Inhibition of corticosterone binding in vitro, in rabbit hippocampus, by chromatin bound aluminum

Brains of patients with senile dementia of the Alzheimer type and with the dialysis encephalopathy syndrome, exhibit elevated aluminum levels. In Alzheimer's disease and in the experimental aluminum induced encephalopathy, intracellular aluminum is associated with nuclear chromatin. The work reported here was undertaken to test whether chromatin bound aluminum in hippocampus of the rabbit interferes with nuclear binding of corticosterone-receptor complexes. The results showed that the mean binding of corticosterone decreased from 460 +/- 71 fmol/mg DNA in controls, to 343 +/- 81 fmol/mg DNA in hippocampal nuclei from aluminum treated rabbits, representing a decrease of 25%. This reduction occurred in the absence of aluminum induced neurofibrillary degeneration and indicates a possible functional consequence of the presence of aluminum on chromatin, and importantly, in the absence of morphological changes.