The influence of alpha-tocopherol supplementation on plasma concentration of this vitamin and insulin in sedentary or physically trained rats

Male young growing rats of Wistar strain (n=54) were fed a vitamin E deficient diet for 3 days of adaptation period and then 10 days of experimental period. After adaptation half of the rats ran, once per a day, on a treadmill with a rate of 2.0 m/s for 15 minutes for the following 10 days. Animals were given orally 0, 0.5, 1.0 or 4.0 mg/d/rat of α-tocopherol. The aim of the study was to evaluate the influence of physical training on tocopherol and insulin concentrations in the blood plasma of rats treated with different doses of vitamin E. The concentrations of α-tocopherol (HPLC-UV method used) and insulin (rat insulin specific RIA method used) were estimated in the blood plasma. Lower concentration of vitamin E in physically trained animals was observed, which may suggest increased needs of organisms for antioxidants, as a result of increased free radical production. In trained rats a lower concentration of plasma insulin was also observed. This effect is probably related to improvement in insulin action observed in organisms under physical exercise. The most significant impact on plasma α-tocopherol was due to its supplementation level. The treatment of rats with different doses of α-tocopherol was found to be not related to insulin concentration in plasma. A significant increase in feed conversion factor was noted in vitamin E treated animals. The obtained results suggest that the increased requirement of trained rats for antioxidants might be covered by α-tocopherol supplementation.