Abstract
Purpose :
Aldosterone causes retinal ganglion cell (RGC) death independent of intraocular pressure (IOP). This study investigated the relationship between aldosterone-induced RGC death and systemic blood pressure using an experimental aldosterone hypertension rat model.
Methods :
Aldosterone was administered systemically to Sprague-Dawley rats by subcutaneous implantation of an osmotic pump. The rats had free access to saline (0.9% NaCl) or water. Eplerenone, a mineralocorticoid receptor (MR) antagonist, and the vasodilator, hydralazine, were used to determine the effect of antihypertensive drugs on RGC loss. RGCs were counted at 6 weeks after systemic administration of aldosterone.
Results :
Although there was a significant increase in blood pressure for the saline intake, with or without aldosterone, rats given water instead of saline did not exhibit an increase in blood pressure. The number of RGCs (cells/mm2) for the aldosterone (-)/saline (-), aldosterone (-)/saline (+), aldosterone (+)/saline (-), and aldosterone (+)/saline (+) groups was 1981 ± 109, 2008 ± 185, 1581 ± 56, and 1555 ± 46, respectively. Although RGCs were significantly decreased in aldosterone-treated rats (P < 0.001; ANOVA), RGC loss was not affected by blood pressure. Administration of eplerenone or hydralazine in aldosterone-treated rats given water instead of saline significantly reduced blood pressure from normal values to low values. The number of RGCs (cells/mm2) was 1868 ± 177 and 1554 ± 34 for eplerenone- and hydralazine-treated rats, respectively (P = 0.01; t-test). In all groups, the IOP did not significantly change during the experimental period.
Conclusions :
The RGC loss observed in the experimental aldosterone hypertension rat model was associated with a blood pressure independent loss that occurred without any elevation in the IOP. Furthermore, the MR antagonist, eplerenone, provides neuroprotective effects independent of the IOP or blood pressure.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.