Binding properties of [3H]MS-377, a novel sigma receptor ligand, to rat brain membranes.
MS-377 ((R)-(+)-1-(4-chlorophenyl)-3-[4-(2-methoxyethyl)piperazin-1-yl]++ +methy l-2-pyrrolidinone L-tartrate) is a novel selective sigma receptor ligand, currently being developed for the treatment of schizophrenia. MS-377 showed anti-phencyclidine (PCP), anti-dopaminergic and anti-serotonergic activities, and we anticipated that the anti-psychotic activities of MS-377 were associated with sigma(1) receptors. However, its pharmacological profile is partly distinct from those of selective sigma(1) receptor ligands. Thus, one of the possible speculations is that MS-377 has another site of action. In the present study, we examined the binding properties of radiolabeled MS-377 ([3H]MS-377) to rat brain membranes. [3H]MS-377 showed saturable and reversible binding to rat brain membranes. Scatchard plot and Hill plot from saturation studies were linear, with K(d) of 15.2+/-6.6 nM, B(max) of 599.4+/-58.6 fmol/mg protein and Hill coefficient of 1.01+/-0.01, indicating that [3H]MS-377 bound to a single high-affinity site in rat brain membranes. Displacement studies revealed that the other sigma reference compounds with different structures inhibited the specific binding of [3H]MS-377 in a competitive manner. Stereoselectivity was observed for the inhibition of [3H]MS-377 binding, (+)-isomers were more potent than (-)-isomers. Non-sigma receptor ligand PCP showed weak inhibition of [3H]MS-377 binding. The rank order of potency for the sigma reference compounds to displace [3H]MS-377 binding were as following: haloperidol>MS-377=(+)-pentazocine>DTG (1, 3-Ditolylguanidine)=(-)-pentazocine>BMY14802 (alpha-(4-fluorophenyl)-4-(5-fluoro-2-pyramidinyl)-1-piperazine butanol)>(+)-SKF-10,047>(-)-SKF-10,047=PCP. These results suggested that the MS-377 selectively binds to sigma binding site with high affinity in rat brain membranes. Therefore, the anti-psychotic activities of MS-377 are attributable to association with sigma(1) receptors.
Karasawa
J
J
Medicinal Research Department, Institute of Biological Science, Mitsui Pharmaceuticals, Inc., 1900-1 Togo, Mobara-shi, 297-0017, Chiba, Japan. Junichi_Karawawa@mitsui-pharm.co.jp
Takahashi
S
S
Horikomi
K
K
D000818:Animals; D014150:Antipsychotic Agents / Q000378:metabolism*; D001665:Binding Sites; D001667:Binding, Competitive; D001921:Brain / Q000378:metabolism*; D008024:Ligands; D008297:Male; D010879:Piperazines / Q000378:metabolism*; D011759:Pyrrolidines / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D017480:Receptors, sigma / Q000378:metabolism*; D013644:Tartrates
C464615:1-(4-chlorophenyl)-3-(4-(2-methoxyethyl) piperazin-1-yl)methyl-2-pyrrolidinone tartrate; D014150:Antipsychotic Agents; D008024:Ligands; D010879:Piperazines; D011759:Pyrrolidines; D017480:Receptors, sigma; D013644:Tartrates