Estrogen attenuates VEGF-initiated blood-retina barrier breakdown in male rats.

17β-Estradiol has been demonstrated to protect blood-brain barrier from disruption and attenuate brain injury in various conditions. The aim of this study was to investigate the effect of 17β-estradiol on the blood-retina barrier (BRB) breakdown induced by intravitreous injection of vascular endothelial growth factor (VEGF), a significant mediator of vascular permeability. Intravitreous injection of VEGF was performed to initiate BRB breakdown in male rats with PBS in the contralateral eye as control. 2 doses of 17β-estradiol and vehicle control were given to 3 groups of rats. The integrity of the BRB was quantified by Evans blue technique and assessed by fluorescent dyes in retinal sections and wholemounts. BRB breakdown was achieved by VEGF as retinal vascular permeability was increased compared with control eyes (14.66±4.09 vs. 4.94±1.20 μl/g/h, p<0.01). Vascular permeability in the 2 groups treated with 17β-estradiol was reduced compared with control (14.66±4.09 vs. 10.26±3.67 vs. 7.37±2.22 μl/g/h, p<0.01). Rhodamine isothiocyanate (RhIC) extravasation in retinal sections and Evans blue-albumin complex leakage in retinal wholemounts were also decreased in the 2 treatment groups. These results suggest that 17β-estradiol attenuates BRB breakdown induced by VEGF in male rats, which may provide a new role of 17β-estradiol in ocular diseases. Georg Thieme Verlag KG Stuttgart · NewYork.