Inhibition of Japanese cedar pollen-induced nasal allergic response by lemon grass (Cymbopogon citratus) essential oil in mice

Abstract

Current study determined effects of lemon grass (LG) essential oil on allergic rhinitis (AR) induced by Japanese cedar pollen (JCP). Male ICR mice were sensitized by i.p. injections with JCP+alum on days 0, 7 and 14. From day 21, the sensitized mice were challenged by intranasal (i.n.) administrations of JCP for 4 consecutive days. Animals were also treated with LG (i.n.) 30 min before each JCP challenge. Frequency of sneezing was counted for 20 min after each nasal challenge. Sneezing induced by histamine (Hist, i.n.) was also counted on days 18 and 25. In the JCP sensitized and repeatedly challenged mice, both serum levels of IgG and IgE specific for Cry J1, a major allergen of JCP, were significantly increased. The i.n. JCP challenge to sensitized mice caused a significant increase in sneezing, indicating an induction of nasal allergic response. An increase in sneezing was also induced by the i.n. application of Hist. The Hist-induced sneezing was further increased significantly on day 25, indicating an induction of nasal hyperresponsiveness (NHR) after the repeated JCP challenges. Both the JCP-induced nasal allergic response and NHR were inhibited by the pretreatments with LG. It is thus possible that aromatherapy using LG is effective for the treatment of Japanese cedar pollinosis.