Abstract
Purpose: :
Most metals, vitamins and lipids are carried across Bruch’s membrane bound to protein carriers similar in size to the albumin molecule. Ageing is associated with a decline in macromolecular transport with the reduction in vitamin A transport leading to diminished scotopic thresholds in the elderly. A more severe reduction is observed in age-related macular degeneration (AMD) contributing to the pathological stress in this disease. The potential use of ginseng compounds with their anti-oxidative and ‘detergent’-like properties to improve the macromolecular transport pathway has been assessed.
Methods: :
Bruch’s-choroid preparations (from nine donors aged 56-92 years) were mounted in Ussing chambers (6mm diameter aperture) and the Bruch’s-facing half-compartment filled with 1.0mls of 0.1mM FITC-albumin (MW 65kDa) made in Tris-HCL buffer. Other half chamber was filled with Tris-HCl. After an incubation period of 24hours at 37oC, solutions were removed and the amount of FITC-albumin diffusing across was determined by measuring absorbance at 490nm and a calibration curve. After thorough washing, chambers were filled with either Tris-HCL buffer (control), butanol extract of ginseng (10mg/ml), or 10% ginseng (in Tris-HCl). Following a 24-hour incubation, the diffusional study with FITC-albumin was repeated. Basal diffusional rates were designated 1.0 and effect of the various incubations expressed as -fold change of basal.
Results: :
In the control Tris-HCl incubations, there was a small reduction in diffusional transport (0.86±0.05-fold, Mean ± SD). The butanol-extract treated samples did not show significant alterations in diffusion of albumin (1.24 ±0.34). Incubation with 10% ginseng considerably improved the diffusion of FITC-albumin by 1.74±0.04-fold Mean ± SD, p<0.001.
Conclusions: :
Ginseng considerably improved the trafficking of carrier sized protein molecules across Bruch’s membrane. Oral ginseng supplementation of the AREDS formulation may serve to improve the diffusional status of ageing Bruch’s membrane to address the problems of vitamin A transport in the elderly and in AMD to slow the degenerative changes.
Keywords: extracellular matrix • Bruch's membrane • age-related macular degeneration