YF476 is a new potent and selective gastrin/cholecystokinin-B receptor antagonist in vitro and in vivo

Background: We newly synthesized YF476 ((R)-1-[2,3-dihydro-2-oxo-1-pivaloylmethyl-5-(2'-pyridyl)-1H-1, 4benzodiazepin-3-yl]-3-(3-methylamino-phenyl)urea) as a Gastrin/cholecystokinin-B (CCK-B) receptor antagonist. We investigated the pharmacological profile of YF476 in vitro and in vivo.

Methods: We examined the binding properties of YF476 to the rat brain, cloned canine and cloned human Gastrin/CCK-B receptors, and the effect of YF476 on secretagogue-induced gastric acid secretion in rats and Heidenhain pouch dogs.

Results: YF476 replaced the specific binding of [125I]CCK-8 to the rat brain, cloned canine and cloned human Gastrin/CCK-B receptors, with Ki values of 0.068, 0.62 and 0.19 nM, respectively. The affinity of YF476 for rat brain Gastrin/CCK-B receptor was 4100-fold higher than that for rat pancreatic CCK-A receptor. In anaesthetized rats, intravenous YF476 inhibited pentagastrin-induced acid secretion with an ED50 value of 0.0086 micromol/kg, but did not affect histamine- and bethanechol-induced acid secretion at a dose of 10 micromol/kg. In Heidenhain pouch dogs, intravenous and oral YF476 inhibited pentagastrin-stimulated gastric acid secretion in a dose-dependent manner with ED50 values of 0.018 and 0.020 micromol/kg, respectively, but did not affect histamine-induced acid secretion.

Conclusion: These results suggest that YF476 is an extremely potent and highly selective Gastrin/CCK-B receptor antagonist, and that the Gastrin/CCK-B receptor is not involved in histamine- or bethanechol-induced gastric acid secretion in dogs or rats.