Chronic administration of aluminum–fluoride or sodium–fluoride to rats in drinking water: alterations in neuronal and cerebrovascular integrity

Abstract

This study describes alterations in the nervous system resulting from chronic administration of the fluoroaluminum complex (AlF 3) or equivalent levels of fluoride (F) in the form of sodium–fluoride (NaF). Twenty seven adult male Long–Evans rats were administered one of three treatments for 52 weeks: the control group was administered double distilled deionized drinking water (ddw). The aluminum-treated group received ddw with 0.5 ppm AlF 3 and the NaF group received ddw with 2.1 ppm NaF containing the equivalent amount of F as in the AlF 3 ddw. Tissue aluminum (Al) levels of brain, liver and kidney were assessed with the Direct Current Plasma (DCP) technique and its distribution assessed with Morin histochemistry. Histological sections of brain were stained with hematoxylin & eosin (H&E), Cresyl violet, Bielschowsky silver stain, or immunohistochemically for β-amyloid, amyloid A, and IgM. No differences were found between the body weights of rats in the different treatment groups although more rats died in the AlF 3 group than in the control group. The Al levels in samples of brain and kidney were higher in both the AlF 3 and NaF groups relative to controls. The effects of the two treatments on cerebrovascular and neuronal integrity were qualitatively and quantitatively different. These alterations were greater in animals in the AlF 3 group than in the NaF group and greater in the NaF group than in controls.