| 【Background】Optic nerve crush is a common injury in traffic accident, personalinjury, work injury and unforeseen accident, resulting in a decline in the visualfunction which is one of the most common clinical manifestations in forensicexpertise. Its severity is directly related to the magnitude of injury or disability. Asthese cases involve financial reimbursement, thus a gross of wounded frequently toconceal, overstate symptoms or disguise their visual impa irment. Visual evokedpotential is a widely used method in the assessment of visual function. It canobjectively reflect the real state of visual function after optic nerve injury. But itsresults are suspectively infected by the mental state and attention of the patients andso on, thus restricts its widely application in clinical medicine. Growth associatedprotein(GAP-43), a specifically mark of nerve regeneration, its temporal sexualexpression can reflect the renovation of visual system after injury to a certain extentand elaborates the molecular mechanism of the variation of visual function. Afteroptic nerve injury, the visual function varies as time changes. Now there is rare jointresearch on the relationship between VEP detection and GAP-43expression, furtherstudy has important significance in comprehensive visual assessment.【Objectives】Investigating the changing rules of visual function after optic nerveinjury from the level of electrophysiology and protein, offering the evidential supportto the evaluation of visual function after injury.【Methods】The experimental models of optic nerve crush were made in forty-twoSD rats, including one normal group, one sham-operated group and five juriedgroups(one day, two days, seven days, fourteen days, twenty-eight days). In the different time after injuries, the changes of RGCs were observed by light microscope,and the pattern reversal evoked potential was recorded in normal and injured rats.Immunohistochemistry technique and computer image analysis me thods wereperformed to observe the changes of GAP-43on the retinal ganglion cells in rats andmake a comparison with the detection of PRVEP.【Results】(1)The latency of P100in normal control rats was73.532.11ms,amplitude13.342.88uv. There was no significant difference between normal groupand sham-operated group. The latency of P100was longer than normal group(106.377.33ms), and went longer in the coming groups. The latency reached maximum in14d group, then became shorter gradually, and almost recovered to normal level in28d group(74.073.59ms). The amplitude dropped obviously in1d group after opticnerve injury(4.791.43uv), compared with normal group. Then it descended tobottom in3d group(4.091.23uv), then went up gradually and nearly returned tonormal in28d group(13.064.49uv).(2)There was little GAP-43expression innormal and control groups, mainly located in inner plexiform layer. It increasedobviously in3d group and came to peak in7d group, then fall off and approached tonormal group in28d group.(3)There was a relationship between the mean opticdensity of GAP-43expression and PRVEP detection in injured groups. The degree ofcorrelation varied as time changed. The absolute value of correlation coefficientbetween GAP-43and latency was higher than that in GAP-43and amplitude.【Conclusion】The latency of PRVEP obviously extended in one day after crush,recovered in fourteen days and became stable in twenty-eight days. This has a guidingsignificance to correctly evaluate the visual function, prognosis and will offer newclues for concluding injury time. There is rare GAP-43expression in normal rats, theup-regulation of GAP-43expression after optic crush is an important foundation inthe procedure of visual status regeneration. The variation of GAP-43expression has acombination to the changes of PRVEP detection, reflecting objectively the recoveryprocedure of visual function from molecular level. |
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