Characteristics of binding of [3H]NE-100, a novel sigma-receptor ligand, to guinea-pig brain membranes.
We examined the characteristics of binding of radiolabeled N,N-dipropyl-2-[4-methoxy-3-(2-phenyl-ethoxy)phenyl]- ethylamine monohydrochloride ([3H] NE-100), a highly potent and selective sigma-receptor ligand, to guinea-pig brain membranes. [3H]NE-100 showed saturable and reversible binding to sigma binding sites. A dissociation constant (Kd) and maximal numbers of binding sites (Bmax) obtained from Scatchard plot analysis were 1.2 +/- 0.1 nM and 1049.3 +/- 115.1 fmol/mg protein (n = 3), respectively. NE-100 was the most potent inhibitor of [3H]NE-100 binding among several structurally dissimilar sigma-receptor ligands, including haloperidol and (+)-pentazocine. (+)-Benzomorphanes had more than a 10-fold potent inhibitory activity over (-)-benzomorphanes, with regard to [3H]NE-100 binding. The binding of [3H]NE-100 was not influenced by histaminergic, dopaminergic, adrenergic, serotonergic cholinergic or glutaminergic agents at 10(-7) M. GTP-gamma-S and phenytoin also did not affect the binding of [3H]NE-100. A higher [3H]NE-100 binding was observed in the cerebellum and medulla oblongata. Except for the nuclear fraction, the highest level of [3H]NE-100 binding to subcellular fractions was observed in microsomal fractions. These results suggest that NE-100 selectively binds, with a high affinity, to sigma-1 binding sites in guinea-pig brain membranes, as an "antagonist".
Tanaka
M
M
Department of Pharmacology, Taisho Pharmaceutical Co., Ltd., Saitama, Japan.
Shirasaki
T
T
Kaku
S
S
Muramatsu
M
M
Otomo
S
S
D000818:Animals; D000840:Anisoles / Q000378:metabolism*; D001667:Binding, Competitive / Q000187:drug effects; D001921:Brain / Q000378:metabolism*; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007700:Kinetics; D008024:Ligands; D008297:Male; D008566:Membranes / Q000378:metabolism; D009711:Nucleotides / Q000494:pharmacology; D010672:Phenytoin / Q000494:pharmacology; D011437:Propylamines / Q000378:metabolism*; D017480:Receptors, sigma / Q000378:metabolism*; D013347:Subcellular Fractions / Q000378:metabolism
D000840:Anisoles; D008024:Ligands; D009711:Nucleotides; D011437:Propylamines; D017480:Receptors, sigma; C083832:N,N-dipropyl-2-(4-methoxy-3-(2-phenylethoxy)phenyl)ethylamine monohydrochloride; D010672:Phenytoin