Pathological changes in the retina and growth associated protein-43 expression following treatment of intracanalicular optic nerve injury via optic canal decompression, dexamethasone or their combination

摘要

BACKGROUND:The main clinical treatments for optic nerve injury are optic canal decompression and systemic administration of hormones,but both treatments have disadvantages.OBJECTIVE:To observe the pathological changes in the retina and growth associated protein-43(GAP-43) expression,to compare the treatment of optic canal decompression,hormones,and their combination with the intracanalicular optic nerve injury.DESIGN,TIME AND SETTING:A randomized,controlled animal study was performed at the Department of Anatomy,Weifang Medical University,China,from September 2007 to November 2008.MATERIALS:Dexamethasone(Shandong Huaxin Pharmaceutical,China) and rabbit anti-GAP-43 polyclonal antibody(Boster,China) were used.METHODS:All 36 healthy adult rabbits were randomly assigned to control group(n = 4),simple injury group(n = 20),and treatment group(n = 12).Intracanalicular optic nerve injury models were established using the metal cylinder free-fall impact method.The control group was left intact.The treatment group(four rabbits in each subgroup) was treated by optic nerve decompression,dexamethasone treatment(1 mg/kg daily via two intravenous infusions,1/5 total dose reduction every 3 days,for 14 days),and simultaneously giving surgery and hormone treatment.MAIN OUTCOME MEASURES:Pathological changes in the retina were determined using hematoxylin-eosin staining.GAP-43 expression was detected using immunohistochemistry in the retina.RESULTS:Retina injury induced obvious pathological changes in the retina.With prolonged time after optic nerve injury,the number of retinal ganglion cells was gradually decreased,and reached the minimum on day 14(P < 0.01).All three treatments increased the number of retinal ganglion cells(P < 0.01),but surgery + hormone treatment was most effective.No GAP-43 cells were present in the normal retinal,but they appeared 3 days after injury,peaked 7 days after injury,and then began to decline.CONCLUSION:Intracanalicular optic nerve injury induced obvious pathological changes in the retina,including increased GAP-43 expression.Optic canal decompression and hormones improved nerve repair after injury,and their combination produced better outcomes.