The effect of dietary alpha-tocopherol on the experimental vasogenic brain edema

It has become increasingly obvious that free radicals and lipid peroxidation contribute to brain damage from trauma by mediating edema formation and ischemia. It should, therefore, be expected that the actual level of endogenous antioxidants, as for example, vitamin C and E in plasma, has an influence on the extent of free radical-induced injury. In this communication we investigate the effect of dietary changes in the free radical scavenger alpha-tocopherol on posttraumatic cerebral swelling in Sprague-Dawley rats. Low, normal, and high plasma levels of alpha-tocopherol were established by respective diets supplied over 2 weeks. Animals of all groups received the same food without alpha-tocopherol. One group was fed a vitamin E-free diet. The pellet-food for the other animals was supplemented either with 5-mg alpha-tocopherol/100 g or 250-mg alpha-tocopherol/100 g dry mass, respectively. The vitamin E-free diet lowered the alpha-tocopherol level in plasma to 30% of control, whereas supplementation with 250 mg/100 g led to a plasma concentration of 200% of control. The animals were then subjected to a focal cold injury of the left cerebral hemisphere. Twenty-four hours after trauma the brain was removed and the water content of each hemisphere was determined by the wet-dry weight method. Swelling of the traumatized hemisphere was calculated as the difference in weight between the traumatized and contralateral control hemisphere. The 2-week alpha-tocopherol supplementation or -deletion diet, respectively, did not either afford significant reduction or lead to an enhancement of traumatic brain swelling. Likewise, the increase in brain water content of the traumatized hemisphere was not affected. It is concluded that supplementation or depletion of alpha-tocopherol for 2 weeks, resulting in a marked increase or decrease of the vitamin E plasma level, does not influence formation of posttraumatic vasogenic brain edema.