Monosodium glutamate induced convulsions in rats: Influence of route of administration, temperature and age.

Treatment of developing rats with monosodium glutamate (MSG) produces an increase of glutamate levels in the brain, being this elevation dependent on both route of administration and animal's age. The capacity of exogenous MSG to induce convulsions seems to be related to the rate of glutamate elevation in the brain, rather than to the absolute value of glutamate concentration reached. Short exposure of MSG-treated rats to moderate hyperthermia potentiated the convulsive incidence and extended the brain damage to areas not affected by treatment with MSG alone, suggesting that the synergic effect of hyperthermia on glutamate neurotoxicity may be related to an increase in the permeability of the blood-brain barrier in the hyperthermic developing rats.