Intranuclear aluminum content in Alzheimer's disease, dialysis encephalopathy, and experimental aluminum encephalopathy.

Nuclear and chromatin fractions were prepared from cerebral cortex of 34 human and 37 animal brains. Chromatin was separated into a heavy heterochromatin fraction and two euchromatin fractions: intermediate euchromatin and light euchromatin. Compared to age-matched controls, aluminum content expressed per gram of DNA was significantly increased in nuclear and heterochromatin fractions in pre-senile Alzheimer's disease. In contrast nuclear preparations from brains of patients who had died with dialysis encephalopathy contained less aluminum than controls, although whole tissue concentrations were elevated ten to fifteen times above the control concentrations. Direct injection of aluminum into the cerebrospinal fluid of cats resulted in a progressive encephalopathy with neurofibrillary degeneration and increased intranuclear aluminum content. It is speculated that in Alzheimer's disease the normal blood-brain and cytoplasmic barriers for this neurotoxic metal are defective permitting aluminum to gain access to DNA-containing constitutents of the nuclei.