Daily body weight of rats in NC group, UC group and UC+Cit group from 0th to 7th day after modeling (a). Body weight of UC group rats significantly decreased on the 7th day after modeling, *P<0.05 vs. the initial body weight at day 0. Weight of rats in UC+Cit group also decreased on the 7th day after modeling, but there was no significant difference from the initial weight (b). The histopathology score of UC group rats was significantly higher than that of NC group (*P<0.05), while the score of UC+Cit group was significantly lower than that of UC group (#P<0.05) (c). In the NC group, the epithelial cells were neatly arranged, goblet cells were abundant, gland structure was clear, capillaries and lymphocytes were scarce (d) (×100). Ulcerative defects were observed in the mucosal epithelium of the UC group, with mucosal hyperemia, obvious destruction of glandular structure, significant reduction of goblet cells, and a large number of inflammatory cell infiltration (e) (×100). The intergrity of mucosal epithelium cells, glandular structure and goblet cells were retained in UC+Cit group rats, with slight hyperemia and fewer infiltrated inflammatory cells around (f) (×100).