Retinal Ganglion Cells And Visual Electrophysiological Changes Of Rats In Traumatic Optic Nerve Model

Object:1.To study the number of retinal ganglion cells(RGCs)in traumatic optic nerve(TON)model of rats2.To study visual electrophysiology of TON model of rats Methods:Part I:To establish optic nerve crush(ONC)model and count RGCs1.Retrograde labeling of fluorogold(FG):After perforating the corresponding the skull on both sides,FG is injected into the bilateral superior colliculus using the microscopic syringe.2.Establishment of ONC model:After retrograde labeling for 7 days,the left optic nerves of Wistar rats were exposed by conjunctival approach,and clamped vertically for 10s.3.Counting RGCs:After establishment of ONC model for 7 days,the rats were sacrificed,the eyeballs were removed and soaked in 4%paraformaldehyde for 30minutes.Then the retinas were stretched and photographed under fluorescence microscope.Part 2:To detect visual electrophysiological of ONC model1.Establishment of ONC model2.Detection of f-VEP and ERG:The f-VEP of normal and clipped eyes on the 5th day after injury and f-ERG of both on the 5th,12th,21th,and 28th day after injury were detected.Result:1.The average density of RGCs in normal eyes was 2400±150/mm~2,and clipped eyes was 1063±143/mm~2.On the 7th day after injury,the average density of RGCs in the normal group was significantly greater than that in the ONC group(P<0.001),and the RGCs in the ONC group were reduced by approximately 55.7%.2.The N-P-N waveform can be induced by f-VEP on the 5th day after operation in both normal and ONC eyes.The P1 latency of the ONC eyes was longer than that of the normal eyes on the 5th day(P<0.001),and the amplitude was lower than that of the normal eyes(P<0.05).3.The amplitudes of rodresponse b-wave,maximum response a,b-wave,oscillatiory potentials(Ops)and coneresponse b-wave of the ONC group were significantly lower than those of the normal eyes at 5d,12d,21d,and 28d after injury(P<0.01).There was no statistical difference of the latency between normal eyes and ONC eyes(P>0.05).The amplitude of waves of the ONC eyes at 5d,12d,21d,and 28d decreased with the injury days.Conclusion:1.Stable and reproducible animal models were established by using special cross action forceps.2.As a retrograde tracer,FG is a good indicator for quantitative analysis of RGCs after ONC.On the 7th day after operation,significant decrease of RGCs was observed.3.On the 5th day after ONC,in ONC eyes latency of P1 had prolonged and amplitude of it had decreased,it meaned the function of visual conduction pathway was impaired.The amplitude of waves of f-ERG in ONC eyes was significantly lower than that in normal eyes on the 5th,12th,21th,and 28th days.It may be related to the stress biochemical response after injury and not separating the blood vessels from the optic nerve.There are many issues that require further study and discussion.