急性高眼压模型兔眼不同眼压状态下视神经轴浆运输的改变

Axonal transport of rabbit optic nerve under acute ocular hypertension

目的观察急性高眼压模型兔眼不同眼压状态下视神经轴浆运输的改变。方法成年新西兰大白兔24只，分为眼压20、30、40mmHg（1mmHg=0．133kPa）组和眼压为10～15mmHg的对照组，每组均为6只兔。采用前房穿刺灌注法联合压力持续监测法建立急性高眼压模型。实验开始时，兔眼玻璃体腔中注射罗丹明异硫氰酸（RITc）标记轴浆运输。持续3h高眼压后，过量麻醉处死兔后取下视神经。荧光显微镜下观察视神经轴浆运输情况的改变。采用德国Leica公司Q500IW图像分析软件对RITC进行灰度定量分析，并对各眼压组平均灰度值和筛板前、筛板区、筛板后350μm区域灰度值进行统计学分析处理。结果RITC在视神经中心呈顺行标记染色。不同眼压组轴浆运输情况不同，随着眼压升高，轴浆运输能力减弱，差异有统计学意义（F=159．3，P〈0．05）。筛板前区，各眼压组间灰度值比较，差异无统计学意义（F=0．2545，P〉0．05）。40mmHg组灰度值与对照组灰度值比较，在筛板区（t=5．684）和筛板后350μm区域（t=5．124）差异均有统计学意义（P〈0．05）；20、30mmHg组灰度值与对照组灰度值比较，差异无统计学意义（t=1．747，P〉0．05）。结论眼压40mmHg持续3h将导致视神经轴浆运输改变，轴浆运输障碍部位以筛板区及以后的区域为主。

Objectives To observe the changes of axonal transport in the rabbit optic nerve under acute ocular hypertensions. Methods 24 adult healthy New Zealand white rabbits were divided into 4 groups according to the intraocular pressure （IOP）, with 6 rabbits in each group. There are 3 experimental groups with an IOP of 20, 30, 40 mm Hg （1 mm Hg=0. 133 kPa）. respectively, and 1 control group with an IOP of 10 - 15 mm Hg. Two 25-gauge cannulas were inserted into each rabbit＇s anterior chamber to create the model of acute ocular hypertension. At the beginning of the experiment, rhodamine-β-isothiocyanate （RITC） was injected into the vitreous of each eye to label axonal transport. After 3 hours of high intraocular pressure, rabbits were sacrificed with anesthetic overdose. The retina and the optic nerve were then carefully exposed. Fluorescent microscopy was used for quantitative measurements of the changes of optic nerve axonal transport. Statistically analyze the average grey level in different groups and sites by Leica RITC Q5OOIW image analysis software. Results RITC, a fluorescent tracer, was transported in the anterograde direction by axonal transport. With the increasing of the intraocular pressure, the distance of the axonal transport was declined （F= 159.3, P〈0.05）. The difference of the grey level in the pre-laminar region of 20, 30, 40 mm Hg group was not statistically significant （F=0.2545,P〈0.05）. Compared the grey level of 40 mm Hg group with control group, the differences in lamina cribrosa（t= 5. 684）and the proximal 350 μm of the post-laminar （t=5. 124） were statistically significant （P〈0.05）. Compared the grey level of 20, 30 mm Hg group with control group, the difference was not statistically significant（t= 1. 747, P〉0. 05）. Conclusion 40 mmHg intraocular pressure lasts for 3 hours can reduce axonal transport in the lamina cribrosa and post laminar of optic nerve.