Background: Current dogma suggests that chronically demyelinated axons are at risk for degeneration, with axonal loss resulting in permanent disability in myelin disease. However, the trophic role of the myelin sheath in long-term axonal survival is incompletely understood. Previous observations of the effect of dysmyelination or demyelination on axonal survival in the myelin mutants has been limited because of their short life span.
|Myelin staining a 5–6 month old wild-type (WT, left panels) and les rat.. They shows prominent myelin labeling in the WT rat (A/C) with no detectable myelin staining in the les rat (B/D).|
It is not just dogma, but has been shown that in many different situations that loss of myelin can make nerves vulnerable to damage, However, it also seems clear that this is a slow process and demyelinated nerves do survive for some time, otherwise the pathologists would have seen that all demyelinated nerves would have markers of death induction. However, it is also the case that many of the dymyelinating or dysmyelinating mutants get neurological conditions and die. These include naturally occurring mutants such as Jimpy, Shiverer mice and Shaking pup animals, Taiep rat. The Long –evans shaker survive for some time and get demyelinated nerves.and so have adapted to this effect and the study indicates that these rats produce a number of nerve growth factors that may aid this. These obviously provide routes to help support demyelinated nerves that are clearly are present in MSers.