215 - Awardee Talk: Astaxanthin Supplementation During Deconditioning and Reconditioning Periods Reduces Oxidative Stress in Circulation in Polo Ponies

Abstract: Oxidative status is impacted by fitness and dietary nutrients, such as antioxidants. We hypothesized that astaxanthin (ASTX) supplementation would improve oxidative status in the circulation and muscle in response to exercise following deconditioning and reconditioning in horses. Twelve conditioned polo ponies (14.8 ± 1.7 yr) were assigned to control (CON; n = 6) or astaxanthin supplemented (ASTX; n = 6; 75 mg ASTX daily) groups. Horses performed 26 min submaximal exercise tests (SET) followed by 30 min of recovery while in condition (SET1), after 16 wk of deconditioning (SET2), and after 16 wk of reconditioning (SET3). Blood samples were collected 30 min before and 0, 15, 30, and 60 min after each SET. Semitendinosus muscle biopsies were collected 2 wk before and 2 hr after each SET. Using commercially available kits, plasma and muscle superoxide dismutase (SOD) and glutathione peroxidase (GPX) activities and plasma malondialdehyde (MDA) concentrations were determined. At SET2, ASTX had 116% greater plasma SOD activities than CON (P=0.001). Both treatment groups increased from SET2 to SET3 (P< 0.001), but there were no treatment effects at SET3 (P=0.788). At SET2, plasma GPX activities were 49.3% greater in ASTX than CON (P=0.012), and ASTX tended to be 21.2% greater than CON at SET3 (P=0.096). Plasma MDA concentrations were 22.2% greater in CON than ASTX at SET2 (P=0.034), but not at SET1 or SET3 (P≥0.449). There were no detectable differences in muscle SOD or GPX activities 2 wk before or 2 hr after any SET (P≥0.309). In conclusion, ASTX supplementation maintained circulating antioxidant capacity and minimized oxidant activities during deconditioning, reducing oxidative stress in response to the SET in the circulation but not in the skeletal muscle. This may enable horses to adjust to strenuous exercise more efficiently, improving athletic performance, especially when they are re-introduced to exercise after deconditioning.