TY - JOUR T1 - Opiate Receptors in the Rat Brain JF - Molecular Pharmacology JO - Mol Pharmacol SP - 263 LP - 268 VL - 20 IS - 2 AU - ALAIN PUGET AU - PHILIPPE JAUZAC AU - JEAN-MARIE ZAJAC AU - JEAN-CLAUDE MEUNIER Y1 - 1981/09/01 UR - http://molpharm.aspetjournals.org/content/20/2/263.abstract N2 - A crude membrane fraction (CMF) from rat brain is labeled with [3H]etorphine (2 x 10-9 M) in the absence (total binding, -L) and in the presence (nonspecific binding, +L) of 2 x 10-6 M levorphanol. The 3H-labeled CMF (±L) is solubilized with 1% (w/v) cholic acid (sodium salt) and centrifuged. The high-speed (100,000 x g) supernatant is analyzed by molecular exclusion chromatography on Sephadex G-25, Sephadex G-100, and Sepharose 6B. A comparison of the radioactivity profiles reveals, in addition to the previously identified 500,000 mol wt species [Puget et al., F. E. B. S. Lett. 122:199-202 (1980)] lower molecular weight, tritium-labeled entities distinct from monomolecular [3H]etorphine. These small complexes are readily separated from free radioligand upon dialysis in the cold. They appear to be opiate-specific, since they are not observed in 3H-labeled CMF (+L) soluble extracts. ER -