Binding properties of SA4503, a novel and selective sigma 1 receptor agonist.
The binding profiles of SA4503 (1-(3,4-dimethoxyphenethyl)-4-(3-phenylpropyl)piperazine dihydrochloride), a novel sigma receptor ligand, to sigma 1 and sigma 2 receptor subtypes in guinea pig and rat brain membranes were evaluated. SA4503 showed a high affinity for the sigma 1 receptor subtype labeled by (+)-[3H]pentazocine (IC50 = 17.4 +/- 1.9 nM), while it had about 100-fold less affinity for the sigma 2 receptor subtype labeled by [3H]1,3-di(2-tolyl)guanidine ([3H]DTG) in the presence of 200 nM (+)-pentazocine. SA4503 showed little affinity for 36 other receptors, ion channels and second messenger systems. The inhibition curves of SA4503 for (+)-[3H]pentazocine binding were shifted to the right in the presence of guanosine 5'-o-(3-thiotriphosphate) (GTP gamma S), as similar to those of (+)-3-(3-hydroxyphenyl)-N-(1-propyl)piperidine ((+)-3-PPP) and (+)-pentazocine, sigma 1 receptor agonists. SA4503 significantly increased the KD value, but did not affect the Bmax value for specific (+)-[3H]pentazocine binding. These results indicated that SA4503 is a potent and selective agonist for the sigma 1 receptor subtype in the brain. In addition, SA4503 inhibited specific (+)-[3H]pentazocine binding in a competitive manner.
Matsuno
K
K
Central Research Laboratories, Santen Pharmaceutical Co., Ltd., Osaka, Japan.
Nakazawa
M
M
Okamoto
K
K
Kawashima
Y
Y
Mita
S
S
D000818:Animals; D001667:Binding, Competitive; D001921:Brain / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D006168:Guinea Pigs; D008297:Male; D009292:Narcotic Antagonists / Q000378:metabolism; D009294:Narcotics / Q000378:metabolism*; D010423:Pentazocine / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010879:Piperazines / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D017480:Receptors, sigma / Q000378:metabolism*; D013379:Substrate Specificity
D009292:Narcotic Antagonists; D009294:Narcotics; D010879:Piperazines; D017480:Receptors, sigma; C101789:SA 4503; D010423:Pentazocine