A new CysLT 1 and CysLT 2 receptors-mediated anaphylaxis guinea pig model.

Although the effectiveness of CysLT1 receptor antagonists on asthma has been clinically established, the effects of CysLT2 receptor antagonists are still unclear. The purpose of this study was to develop a new CysLT1 and CysLT2 receptors-mediated anaphylaxis guinea pig model using S-hexyl GSH, a γ-glutamyl transpeptidase (GTP) inhibitor, to suppress conversion of LTC4 to LTD4 . Actively sensitized guinea pigs were challenged with OVA in the absence or presence of S-hexyl GSH, and survival rate following anaphylactic response was monitored. OVA-induced fatal anaphylaxis in the absence of S-hexyl GSH was almost completely inhibited by montelukast, a CysLT1 receptor antagonist, but not by the CysLT2 receptor antagonist BayCysLT2 RA. However, under treatment with S-hexyl-GSH, the inhibitory effect of motelukast was dramatically diminished, whereas that of BayCysLT2 RA was markedly increased. The dual CysLT1/2 receptor antagonist ONO-6950 effectively inhibited anaphylactic response in both S-hexyl GSH-treated and non-treated animals. LC/MS/MS analysis revealed that S-hexyl GSH treatment actually inhibited LTC4 metabolism in the blood and lung tissues. Using S-hexyl GSH, we developed a novel CysLT1 and CysLT2 receptors-mediated anaphylaxis guinea pig model that can be useful for not only screening both CysLT2 and CysLT1/2 receptors antagonists, but also for functional analysis of CysLT2 receptors.