Animal experimental design
Twenty-four 7-to 8-week-old male C57BL/6 mice were purchased from CAVENS
LAB ANIMAL Co., (Changzhou, China). After two weeks of adaptive feeding,
they were randomly divided into four groups: Normal group (6 mice), DSS
group (6 mice), DSS+LE group (6 mice), DSS+HE group (6 mice). Except for
the normal group treatment with drinking water, the remaining groups
received 3% DSS in drinking water for 8 days. From the first day of
adding DSS to the drinking water, EGCG treatment was administered to
mice at a dose of 10 and 20 mg/kg per day by gavage for 1 week. During
modelling and drug treatment, the stool consistency, rectal bleeding and
weight were recorded daily. The disease activity index (DAI), a score
used to assess the severity of colitis, was calculated as previously
described14. All animal experiments were undertaken
according to the institutional guidelines and were approved by the
Institutional Animal Care and Use Committee of the Yunnan Agricultural
University.
At the end of the experiment, all mice were killed with sodium
pentobarbital and received colon tissue,whose length was measured, and
then portions of colon were stored at -80℃ for the western blot and
enzyme-linked immunosorbent assay (ELISA).Portions of colons were fixed
in formalin for histopathological and immunohistochemical analysis.