Abstract
Purpose:
To use 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.
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 the lens condition. 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 ginseng were tested. Lenses were exposed to radiation stress by exposure to 74 MeV proton radiation for 1-10 Gy. Each day photos of the lens were taken and protein leakage in the medium was determined by a Bradford assay.. ScantoxTM at the termination of the incubation and Scion Image analysis of daily lens photographs were used to estimate cataract image blurring. After post-stress incubation for 7 days, the lenses were weighed and homogenized. The homogenates were analyzed as appropriate for Hsps 90, 70, 47, 27, HSF1, Akt, MnSOD, and Cu/ZnSOD, by western blotting
Results:
The cataract grade determined by ScantoxTM or Scion image analysis 7 days after radiation showed increased opacification after 7.5 and 10 Gy,proton irradiation, but little protection by either ALC-G or AQ-G. Iincreased induction of Hsp 70, Hsp 90, Cu/Zn SOD and Akt (markers of stress) was observed at 5 Gy, while increases in Hsp 70 and Hsp 90 were prevented by AQ-G and ALC-G, respectively. Protein leakage in lenses was increased at 24 hr in untreated and ALC-G, but was lower with AQ-G. At 7 days protein leakage was higher with AQ-G.
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. Ginseng by itself is an antioxidant (AQ-G). Hsp 70 was preserved at 5 Gy in proton- irradiated lenses if they were treated with AQ-G or ALC-G, and Hsp 90 was preserved by ALC-G, AQ-G treatment resulted in increased protein leakage after 7 days in culture,although it was protective at 24 hours.
Keywords: 424 antioxidants •
445 cataract •
670 radiation damage: light/UV