ALUMINUM(III) INFLUENCES THE PERMEABILITY OF THE BLOOD-BRAIN-BARRIER TO [C-14] SUCROSE IN RATS

To determine the influence of the metal coordination sphere on the permeability of the blood-brain barrier (BBB), rats were injected intraperitoneally with aluminum lactate (Al(lact)3), aluminum acetylacetonate (Al(acac)3), aluminum maltolate (Al(malt)3) at pH 7.5, or with physiological saline. Two h after each treatment, [C-14]sucrose physiological saline solution was injected in animals, and the radioactivity was measured in 5 brain regions (cerebral cortex, mesencephalon, diencephalon, medulla-pons, cerebellum). Radioactivity was significantly elevated in brains from animals treated with Al(malt)3 (hydrolytically stable and hydrophilic), and with Al(acac)3 (hydrolytically stable and lipophilic) but not with Al(lact)3. Time-course study carried out at 2, 4 and 24 h with different aluminum compounds showed a persistent radioactivity 24 h after treatment only in the brain from animals treated with Al(acac)3. Morin stain localized Al(III) only in neurons from animals treated with Al(acac)3. These findings indicate that Al(III) alters the BBB function in the rat either permanently or transiently depending on the physicochemical properties of the metal coordination sphere. Implications of these results, in terms of Al(III) as a potential toxic factor in humans, are considered and discussed.