The Supression Effects Of CAT And MP On Experimental Demyelinating Optic Neuritis

Objective: To investigate the pathogenesis of active oxygen scavenger(catalase,CAT) and methylprednisolone sodium succinate(MP) on experimental demyelinating optic neuritis.Method: 71 healthy,female wister rats were randomly divided in four groups: catalse group(group CAT,n=22)establish EAE model ,then received intraperitoneal injections of CAT at a dose of 12,000 U/kg per day for 3 days,then 1,200 U/kg daily for the next week,commencing 3 days after antigenic sensitization; control group(group PS,n=22) establish EAE model, then received intraperitoneal injections of PS at a volum of 1ml per day for 10 days, commencing 3 days after antigenic sensitization; methylprednisolone group (group MP,n=22) establish EAE model,then received intraperitoneal injections of MP at a dose of 30mg/kg ever other day for 5 times ,commencing 3 days after antigenic sensitization; normal group(group N ,n=5)received normal food and water. On day 7 and 14 after antigenic sensitization, H2O2 measurement,histomorphology observation,patho-image analysis,histiocyte ultrastructure analysis were applied to study the effects of CAT and MP on experimental demyelinating optic neuritis.Result:1. On day 7 and 14 after antigenic sensitization, the count of Ce-H2O2 and H2O2 concentration of optic nerve in control group(group PS) was significantly higher than that in normal group (group N)(P<0.01);the count of Ce-H2O2 and H2O2 concentration in catalase group (group CAT) and methylprednisolone group(group MP) reduced ,but was still significantly higher than that in group N(P<0.01);the count of Ce-H2O2 and H2O2 concentration in group MP was higher than that in group CAT(P<0.05).2. On day 7 after antigenic sensitization, there were no inflammatory cell and reactive astroglial cells obviously each group . On day 14 after antigenic sensitization, the count of inflammatory cells(lymphocyte,neutrophil ) and reactive astroglial cells in group PS,group CAT and group MP was significantly higher than that in group N(P<0.01);the count of inflammatory cells and reactive astroglial cells in group CAT and group MP was lower than that in group PS(P<0.01);the count of inflammatory cells and reactive astroglial cells in group MP was not significantly different with that in group CAT(P>0.05).3. On day 7 and 14 after antigenic sensitization, transmission electron microscopy of the optic nerve revealed that group N was the normal myelin ,and all rats sensitized for EAE exhibited loss of the myelin sheaths that envelop axons, foci of demyelination, naked axons, and axons enveloped by thin sheaths of myelin, the mitochondrion swelling, The cytoplasm of capillary endothelial cell destroyed .The pathological changes in group PS seemed more severity than that in group CAT and group MP, and the pathological changes on day 14 were more severity than that on day 7.The areas of myelin in group PS were significantly lower than that in group N(P<0.01); the areas of myelin in group CAT and group MP were larger than that in group PS, but were smaller than that in group N; the areas of myelin in group MP were lower than that in group CAT(P<0.05).Conclusion: (1)The H2O2 in optic nerve of experimental demyelinating optic neuritis was higher than that of the normal optic nerve,which supposed that H2O2 may has some relationship with the occurrence of experimental demyelinating optic neuritis.(2) CAT and MP can reduce not only the H2O2 in optic nerve of EAE rats, but also the number of inflammatory cells and reactive astroglial cells,the extent of demyelination in the retrobulbar optic nerve. But the effect MP on H2O2 scavenging and myelin protection is weaker than CAT.