Protective Effect Of Polyunsaturated Fatty Acids On Radiation-induced Intestinal Injury

Objective:Radiation intestinal injury is one of the major complications of radiation therapy,and its malnutrition can seriously affect the clinical outcome and long-term quality of life.The aim of this study is to investigate the protective effect of polyunsaturated fatty acids(PUFAs)on mice with radiation induced intestinal injury,and to preliminarily explore the related mechanism,so as to provide experimental data and theoretical basis for clinical diagnosis and treatment of radiation intestinal injury.Method:In this study,thirty-six 18-22 g healthy male BALB/C mice,6-week-old,were selected for free diet and water under the clean level environment.After 1 week of feeding,all of the experimental animal were randomly divided into 6 groups,6 rats in each group: blank control group,model group,irradiation induced intestinal injury / radioactive glucose intervention group,irradiation induced intestinal injury / glucose /ω-3 intervention group,irradiation induced intestinal injury / glucose /ω-6 intervention group,irradiation induced intestinal injury / glucose /ω-3&ω-6 combined intervention group.The mice model of irradiation induced intestinal injury was treated with full abdominal irradiation,the dose of 4.65Gry/min,2mins,and free diet and water after irradiation.Except for control group and intestine injury group,the rest were given intragastric administration(0.1ml/d only)on the day before irradiation,of which the concentration of ω-3 andω-6 was 0.09 g/ml./ω-3&ω-6 combined intervention group DHA:EPA:AA=1:1:1,and the glucose concentration was 0.80 g/ml.The changing state of mice was recorded every day,continuous intragastric administration for seven days.All experimental animal was sacrificed,one of the part of small intestine,4% paraformaldehyde,paraffin embedded,and HE staining;the rest part for preservation in-80 ℃,inflammatory factor Cox-1,Cox-2 and PGE-2 protein expression in small intestine of mice were analyzing by Western blot method.Results:(1)Model building: after irradiation,mice reduced their activities,with shineless hair,low body weight,food intake decreased,and the emergence of different degrees of diarrhea and bloody stool;after anatomy,visual observation of intestinal radiation injury group with scattered bleeding points and intestinal swelling;HE staining of the intestinal tract in control group with intestinal villus integrity in lamina propria of normal intestinal tissue of mice,in the model group,mice with incomplete,damaged intestinal wall structure,epithelial shedding,thickening of the lamina propria increased,small intestinal mucosa morphology and fracture morphology changed,villous hypertrophy,capillary congestion,local lesion and hemorrhage,which diffused inflammation infiltration of inflammatory cells.It was confirmed that the mice model of irradiation induced intestinal injury was successful.(2)Analysis of the changes of body weight and survival: compared with the control group,intestinal injury model group mice after radiation,their activity began to decrease,body weight and food intake decreased;compared to the irradiation induced intestinal injury model group,glucose intervention group and the ω-3intervention group,mice eating and drinking are reduced compared with the control group.However,the condition of mice is still relatively active;the status of mice in ω-6 intervention group andω-6&ω-3 combined intervention group were gradually became worse,less active,with diarrhea,anorexia and other symptoms;compared with the control group,survival rate and weight in intestinal injury model group,ω-3 intervention group,ω-6 intervention group,ω-3&ω-6combined intervention group,were significantly different,and the difference was statistically significant(P<0.05);compared with the irradiation induced intestinal injury model group,mortality in ω-3 intervention group,ω-3&ω-6 combined intervention group were decreased,the difference was statistical significance(P<0.05).Compared with the glucose treatment group,the mortality of mice in the ω-3 intervention group was decreased,and the mortality rate of the ω-3&ω-6 combined intervention group increased significantly(P<0.05).The difference between the two groups was statistically significant(P<0.05).Compared with glucose group,the result shown that death rate in ω-3 intervention group was decreased,while ω-6 intervention group was increased.The difference was statistically significant(P<0.05).(3)Histopathology results showed: compared with the control group,irradiation induced intestinal injury model mice showed intestinal tract enlarged,inflammatory exudation of the outer wall of the intestine was more and accompanied by mucosal injury;glucose intervention group and ω-3 intervention group,ω-6 intervention group and ω-3&ω-6 combined intervention group,small intestine were injured in different degree;and the intestinal radiation injury model group,glucose intervention group,ω-3 intervention group,ω-6 intervention group andω-3& ω-6 combined intervention group,mice with less injury.(4)Protein expression results: Compared with the control group,the expression of COX-1 protein was decreased in intestinal injury model group,COX-2 and PGE-2 protein expression increased slightly,and the difference was statistically(P< 0.01).In glucose intervention group,COX-1,COX-2 and PGE-2 protein expression were significantly increased,the difference was statistically significant(P< 0.01).For ω-3 group,compared with the control group,the expression of COX-1,COX-2 and PGE-2 protein expression was increased,the difference was statistically significant(P< 0.01);the expression of COX-1 protein decreased,COX-2 and PGE-2 protein expression were significantly increased in ω-3 &ω-6 intervention group,the difference was statistically significant(P <0.01).Compared with the glucose group,the expression of COX-1 protein increased,COX-2 and PGE-2 protein expression was decreased in ω-3 intervention group,and the difference was statistically significant(P< 0.01).COX-1,COX-2 and PGE-2 protein expression in ω-6 intervention group were significantly increased,the difference was statistically significant(P <0.01).COX-1 protein decreased,COX-2 and PGE-2 protein expression increased in ω-3&ω-6 combined intervention group,the difference was statistically significant(P <0.01).Conclusion:(1)The intervention of glucose can improve the intestinal inflammatory response and prolong the survival period of mice with radiation injury.(2)PUFAs has a protective effect on radiation-induced intestinal injury,the ω-3group had the most obvious effect,and better than glucose intervention group;ω-3 PUFAs can upregulate the expression of Cox-1 protein,down regulate the expression of Cox-2 and PGE-2 protein,in order to have protectively affect on intestinal injury mouse model after radiation.(3)The ω-3&ω-6 PUFA combined intervention has a certain protective effect on irradiation induced intestinal injury model.(4)This study showed that ω-6 PUFA intervention reduces the protective effect on mice with irradiation induced intestinal injury.