Aim: 

Apo D is a member of the lipocalin family that binds and transports small hydrophobic ligands. This apolipoprotein is secreted by fibroblasts of the peripheral nervous system (PNS) and this secretion is increased following a lesion and during normal aging. In previous studies we demonstrated the importance of apo D in myelinization by morphometric comparation between wild-type mice and mice that lack apo D. The aim of the present work was to study the role of apo D in age-related peripheral nerve changes in these animal models.

Methods: 

Samples of sciatic nerves from wild-type and apo D KO mouse of 4 and 10 months of age were processed for electron microscopy. Semithin sections of 1mm in thickness were cut, stained and photographed (20X). Then, all myelinated fibers in the sample areas were counted and measured automatically using a novel automatic morphometric method developed in our laboratory.

Results: 

Preliminary data showed no significant differences in the myelin thickness and the number of myelinated fibers in wild-type mice between young and adult mice. In the KO mice we found a loss of myelinated fibers with age but we did not find significant differences in myelin thickness values.

Conclusion: 

These results support the idea that apo D plays an important role in the maintenance of age-related peripheral nerve structure since the lack of apo D results in a decrease in the number of fibers. Thus, apo D could be involved in lipid transport during nerve myelinization.