Synthesis and pharmacological in vitro and in vivo profile of SHA 68 (3-Oxo-11-diphenyl-tetrahydro-oxazolo34-apyrazine-7-carboxylic acid 4-fluoro-benzylamide) a selective antagonist of the Neuropeptide S receptor

摘要

Neuropeptide S (NPS) has been shown to modulate arousal, sleep-wakefulness, anxiety-like behavior and feeding after central administration of the peptide agonist to mice or rats. We report here the chemical synthesis and pharmacological characterization of SHA 66 (3-Oxo-1,1-diphenyl-tetrahydro-oxazolo[3,4-a]pyrazine-7-carboxylic acid benzylamide) and SHA 68 (3-Oxo-1,1-diphenyl-tetrahydro-oxazolo[3,4-a]pyrazine-7-carboxylic acid 4-fluoro-benzylamide), two closely related bicyclic piperazines with antagonistic properties at the NPS receptor (NPSR). The compounds block NPS-induced Ca²⁺-mobilization and SHA 68 shows displaceable binding to NPSR in the nanomolar range. The antagonistic activity of SHA 68 appears to be specific as it does not affect signaling at fourteen unrelated G protein-coupled receptors. Analysis of pharmacokinetic parameters of SHA 68 demonstrates that the compound reaches pharmacologically relevant levels in plasma and brain following intraperitoneal (i.p.) administration. Furthermore, peripheral administration of SHA 68 in mice (50 mg/kg, i.p.) is able to antagonize NPS-induced horizontal and vertical activity as well as stereotypic behavior. Therefore, SHA 68 could be a useful tool to characterize physiological functions and pharmacological parameters of the NPS system in vitro and in vivo.