Anti-inflammatory and anti-apoptotic effects of Shaoyao decoction on X-ray radiation-induced enteritis of C57BL/6 mice

As a typical heat-clearing prescription, Shaoyao decoction (SYD) has a robust function of clearing viscera heat for the treatment of several intestinal discomfort symptoms. Clinical evidence indicated that it had the potential to cure radiation enteritis. However, its underlying mechanisms remain unclear.The present study was designed to probe the protective effects and the involved mechanisms of SYD on X-ray radiation-induced enteritis of C57BL/6 mice.X-ray irradiation were used to establish the radiation enteritis model. Forty-eight male C57BL/6 mice (20 ± 2 g) were randomly divided into six groups: the control group, model group, dexamethasone group (DEX, 0.12 mg/kg) and SYD groups (0.12, 0.24 and 0.36 g/mL), respectively. All mice (except the control group) were intragastrically administrated for a continuous 7 days. H&E and Masson staining were employed to evaluate the morphological and collagen fibers changes of the colon. ELISA was performed to assess the levels of MDA, SOD, COX, LPS, IL-6, IL-1β and TNF-α in serum. Moreover, TUNEL fluorescence, western blot and qRT-PCR were used to detect the levels of apoptosis-related proteins and genes of Dclk-1, ATM, MRE-11, Bcl-2, Bax, Caspase-3, and Cyto-c. Furthermore, immunofluorescent staining was applied to detect the protein levels of p53 and Claudin-1 in colon.Treatment with SYD decreased the exfoliated and necrotic epithelial cells and prevent the proliferate from damaged fibrous tissue in the crypt layer of mucos. The levels of serum peroxidation and pro-inflammatory cytokines (MDA, COX, LPS, IL-6, IL-1β and TNF-α) were obviously inhibited, while SOD sharply increased in serum after administration. Moreover, SYD can significantly ameliorate the apoptosis of colon cells, evidenced by the reduced positive expression of TUNEL staining. Meanwhile, the results of qRT-PCR and western blot demonstrated that SYD can dramatically stimulate the expression of genes and proteins Dclk-1, ATM and MRE-11, thus promoting the expression of mitochondrial pro-apoptotic proteins Bax, Caspase-3 and Cyto-c, while increasing the level of anti-apoptotic protein Bcl-2. Furthermore, immunofluorescence revealed that SYD can notably decreased the protein level of p53 while reverse the reduction of Claudin-1.These results indicated that radiation enteritis in C57BL/6 mice can be ameliorated by treatment with SYD. The potential protection mechanisms may be involved in ameliorating tissue fibrosis by decreasing inflammatory and apoptotic events.