Carbohydrate--energy restriction may protect the rat brain against oxidative damage and improve physical performance

Chronic energy restriction, (alpha)-tocopherol supplementation and their interaction with exhaustive exercise were investigated. Eleven-week-old male Wistar rats (n 6×10) were fed either a control (C), a 30 % carbohydrate-energy-restricted control (R) or an (alpha)-tocopherol-supplemented (S) diet for 5 months. The animals in each diet were divided into exercised (E) and non-exercised (NE) groups. Before killing, the exercised rats were required to run to exhaustion (39 (SE 6), 69 (se 11) and 18 (se 2) min for the C, R and S groups, respectively). Lipid peroxidation (thiobarbituric acid-reactive substances; TBARS), protein damage (reactive carbonyls) and (alpha)-tocopherol were determined in gastrocnemius, liver, brain and/or plasma. There was no difference in lipid peroxidation between the R and C groups, but in liver and muscle peroxidation appeared significantly lower in the S than the other two diets. TBARS in the brain were similar in all groups. On the other hand, reactive carbonyls showed that both the R and S diets reduced protein damage in the brain, while exhaustive exercise increased it. For liver and muscle, however, reactive carbonyl levels were similar in all groups. (alpha)-Tocopherol supplementation increased the vitamin concentrations in liver, muscle and plasma, but exercise decreased them in plasma and brain. Carbohydrate-energy restriction increased (P=0·0025) resistance to exhaustive exercise considerably without depleting stores of (alpha)-tocopherol or exacerbating oxidative damage in monitored tissues. It is concluded that while exhaustive exercise promotes a tissue-specific oxidative damage detectable only in brain proteins, both experimental diets tended to ameliorate this condition.