Visual Pathway Tracing And Effects Of Form Deprivation On The Retina And Visual Cortex Synapsesof Tree Shrews(Tupaia Belangeri).

Objectives:Preliminary study on visual pathway of normal tree shrews,lay the foundation for form deprivation amblyopia visual pathway tracing for tree shrew.To observe the change of form deprivation amblyopia of tree shrewretinal cone pedicles ultrastructure and expression of mGluR6 bipolar cells.And to observe the change of dendritic branches,length and spine density of neurons in the visual cortex.Preliminary study the relationship may exist between retinal and visual cortex plasticity,and provide a theoretical basis for further understanding the pathogenesis of amblyopia.Methods:1.Normal tree shrews were born 80 days,and virus with pAAV-EGFP by intravitreal and visual cortex injection.After injected of virus one month,took material and made slices then observed by fluorescence microscope pAAV-EGFP visual pathway tracing.Virus with rAAV--EGFP and RV-dsRed by eye subretinal injection,AfterrAAV--EGFP injected of virus one month,the same area inject of RV-dsRed.After injected of virus 1 weeks,took material and made slices then observed by fluorescence confocal microscope the visual pathway.2.There were 18 tree shrews born 18 days were randomly divided into 6 groups(n = 3).Groups:form deprivation amblyopia model groups:S30(suture right eye one month),S60(suture right eye two month):form deprivation amblyopia recovery model groups:060(after sutured right eye one month and open it.suture left eye one month),U60(after sutured right eye one month and open it.keep eyes open one month);control groups:C30(keep eyes open one month).C60(keep eyes opentwo month).After have built model,retina of right eye and visual cortex were taken and made slices.Observe the change of retinal cone pedicles ultrastructure by transmission electron microscope,and mGluR6 expression by immunofluorescence staining.Golgi staining observethe changes of dendritic branches,length and spine density of visual cortical neurons.Results were analyzed through these softwares of IPP6.0 and ImageJ.Results:1.Tracer was injected through visual cortex:visual cortex,lateral geniculate and substantia nigra;subretinal injection of tracer:retina,lateral geniculate,visual cortex,hippocampus,posterior hypothalamic and paraventricular nucleus.2.The shapes of retinal cone pedicles ultrastructure were not significantly change.The expression of mGluR6 of bipolar cells in form deprivation amblyopia model groups was lower than control groups(P<0.01),S60 group of bipolar cells mGluR6 expression was lower than S30 group(P<0.01).There was no statistically significant difference between U60.group and S30 group that the expression ofof mGluR6 bipolar cells(P>0.05),060 group and C30 group had no obvious statistical difference(P>0.05).The dendritic branches,length and spine density of neurons in the visual cortex of form deprivation amblyopia model groups lower than control groups(P<0.01).With time extension of keeping form deprivation,S30group and S60group were no obvious changes of dendritic branches and length.(P>0.05),Dendritic spine density of S30 group is higher than S60 group(P<0.01).To compare with both S30 group and S60 group,dendritic branches and the length of neurons in the visual cortex of form deprivation amblyopia recovery U60 grouphad no significant difference(P>0.05),060 group and C30 group had no statistically significant difference(P>0.05)Dendritic spine density of between C30 group and U60 group had no significant difference.(P>0.05).060 group comparing with deprivation amblyopia model groups and control groups had statistical significance(P<0.01).Conclusions:1.Tracing visual pathway of tree shrews may indicate the existence of each loop.2.Retina has changed in form deprivation and recovery model.3.Retinal and visual cortical synapses have plasticity in form deprivation and recovery model.