Experimental Study On Anti-fatigue Property Of SOYBEAN ISOFLAVONES And The Mechanism Involved

Objective1. We establish an animal model for loaded swimming in order to investigate the effects of soybean isoflavone on anti fatigue effects in swimming mice and determine the dose effect relationship of anti fatigue function of soybean isoflavone.2.To investigate the effects of soybean isoflavone on anti fatigue function of mechanism in swimming mice,we study the effect of soybean isoflavone on energy metabolism and antioxidant function in swimming miceMethods1 Forty male Kunming mice were randomly divided into four groups and were fed an AIN-93M diet for 14 days, and then forced to swim for 30,60 or 120 minutes, respectively, with a load on their tails equivalent to 2% body weight. The over all changes of serum metabolic profiles were analyzed using a 1H NMR based metabolomic approach. Meanwhile, some biochemical measurements were also carried out so as to monitor the changes in energy metabolism. The optimal swimming time for further studies and new biochemical markers potentially for fatigue were investigated.2.Forty male Kunming mice were randomly divided into four groups based on their weight:normal control、SI0.2、SI0.4、SI0.8 groups. Normal control were fed basic AIN-93M diet.The other three gruops were supplemented with AIN-93M which contain soybean isoflavone at a dose of 2g/kg、4g/kg、8g/kg. Two weeks later, the mice didn’t stop swimming with a load on their tails equivalent to 2　body weigh until they were eshausted.Compared with the swimming time of normal control, the dose dependent effects of soybean isoflavone on swimming time were established.3. Thirty male Kunming mice were randomly divided into three groups based on their weight:normal control、 swimming control.. SI0.4 groups The mice of SI0.4 groups were fed an AIN-93M diet supplemented with the dose of 4g/kg soybean isoflavones and the other two groups were fed an AIN-93M diet.14 days later the mice in swimming and SI0.4 groups were forced to swim for 60min with a load on their tails equivalent to 2% body weigh. and then executes all the mice,the samples of blood,liver and muscles of hind legs were collected.The serum contents of glucose, lactate, nonprotein nitrogen, free fatty acids, VC, VE, and hepatic or muscular contents of glycogen, activities of GSH-Px, MDA, SOD succinate dehydrogenase, ATPase were measured, respectively.4. Thirty male Kunming mice were randomly divided into three groups based on their weight:normal control、swimming control、SI0.4 groups The mice of SI0.4 groups were fed an AIN-93M diet supplemented with the dose of 4g/kg soybean isoflavones and the other two groups were fed an AIN-93M diet.14 days later the mice in swimming and SI0.4 groups were forced to swim for 60min with a load on their tails equivalent to 2% body weigh, and then executes all the mice. Muscles of hind legs were collected, and the mitochondria were isolated from skeleton muscles by differential centrifugation. Mitochondrial respiratory chain complex, membrane fluidity, membrane potential, mitochondrial respiratory function, permeability transition pore ATPase and antioxidant indices such as T-AOC、GSH-Px、SOD、MDA were measured.Results1. The serum metabolomics experiment data show that:serum metabolic profiles changed significantly after loaded swimming. Serum lactate, BUN and lipid are increased, while glucose decreased with the time dependent. The results of metabolomic analysis are consistent with the date of biochemical analysis. In addition, date of 60min metabolism in mice has obvious changes, and the data discrete tendency is smaller than 120m in, so 60min can be selected as the time point whichi was suitable for further studies.2.The endurance of soy isoflavones on mice swimming time:the normal group is 75.5 minutes,the 2g/kg group is 85.6minutes,the 4g/kg group is 105.8 minutes and the 8g/kg group is 88.1 minutes. The dose of 4g/kg in the test has the best effect on anti fatigue,so in the following experiment the dose of soybean isoflavone is determined as 4g/kg.3. Soy isoflavones have significant influence on the energy metabolism and antioxidant function in swimming mice.Compared with the normal control, the contents of lactate and BUN increased significantly in serum after swimming and decreased after soybean isoflavone supplementation, the content of free fatty acids in serum was sigmificantly improved in the group of the swimming control and SI0.4,which indicate that soybean isoflavones can improve energy metabolism by decreasing protein oxidation and increasing lipid mobilization. Soybean isoflavone also improved TCA cycle by increasing SDH CKand ATPase activities. The MDA content decreased and T-AOC、SOD、GSH-Px activities increased in muscle and tissues after soybean isoflavone supplementation.All of these changes can improve antioxidant capacity of the swimming mice.4. Mitochondrial function in skeletal muscle of mice was protected significantly after the supplementation of soybean isoflavone. The activity of mitochondrial respiratory chain complex, mitochondrial membrane potential and membrane fluidity deceased after loaded swimming and recovered after soybean isoflavone supplementation. Compared with swimming control group, mitochondrial content of T-AOC、SOD and GSH-Px activities increased and MDA content decreased in SI0.4 group, indicating that oxidative stress of mitochondria induced by swimming could be prevented by soybean isoflavones. The decrease of mitochondrial ATPase activity after swimming was also increaseded partially after soybean isoflavone supplementation. The improved mitochondrial function contributes significantly to the anti-fatigue effect of soybean isoflavone.ConclusionWe establishe an animal model for loaded swimming, to investigate the effects of Soybean Isoflavone on the antifatigue effects in swimming mice.The animal model of swimming mice used in this study has advantage in reflecting the status of energy metabolism. Soybean isoflavone is a powerful anti-fatigue and the optimal dose for supplementation is 4g/kg. The energy metabolism, antioxidant capacity, as well as mitochondrial function are improved significantly after soybean isoflavones supplementation in swimming mice and all of these contribute to the anti-fatigue effect of soybean isoflavone.