Plasticity Of Retinal Ganglion Cells In Tree Shrews With Form Deprivation Amblyopia

Objectives:To preliminarily explore the plasticity of retina during the development of amblyopia,we observe the number and structure of retinal ganglion cells and intrinsically photosensitive retinal ganglion cells in tree shrews with form deprivation amblyopia.This can provide theoretical basis for further understanding of the pathogenesis of amblyopia.Methods:48 tree shrews,which were bom about 18 days after birth ande have not opened their eyes,were randomly divided into 6 groups(8 in each group),regardless of gender.Groups:form deprivation amblyopia model group S1(right eye was sutured for 1 month)and S2(right eye was sutured for 2 months),the recovery model of form deprivation amblyopia group R1(the right eye was sutured for 1 month,then open it and suture the left eye for 1 month)and R2(the right eye was sutured for 1 month,then keep binocular vision for 1 month),Control group C1(normal binocular vision for 1 month)andC2(normal binocular vision for 2 months).After the modeling was completed,the retinal frozen section and the retinal patch were prepared.Immunofluorescence staining was used to observe the number and morphology of ganglion cells and intrinsically photosensitive retinal ganglion cells,as well as the changes of the synaptic connections between intrinsically photosensitive retinal ganglion cells and bipolar cells.The results were analyzed by IPP6.0 and SPSS 17.0 software.Results:1.The intrinsically photosensitive retinal ganglion cells of normal tree shrews are located in the retinal ganglion cell layer and the inner nuclear layer,and their dendrites are located in the retinal inner plexiform layer.Retinal ganglion cells were labeled by Bm3a antibody and photosensitive ganglion cells were labeled by melanopsin antibody.They are different types of cells.The shape of part of the ipRGCs in the S2 and R2 groups changed from round to fusiform,and the green fluorescence of the melanopsin santibody on the dendrites was weakened.2.Statistical analysis of the number of retinal ganglion cells:the population mean of retinal ganglion eells in the two groups of form deprivation amblyopia model S1 and S2 was higher than that in the normal control group C1 and C2,respectively,but the difference was not statistically significant(P>0.05).The two groups of form deprivation amblyopia recovery model R1 group,R2 group compared with C2 normal control group,the population mean of R1 group retinal ganglion cells was lower than the C2 group,the difference was not statistically significant(P>0.05),the population mean of R2 retinal ganglion cells was lower than C2 group,the difference was statistically significant(P<0.05).The R2 group compared with the R1 group,the population mean of ganglion cells was lower than Rl group,the difference was statistically significant(P<0.05).The R2 group compared with the S2 group,the population mean of ganglion cells was lower than S2 group,the difference was statistically significant(P<0.05).3.Statistical analysis of the number of intrinsically photosensitive retinal ganglion cells:The comparison of C1 group and C2 group,the population mean of intrinsically photosensitive retinal ganglion cells in C2 group was lower than that in C1 group,the difference was statistically significant(P<0.05).The two groups of form deprivation amblyopia model S1 group,S2 group respectively compared with the normal control group C1 and C2,the population mean of intrinsically photosensitive retinal ganglion cells of form deprivation amblyopia model was lower than the normal control group,the difference was statistically significant(P<0.05).The population mean of intrinsically photosensitive retinal ganglion cells in R1 group and R2 group was higher than that in S2 group,but the difference was not statistically significant(P>0.05).The population mean of intrinsically photosensitive retinal ganglion cells in R1 group was lower than that in C2 group,but the difference was not statistically significant(P>0.05).The population mean of intrinsically photosensitive retinal ganglion cells in R2 group was lower than that in C2 group,and the difference was statistically significant(P<0.05).Conclusions:1.Monocular form deprivation may leads to morphological structure change of ipRGCs and decrease in the number of ipRGCs in amblyopia.2.After removing the form deprivation factors,covering the fellow eye can effectively improve the reduction of ipRGCs caused by form deprivation,indicating the plasticity of ipRGCs.3.After the removal of the form deprivation factor,the number of RGCs in the retina of amblyopic eyes would be reduced if the fellow eyes were not covered,while the number of RGCs would remain stable if the fellow eyes were covered,indicating the plasticity of RGCs.