An Experimental Study Of Effect Of Gypenosides On Optic Nerve And Retina In Experimental Optic Neuritis

Objective Established a model of experimental autoimmune encephalomyelitis(EAE)in C57BL/6 mice,after gypenosides(GPs)were administrated,observe the clinical progression,histopathology changes of optic nerve and retina,and detecte the apoptosis of retinal ganglion cells(RGCs),explore the protective effect on EAE.Methods EAE was induced with myelin oligodendrocyte glycoprotein peptide add complete Freund's adjuvant in C57BL/6 mice.Mice were randomly divided into 5 groups as normal control,EAE,GPs monotherapy,methylprednisolone monotherapy,combination of GPs and methylprednisolone group.On day 7 after immunization,mice in GPs group were daily intraperitoneal injection with GPs(30mg/kg)until sacrificed.From day 7 to day10,Mice in methylprednisolone group were daily intraperitoneal injection with methylprednisolone(20mg/kg).Combined treatment group were daily intraperitoneal injection with GPs(30mg/kg)and methylprednisolone(20mg/kg)respectively.Clinical signs and weight were scored daily,visual evoked potential was performed on day 7,OCT was performed on day 14,20,30,40.HE and TUNEL were performed on day 20,40.Results 1.Mice in control group were no symptoms,the weight of experimental groups mice were down a bit within a week,and then gradually increased,on day 9 after immunization were started to attack.The incidence rate in EAE group was 100%,symptom score was higher and the sickest.The incidence rate in GPs group was 97%,The incidence rate in COM and MP group were 90%.COM group can delay the disease onset,compared with EAE group,the difference has statistical significance.The score in control group mice was 0,on day 14 after immunization,compared with EAE group,the symptom in COM group was lighter and the score was low,the difference has statistical significance.2.Compared with the control group,N1,P1,P2 latency were prolong and P1 amplitude was decline in EAE group,the difference has statistical significance.N2 latency,P2 amplitude of two group were no significant difference.3.On day 20 after immunization,RNFL thickness in EAE group was thinner,three drug intervention group were similar to control group.On day 30,RNFL thickness in EAE group was further thinning,EAE group and MP group were significant thinning,GPs group and COM group were similar to control group and thicker than MP group.On day 40,the RNFL significantly decreased in EAE and MP group when versus normal,GPs group and COM group were similar to control group and thicker than EAE group.At this point,the differences between the three drug intervention group was more obvious,present as MP group was significantly decreased when versus GPs,COM group(P<0.01).4.In control group,retina and nerve fiber arranged evenly,dyeing uniformity,inflammatory cells infiltration has not been found.On day20,obvious inflammatory cell infiltration appeared in optic nerves and retina ofEAE group,edema was obvious,disordered arrangement of nerve fibers,a large number of cavity formation.In the treatment group,there were less infiltration of inflammatory cells.On day 40,the inflammatory cell infiltration were reduced,edema relieve in all group,three drug intervention group were better than EAE group.The RGCs in EAE group and MP group were significant reduce,loosely arranged.5.There was almost no apoptosis cells in control group,the experimental group were obviously different degrees of RGCs apoptosis,EAE group and MP group were much more obvious.As time goes on,the number of apoptotic cells gradually increased,and significant difference with control group.GPs,COM group were relatively less than EAE,MP group.Conlusion 1.The combination of GPs and methylprednisolone can delay the onset of EAE mice.2.GPs alone or with methylprednisolone use can prevent thinning of retinal nerve fiber layer.3.GPs can suppress inflammatory response in EAE.4.GPs inhibit the apoptosis of RGCs.