Immunohistochemical Analysis of Cerebral Cortical and Vascular Lesions in the Primate Microcebus murinus Reveal Distinct Amyloid β1–42 and β1–40 Immunoreactivity Profiles

Abstract

Recent reports have shown that amyloid β deposits in the brains of Alzheimer's disease patients consist mainly of two distinct species of amyloid β protein (Aβ) with different C-termini, Aβ1–42 (Aβ42) and Aβ1–40 (Aβ40). The nature of the Aβ species in Microcebus murinus brain was investigated immunocytochemically using polyclonal antibodies with clear specificity for the Aβ42 and Aβ40 C-termini. The cortical vascular deposits were immunopositive for both Aβ42 and Aβ40. However, most of the diffuse plaques were strongly positive for Aβ42 whereas only a subset of deposits were positive for Aβ40. Numerous cortical plaques were Aβ42-immunopositive but tested negative for Aβ40. This suggests that Aβ42 is probably associated with early stages of plaque maturation. This neuropathological feature reminiscent of that observed in brains affected by Alzheimer's disease further supports the idea that M. murinus could be used as a potential model of the early stages of this neurological disease.

Keywords

• β amyloid C-terminus epitope
• ageing
• brain
• microcebe
• primate.