Vitamins C and E improve rat embryonic antioxidant defense mechanism in diabetic culture medium

Background: Diabetes teratogenicity seems to be related to embryonic oxidat ive stress and the extent of the embryonic damage can apparently be reduced by antioxidants. We have studied the mechanism by which antioxidants, such as vitamins C and E, reduce diabetes-induced embryonic damage. We therefor e compared the antioxidant capacity of 10.5-day-old rat embryos and their y olk sacs cultured for 28h in diabetic culture medium with or without vitami ns C and E. Methods: The embryos were cultured in 90% rat serum to which 2mg/ml glucose , 2mg/ml beta hydroxy butyrate (BHOB) and 10 mug/ml of acetoacetate were ad ded. Rat embryos were also cultured in a diabetic medium with 25 mug/ml of vitamin E and 50 mug/ml of vitamin C. Control embryos were cultured in norm al rat serum with or without Vitamins C and E. Results: Decreased activity of Cu/Zn superoxide dismutase (SOD) and of cata lase (CAT) in the "diabetic" embryos and their yolk sacs, and reduced conce ntrations of low molecular weight antioxidant (LMWA) were found. Under thes e conditions we also found a decrease in Vitamin C and vitamin E concentrat ions in the embryos, as measured by HPLC. In situ hybridization for SOD mRN A showed a marked reduction of SOD mRNA in the brain, spinal cord, heart an d liver of embryos cultured in diabetic medium in comparison to controls. F ollowing the addition of vitamins C and E to the diabetic culture medium, S OD and CAT activity, the concentrations of LMWA, the levels of vitamin C an d E and the expression of SOD mRNA in the embryos and yolk sacs returned to normal. Conclusions: Diabetic metabolic factors seem to have a direct effect on emb ryonic SOD gene and perhaps genes of other antioxidant enzymes, reducing em bryonic endogenous antioxidant defense mechanism. This in turn may cause a depletion of the LMWA, such as vitamins C and E. The addition of these vita mins normalizes the embryonic antioxidant defense mechanism, reducing the d amage caused by the diabetic environment. Teratology 64:33-44, 2001. (C) 20 01 Wiley-Liss, Inc.