Effect and mechanism of dihydromyricetin protection against radiation-induced intestinal injury

Objective

To investigate the protective effects of dihydromyricetin (DHM) against radiation-induced intestinal injury (RIII) and its underlying mechanism by both in vivo and in vitro experiments.

Methods

Sixty male mice were randomly divided into 6 groups: control group, whole-abdominal irradiation (WAI)+0.5% sodium carboxymethyl cellulose (CMCNa) group, WAI ​+ ​DHM (50 ​mg/kg) group, WAI ​+ ​DHM (100 ​mg/kg) group, WAI ​+ ​DHM (200 ​mg/kg) group, and WAI ​+ ​amifostine (100 ​mg/kg) group. An animal model of RIII was then established by administering 12 ​Gy abdominal local irradiation to all groups. The protective effects of DHM was evalauted by hematoxylin and eosin staining (HE), villin staining, and the FITC-dextran method. The in vitro radioprotective effects of DHM was further evaluated by colony formation assay. Flow cytometry was used to analyze cell cycle distribution, apoptosis, and reactive oxygen species (ROS) levels. Western blot assay was used to examine the expression of proteins related to apoptosis, ferroptosis, ROS, DNA damage, and autophagy. Additionally, immunofluorescence staining was performed to detect γ-H2AX foci formation as a marker of DNA double-strand breaks. Finally, the effect of DHM on colon cancer radiosensitivity was tested by in vitro and in vivo colony formation and tumor-bearing experiments.

Results

In the RIII model, DHM showed radioprotective effects by increasing colon length, ameliorating villus injury, promoting crypt cell proliferation, and mitigating mucosal barrier damage (P ​< ​0.05). In vitro experiment indicated that DHM significantly reduced radiation-induced apoptosis (control: 4.27 ​± ​0.61, DHM: 3.46 ​± ​1.31, IR: 23.46 ​± ​0.89, IR ​+ ​DHM: 12.47 ​± ​0.36, P ​< ​0.001), ROS accumulation (P ​< ​0.05), and DNA damage (P ​< ​0.001). The radioprotective effects of DHM might be closely associated with autophagy regulation and Nrf2 pathway activation. Moreover, DHM showed antitumor activity against colon cancer cells without conferring radioprotective effects on them.

Conclusions

DHM can effectively alleviate RIII indicated by both in vivo and in vitro experiments, suggesting its potential to be used as a radioprotective agent.