Identification of inosine and hypoxanthine as endogenous ligands for the brain benzodiazepine-binding sites.
Two endogenous ligands for the brain benzodiazepine-binding sites were isolated from bovine brain through gel filtration, paper electrophoresis, and paper chromatography. These ligands were identified as inosine and hypoxanthine, and both had a higher affinity for the brain benzodiazepine-binding sites than for benzodiazepine sites in some peripheral tissues. They did not bind to any other receptors tested, such as the opiate, muscarinic cholinergic, gamma-aminobutyric acid, and beta-adrenergic receptors. Both inosine and hypoxanthine competitively inhibited the binding of [3H]diazepam to the brain binding site.
D000818:Animals; D001569:Benzodiazepines / Q000276:immunology / Q000378:metabolism*; D001666:Binding Sites, Antibody; D001667:Binding, Competitive; D001921:Brain / Q000378:metabolism*; D002417:Cattle; D003975:Diazepam / Q000378:metabolism; D007042:Hypoxanthines / Q000378:metabolism*; D007288:Inosine / Q000378:metabolism*; D008024:Ligands; D011955:Receptors, Drug / Q000378:metabolism*
D007042:Hypoxanthines; D008024:Ligands; D011955:Receptors, Drug; D001569:Benzodiazepines; D007288:Inosine; D003975:Diazepam