Ascorbic acid and alpha-tocopherol protect age-dependently from hypoxia-induced changes of cortical excitability in developing rats.

OBJECTIVES: The effects of ascorbic acid and α-tocopherol pre-treatment on hypoxia induced changes in brain cortex excitability were tested in immature rats exposed chronically to simulated altitude of 7 000 m.

METHODS: Rat pups were kept together with their mothers for 8 hours a day in hypobaric chamber since the day of the birth till the postnatal day 11 or 17. Each day immediately before placing to hypobaric chamber pups were pretreated intraperitoneally either with ascorbic acid (100 mg/kg) or α-tocopherol (1 500 mg/kg). Cortical afterdischarges were elicited by repeated stimulation of the right sensorimotor cortex. The duration of evoked cortical afterdischarges was analyzed.

RESULTS: Duration of cortical afterdischarges progressively declines with age. Hypoxia prolonged the duration of afterdischarges in 12-, 18- and 25-day-old animals. Pretratment with ascorbic acid or α-tocopherol shorted afterdischarges duration in youngest experimental group when compared with animals exposed to hypoxia only.

CONCLUSION: Hypoxia significantly affects the brain cortex excitability by prolonging afterdischarges duration. This effect differs with age. Antioxidant pre-treatment brought about shorter duration of cortical afterdischarges only in the youngest experimental group. The antioxidant effect is therefore age dependent.