Apolipoprotein D synthesis progressively increases in frontal cortex during human lifespan

摘要

Apolipoprotein D (apo D) is a lipocalin present in the nervous system that may be related to processes of reinnervation, regeneration and neuronal cell protection. On the other hand, apo D expression has been correlated, in some brain regions, with normal ageing and neurodegenerative diseases. To elucidate the regional and cellular expression of apo D in normal human brain during ageing, we performed a detailed and extensive study in samples of post-mortem human cerebral cortices. To achieve this study, slot-blot techniques, for protein and mRNA, as well as immunohistochemistry and hybridohistochemistry methods, were used. A positive correlation for apo D expression with ageing was found; furthermore, mRNA levels, as well as the protein ones, were higher in the white than in the grey matter. Immunohistochemistry and non-isotopic in situ hybridization showed that apo D is synthesised in both neurons and glial cells. Apo D expression is notorious in oligodendrocytes, but with ageing, the number of neurons that synthesise apo D is increased. Our results indicate that apo D could play a fundamental role in central nervous system ageing and in the reduction of products derived from lipid peroxidation. The increment in the expression of apo D with ageing can be included in a global mechanism of cellular protection to prevent the deleterious effects caused by ageing.