Thromboxane receptor (TP) mediates nasal obstruction, a typical symptom of allergic rhinitis. Since it has been reported that several types of eicosanoids, such as non-enzymatic oxidation product of arachidonic acid isoprostane, act as a TP ligand, there is a possibility that some other eicosanoids contribute to the TP-mediated nasal obstruction. The aim of this study is to investigate the mechanisms of TP-mediated nasal obstruction. Intranasal challenges of ovalbumin (OVA) induced nasal obstruction in mice. Pharmacological blockade of TP receptor but not thromboxane A2 synthase inhibited OVA-induced nasal obstruction. Simultaneous analysis of eicosanoids in nasal lavage fluid and the responses in trans-endothelial resistance suggested that 8-iso-prostaglandin E2 (PGE2 ) can be a candidate for TP ligand. Intranasal challenge of 8-iso-PGE2 induced vascular hyperpermeability and nasal obstruction in TP receptor-dependent manner. Wholemount immunostaining of nasal septum mucosa revealed that 8-iso-PGE2 increased plasma leakage accompanied by distention of venous sinusoids. This study shows that 8-iso-PGE2 is a contributor in TP-mediated nasal obstruction in mice.
Keywords: 8-iso-PGE2; allergic rhinitis; isoprostane; nasal obstruction; thromboxane receptor.
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