Effect of aluminum on the blood-brain barrier permeability in acute and chronically hyperglycemic rats

This study examined the changes in blood-brain barrier (BBB) permeability following acute aluminum (Al) exposure during acute and chronic hyperglycemia in rats. Acute hyperglycemia was induced by intraperitoneal injection of glucose solution at 30 min after giving Al. Chronic hyperglycemia was made by an injection of alloxan monohydrate. BBB permeability was measured in the four regions of the brain at 1 h after administrating Al by spectrophotometric quantification of Evans blue (EB) dye. The extravasation of EB dye was significantly more extensive in the two regions of brain in the groups treated with Al, Al plus glucose, and alloxan plus Al than in the groups treated with saline, glucose, and alloxan alone (p < 0.05). Under acute and chronic hyperglycemia plus Al treatment, the BBB permeability to EB was significantly higher than that observed solely in Al-treated rats (p < 0.05). These data indicate that Al toxicity leads to an additional increase in BBB permeability, in which acute and chronic hyperglycemia potentiates the effects of Al to enhance BBB permeability to EB.