Pharmacological Characterization of Ro 63-1908 (1-[2-(4-Hydroxy-phenoxy)-ethyl]-4-(4-methyl-benzyl)-piperidin-4-ol), a Novel Subtype-SelectiveN-Methyl-d-Aspartate Antagonist

Abstract

Ro 63-1908, 1-[2-(4-hydroxy-phenoxy)-ethyl]-4-(4-methyl-benzyl)-piperidin-4-ol, is a novel subtype-selective N-methyl-D-aspartate (NMDA) antagonist that has been characterized in vitro and in vivo. Ro 63-1908 inhibited [ 3 H]dizocilpine ( 3 H-MK-801) binding in a biphasic manner with IC 50 values of 0.002 and 97 M for the high-and low-affinity sites, respectively. Ro 63-1908 selectively blocked recombinant receptors expressed in Xenopus oocytes containing NR1C ϩ NR2B subunits with an IC 50 of 0.003 M and those containing NR1C ϩ NR2A subunits with an IC 50 of Ͼ100 M, thus demonstrating greater than 20,000-fold selectivity for the recombinant receptors expressing NR1C ϩ NR2B. Ro 63-1908 blocked these NMDA NR2B-subtype receptors in an activity-dependent manner. Ro 63-1908 was neuroprotective against glutamate-induced toxicity and against oxygen/glucose deprivation-induced toxicity in vitro with IC 50 values of 0.68 and 0.06 M, respectively. Thus, the in vitro pharmacological characterization demonstrated that Ro 63-1908 was a potent and highly selective antagonist of the NR2B subtype of NMDA receptors. Ro 63-1908 was active against sound-induced seizures (ED 50 ϭ 4.5 mg/kg i.p. when administered 30 min beforehand) in DBA/2 mice. The dose required to give a full anticonvulsant effect did not produce a deficit in the Rotarod test. NMDA-induced seizures were also inhibited by Ro 63-1908 with an ED 50 of 2.31 mg/kg i.v. when administered 15 min before testing. Ro 63-1908 gave a dose-related neuroprotective effect against cortical damage in a model of permanent focal ischemia. Maximum protection of 39% was seen at a plasma concentration of 450 ng/ml. There were, however, no adverse cardiovascular or CNS side-effects seen at this dosing level.Native NMDA receptors are composed of an NR1 subunit (can occur as eight different splice variants), which combines with NR2A-D subunits to form heteromeric receptors (for reviews see McBain and Mayer, 1994;Kemp and Kew, 1998). NMDA receptors are thought to be tetramers that are composed of two NR1 and two NR2 subunits (Laube et al., 1998), which is compatible with earlier electrophysiological evidence demonstrating that NMDA receptor activation requires occupation of two independent glycine binding sites and two independent glutamate sites (Benveniste and Mayer, 1991;Clements and Westbrook, 1991). The glutamate and glycine binding sites are believed to be located on the NR2 and NR1 subunits, respectively (Wafford et al., 1995;Hirai et al., 1996;Laube et al., 1997;Anson et al., 1998). However, the proposed tetrameric stoichiometry of NMDA receptor remains controversial because evidence also exists for a pentameric structure (for review see Kemp and Kew, 1998).In the adult rodent and human brain the NR1 subunit is widely distributed throughout the brain, whereas the NR2 subunits are expressed in a distinct spatio-temporal manner (Watanabe et al., 1993;Monyer et al., 1994;Rigby et al., 1996;Wenzel et al., 1997). The predominant NR2 subunits in the forebrain are NR2A and NR2...

Upregulation of Forebrain NMDA NR2B Receptors Contributes to Behavioral Sensitization after Inflammation

“…8 A). We also evaluated 1 g/0.5 l (5.0 mM) Ro 63-1908 (IC 50 ϭ 0.003 M) (Gill et al, 2002), another NR2B inhibitor (Gill et al, 2002;Higgins et al, 2003) and obtained similar results (n ϭ 5 mice) (Fig. 8 A).…”

Novel Drugs and Therapeutic Targets for Severe Mood Disorders

“…Indeed, the NR2B antagonist Ro 25-6981 had antidepressant-like properties in the forced swim test (Maeng et al, 2007). From a safety perspective, this compound also has not been associated with vacuolization in rodents (Gil et al, 2002), in contrast to the reversible vacuolization at high doses observed with noncompetitive NMDA antagonists such as ketamine and dizocilpine (Olney et al, 1989).…”

On the Hypes and Falls in Neuroprotection: Targeting the NMDA Receptor

“…These transgenic mice showed an enhanced behavioral response to hindpaw inflammation, suggesting a role of NR2B subunits in prolonged models of peripheral inflammation (Wei and others 2001;Miki and others 2002). The in vivo antinociceptive action of selective NR2B antagonism was demonstrated by two compounds, Ro63-1908 (benzyl-piperidinyl-4-ol) and CP101,606 (an ifenprodil analog) (Chazot and others 2002;Gill and others 2002). Furthermore, flupirtinmaleate (Katadolon ® ) was discussed as an NMDA receptor antagonist (Muller and others 1996;Seyfried and others 2000), and studies on human brain slices also showed that flupirtinmaleate is neuroprotective.…”

“…Specific receptor blockers of the NMDA receptor are thought to selectively interrupt the excitotoxic process after ischemia. Chazot and others (2002); Gill and others (2002) CP101,606…”

“…Chazot and others (2002); Gill and others (2002) Summary of the agonist and antagonists of NMDA, AMPA, and kainate receptors according to http://www.ncbi.nlm.nih.gov/entrez/query.fcgi, search: PubChem Compound. The compound identity numbers are listed in the second right column (CID: XX).…”