| ObjectiveTraumatic optic neuropathy(TON) is the most popular kind of optic nerve injury, in which the majority is indirect injury. At present, the treatment of TON is under the research phase and there are many problems what can't be solved. The treatment of high dosage methylprednisolone on TON is effective when using in time. But, actually, the majority of the patients with TON couldn't be treated in time due to remote living area. We wonder to know weather the treatment is effective at 48h after trauma.We established the measurable model of optic nerve crush in this study and gave high dosage methylprednisolone after 48h. Apoptosis cells, bcl-2 and bax positive cells of retinal, were observed to identify the effect-time relation of high dosage methylprednisolone on traumatic.Material and methodOne hundred and eight healthy adult Wister rats without eye diseases weredivided into three groups randomly: normal group, crush group and treatment group. According to the surviving time after crush, the groups were sub-divided into 3 time points: 4d, 7d and 14d. The rats of the crush group and treatment group received optic nerve crush both eyes by the measurable optic nerve crusher to 100g for 12s. Treatment group were given the first dose 30mg/kg MP after 48h, and 6h later, received 5.4mg/kg per hour to 96h. Crush group were given the equal volume normal saline. At each point, the cell apoptosis of RGC from the injured optic nerve was examined by the terminal deoxynucleotidyl transferase mediated DUTP-biotin nick end labeling (TUNEL) reaction, and the expressions of bcl-2 and bax genes were measured with immunohistochemical method. All the data were analyzed statistically by ANOVA.Result1. The location and calculation of apoptosis cellsCells with DNA fragmentations were detected using TUNEL staining. Apoptosis cells were only seen in the ganglion cell layer. Few TUNEL-positive cells were observed at normal retina. In the crush group, a lot of labeled cells were detected at 4d after optic nerve crush, TUNEL-positive cells were 14.57+ 0.27/mm2, 22.79+0.04/mm2 and 5.40+0.05 /mm2 at 4d,7d and 14d post-crush, respectively. In the treatment group, TUNEL-positive cells were 14.51 0.30/mm2, 22.78+0.05/mm2 and 5.39+0.05 /mm2 at 4d,7d and 14d post-crush, respectively.2. The location and the nember of bcl-2 positive cellsBcl-2 positive cells were only seen in the ganglion cell layer at all kind of points. Low level expression of bcl-2 gene was seen in normal retina, the number of the positive cell were 6.25 0.14/mm2, 6.66 0.25/mm2 and 5.74 0.30/mm2 at 4d, 7d and 14d after injury, respectively. In the crush group, the number ofBcl-2 positive cells were 17.47 0.31/mm2, 21.55 0.35/mm2 and 27.55 + 0.29/mm2 at 4d, 7d and 14d after injury, respectively. In the treatment group, the number of Bcl-2 positive cells were 17.44 0.25/mm2, 21.55 0.30/mm2 and 27.53 0.27/mm2 at 4d,7d and 14d after injury, respectively.3. The location and the number of bax positive cellsBax positive cells were only seen in the ganglion cell layer at all points. In normal control group, the number of the positive cell was 5.67 0.40/mm2, 5.91 + 0.43/mm2 and 5.65+0.41/mm2 at 4d, 7d and 14d after injury , respectively. In the crush group, the number of Bax positive cells was 21.50 0.30/mm2, 33.52 1.4/mm2 and 31.19+ 1.07/mm2 at 4d,7d and 14d after injury, respectively. In the treatment group, the number of Bax positive cells was 21.57 + 0.62/mm2, 33.41 ?1.12/mm2 and 31.07 +1.06/mm2 at 4d, 7d and 14d after injury, respectively.Conclusion1. The measurable optic nerve crusher can measure the strength to the optic nerve and the precision is 1g.2. No significant effect was founded in the treatment of high dosage methylprednisolone on traumatic optic neuropathy after 48h optic nerve crush.
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