ABSTRACT
Objective:To investigate the inhibitory effect of specific inhibitor of necroptosis necrostatin-1 (Nec-1) on necroptosis of retinal ganglion cells (RGCs) in rats with acute ocular hypertension.Methods:Twenty-four adult male Sprague Dawley rats were randomly divided into normal control group, model control group, Nec-1 treatment group and negative control group by random number table method, with 6 rats in each group.High intraocular pressure (IOP)-induced ischemia and reperfusion model was established through anterior chamber irrigation of 0.9% sodium chloride solution in left eyes of the rats, raising the IOP to 110 mmHg (1 mmHg=0.133 kPa) for 60 minutes.Nec-1 (4 mmol/L, 2 μl) or dimethyl sulfoxide (2 μl) was intravitreally injected immediately in Nec-1 treatment group and negative control group following modeling, respectively, according to grouping.No intervention was administered to the normal control group.Paraffin sections of rat retinas of the left eyes in different groups were prepared seven days after modeling.The retinal structure was observed by hematoxylin-eosin staining, and the expression levels of thymocyte antigen-1 (Thy-1) and glial fibrillary acidic protein (GFAP) were detected via immunohistochemical staining.All animal experiments were approved by an Ethics Committee of Tianjin Union Medical Center (No.2017 Quick audit C01).Results:Seven days after modeling, compared with normal control group, the retinal nerve fiber layer was thinner in model control group and negative control group, and the RGCs were arranged loosely, and cells in the inner nuclear layer were reduced and arranged disorderly, and cells in the outer nuclear layer were normal or enlarged.Compared with model control group and negative control group, the nerve fiber layer was thickened and the number of RGCs was significantly increased in Nec-1 treatment group.The number of Thy-1-positive RGCs was decreased in model control group, negative control group and Nec-1 treatment group than normal control group, and there were more Thy-1-positive RGCs in Nec-1 treatment group than model control group and negative control group.The integrated absorbance ( A) value of GFAP protein in normal control group, model control group, negative control group and Nec-1 treatment group was 47.209±15.311, 116.220±18.194, 116.382±19.020, 92.818±10.236, respectively, showing statistically significant differences among them ( F=24.675, P<0.001). The integrated A value of GFAP protein was significantly increased in model control group, negative control group and Nec-1 treatment group than normal control group, and the integrated A value of GFAP protein in Nec-1 treatment group was lower than that in model control group and negative control group, with statistically significant differences (all at P<0.05). Conclusions:Nec-1 can promote RGCs survival by inhibiting the necroptosis of RGCs in rats with acute intraocular hypertension.
ABSTRACT
Objective:To investigate the breakdown of blood-retinal outer barrier in the ischemia-reperfusion injury mice following acute intraocular hypertension.Methods:Fifty-seven SPF male C57BL/6J mice were selected and divided into the control group and high-intraocular pressure (IOP) group by using the random number table method.There were 25 mice in the control group and 32 mice in the high-IOP group.After the failure and poor modeling excluded, 20 mice were included in each group, and the left eyes were selected as the experimental eyes.The ischemia-reperfusion injury model of the high-IOP group was established following acute intraocular hypertension by anterior chamber perfusion of 0.9% sodium chloride solution, and the control group only received anterior chamber puncture.Optical coherence tomography was used to detect retinal thickness.Immunofluorescence staining was utilized to identify zonula occludens-1 (ZO-1) protein distribution in retina.Retinal capillary degeneration was identified by trypsin digestion.Inflammatory cell infiltration in retinal sections was observed by hematoxylin and eosin staining.The use and care of the animals complied with the Statement of the Association for Research in Vision and Ophthalmology, and the study protocol was approved by an Ethics Committee of Changsha Aier Eye Hospital (No.2018-KYPJ005).Results:Compared with the control group, the structure of the retinal pigment epithelium (RPE) layer was irregular with obvious exudation and local neuroepithelial detachment and elevation.The thickness of the full retinal layer of mice in the high-IOP group was (235.8±5.3)μm, which was significantly thicker than (213.3±3.9)μm in the control group ( t=3.427, P=0.009). ZO-1 staining results showed that ZO-1 was mainly located in cell membrane and a small part in cytoplasm in the RPE layer of mice.Two days after modeling, ZO-1 in the high-IOP group was significantly internalized with decrease in cell membrane and increase in cytoplasm, and its distribution was irregular.Seven days after modeling, retinal capillary degeneration was observed in the high-IOP group, and the number of degenerated retinal capillaries was 201.0±13.2, which was significantly larger than 11.2±1.7 in the control group ( t=14.280, P<0.01). Hematoxylin-eosin staining results showed that inflammatory cell infiltration, mainly neutrophils, could be observed in the mice retina with high IOP, and the infiltrated inflammatory cells were mainly located under the internal limiting membrane. Conclusions:Acute intraocular hypertension induced retinal ischemia-reperfusion injury in mice destroys the integrity of the outer retinal barriers, and causes granulocyte infiltration in the peripheral circulation, retinal edema as well as retinal capillary degeneration.