RESUMO
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.
RESUMO
Objective:To investigate the effect of ionizing radiation on the N 6-methyladenine (m 6A) modification profile of circular RNA (circRNA) in mouse bone marrow cells and provide scientific basis for revealing the relationship between RNA epigenetic modification and hematopoietic radiation injury. Methods:A total of twenty four C57BL/6 J mice were randomly divided into two groups: the healthy control group ( n=12), and ionizing radiation group ( n=12) irradiated in total body with 4 Gy of 137Cs γ-rays. At 5 min after irradiation, mice were killed and bone marrow cells were collected from the femur. Total RNAs were extracted and the changes in circRNA m6A modification profiles were investigated by RNA immunoprecipitation-high-throughput sequencing (MeRIP-Seq) technology and bioinformatics analysis. The representative alterations of m 6A peaks were validated by MeRIP-PCR assay. Results:325 and 455 m 6A sites were identified on circRNAs in the healthy control group and ionizing radiation group (178 common sites, 147 specific sites in the healthy control group and 277 specific sites in ionizing radiation group), respectively. 1 275 and 1 017 deriving genes of m 6A-circRNAs were identified in the healthy control group and ionizing radiation group (767 common genes, 508 specific genes in the healthy control group and 250 specific genes in ionizing radiation group), respectively. Compared with the control healthy group, 414 (178) m 6A peaks was significantly up- (down-) regulated in the ionizing radiation group( P < 10 -10; fold-change cut-off > 5). Moreover, Gene Ontology (GO) assay revealed that the deriving genes of circRNAs with differentially methylated m 6A sites between two groups involves various functions including chromatin regulation, ciliary transition fiber and poly (A)-specific ribonuclease activity. Kyoto Encyclopedia of Genes and Genomes (KEGG) assay revealed that the deriving genes of circRNAs with differentially methylated m 6A sites between two groups included numerous pathways such as platelet activation, Fc γ R-mediated phagocytosis and B cell receptor signaling pathway. Conclusions:Ionizing radiation triggers rapid alterations in the m 6A modification profile of circRNA in mouse bone marrow cells. The deriving genes of differentially methylated circRNAs are associated with a variety of functions and signaling pathways of hematopoietic radiobiology.
RESUMO
Objective To investigate the protective effect of indole-3-carbinol (I3C) on radiation-induced mouse bone marrow hematopoietic cell injury and the involved mechanisms. Methods (1) The bone marrow nuclear cells (BMNCs) from CD45.1 subtype of C57BL/6J mice were collected by a density gradient centrifugation method. The BMNCs were pretreated with a series doses of I3C (0 mol/L, 10-8 mol/L-10-3 mol/L) and then exposed with radiation of 137Csγ-ray (doses of irradiation were 0 Gy, 1 Gy and 4 Gy). After 18-hour culturing, the bioluminescence method was used to detect the cell viability. (2) These cells were divided into control group and 10-6 mol/L I3C group. Both groups were received the irradiation (0 Gy, 1 Gy and 4 Gy) and inoculated into the methylcellulose semi-solid culture medium to incubate 7 days, the colony forming unit-granulocyte monocytes (CFU-GM) were observed. (3) Twenty-four CD45.2 subtype mice used as the receptor were exposed with 8 Gy radiation. The CD45.1 BMNCs were divided into control group, 4 Gy irradiation group, 4 Gy irradiation and 10-6 mol/L I3C group. Donor cells were harvested from C57BL/6J (CD45.1) mice after they received various treatments, and were then mixed with competitive BMNCs from C57BL/6J (CD45.2) mice. The mixed cells were transplanted into recipient mice (8 mice/group). Flow cytometry was used to analyze the proportion of donor cells in peripheral blood of receptor. (4) The cells were divided into control group, 10-6 mol/L I3C group, 1 Gy irradiation group, 1 Gy irradiation with 10-6 mol/L I3C group. After 24-hour culturing, Western blot assay was used to detect the expression levels of nuclear factor erythroid 2-related factor 2 (Nrf2) and hemeoxygenase-1 (HO-1). Results (1) I3C showed a significant cytotoxic effect on the BMNCs when its concentration was above 10-4 mol/L. 10-7-10-6 mol/L I3C could reduce the radiation injury of BMNCs under the same dose of irradiation. Therefore, 10-6 mol/L I3C was chosen for subsequent experiments. (2) The CFU-GM was significantly higher in 10-6 mol/L I3C group than that of control group (P<0.05). (3) Results of flow cytometry showed that the proportion of donor cells in receptor was significantly higher in 4 Gy irradiation group than that of control group, which decreased the engraftment capability of irradiated HSCs (P<0.05), although the engraftment capability of irradiated HSCs improved after 10-6 mol/L I3C treatment. (4) I3C significantly enhanced the increased protein expression of Nrf2 and HO-1 caused by radiation (P<0.05). Conclusion I3C has a protective effect on hematopoietic cells following radiation-induced injury, which may be related with activating the Nrf2/HO-1 signal pathway.
RESUMO
Objective To investigate the protective effect of 3,3′-diindolylmethane (DIM) on radiation-induced injury in mouse hematopoietic system. Methods Thirty C57BL/6 mice were randomly divided into control group, 2 Gy irradiation group and 2 Gy irradiation+DIM group (n=10 for each group). Mice of control group received sham irradiation, and the other two groups accepted 2 Gy 137Cs γ-ray total body irradiation. Mice in 2 Gy irradiation +DIM group were intraperitoneally injected 75 mg/kg DIM 30 min before irradiation. Mice of other two groups were treated with reference solution. After 7 d and 15 d of 2 Gy irradiation, the peripheral blood samples were collected to count the number of bone marrow nuclear cells (BMNCs). The level of reactive oxygen species(ROS) was measured by DCFH-DA. The levels of colony forming units-granulocyte-macrophage (CFU-GM) were also detected. Results The numbers of white blood cell (WBC), platelet count (PLT), BMNCs and CFU-GM were significantly decreased and the ROS level of bone marrow cells increased significantly in the irradiated group than those of control group (P<0.05). Compared to 2 Gy irradiation group, the numbers of WBC, PLT, BMNCs and CFU-GM were significantly increased in 2 Gy irradiation +DIM group, and the level of ROS was decreased significantly (P<0.05). Conclusion DIM has a protective effect on hematopoietic cells following radiation-induced injury, which may be related with the decreased ROS level.