Protective effects of estrogen on chronic ocular hypertension-related rabbit retinal damages

Abstract

Objective To investigate the protective effects of estrogen on rabbit retinal damages induced by chronic ocular hypertension. Methods A total of 18 white New Zealand female rabbits were randomly divided into ovariectomized (OV) group and sham OV (SOV) group. Bilateral ovaries were remove in OV group while only the adipose tissue around ovarian were remove in SOV group. Chronic ocular hypertension was induced by anterior chamber injection of carbomer. Retinal cell apoptosis was measured by terminal deoxynucteotidyl transferase-mediated dUTP nick end labeling (TUNEL), the expression of bcl-2,bax were detected by immunohistochemistry. The images were captured under microscope and analyzed with computer-image-analysis system. Results Four, six and eight weeks after ocular hypertension modeling,the OV retinas have less retinal ganglion cells, thinner optic nerve fiber layer and inner nuclear layer and more TUNEL positive cells (t = 3. 285, 4. 012, 3. 624; P< 0.01). The OV retinas also have less bcl-2 expression (t=4. 256,3. 867,3. 459;P<0. 01), more bax positive cells (t=3. 211,3. 625,3. 253;P<0. 01).Bcl-2 expression was negatively correlated with TUNEL positive cells indicating bcl-2 can inhibit apoptosis.Bax expression was positively correlated with TUNEL positive cells indicating bax induce apoptosis.Conclusion Estrogen has a neuroprotection role to rabbit retina under chronic ocular hypertension by reducing apoptosis. Key words: Estrogens/physiology; Retinal ganglion cells; Apoptosis; Bcl-2-associated X protein; Animal experimentation