| Objective: To establish sustainable and stable rabbit model of chronic high intraocular pressure and to investigate protective effects and mechanisms of Ginaton and fleabane on retinal ganglion cells injury induced by continuous high intraocular pressure (IOP) in the rabbits.Methods: The intraocular pressure of 20 New Zealand white rabbits were measured to exclude abnormal IOP and four rabbits were randomly choosed as normal control group. The rest rabbits were injected a - chymotrypsin(0.2ml)(2667.2μkat) into rabbit posterior chamber to build up chronic high intraocular pressure model. After 24 hours and 72 hours the IOP were measured to establish the rabbit model of chronic high intraocular pressure.It were successful if the IOP was over 30 mmHg in 24 hours and over 26.6mmHg in the 72 hours. 16 successful samples were choosed to devide them into four groups randomly,8 eyes in each group and were treated 72 hours after establishing models for four weeks.The methods of treatment as follows:lavaging the sromach with Ginaton 150mg/Kg once a day; lavaging the sromach with fleabane 150mg/Kg once a day; lavaging the sromach with Ginaton 150mg/Kg and fleabane150mg/Kg once a day; no treatment. All the rabbits were killed on the 29th of treatment and immediately remove the eyes of the rabbits. The same amount of formaldehyde solution were replaced after taking part of the eye tissue in the eye equator with 5mL syringe and then were soaked for 24 hours in the formaldehyde solution. Paraffin embedded sliced, HE staining, pathologicl changes of retinal layers with optical microscope were observed in the slices. The numbers of natural particles in the nuceus were calclated after silver staining.and the activity and function of the cell were analyzed and expression of retinal caspase-3 protein with immunohistochemical methods and the apoptosis of retinal ganglion cells and normal ganglion cells were detected.Results: 1.α-chymotrypsin (0.2ml) (2667.2μkat) were injected into the posterior chamber of eyes of rabbits, which result in experimental chronic ocular hypertension at least for 1 month, postoperation IOP remained over 30mmHg.Under high intraocular pressure conditions, the thickness of internal limiting membrane to the outside of ganglion cell layer was obviously thinning. Compared with the normal eyes and control eyes, there was a significant difference (P<0.05).2.The descending order of number of TUNEL-positive cells in retinal ganglion cell layer is the saline group, treatment group alone, the combination group, the normal group. The difference of apoptotic index among the four groups was significant3.Normal group and the combined treatment group RGCs nucleus particles of silver staining was no significant difference (P> 0.05); RGCs nucleus particles of silver staining of saline group and treated groups decreased by silver staining, and the difference of the normal group and the combined treatment group was significant (P <0.05), in which treatment group was more than the saline group, the difference was also significant (P <0.05).4.In the retinal ganglion cell layer Caspase-3 expression of each group was significantly increased compared with normal group. The largest number of positive cells is the saline group; the combination group was significantly lower than the drug group. Differences between two groups were significant (P <0.05).Conclusion:1.α-chymotrypsin (0.2ml) (2667.2μkat)was injected into the posterior chamber of the rabbit eyes, sustained and stable experimental model of chronic ocular hypertension were built up.2. Erigeron Ginkgo biloba extract on the injuried retinal ganglion cell caused by persistent high intraocular pressure was significantly protective effect.3. Erigeron Ginkgo biloba extract can inhibit the expressions of Caspase-3 in the retinal ganglion cells to protect retinal ganglion cells in rabbits.
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