Evaluating the neuroprotective effect of 17β-estradiol in rodent models of oxidative retinopathies.

PURPOSE: To determine the neuroprotective effect of estrogen on the structure and function of the retina exposed to an oxidative stress.

METHODS: Male Sprague-Dawley rat pups were exposed to either hyperoxia (O2 E: from P8 to P14) or bright light (LE: from P14 to P28) with or without 17 β-estradiol (βE2 ) treatment. Retinal structure (histology) and function (ERG) were assessed at selected time points.

RESULTS: In the O2 E model, βE2 injections caused a significant reduction of the ERG and a significantly thinner OPL compared to untreated oxygen-exposed group (O2 -exposed) rats. In contrast, in the LE model βE2 , treatment was beneficial to the retinal structure (thicker ONL) and function (better preserved ERG amplitudes) compared to untreated light-exposed group (light-exposed rats).

CONCLUSION: Our results show that in conditions where the primary target of the oxidative stress is the outer retina (i.e., the photoreceptors) estrogen can protect the retina, while in situations where the inner retina (or retinal vasculature) is the main site of oxidative damage, estrogen may potentiate the detrimental effect of oxidative stress on the retina.