Effects of Tween-80 and butyric acid on radiation-induced bile acid enterohepatic circulation disturbance and the treatment strategy / 中华放射医学与防护杂志

ABSTRACT

Objective:To study the effect of emulsifier Tween-80 on radiation-induced bile acid enterohepatic circulation disturbance and the treatment strategy.Methods:Male C57BL/6 J mice were randomly divided into healthy control group, radiation-only group, radiation + Tween-80 group and radiation + Tween-80 + butyric acid group. The mice were exposed to total abdominal irradiation (TAI) using a specific steel lead chamber and γ-ray irradiator was used throughout the experiments. Mice in radiation+ Tween-80 group and radiation+ Tween-80+ butyric acid group were intragastrically administrated with Tween-80 for 7 d before irradiation, while healthy control group and radiation-only group were treated with sterile water. After irradiation, butyric acid was administrated to mice in radiation+ Tween-80+ butyric acid group until euthanasia, while healthy control group, radiation-only group and radiation+ Tween-80 group were treated with sterile water until euthanasia. Small intestine and fecal particles were collected 21 d after irradiation. The concentrations of bile acid in small intestinal and fecal samples were measured using enzyme linked immunosorbent assay (ELISA), the expression of TGR5 and JAM-A, as well as the ratio of IL-10/IL-12 in intestine were detected by quantitative real-time PCR (qRT-PCR). The expression levels of GPR43 in the colon were compared using immunohistochemistry (IHC).Results:Tween-80 pretreated mice exhibited lower concentration of bile acid in small intestine and higher level of bile acid in fecal sample after irradiation (7.92%, 7.99%, t=3.93, 2.94, P<0.05), the expression of TGR5, which mediating the biological function of bile acid, and it′s downstream JAM-A gene were down-regulated (20.93%, 9.91%, t=4.85, 5.14, P<0.05), the ratio of IL-10/IL-12 (indicator related to inhibition of inflammation) (4.59%, t=3.39, P<0.05) as well as the expression of GPR43 protein, a G-protein-coupled receptor for butyric acid, decreased in the colon of Tween-80-pretreated mice compared with the radiation-only group. ELISA assay revealed that butyric acid administration elevated bile acid level in small intestines (8.06%, t=9.25, P<0.05), but reduced that in feces (14.41%, t=4.71, P<0.05). In addition, TGR5 and JAM-A showed higher expression in the intestine of butyric acid-treated mice (19.35%, 32.71%, t=7.69, 19.23, P<0.05), as well as the ratio of IL-10/IL-12 (2.39%, 4.05%, t=3.38, 5.92, P<0.05) and the content of GPR43 protein in colon. Conclusions:Tween-80 deteriorates the disturbance of bile acid enterohepatic circulation induced by ionizing radiation in mice. Butyric acid administration erases the adverse effects of Tween-80.