Effectiveness of quercetin in an experimental rat model of allergic rhinitis.

We aimed to investigate whether quercetin had a therapeutic effect in an experimental rat model of allergic rhinitis. The study was conducted with 35 rats, which were randomly assigned into 4 groups: group 1 (n = 5), sham group; group 2 (quercetin group, n = 10) received 80 mg/kg day quercetin; group 3 (steroid group, n = 10) received steroid (mometasone furoate); and group 4 (control group, n = 10), received ovalbumin alone. Rats were sensitized by administration of ovalbumin on alternate days over 14 days via an intraperitoneal route. On day 15, in addition to ovalbumin via an intranasal route, quercetin and steroid were given over 7 days to the corresponding groups. All rats were then sacrificed and nasal turbinates were evaluated histopathologically, and serum total IgE and ovalbumin (OVA)-specific IgE values were measured before and after treatment. A significant increase in OVA-specific IgE values was detected in all groups except sham group. A significant increase was detected in post-treatment total IgE levels in the control group, while no significant change was detected in the sham, quercetin, and intranasal steroid groups. On histopathological evaluation, it was observed that findings of allergic rhinitis were suppressed in the quercetin group when compared to the control group. In immunohistochemical evaluation, it was detected that COX-2 and VIP expressions were weaker in the quercetin group compared to the control group. Based on these findings, we conclude that quercetin was effective in allergic rhinitis induced by ovalbumin in rats both histopathologically and serologically.