The Establishment Of Chronic Ocular Hypertension Mice Model And Expression Of JNK3 In Retina Of The Models

Objective:To standardize a method of non-invasive measurement of intraocular pressure(IOP) in mice,and establish an experimental model of chronic ocular hypertension in the mice.To examine the expression of c-Jun N-terminal kinase3(JNK3) in the retina of mouse with normal and experimental model of chronic ocular hypertension and to determine the relationship of c-Jun N-terminal kinase3(JNK3) with ganglion cell death.Methods:l.The normal IOP of 20 C57BL/6 mice were measured by TONO-PEN AVIA for five days.2.Experimental model of chronic ocular hypertension was induced unilaterally in Forty-four C57BL/6 mice.After anesthesia and pupil dilation,the anterior chanber was flattened by paracentesis of anterior chamber.Laser photocoagulation(532nm wavelength, 100mW power,0.05 second duration,200um spot size)then was performed at the limbus.The fellow eye served as a control. TONO-PEN AVIA Tonomter was used to measure IOP to guarantee IOP value at 1 week,2 week,4 week,8 week. Slit lamp biomicroscopy was performed throughout the period and the structural changes were assessed histologically.3.And then,their eyes were enucleated,postfixed,cryoprotected,and embedded in optimal cutting temperature(OCT) medium.After hematoxylin and eosin stain(HE stain),Cryosections of the retina were observed under light microscope.TdT-mediated biotin-dUTP nick end labeling(TUNEL) was performed on the retinal sections to determine the rate of cell death.RT-PCR detect the variation of the JNK3 mRNA expression in normal mice retina and chronic intraocular hypertension mice on the first week,second week,4th week,8th week. Results:1.The mean normal IOP of mice was 13.46±2.05mmHg.The highest IOP is 19mmHg and the lowest IOP is 9mmHg.2.Laser-treated eyes showed significantly higher IOP than control eyes from 1 to 8 weeks(p<0.05). The highest IOP is 31mmHg, but only one eye. The IOP is mainly around 20mmHg.Throughout the total study period,untreated eyes did not have any complication.In the laser-treated eyes,corneal edema was seen in all eyes and was completely resolved by the third day of the study.Corneal opacity and cataract formation were respectively seen in two eyes.Atrophy of eyeball was seen in one eye.Corneal perforation was seen in one eye.Four laser-treated eyes were not significantly different compared with control eyes.3.In laser-treated eyes,the angle of anterior chamber were narrow.Number of cells in the inner nuclear layer and retial gangllion cell layer was slightly lower than in control eyes at 2 weeks,but by 4 weeks and 8 weeks the number of cells was significantly lower than in the control contralateral eyes.Mean number of TUNEL-positive cells in the retinal ganglion cell layer of eyes with experimental ocular hypertension was 0.38±0.49,0.52±0.64,0.46±0.66 and0.50±0.59 at 1 weeks,2 weeks,4 weeks and 8 weeks,respectively.No TUNEL-positive cells were noted in control eyes.RT-PCR show that the expressions of JNK3 mRNA was up-regulated after the elevation of IOP,but no statistically significant differences on each time point in laser-treated eyes.Conclusion:1.The TONO-PEN AVIA can be used for rapid and reproducible measurements of IOP in mice.The method is easy to apply and can provide a useful means for IOP measurement in mouse models of induced ocular hypertension.2.The laser photocoagulation of limbus cause a chronic elevation of IOP and this method may be a promising experimental model for the ivnestigation fo the biological mechanisms of glaucomatous optic neuropathy.3.The change in the level of expressed of JNK3 mRNA in the retina is correlated with chronic elevation of IOP.JNK3 may play a role in retinal ganglion cell death.