Oxidative Stress and Antioxidant Defenses in Lymphocytes Following High Intensity Interval Training
Type of Degreedissertation
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A substantial body of evidence suggests strenuous exercise causes perturbations to the immune system and increases the formation of reactive oxygen species. Performing routine moderate exercise stimulates the immune system, while strenuous exercise has been shown to cause immunosuppression during recovery. Perturbations to these systems are known to occur from exercise, yet information regarding the interactions between antioxidants and the immune system is sparse. The purposes of this study were to: 1) examine the immune and oxidative stress responses following high intensity interval training (HIIT); 2) determine whether changes in antioxidant enzyme gene expression and enzyme activity occurs in lymphocytes following HIIT; and 3) determine whether changes in antioxidant expression and activity would improve lymphocyte cell viability following hydrogen peroxide (H2O2) exposure in vitro. Eight recreationally active males completed three identical high-intensity protocols. Each session was performed following an overnight fast. Blood samples were obtained pre-exercise, immediately post-exercise, 3hrs post-exercise, and 24hrs post-exercise. Total number of circulating leukocytes, lymphocytes, and neutrophils; as well as lymphocyte antioxidant enzyme activities, lymphocyte gene expression, lymphocyte cell viability, and plasma malondialdehye (MDA) levels were measured. Analytes were compared using a three (day) x four (time) ANOVA with repeated measures on both day and time. Significant differences were further explored using a Tukey post hoc analysis. The significance level for all analyses was set at p < 0.05. HIIT increased the number of lymphocytes and the activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPX). There were no significant increases in lymphocyte SOD, CAT, or GPX gene expression. Circulating neutrophils significantly increased 3hrs post exercise. A significant increase in MDA was found following HIIT on Days 1 and 2. Lymphocyte cell viability following H2O2 exposure in vitro significantly increased on Days 2 and 3 compared to Day 1 of HIIT. Additionally, there was a significant decrease in cell viability at 3hrs compared to pre-exercise and 24hrs post-exercise. These findings indicate that lymphocytes respond to oxidative stress by increasing SOD, GPX, and CAT activity. Additionally, HIIT causes oxidative stress but did not induce a significant post-exercise lymphopenia. Analyses in vitro suggest lymphocytes may be fortified by increasing their antioxidant enzyme activities and become more resistance to subsequent episodes of oxidative stress. Furthermore, analysis in vitro confirms that lymphocytes are more vulnerable to cytotoxic molecules during recovery from exercise.