Purchase this article with an account.
L. Ma, X. Chen, J. Zhang, Y. Liu, M. Zhang, M. Zhang, F. Lu; Protective Effects of Estrogen on Retinal Light Injury . Invest. Ophthalmol. Vis. Sci. 2006;47(13):2046.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
To study the mechanism of retinal light injury and the protective effects of estrogen on light–induced retinal photoreceptor degeneration.
Thirty–eight female SD rats were randomly divided into 4 groups: control, ovariectomized (OVX), sham–ovariectomized, ovariectomized and estrogen (E2) replacement group(OVX+E2). One week post ovariectomy, E2 (50µg/kg) was subcutaneously injected once on alternate days in the OVX+E2 group, and serum estrogen concentration in the treated group were tested by chemiluminescence’s method. Two weeks post operation, all the rats in the treated group were exposed to 12–hr light/12–hr dark cyclic white fluorescent light (600±35.4lux) for 14 days . The f–ERG including scotopic blue and white ERG was tested after 24hrs dark–adaptation. Afterwards the eyes were extracted to make paraffin sections stained by HE and the thickness of ONL was measured. TUNEL method was used to evaluate apoptosis cells in ONL. The expression of nitric oxide synthetase (NOS) in retinal cells was investigated by immunohistochemistry.
Serum estrogen concentrations were 45.99±10.41, 136.04±51.69 and 153.64±29.34 pmol/L in the OVX, sham–OVX and OVX+E2 group respectively. Serum estrogen concentrations in the OVX group were significantly less than those of the other groups. The amplitudes of b wave of scotopic blue and white ERG were 24.30±8.44 and 38.54±11.86, 40.05±10.59 and 66.61±16.97, 37.52±10.01and 62.74±17.89µv in the OVX, sham–OVX and OVX+E2 group respectively. Difference between OVX group and the other groups was significant. The retinal structures in the control group were normal.Nuclear chromatin of photoreceptors was dense. No positive marked cell was found by TUNEL method. In the treated group, the thickness of ONL became thinner, but the ONL in the OVX group was obviously thinner than those in the other groups. Positive marked cells were 27.53±6.95, 16.15±5.44 and 17.49±5.97/1000µm2 in the OVX, sham–OVX and OVX+E2 group respectively; the difference between the OVX group and the other groups was significant. The values of integral optical density were 0.3675±0.06621, 0.2941±0.03498, and 0.3027±0.03217 in the OVX, OVX+E2 and sham–OVX group respectively. The NOS levels in the OVX group were significantly higher than those in the OVX+E2 and sham–OVX group.
Moderate and low intensities of cyclic light may induce photorecepter degeneration and retina damage. Estrogen maybe inhibit photorecepter apoptosis by the way of controlling the expression of nitrogen monoxide synthetase.
This PDF is available to Subscribers Only