Abstract
The permeability of the blood-brain barrier to glutamate was measured by quantitative autoradiography in brains of 7-day-old rats (average plasma glutamate 114 μM) and rats injected subcutaneously with glutamate (average plasma glutamate 2,670 μM). Measurements of glutamate permeability were initiated by the injection of [14C]glutamate into the inferior vena cava and the 7-day-old rats sacrificed at 1 minute to avoid the accumulation of [14C]glutamate metabolites in plasma. Glutamate entered the brain at a slow rate, with an average permeability-surface area product of 12 μl⊙min−1⊙g−1, except in those areas known to have fenestrated capillaries. Thus, glutamate readily entered and accumulated in circumventricular organs where the radioactivity was localized. Although three areas with a blood-brain barrier, the cerebral cortex, the hypothalamus and the midbrain, of 7-day-old rats had permeabilities similar to adult rats, the other areas of the brain with a, blood-brain barrier had a permeability about 1.5–1.9 times that of adult rats. The greater permeability of the brain of 7-day-odl rats may reflect the degree of immaturity of the blood-brain barrier.
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Viña, J.R., Dejoseph, M.R., Hawkins, P.A. et al. Penetration of glutamate into brain of 7-day-old rats. Metab Brain Dis 12, 219–227 (1997). https://doi.org/10.1007/BF02674614
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DOI: https://doi.org/10.1007/BF02674614