Congo red protects against toxicity of beta-amyloid peptides on rat hippocampal neurones.

beta-Amyloid peptides are neurotoxic when applied to primary cultures of hippocampal neurones from the embryonic rat. This neurotoxic effect can be inhibited completely by certain disazo dyestuffs. The most potent of these are Congo Red and Congo Rubin, whilst Direct Garnet and sodium 4-aminonaphthalene-1-sulphonate are inactive. Congo Red also inhibits the neurotoxic effects of the human pancreatic amyloidogenic peptide amylin. It is postulated that these dyes, by interacting with the beta-pleated sheet structure of amyloidogenic peptides, prevent aggregation and hence neurotoxity.