title: Suppression of neuropeptide production by quercetin in allergic rhinitis model rats.
abstract: BACKGROUND
  Quercetin, a dietary flavonoid found in many fruits, red wine and onion, among others, has been reported to have potent anti-oxidant, anti-viral and anti-cancer effects. Although quercetin is also reported to have anti-inflammatory and anti-allergic effects, the precise mechanisms by which quercetin favorably modify the clinical conditions of allergic diseases such as allergic rhinitis (AR). The present study was designed to examine the influence of quercetin on the development of AR by using AR model rats.
  
  
  METHODS
  Sprague-Dawley (SD) rats were sensitized with toluene 2,4-diisocyanate (TDI) by intranasal instillation of a 10 % TDI in ethyl acetate in a volume of 5 μl once a day for 5 consecutive days. This sensitization procedure was repeated after a 2-day interval. After 5 days of the second sensitization, rats were treated with various doses of quercetin once a day for 2 to 7 days. Nasal allergy-like symptoms, which were induced by bilateral application of 5 μl of 10 % TDI in ethyl acetate, were assessed by counting sneezing and nasal rubbing behaviors for 10 min just after TDI nasal challenge. The levels of substance P (SP), calcitonin gene-related peptide (CGRP) and nerve growth factor (NGF) in nasal lavage fluids obtained 6 h after TDI nasal challenge was examined by ELISA.
  
  
  RESULTS
  Oral administration of quercetin for 5 and 7 days, but not 2 and 3 days, could inhibit sneezing and nasal rubbing movements, which were increased by TDI nasal challenge. The minimum dose that caused significant inhibition was 25 mg/kg. Oral administration of quercetin at more than 25 mg/kg for 5 days significantly inhibited the increase in SP, CGRP and NGF contents in nasal lavage fluids induced by TDI nasal challenge.
  
  
  CONCLUSIONS
  The present results strongly suggested that quercetin will be a good candidate for the supplement on the management and treatment of allergic diseases, especially AR.
authors.affiliation: Graduate School of Nursing and Rehabilitation Sciences, Showa University Graduate School, Midori-ku, Yokohama, 226-8555, Japan.
authors.forename: Misako
authors.initials: M
authors.lastname: Kashiwabara
authors.affiliation: Graduate School of Nursing and Rehabilitation Sciences, Showa University Graduate School, Midori-ku, Yokohama, 226-8555, Japan. asanok@med.showa-u.ac.jp.|Division of Physiology, School of Nursing and Rehabilitation Sciences, Showa University, 1865 Touka-Ichiba, Midori-Ku, Yokohama, 226-8555, Japan. asanok@med.showa-u.ac.jp.
authors.forename: Kazuhito
authors.initials: K
authors.lastname: Asano
authors.affiliation: Department of Otolaryngology, School of Medicine, Showa University, Shinagawa-ku, Tokyo, 142-8555, Japan.
authors.forename: Tomomi
authors.initials: T
authors.lastname: Mizuyoshi
authors.affiliation: Department of Otolaryngology, School of Medicine, Showa University, Shinagawa-ku, Tokyo, 142-8555, Japan.
authors.forename: Hitome
authors.initials: H
authors.lastname: Kobayashi
mesh_terms: D000818:Animals; D018926:Anti-Allergic Agents / Q000627:therapeutic use*; D015740:Calcitonin Gene-Related Peptide / Q000096:biosynthesis; D008297:Male; D017817:Nasal Lavage Fluid; D020932:Nerve Growth Factor / Q000096:biosynthesis; D009479:Neuropeptides / Q000096:biosynthesis*; D011794:Quercetin / Q000627:therapeutic use*; D051381:Rats; D017207:Rats, Sprague-Dawley; D065631:Rhinitis, Allergic / Q000139:chemically induced / Q000188:drug therapy*; D013373:Substance P / Q000096:biosynthesis; D014051:Toluene 2,4-Diisocyanate
chemical_list: D018926:Anti-Allergic Agents; D009479:Neuropeptides; D014051:Toluene 2,4-Diisocyanate; D013373:Substance P; D020932:Nerve Growth Factor; D011794:Quercetin; D015740:Calcitonin Gene-Related Peptide
keywords: Calcitonin gene-related peptide; Nasal allergy-like symptom; Nerve growth factor; Quercetin; Rat; Substance P; Suppression