Effect of various time courses of endurance training on alterations of antioxidant enzymes activity in rat liver tissue

Anti oxidative enzymes activity is an important issue in oxidative stress. Most previous researches have dealt with the effect of brief and anaerobic exercise on these enzymes; the purpose of this study was to determine the alterations of antioxidant enzymes viz. superoxide desmutase, catalase and glutathione (SOD, CAT, and GPX) activity after endurance training in rat liver tissue. In this experimental study, 62 male Wistar rats were selected randomly and divided into 3 control and 3 experimental groups. Experimental rats trained for 6, 9 and 12 weeks, 5 days/week running on treadmill with initial speed of 10 m/min for 10 minute to the ultimate speed of 25 m/min for 60 minute. For control groups the protocol was walking on treadmill with 10 m/min speed for 3 days/ week. After each course (6, 9, 12 wk.), rats were anesthetized and samples taken from the livers of all animals in the study. Determination of antioxidant enzymes activity was done with enzymatic color assay method. The results showed that 6, 9 and 12 weeks of endurance training have no significant effect on GPX activity. Also, 6 and 9 weeks of endurance training did not alter the activity of SOD and CAT in liver tissue, but, 12 weeks of endurance training decreased SOD and CAT activity significantly, (CAT activity in experimental group was 23.11 ± 7.27 U/mL and in control group it was 31.43 ± 7.21 U/mL; SOD activity in experimental group was 47.70 ± 0.56 U/mL and in control group it was 48.20 ± 0.48 U/mL, (P<0.05)). Results of this study reveal that participating in 9 weeks of moderate exercise does not have detectable effects on the anti oxidative system, but when the exercise continues until 12 weeks, it decreases the SOD and CAT enzyme activity.