Immunohistochemical detection of tau protein in various non‐human animal brains

Abstract

In order to clarify the tau phosphorylation in aged non‐human animal brains, paraffin sections of human and non‐human animal brains were examined immunohistochemically using two antibodies against tau. The monoclonal antibody (mAb) tau‐2 is known to bind non‐phosphorylated and phosphorylated forms of tau protein and to recognize neurofibrillary tangles (NFT) in the human brain, whereas rabbit antiserum against tau recognizes the protein in a wide variety of mammalian species. In this study, both antibodies recognized axons, neurites, and cytoplasm of neuronal cells together with oligodendrocytes in non‐human animal brains as reported in human brains, suggesting that the distribution of normal tau is quite similar between human and non‐human animal brains. Neurofibrillary tangles detected by the Gallyas method were not found in non‐human animal brains. Tau‐2 intensely labeled NFT in the human brain and neurons of brain stem nuclei in the canine brain. The results may suggest very early stage of abnormal tau phosphorylation leading to NFT formation in the aged canine brain. It is probable that phosphorylation develops over a long period of time (more than 25–30 years) and as a result abnormal tau becomes apparent in humans because they have a long life‐span in comparison with most non‐human animals.