Intrathymic and intrasplenic oxidative stress mediates thymocyte and splenocyte damage in acutely exercised mice

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Abstract
Reactive oxygen species may contribute to apoptosis in lymphoid tissues observed after exercise. Thymic and splenic tissues excised from control mice (C) or mice immediately after ( t 0) or 24 h after ( t 24) a run to exhaustion (RTE) were assayed for biochemical indexes of oxidative stress [thymic and splenic membrane lipid peroxides, superoxide dismutase, catalase, plasma uric acid (UA), and ascorbic acid (AA)]. There were significant increases in membrane lipid peroxides in thymus ( P < 0.001) and spleen ( P < 0.001) in acutely exercised mice relative to controls (thymus: C = 2.74 ± 0.80 μM; t 0 = 7.45 ± 0.48 μM; t 24 = 9.44 ±1.41 μM; spleen: C = 0.48 ± 0.22 μM; t 0 = 1.78 ± 0.28 μM; t 24 = 2.81 ± 0.34 μM). The thymic and splenic tissue antioxidant enzymes concentrations of superoxide dismutase and catalase were significantly lower in samples collected at t 0 relative to C and t 24 mice ( P < 0.001). Plasma UA and AA levels were used to assess the impact of the RTE on the peripheral antioxidant pool. There was no significant change in UA levels and a significant reduction in plasma AA concentrations ( P < 0.001); the reduction in plasma AA occurred at t 24 (6.53 ± 1.64 μM) relative to t 0 (13.11 ± 0.71 μM) and C (13.26 ± 1.2 μM). These results suggest that oxidative damage occurs in lymphoid tissues after RTE exercise and that such damage may contribute to lymphocyte damage observed after acute exercise.