| Betulinic acid(BA),a naturally occurring pentacyclic triterpenoid,which has been proved to have a variety of biological activities,such as antioxidant,anti-inflammatory and anti-viral activities.In previous study,BA attenuated CYP-induced intestinal mucosal damage.However,the potential protective mechanism of BA on CYP-induced intestinal mucosal damage has not been reported in literature.Objectives: In this study was to investigate the potential protective mechanism of BA on CYP induced intestinal barrier dysfunction by regulating NF-κB/MAPK/Nrf2 signaling pathway which may help to form the theoretical basis for the establishment of new methods to alleviate intestinal injury,and to explore new ways for immunomodulator and antioxidant in animals.Therefore,the present project may give rise to a viable alternative that can ensure and maintain optimal animal health and growth performance.Methods: The healthy male Kunming mice were selected and administered orally with different doses of BA for 14 d.The intestinal damage model was set up by injecting CYP intraperitoneally at the dose of 50 mg/kg b.w.for 2 days on the 15 th and 16 th day.The mice were fasted 16 h after the last administration of CYP,and blood and intestinal tissues were collected for detection of hematology,intesital morphology,intestinal barrier function and expression of related proteins.Results: 1)BA pretreatment effectively alleviated the shortening,rupture,shedding of intestinal villi and infiltration of inflammatory cells in the intestinal epithelium of mice induced by CYP.Besides,BA pretreatment increased the level of hemoglobin(HGB)in blood(p <0.05,p <0.01)and effectively relieved the intestinal physical barrier dysfunction and anemia.2)BA pretreatment increased the levels of intestinal fatty acid-binding protein(i FABP)and diamine oxidase(DAO)in intesitne(p <0.05,p <0.01),effectively relieved intestinal chemical barrier dysfunction induced by CYP.3)BA pretreatment increased the blood neutrophil(Neut)content(p <0.05,p <0.01),and decreased the ratio of neutrophils to lymphocytes(Lymph),relieved the reduction of complement C3,C4 and immunoglobulin G(IgG)levels induced by CYP,but the 1 mg/kg BA group significantly reduced IgM secretion(p <0.05).In addition,BA pretreatment reduced the proinflammatory cytokines interleukin-1β(IL-1β),IL-6 and tumor necrosis factor(TNF-α)mRNA expression,and increased the mRNA expression of anti-inflammatory cytokine IL-10 mRNA,which shown a protective effect on the intestinal immune barrier.4)BA pretreatment significantly reduced reactive oxygen species(ROS)production and apoptosis percentage in intestine caused by CYP(p<0.01).5)Western blot analysis showed that BA reduced the phosphorylation of p38,c-Jun N-terminal kinase(JNK)and extracellular signal-regulated kinase(ERK)proteins expression of the intestinal tissue of CYP-treated mice(p <0.01).In addition,BA down-regulated nuclear transcription factor kappa B(NF-κB)and NF-κB inhibitor-alpha(IκBα)protein phosphorylation levels,and inhibited the activation of mitogen-activated protein kinase(MAPK)/NF-κB signaling pathway,thereby alleviating intestinal inflammation.6)BA pretreatment up-regulated the protein expressions of nuclear factor erythroid-2 related factor2(Nrf2)and heme oxygenase-1protein(HO-1),and activated Nrf2 signal pathways to relieve intestinal oxidative stress.7)BA significantly alleviated the decreasing of the B-cell lymphoma-2/Bcl-2 associated X protein(Bcl-2/Bax)ratio and the increasing the protein expression of Caspase-3 in the intestine induced by CYP(p <0.05,p <0.01),thereby shown protective effect on CYP-induced intestinal apoptosis.Conclusion:BA has interventive effects on CYP-induced intestinal mucosal damage in mice by enhancing intestinal anti-inflammation and antioxidant activities,and decreasing intestinal apoptosis via inhibition of the NF-κB/MAPK signaling pathway and activation of Nrf2 signaling pathway. |
PDF Full Text Request