Description_x000D_ Application_x000D_ (-)-Quinpirole hydrochloride has been used as a selective D2 dopamine (DA) receptor agonist in various experiments._x000D_ Packaging_x000D_ 10, 25, 100 mg in glass bottle_x000D_ Biochem/physiol Actions_x000D_ The putative D2 dopamine receptor agonist quinpirole (LY 171,555) is the most widely used D2 agonist in in vivo and in vitro studies Active enantiomer of (±)-quinpirole. Quinpirole is a dopamine agonist with high affinity for the D2 and D3 dopamine receptor subtypes. Specific [3H]quinpirole binding in rat brain was saturable, and dependent on temperature, membrane concentration, sodium concentration and guanine nucleotides. Saturation analysis revealed high affinity binding characteristics (KD = 2.3 +/- 0.3 nM) which were confirmed by association-dissociation kinetics. The regional distribution of [3H]quinpirole binding sites roughly paralleled the distribution of [3H]spiperone binding sites, with greatest densities present in the striatum, nucleus accumbens and olfactory tubercles. A variety of drugs, most notably monoamine oxidase inhibitors (MAOls), inhibit the binding of [3H]quinpirole, but not [3H]spiperone or [3H](-)N-n-Propylnorapomorphine, in rat striatal membranes by a mechanism that does not appear to involve the enzymatic activity of MAO. Clinically antidepressant MAOIs exhibited selectivity between sites labeled by [3H]quinpirole and [3H]spiperone as did a number of structurally related propargylamines and N-acylethylenediamine derivatives and other drugs such as debrisoquin and phenylbiguanide. The MAOIs clorgyline and Ro 41-1049 were the most potent. MAOIs interact with a novel binding site that is labeled by [3H]quinpirole or that modulates [3H]quinpirole binding. This site may be associated with D2-like dopamine receptors._x000D_ Features and Benefits_x000D_ This compound is also offered as part of Sigma′s Library of Pharmacologically Active Compounds (LOPAC®1280), a biologically annotated collection of high-quality, ready-to-screen compounds. Click here to learn more._x000D_ Legal Information_x000D_ Manufactured and sold with the permission of Eli Lilly and Company._x000D_ LOPAC is a registered trademark of Sigma-Aldrich Co. LLC