Binding of [ 3H]FH-510 to σ ligand recognition sites in guinea-pig brain membranes

• Published in: European journal of pharmacology Vol. 238; no. 1; pp. 93 - 100
• Main Authors: Makoto, Tanaka, Shinsuke Kaku, Makoto Muramatsu, Otomo, Susumu
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 06.07.1993; Elsevier
• Subjects: Animals; Anti-Anxiety Agents - metabolism; Binding Sites; Binding, Competitive - drug effects; Biological and medical sciences; Brain (guinea-pig); Brain - drug effects; Brain - metabolism; Carbazoles - metabolism; Carbazoles - pharmacology; Dopamine Agents - metabolism; FH-510 (5,8-dimethyl-4-(2-di-n-propylaminoethyl)carbazol monohydrochloride); Guinea Pigs; Histamine - analogs & derivatives; Histamine - metabolism; In Vitro Techniques; Kinetics; Male; Medical sciences; Microsomes - metabolism; Miscellaneous; Neuropharmacology; Neurotransmitters. Neurotransmission. Receptors; Pharmacology. Drug treatments; Phenazocine - analogs & derivatives; Phenazocine - metabolism; Piperidines - metabolism; Propylamines - metabolism; Propylamines - pharmacology; Pyrimidines - metabolism; Radiolabeled ligand binding; Radioligand Assay; Receptors, sigma - metabolism; Serotonin - analogs & derivatives; Serotonin - metabolism; σ Binding sites; FH-510 (5,8-dimethyl-4-(2-di-n-propylaminoethyl)carbazol monohydrochloride); Radiolabeled ligand binding; σ Binding sites; Brain (guinea-pig); Ligand binding; Vertebrata; Mammalia; Guinea pig; Ligand; Animal; Carbazole derivatives; Rodentia; Central nervous system; Sigma receptor; In vitro; Brain (vertebrata)
• ISSN: 0014-2999; 1879-0712
• DOI: 10.1016/0014-2999(93)90510-O

We examined the characteristics of the binding of radiolabeled 5,8-dimethyl-4-(2-di-n-propylaminoethyl)carbazol monohydrochloride ([ 3H]FH-510), a highly potent and selective σ ligand, to guinea-pig brain membranes. [ 3H]FH-510 showed saturable and reversible binding to σ binding sites. The association rate constant (k +1) and dissociation rate constant (k −1) and dissociation (k −1) of [ 3H]FH-510 were 0.23 min −1·nM −1 and 0.081 min −1, respectively. Scatchard plot analysis showed a dissociation constant (K d and maximal number of binding sites (B max) of 6.0 ± 0.63 nM and 1763.3 ± 177.4 fmol/mg protein (n = 7), respectively. The rank order of potency (K i) of several structurally dissimilar σ ligands obtained for the displacement of [ 3H]FH-510 binding was highly correlated with that determined for [ 3H](+)-3-(3-hydroxyphenyl)-N-(1-propyl)piperidine ([ 3H](+)-3-PPP) binding. The binding of [ 3H]FH-510 was not influenced by histaminergic, dopaminergic, adrenergic, serotonergic or cholinergic agents at 10 −7 M. Higher [ 3H]FH-510 binding to brain regions was observed in the cerebellum and pons-plus-medulla. Except for the nuclear fraction, the highest level of [ 3H]FH-510 and [ 3H](+)-3-PPP binding to subcellular fractions was observed in the microsomal fraction. From these results, it is suggested that FH-510 selectivity binds with high affinity to σ binding sites in guinea-pig membranes.