide inhibited 3H-dopamine binding to dopamine receptors in bovine striatal membranes with Ki values of 2.5, 4.6 and 15.5 nmol/l, respectively. Despropyl pergolide and despropyl pergolide sulfoxide are not as potent, with Ki values of 58.6 and 158.8 nmol/l, respectively. The derivatives of pergolide inhibit the binding of antagonist ligands 3H-Sch23390 and 3H-Spiperone to D1 and D2 dopamine receptors, respectively, in bovine striatal membranes with higher Ki concentrations. Upon administration to rats, pergolide sulfoxide and sulfone were as effective as pergolide in increasing acetylcholine levels and decreasing the metabolites of dopamine, 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) levels in striatum, while the despropyl derivatives of pergolide and pergolide sulfoxide were only marginally effective in increasing acetylcholine levels in striatum.