Abnormally phosphorylated protein tau in the cortex of aged individuals of various mammalian orders

Aged individuals of mammalian species displaying hyperphosphorylated tau protein may be suitable natural models for investigating neurodegenerative alterations occurring, for example, in Alzheimer's disease. Therefore, autoptic tissue from the entorhinal, motor and prefrontal cortices of 14 mammalian species was screened using the monoclonal antibody AT8, which is directed against a phosphorylated epitope of human tau and applicable to the tissues of aged domestic animals, as shown in previous studies. AT8-immunoreactive neuronal processes and perikarya were revealed in Campbell's guenon, rhesus monkey, baboon, rabbit, spectacled bear, guanaco, reindeer and bison. Signs for considerable neuropathological alterations in aged bisons also included neuropil threads, whereas AT8 immunoreactivity in the other species was only sparsely scattered. Hyperphosphorylated tau in the brain of an 28-year-old rhesus monkey was also detected by AT100, PHF-1 and TG-3 antibodies, but only in the hippocampal formation and entorhinal cortex, which are known as starting point for tangle spreading in the cortex of Alzheimer patients.