The Study On Effects Of High-fat Diet And LA To The Oxidative Stress And The Function Of Digestive System Of Mouse

This investigation was conducted to evaluate the effect of high-fat diet on the oxidative stress of digestive system,blood lipid metabolism and the function of gastrointestinal tract of mouse.The study was also carried out to determine the effect of lipoic acid(LA) on the scavenging of free radical and the regulating of blood lipid metabolism of mouse fed with high-fat diet.This research contributed to the pathology mechanism of cardio-cerebral vascular diseases,which disturbed the function of gastrointestinal tract.It also provided the theoretical basis for LA as an antioxidant.Method:70 Kunming male mice were randomly divided into 7 groups.The control group was fed with basal diet containing 4.69%of crude fat;three groups were fed with high-fat diet containing 12.15%of crude fat(HF12.15%),high-fat diet plus 0.05%LA (HF12.15%+0.05%LA) and high-fat diet plus 0.1%LA(HF12.15%+0.1%LA) respectively; another three groups were fed with high-fat diet containing 20.00%of crude fat(HF20.00%), high-fat diet plus 0.05%LA(HF20.00%+0.05%LA) and high-fat diet plus 0.1%LA (HF20.00%+0.1%LA) respectively.After 5 weeks,the metabolism experiment was carried out in control group,HF20.00%group,HF20.00%+0.05%LA group and HF20.00%+0.1%LA group.The activity of proteolytic enzyme,lipase and amylase in the digestive tract,the level of PGE2,the activity of H⁺,K⁺-ATP and proteolytic enzyme in gastric mucosal were detected 6 weeks later.Meanwhile,the mouse's blood and gastrointestinal organ level of free radical, antioxidation index,the level of TG,TC,HDL-C and LDL-C in blood plasma were examined. The activities of LPL and HL in liver were also determined respectively.The results were shown as follows:The level of free radical produced in digestive system of high-fat diet groups were increased by feeding high-fat diet compared with control group.The antioxidation indexes of mouse of high-fat diet groups were decreased compared with control group.The high-fat diet disturbed blood lipid metabolism in mouse.The activities of LPL and HL of mouse were decreased by feeding with high-fat diet compared with control group.Addition of LA in the high-fat diet could scavenge free radical;increase the antioxidation index and adjust the blood lipid metabolism of mouse.The level of free radical in digestive system and the antioxidation index of mouse were recovered approaching to the control group when 0.1%LA was added.Feeding mouse with high-fat diet for long-term could improve the activity of the lipase in the digestive tract and H⁺,K⁺-ATP in gastric mucosal,decrease the level of PGE₂ and the activity of the protease and amylase, decline the digestibility of the fat,protein and the sedimentation rate of the protein.However, adding LA to the high-fat diet could enhance the activity of these enzymes and digestibility of the fat,protein and the sedimentation rate of the protein. Conclusion:High-fat diet resulted in oxidative stress in digestive system and disturbed the blood lipid metabolism of mouse.The optimum dose of LA could be able to eliminate free radical,increase the antioxidative capacity,adjust the blood lipid metabolism,and increase the activity of the digestive enzymes and the absorption of the nutrition,improve the structure of intestinal tract and relieve the oxidative stress.