Abstract
Purpose: :
Using a model in vitro lens incubation system to investigate the possible reduction of cataract risk for astronauts, jet crews and radiation accident workers by dietary agents and formulations containing antioxidants and Ontario ginseng(Panax quinquefolius L.).
Methods: :
Pig eyes obtained from a local abattoir were dissected aseptically and the lenses incubated in medium M199 without serum for 4 days to stabilize. Those with protein leakage less than 10 mg/L were taken for further testing. Incubation media containing either an alcohol (ALC-G) or an an aqueous (AQ-G) extract of Ontario-grown ginseng were tested. Lenses were exposed to radiation stress by exposure to a neutron spectrum similar to the atmospheric spectrum of neutrons from 1- 400 MeV . Each day photos of the lens trays placed on graph paper, and protein leakage in the medium were determined by a Bradford assay. After post-stress incubation for 24 hr. or up to 7 days, the lenses were weighed and homogenized. The homogenates were analyzed as appropriate for Hsps 90, 70, 47, 27, HSF1, Bcl2, Bak, Akt and PAkt, MnSOD, Cu/ZnSOD, αB-crystallin by western blotting, and antioxidant levels in lenses and incubation media. BVD-SEM measured by ScantoxTM at the termination of the incubation and Scion Image analysis of daily lens photographs on graph paper were used to estimate cataract image blurring.
Results: :
AQ-G extract antioxidant activity was much greater than ALC-G. The cataract grade (BVD-SEM) determined by ScantoxTM 7 days after radiation showed ALC-G protection at doses of 1 and 2 Gy neutron irradiation, which correlated with decreased induction of HSF-1, Hsp27, Hsp47, Hsp 40, MnSOD and Cu/Zn SOD, and decreased Hsp70 and Bcl2, but BVD-SEM was decreased by AQ -G, which correlated with preservation of Bcl2, MnSOD, Cu/Zn SOD activity and higher HSF-1, Hsp47, and lower Hsp27, and Bak.
Conclusions: :
Mixtures of antioxidant food factors were previously shown to be promising in reducing risk of cataract following exposure of eye lenses to high energy protons or neutrons. Treatment with an aqueous extract of ginseng, which has more antioxidant activity than the alcoholic extract, results in decreased cataract risk after low doses (1-2 Gy) of neutron irradiation. MnSOD, Hsp47 (collagen-related) and Bcl2 were preserved and HSF-1 heat shock factor appeared to be protected if they were treated with AQ-G.
Keywords: cataract • radiation damage: light/UV • antioxidants