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Y. Liu, Y. Dai, X. Chen, N. Li, D. Liu, M. Li, R. Pan; Estrogen Protects Retinal Ganglion Cell from Death in Chronically Elevated Intraocular Pressure in Ovariectomized Rats . Invest. Ophthalmol. Vis. Sci. 2006;47(13):1573.
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© ARVO (1962-2015); The Authors (2016-present)
To investigate whether estrogen can protect retinal ganglion cell (RGC) from death in a chronic glaucoma model in ovariectomized rats.
Unilaterally chronic elevation of intraocular pressure (IOP) was induced in 30 ovariectomized adult Sprague–Dawley rats by repeated laser trabecular meshwork photocoagulation using a krypton laser with wavelength of 532 nm. Two weeks later, after a moderate elevation of IOP was reached in laser treated eye, 17ß–estradiol (50µg/kg) or physiological saline (vehicle) was subcutaneously injected randomly, on every other day for 5 weeks. The eyes were then enucleated and the retinal section was stained with H&E. The density of RGC was quantitatively analyzed. RGC apoptosis was assayed by TdT–mediated biotin–dUTP nick end labeling (TUNEL), and the expression level of bcl–2, caspase 3 and bax was determined by real–time fluorescent quantitative reverse transcription polymerase chain reaction (RT–PCR).
After the elevated IOP (mean 24.66±3.82 mmHg) was maintained for 7 weeks, the number of surviving RGC in 17 ß–estradiol treated eyes and in vehicle treated eyes was 5.83±1.47 and 3.67±0.82 per 100 um of length in retinal sections as linear cell densities, respectively (p<0.000). The number of TUNEL–positive cells in the ganglion cell layer of 17 ß–estradiol treated eyes and vehicle treated eyes was 2.83±0.98 and 4.33±1.03 per 50 um of width of the retinal area at 2 mm periphery from the center of the optical nerve head, respectively (p=0.028). The expression of bcl–2 mRNA was increased (p=0.022) and that of caspase 3 mRNA was decreased (p=0.040) in 17 ß–estradiol treated eyes. There was no significant difference in expression of bax between these two groups.
Estrogen improved survival of RGCs from chronic experimentally elevated IOP in ovariectomized rats, suggesting that estrogen has a neuroprotective effect on RGCs in the glaucomatous eyes.
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