Effects Of Selenium On Lipid Metabolism And Oxidative Stress In Rats With Different Dietary Structure

ObjectiveAs one of the essential trace elements of the human body,selenium can combined with protein and other organic groups to form various enzymes,hormones and other macromolecular substances,which undertakes complex and important physiological and biochemical functions in the body.At the same time,unhealthy eating habits have been proven to be the most important risk factors for non-communicable diseases such as cardiovascular disease and diabetes.Studying the diet structure can provide advice to guide residents to a reasonable diet and a balanced diet.In this experiment,Wistar rats were selected as the research object,and high-fiber,high-protein,high-sucrose,and high-fat diet groups were set.After adding selenium to the feed,the blood lipid level,LPS activity,liver and heart oxidative stress indicators were measured,structural and pathological changes of liver tissue were also observed.To study the effect of selenium on lipid metabolism and antioxidant capacity of rats under different dietary structures.Methods1.Grouping of experimental animalsAfter adaptively feeding 450 SPF-grade healthy Wistar rats for 1 week,they were randomly divided into 15 groups according to body weight,with 30 rats in each group,with a half number of male and female.The groups are as follows:ordinary low selenium group(NC),ordinary medium selenium group(NC+),ordinary high selenium group(NC++),high fiber low selenium group(HC),high fiber middle selenium group(HC+),high fiber high selenium group(HC++),high protein low selenium group(HP),high protein middle selenium group(HP+),high protein high selenium group(HP++),high sucrose low selenium group(HS),high sucrose middle selenium group(HS+),high sucrose high selenium group(HS++),high fat low selenium group(HF),high fat middle selenium group(HF+)and high fat high selenium group(HF++).Rats eat and drink freely.Observe and record the health status of rats.2.Animal handlingFive male and female rats were randomly selected from each group of rats in the fourth week,the eighth week,and the sixteenth week of continuous feeding,and were sacrificed after taking blood through the abdominal aorta.The heart and liver were taken,weighed and recorded,and stored in the refrigerator at-80℃ as soon as possible;1 male and 1 female rat left in each group,and the heart and liver were removed and immersed in 4%paraformaldehyde for fixation.3.Observation of the general state of ratsObserve the survival status of the rats daily,record the eating and drinking conditions,hair color and presence or absence of hair loss,mental state and activity ability,etc.Weigh and record the weight of the rats every two weeks.4.Determination of serum lipid metabolism indexes in ratsSerum samples were taken and thawed at 4℃,and the content of TC and TG in rat serum was determined using an automatic biochemical analyzer;the serum LPS activity was determined by the laboratory in Qilu Hospital of Shandong University.5.Determination of the indexes of the antioxidant system of rat liver and heartA 10%tissue homogenate of rat liver and heart was prepared using physiological saline.After thawing at 4℃,the content of TP and MDA and GSH-Px activity of liver and heart were determined according to the instructions of the kit.6.Pathological observation of rat liver tissueA rat liver and heart tissue block with a thickness of about 3 mm was prepared,dehydrated and transparent,embedded in wax,then cut into 5 μ m thick sections.After HE staining,they were observed under a light microscope and photographed.Results1.General growth and development status of ratsDuring the experiment,the growth and development of rats in the normal diet and high-protein groups were stable,the drinking and eating were normal,the hair was thick and smooth,and the mental state and activity ability were good.Diarrhea and weight loss were observed in rats on the high-fiber diet.Rats on the high-sucrose diet had normal body size and significantly increased water intake.Rats on the high-fat diet had more food intake and were significantly obese.The liver coefficient of male rats increased,and that of female rats in the HF group increased.2.Effects of selenium on lipid metabolism in rats under different dietary structuresDuring the whole cycle,the TG of female mice in the HC group increased,and at the end of the 16th week,TG content in the HC++group was higher than that in the HC+group.During the whole cycle,TG in female rats and male rats of HS group increased.In the high-fat diet group,TC and LPS of female mice and male mice at the end of the 16th week were significantly increased in the whole cycle,TC increased in the male mice at the end of the 4th week,LPS increased in the HF and HF++groups,TC and LPS increased in the HF group at the end of the 8th week,and TG increased in the HF++group at the end of the 16th week.The differences were statistically significant(P<0.05).Meanwhile,at the end of the 4th week,the TG of female rats in HC+group was lower than that in HC group,the TG of male and female rats in HP++ and HP+group was lower than that in HP group,the TC of female rats in HF+group was lower than that in HF group,and the TC of female rats in HF+group was higher than that in HF and HF+group.At the end of the 8th week,the TG of female rats in the HS+ group was lower than that in the HS group,TG content in female rats in HS++ group was significantly higher than that in HS+group,and TC content in HF group was significantly higher than that in HF group.At the end of the 16th week,TG in the NC+group was lower than that in the NC group;Compared with the female rats in the HC+ and HC++groups,TG content in the female rats in the HC+and HC++groups was lower,and the serum TG content in the male rats in the HP++group was significantly lower than that in the HP+group;TG and TC in the HS+group were higher than that in the HS+group;TG and LPS in the hf+ group were higher than that in the HF and HF+groups.The differences were statistically significant(P<0.05).3.Effects of selenium on antioxidant function of rats under different dietary structureAt the end of the 4th week,GSH-Px in the liver of female mice in the HC++group,HP++group and HP++ group decreased,while MDA in the liver of male mice in the HC group decreased,GSH-Px in the liver of rats on the high-sucrose and high-fat diet decreased,and MDA in the liver and heart increased.At the end of the 8th week,the GSH-Px decreased and MDA increased in the HC and HC+groups,while the GSH-Px increased in the male liver of the HC++ group.The GSH-Px decreased in the female liver of the high-sucrose diet,the MDA increased in the male liver,and the MDA increased in the heart of the high-fat diet rats.At the end of the 16th week,MDA in the liver of female rats on the high-fiber diet increased,GSH-Px in the liver of male rats in the HC++group increased,MDA in the liver of female rats in the HP and HP++ groups increased,MDA in the heart of male rats in the HP group increased,and MDA in the liver and heart of the low-selenium and high-selenium groups increased.MDA levels in liver and heart of rats on a high-sucrose,high-fat diet increased.The differences were statistically significant(P<0.05).At the same time,at the end of the fourth week,MDA content in the hearts of female rats in the NC++ group was significantly lower than that in the NC+group.Compared with HC+group,the content of LIVER MDA in HC++group was increased.MDA in the HC+group was higher than that in the HC+group;MDA in the HC+group was lower than that in the HC+group;The liver MDA content in the HS++ group was higher than that in the HS group,GSH-Px activity in the HF++group was lower than that in the HF group.At the end of the 8th week,liver GSH-PX activity was increased and heart GSH-PX activity was decreased in the high-fat and high-selenium group compared with that in the high-fat and low-selenium group.At the end of the 16th week,the HC+group increased the GSH-Px in the female rats heart compared with the HC group;the HP++group increased the MDA in the female rats liver compared with the HP and HP+ group;the HP+group decreased the MDA in the male rats liver compared with the HP+group;the HP+group increased the MDA in the male rats liver compared with the HP+group;the HS+group decreased the MDA in the female rats heart compared with the HS group;the HF+group decreased the MDA in the female rats heart compared with the HF group.The differences were statistically significant(P<0.05).4.Effects of selenium on rat liver structure under different dietary structureLiver sections were observed under light microscope.During the whole cycle,the morphology and structure of the liver of high-fiber diet rats were not significantly changed compared with those of normal diet rats.The abnormal arrangement of liver cells in the HP group began from the 8th weekend.Some hepatocytes of rats on a high-glycemic diet showed nuclear condensation and eosinophilic changes in cytoplasm,suggesting apoptosis.The liver cells of the rats on the high-fat diet were arranged in a disordered manner.The cells in the lobules showed different sizes and different Numbers of lipid droplet vacuoles.At week 4 and week 8,there was no significant difference in the structure of each group under the same diet.At the end of the 16th week,the cell morphology and arrangement in the HS+group were significantly improved compared with that in the HS group,and the number of cells in the HS+group with nuclear hyperchromia and cytoplasmic eosinophilic enhancement was increased compared with that in the HS+group,but there was no significant difference between the HS group and the HS group.Compared with the HF group,the number of lipid droplet vacuoles formed in hepatic lobules in HF+group was significantly reduced,and the degree of cellular steatosis in HF+group was slightly improved compared with HF group,but the condition was more serious than HF+group.Conclusions1.High-fiber diet can cause lipid metabolism disorder in rats,and has a protective effect on antioxidant function of male rats and causes oxidative stress in female rats;Long-term high protein diet can cause damage to antioxidant system.High carbohydrate and high fat diet can damage the lipid metabolism and antioxidant function of rats.2.Proper addition of selenium can protect the lipid metabolism and antioxidant function of rats.With the extension of feeding time,the protective effect of increased selenium concentration was weakened,which even led to lipid metabolism disorder and oxidative stress in rats.3.Gender and time factors can influence the effects of selenium on rats under different dietary structure.