Protective effects of Polygalae root in experimental TNBS-induced colitis in mice

In this study, the protective effect of Polygalae root was evaluated in a murine model of experimental colitis by intrarectal injection with 2,4,6-trinitrobenzene sulfonic acid (TNBS). Polygalae root, given orally at 2, 4 g/kg body weight of herbs once a day consecutively for 9 days, could recover the lost body weight and decrease the gross rectal bleeding. Polygalae root also reduced the degree of inflammation and improved significantly the histological changes such as infiltration by polymorphonuclear leukocytes and multiple erosive lesions. Furthermore, the cytokine production of intraepithelial lymphocytes was analyzed. The results showed that IFN-gamma was increased, but IL-4 was decreased in TNBS-induced colitis, when those were compared with the sham controls. But the administration of Polygalae root to TNBS-induced colitis mice showed lower production of IFN-gamma and higher production of IL-4 than the TNBS-induced colitis. These results suggest that the protective effects of Polygalae root against the TNBS colitis may be associated with the regulation of cytokine production of intraepithelial lymphocytes.