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The Neuroprotective Effect and Mechanism of Estrogen on Injury of Ratinal after Induction of Chronic Ocular Hypertension in Rabbits

Author: LiuZhenTong
Tutor: HanYao
School: Hebei Medical University
Course: Ophthalmology
Keywords: Chronic ocular hypertension Estrogen Apoptosis Bcl-2/Bax Castration / sham castration Carbomer Rabbit
CLC: R774.1
Type: Master's thesis
Year: 2008
Downloads: 79
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Abstract

Purpose: Glaucoma is a common blinding eye disease, the pathological basis is the loss of retinal ganglion cells (retinal ganglion cells, RGCs) and their nerve fibers. A variety of factors related to their incidence, pathologic ocular hypertension can cause hypoxic-ischemic injury of the retina and lead to the the RGCs eventually lost in the form of apoptosis. Estrogen with castration and sham castration method, the experimental feasibility of eye diseases, and anterior chamber injection carbomer a rabbit chronic ocular hypertension model, the study chronic elevated intraocular pressure in the rabbit retina Bcl-2 protein family expression, observed chronic high intraocular pressure process retinal damage protective effect of estrogen (estrogen) to explore whether estrogen raised the Bcl-2 expression inhibits apoptosis mechanism neuroprotective role for clinically more effective treatment methods to seek the protection of glaucomatous optic to provide experimental basis. Methods: Experimental animals and groups: 28 healthy adult female New Zealand white rabbits were randomly divided into the experimental group (castration group) and the control group (sham castration group) and the normal control group: castrated group removal of the ovaries, false castrated group only the removal of part of the fat tissue around the ovary, both groups produced a model of chronic high intraocular pressure, and in accordance with the duration of high intraocular pressure is divided into four weeks, six weeks, eight weeks group, n = 3 animals, six eye . Standards and the establishment of chronic ocular hypertension animal model: chronic ocular hypertension model intraocular pressure greater than 2. 93 kPa (22mmHg), and can continue as a standard 1 wk. Rabbit anterior chamber injection of 0.3% carbomer solution method of manufacture of elevated intraocular pressure, chronic ocular hypertension model. Were successful modeling corresponding time points after the removal of the animal eye, and made of paraffin sections. 3 serum estrogen levels detected: preoperative one day, after two weeks, four weeks after the operation, after six weeks, eight weeks after surgery, 9:00 blood was collected from the marginal ear vein about 3ml the U.S. Beckman Acess Immunoassy System automatic chemiluminescence analyzer serum estrogen concentrations. 4 retinal histopathology observed: HE staining observed under an optical microscope pathological changes of the retina. 5 Immunohistochemistry was used to detect the expression of Bcl-2: observed under an optical microscope, the cell cytoplasm brown colored positive expression. 6 Immunohistochemistry was used to detect the expression of Bax: optical microscope observation cytoplasmic colored brownish yellow positive expression. 7 apoptosis detection and qualitative analysis: using the TUNEL (terminal deoxynucleotidy transferase mediated x-dUTP nick end labeling) assay to apoptosis. Light microscope, the nucleus was brown as positive. 8 flash visual evoked potential (F-VEP) detection: F-VEP assessment of optic nerve damage. OUTCOME MEASURES F-VEP P1 wave latency the LP1 (ms). Results: IOP: rabbit eye IOP as mean ± standard deviation (x ± s) said. Experiment, intraocular pressure mean 27.89 ± 1.56mmHg, and intraocular pressure peak of 35 to 48 mm Hg. The modeling of the experimental eyes IOP no significant difference in mean intraocular pressure of the three groups of rabbits was 14.50 ± 1.35mmg. 2 retinal histopathology observed: normal control group of rabbit retina of the human eye retina morphology is basically similar, visible layers of tissue, cells arranged in neat uniform, structured, tissue necrosis and cell degeneration. Sham castration group and castrated group retina compared with the normal group thinning, significantly reduced the number of retinal ganglion cells, the nerve fiber layer and kernel layer thinning. Period of sham castration group of retinal ganglion cells and nerve fiber layer thickness is slightly thicker than the castrated group. The 3 serum estrogen levels were measured: the a sham castration group before surgery and the average of the levels of estrogen after the surgery The statistical test showed no significant difference between the two. Castrated group before surgery compared with the average of the levels of estrogen after the surgery, a statistically significant difference. 4 Bcl-2 positive cells: three groups of the retina of Bcl-2 expression in the modeling of each time point to a significant difference between sham castrated group compared with castration group, sham-castrated group each time segment Bcl-2 expression were higher, and the difference was statistically significant. 5 Bax positive cells: Bax expression in the three groups retina modeling each point in time have a significant difference between sham castrated group compared with castration group, fake castration group period Bax expression lower, and the difference was statistically significant. 6 TUNEL-positive cells in the expression: expression of TUNEL-positive cells in the retina of three groups at each time point in the model were significant differences between sham castration group and castrated group compared to sham castration group withered period expression of apoptotic cells were lower, and the difference was statistically significant. 7 F-VEP P1 wave latency the LP1 (ms) changes: modeling different time points after castration group and sham castration group than normal group of P-wave latency, the difference was statistically significant; false castration group and go potential group compared to sham castration group P-wave latency, the difference was statistically significant. Conclusion: 1 of castration and false castration method is the simple and reliable method for the role of estrogen in eye diseases. 2 rabbit anterior chamber injection of 3 g / L carbomer solution is a better method of chronic ocular hypertension model making. 3 chronic high intraocular pressure induced damage to the cells of the inner retina, loss of retinal ganglion cells in the form of apoptosis. 4 estrogen in the process of experimental chronic high intraocular pressure, retinal tissue protective effect, and slow the damage of the retina and visual function. 5 estrogen by upregulating the expression of Bcl-2 protein expression and downregulation of Bax protein expression, inhibition of TUNEL positive expression and play a neuroprotective effect.

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