Astragalus membranaceus is a medicinal herb with potential immunomodulatory property, which has been used in treating
colitis-related
diarrhea. In the present investigation, we aimed to further explore its anti-inflammatory activity by studying the immunoregulatory mechanism of Astragalus root extract (Am) through different routes of administration in
hapten-induced
colitis.
2,4-Dinitrobenzene sulfonic acid (
DNBS) was used to induce experimental
colitis in Sprague-Dawley rats. Results have indicated that both oral and intracolonic Am treatments (administered twice daily for three consecutive days following
colitis induction) exhibited significant protection against
DNBS-induced
colitis in rats, indicated by decreased colonic lesion area and histological damage score as well as amelioration of the elevated colonic
myeloperoxidase activity. Western immunoblotting has revealed that oral Am could diminish the overexpression of
tumor necrosis factor (
TNF)-alpha and
interleukin (IL)-1beta, while concomitantly abolishing the inhibition of
IL-10 expression in rats' colon under
colitis condition. On the other hand, intracolonic Am could only reduce
TNF-alpha and
interferon-gamma overexpression. In summary, we have demonstrated that both oral and locally administered Am possess protective effects against experimental
colitis through differential modulation of colonic
cytokines. This study provides important new insights that may contribute to further development of Am as a novel therapeutic agent for treating
colitis diseases.