2-B-SS11-1 〇尾崎 乃理子¹、坂本 直観¹、堀上 大貴¹、橘 侑里¹、永田 奈々恵¹、小林 幸司²、荒井 美乃³、曽根 正好³、平山 和宏⁴、村田 幸久^1,2,5 Noriko Ozaki¹, Naoaki Sakamoto¹, Daiki Horikami¹, Yuri Tachibana¹, Nanae Nagata¹, Koji Kobayashi², Yoshino Arai³, Masayoshi Sone³, Kazuhiro Hirayama⁴, Takahisa Murata^{1,2,5 1}東京大・院農・放射線動物科学、²東京大・院農・食と動物のシステム科学、³そねクリニック、⁴東京大・院農・獣医公衆衛生、⁵東京大・院農・獣医薬理 ¹Dept. Animal Radiolody., Grad. Agr. & Life Sciences., Univ. of Tokyo, ²Crs. Food and Animal Systemics., Grad. Agr. & Life Sciences., Univ. of Tokyo, ³Sone clinic, ⁴Dept. Veterinary Public Health., Grad. Agr. & Life Sciences., Univ. of Tokyo, ⁵Dept. Veterinary Pharmacol., Grad. Agr. & Life Sciences., Univ. of Tokyo Lipid mediators such as prostaglandins and leukotrienes exacerbated nasal congestion in allergic rhinitis (AR) by increasing blood flow and vascular permeability in nasal mucosa. We here aimed to investigate the effect of a lipoxygenase-metabolite of dihomogammalinolenic acid, 15-hydroxyeicosatrienoic acid (15-HETrE) on functional changes of vasculature, since the previous study showed high level of 15-HETrE was detected in the nasal lavage fluid of AR mouse models. Intranasal administration of 15-HETrE caused abdominal breathing, decreased nasal cavity volume, and increased extravasation of dye injected intravenously in mice. Whole-mount immunostaining revealed that 15-HETrE administration relaxed vessels in nasal mucosa. In ex vivo experiments, the treatment of 15-HETrE relaxed mouse aorta pre-contracted by U46619 in a dose-dependent manner. This 15-HETrE-induced relaxation was inhibited by pre-treatment of prostaglandin D₂ receptor (DP) or prostacyclin receptor (IP) antagonists. Accordingly, the treatment of 15-HETrE on aorta tended to increase the level of intracellular cAMP. Finally, we showed 15-HETrE was detected in patients who complains of AR-related symptoms. These results indicate 15-HETrE can be a novel exacerbating lipid mediator for nasal congestion which stimulates major prostaglandin receptors DP and IP.