The Preliminary Study Of Axonal Degeneration And Microglia Changes After Optic Nerve Crush In Mice

The therapy and nervous functional recovery of central nervous system disorders is a historical serious problem.The eye displays similarities to the brain and spinal cord in terms of anatomy,functionality,response to insult,and immunology.The optic nerve axons can't regerenate and die rapidly,There is no agreement about the role of microglia in trauma and diseases.This study based on THY1-YFP H-lin transgenic mice with axonal markers of optic nerve and GFP-C57BL/6 transgenic mice with microglia markers transgenic mice,and establishing unilateral optic nerve crush model in adult mice.The optic nerve were dissected at 4hours,1day,3days,5days,10 days after optic nerve crush,to observe the neuronal degenerative disorder and microglial responses by confocal laser scanning microscope.The experiment results reveal that the degenerative diseases after optic nerve injury can be divided into three stages,the first stage is the initial stage: The axons are disconnected and the glial scar occurred in injured region of optic nerve,resting microglia proliferation,part of these cells activated and migrate to the injured region at 4 hours after operation.The second stage is neurodegenerative disorders: the optic nerve axons moniliform change from the part to a large number and turn into the process of degeneration,the increasing number of microglia activated and cover the injured region,at 1-5 days after operation.The third stage is neurodegenerative disorders rapidly deteriorating: the moniliform axons turn into debris,the number of activated and agminated microglia was stable,a few of microglia had the tendency for resting state at 5,10 days after operation.It was also found that unilateral optic nerve crush induces bilateral microglia proliferation in mice,although these cells are activated but did not affect the normal neural axon.The above results indicate that the optic nerve occur irreversible degenerative disorder after being injured,meanwhile with the microglial increase and activation.This phenomenon reveal that microglia closely associated with optic nerve degeneration.The study aims to understand central nervous system neurodegenerative disorders and the role of micerglia by optic nerve crush model,in order to provide a new strategy for the research of these diseases.