Inhibitory Effect Of Lycium Barbarum Polysaccharide On Apoptosis Of Intestinal Epithelial Cells In Radiation Injured Mice And Its Mechanism

Objective:Ionizing radiation is a double-edged sword.It can not only be used in medical diagnosis and treatment of diseases,but also can cause damage to the body.With the increasing incidence rate of malignant tumors,the use of radiotherapy is more and more extensive.Radiation enteritis(RE)refers to the disease of normal intestinal tissue damage caused by radiotherapy of malignant tumors in the abdominal cavity,pelvic cavity and retroperitoneum.At present,the use of commonly used radiation protective agents in clinical has various conditions,so it is imperative to find a safe,cheap and effective re treatment method.In this study,Lycium barbarum polysaccharide(LBP),the main active component of Chinese herbal medicine,was used to intervene the intestinal epithelial cells(IECs)of radiation-induced mice,to clarify the protective effect of LBP on the intestinal epithelium of radiation-induced mice,and to explore the degree of inhibition of apoptosis of IECs and the possible mechanism.Method:Using linear accelerator to irradiate the abdomen of mice(the upper boundary is below xiphoid process,the lower boundary is above pubic symphysis,and the rest parts are shielded by lead brick)with 6MV X-ray once and evenly,the mice model of radiation intestinal injury was established.They were randomly divided into normal group,radiation group,low LBP group(radiation + 200mg/kg LBP),medium LBP group(radiation + 400mg/kg LBP)LBP,high LBP group(radiation + 800 mg/kg LBP)and non radiation LBP group(800 mg/kg LBP)were given different concentrations of LBP by gavage continuously once a day,0.5ml each time.The radiation group was given the same dose of normal saline.Seven days later,the pathological sections of small intestine were made and observed under the light microscope.Flow cytometer was used,FCM)was used to measure the apoptosis of mice IECs,CCK-8 method was used to detect the activity of mice IECs,superoxide dismutase(SOD)activity and malondialdehyde(MDA)content were measured by spectrophotometry,Western blotting(WB)was used to compare the expression of B-cell lymphama-2(Bcl-2)and water-soluble related protein(Bax)of the same family with Bcl-2 in IECs of each group.Result:After irradiation,the intestinal villi were significantly shortened,a large number of inflammatory cells infiltrated,the epithelial continuity wasdestroyed,and small ulcers appeared,and the small intestinal epithelium of each group after LBP intervention was recovered to varying degrees.The low-dose LBP group With incomplete epithelium,the intestinal villi are shorter in length and have a lower density.In the medium-dose LBP group,the intestinal villi are shorter in length but neatly arranged,and a relatively continuous epithelium can be found.When the LBP concentration reaches a high dose,the intestinal tissue nearly returns to normal levels.As the LBP dose continues to increase,the intestinal tissue morphology It is also closer to the normal group.Compared with each group treated with LBP[(7.39±0.58)%,(6.71±0.21)%,(5.85±0.07)%] compared with the radiation group [(9.44±0.51)%],the apoptosis rate of mouse IECs was significant Decreased(P<0.05),the non-irradiated LBP group had a lower apoptosis rate than the normal group [(4.88±0.33)% vs(5.67±0.38)%,P<0.05].When the LBP concentration reached 400mg/Kg and 800mg/Kg,compared with the radiation group(1.033±0.577),the medium-dose LBP group(1.189±0.115)and the high-dose LBP group(1.213±0.063)had higher cell viability(P<0.05),but there was no significant difference in cell viability between the medium-dose LBP group and the high-dose LBP group.Seven days after being irradiated,the antioxidant enzyme SOD activity in IECs cells was detected.It was found that compared with the radiation group[(1.13±0.08)U/ml],there was no significant difference in the increase of SOD activity in the low-dose LBP group,the medium-dose LBP group[(1.32±0.06)U/ml],the high-dose LBP group [(1.53±0.03)U/ml] SOD activity is higher,and as the dose of LBP increases,the SOD activity enhancement effect is more obvious,compared with the normal group[(1.53±0.04)U/ml],the non-irradiated LBP group [(1.64±0.06)U/ml]SOD activity is also higher(P<0.05).With the increase of LBP concentration(200mg/kg,400mg/kg and 800mg/kg),the low-dose LBP group [(9.55±0.32)nmol/mgport],the middle-dose LBP group [(7.65±0.61)nmol/mgport],The high-dose LBP group [(5.41±0.31)nmol/mgport] MDA content also showed a gradually decreasing trend(P<0.05).Western blot was used to detect the expression of apoptosis-related proteins Bcl-2 and Bax.The results showed that compared with the radiation group Bcl-2expression(0.79±0.10),the low-dose(1.14±0.11)and medium-dose(1.18±0.20),High-dose LBP group(1.42±0.14)Bcl-2 expression increased significantly(P<0.05,P<0.05,P<0.001),low dose(1.08±0.10),medium dose(0.96±0.17),high dose The expression level of Bax in the LBP group(0.85±0.14)was significantly lower than that in the radiation group(1.33±0.11),(P<0.05,P<0.01,P<0.001),compared with the normal group(0.76±0.07),the non-irradiated LBP In group(0.52±0.11),Bax expression decreased(P<0.05).Conclusion:LBP can protect the small intestinal epithelium of mice and inhibit the damage of IECs caused by radiation injury.Its mechanism includesimproving SOD activity,reducing MDA production and weakening oxidative stress response.At the same time,LBP can also act on the mitochondrial pathway,which can increase the expression of Bcl-2 protein and decrease the expression of Bax protein,which can inhibit the apoptosis of IECs.