Study On Expression And Location Of Nogo-A In Central Nervous System In Rats With Experimental Autoimmune Encephalomyelitis

ObjectiveMultiple sclerosis(MS)is a chronic neurodegenerative disease that causes central nervous system(CNS)inflammation and demyelination,affecting approximately two million people worldwide.In humans,different subtypes of the disease have been noted, characterized by distinct clinical courses and different histopathological manifestations. Children with MS often have such sings and symptoms as extremity paralysis,visual disorder,ataxia,sensory disability and so on.And they often tend to experence permanent sequela of nervous system.Nowadays,etiopathogenisis and pathogenesy of MS haven't been known entirely.At present,people are investigating the desease furthermore,by various means and from every point of view,to research the pathogenesy and seek available treatment.Neurite outgrowth inhibitor is a major obstacle for axonal growth after CNS injury.So far,people have found after injury to the central nervous system(CNS)in adults,axonal regeneration is confined,in part,by the inhibitory factors in CNS myelin, including Nogo-A protein,myelin-associated glycoprotein(MAG)and myelin oligodendrocyte glycoprotein(MOG).The Nogo-A protein associated with CNS myelin might play a crucial role in the failure of the regeneration of axons in CNS. Nogo-A can inhibit neurite outgrowth when CNS is injured,so it is called myeline sheath-associated protein.At present,people focus on the expression and location of Nogo-A,the expression of Nogo-A mRNA,and the treatment of neural injury desease by usting anti-Nogo-A.But,these deseases are mainly about hypoxic-ischemic encephalopathy,cerbral infarction,Alzheimer disease and so on.Up to now,the report about investigating Nogo-A on EAE are seldom in foreign magazine and not found in our country.Axonal damage is a correlate for increasing disability in multiple sclerosis. Animal models such as Experimental Allergic Encephalomyelitis(EAE)may help to develop better therapeutical neuroprotective strategies for the human disease.EAE is widely utilized as the animal model of MS.In our subject,wistar rats were used to establish the animal model.To investigate the roles of Nogo-A in the pathogenesis and the progess of EAE,we dynamicly observed the time interval change of expression and location of Nogo-A in the CNS of normal and EAE rats and the alterring process of myelin sheath in the CNS of EAE rats.Our data and conclusions may be useful in the treatment of progressive MS and other neurodegenerative diseases.MethodsIn our subject,Female wistar rats were used for EAE animal model. Immunohistochemistry S-P was used to detect expressions of Nogo-A.Amyelination was detected by developed acid fuchsin and azulin myelin staining.Results1.Immunohistochemistry results(1)Masculine material of Nogo-A was pale brown,and located intracytoplasm. In the control group CNS,the masculine material was general,but at each position the amount was various.The expression position of each time was same.Comparing with the control group,the expression position of Nogo-A in the EAE group CNS had n't changed.(2)In the control group,differences of expression of Nogo-A in the intumescentia lumbalis or the brain were not obviouse in each group.In the EAE group, expression of Nogo-A could be observed in each group,but their quantities were very different by contrast with in the control group.The tendency of change was coincident between the brain and the spinal cord.One day after rats had clinic symptoms, expression of Nogo-A had decreased somewhat.3 day later,it had reached the lowest point,and was significantly lower than in the control group.7day later it had been come up,on the 14th day,it had achieved peak,by contrast with in the control group,P＜0.01.On the 21st day,it had been lowered.On the 28th day,it had been approached to normal level,but still higher than in the control group,P＜0.01.During the development of EAE,the expression of Nogo-A was a dynamic state,it decreased somewhat in the earlier period,but increased significantly in the later stage,and the end of the dynamic curve was still higher than that of control group.2.It had been shown by myelin staining(1)No amyelination was seen in the CNS of control group rats,normal nerves were dyed,and the appearance of their cross sections were wheel.The axons were blue, and the myelin sheaths were red,whose shapes were round or oval.(2)There were amyelination,axon lose,and disfiguration in CNS white matter of every EAE group rats.One day after rats had clinic symptoms amyelination had been obviouse.On the 3rd day and 7th day it was the most serious,large piece and confertus amyelination focuses could be seen,even neuraxis were absent,and vacuoles were seemed.On the 14th day and 21st day amyelination was reduced,and on the 28th day small amyelination focuses could been seen casually.ConclusionsIn the CNS of rats with EAE,expression of Nogo-A could be observed generally, otherwise,the quantity of expression of Nogo-A was different in different positions. Comparing with that of normal rats,the location of Nogo-A in CNS of EAE rats didn't change during the development of EAE.During the development of EAE,the expression of Nogo-A was mobil.In earlier period it decreased,later it increased. And it was higher than that of control group.Meanwhile,amyelination was the most serious during the earlier period of EAE,and myelin began to recover in midanaphase of EAE.These results indicated Nogo-A had played a central role in the development of EAE,especially in the recovery and structure remodeling during the middle and late period of nerve injury.