Compromised Blood Flow in the Optic Nerve Head after Systemic Administration of Aldosterone in Rats: A Possible Rat Model of Retinal Ganglion Cell Loss

Abstract

PurposeTo investigate the optic nerve head (ONH) blood flow, retinal vessel diameters, and retinal ganglion cell (RGC) loss after systemic administration of aldosterone in rats.MethodsAldosterone (80 µg/kg/day) or vehicle was administered using an osmotic minipump in Brown Norway rats. The mean blur rate in the vessel (MV) and tissue (MT) regions and retinal vessel diameters in the ONH were measured by laser speckle flowgraphy before and 1, 2, and 4 weeks after administration of aldosterone or vehicle. Intraocular pressure (IOP), blood pressure, and heart rate were recorded. The retrogradely labeled RGCs were counted in the retinal flatmounts prepared 5 weeks after treatment.ResultsThe MV and MT in the aldosterone group significantly decreased at 2 and 4 weeks (MV: 2 weeks, p = 0.001, 4 weeks, p < 0.001; MT: 2 weeks, p = 0.02, 4 weeks, p = 0.03). The artery and vein diameters significantly decreased at 1, 2, and 4 weeks in the aldosterone group (all p < 0.001). The MV, MT, and vessel diameters remained unchanged in the vehicle group. Other parameters did not change over time in either group. RGC counts were significantly lower in the aldosterone group than in the vehicle group (p < 0.001).ConclusionsONH blood flow decreased following retinal vessel constriction without changes in IOP or blood pressure in a possible rat model of RGC loss by systemic administration of aldosterone.