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ABSTRACT: Diabetes teratogenicity seems to be related to embryonic oxidative 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 therefore compared the antioxidant capacity of 10.5-day-old rat embryos and their yolk sacs cultured for 28h in diabetic culture medium with or without vitamins C and E.
The embryos were cultured in 90% rat serum to which 2mg/ml glucose, 2mg/ml beta hydroxy butyrate (BHOB) and 10 microg/ml of acetoacetate were added. Rat embryos were also cultured in a diabetic medium with 25 microg/ml of vitamin E and 50 microg/ml of vitamin C. Control embryos were cultured in normal rat serum with or without vitamins C and E.
Decreased activity of Cu/Zn superoxide dismutase (SOD) and of catalase (CAT) in the "diabetic" embryos and their yolk sacs, and reduced concentrations of low molecular weight antioxidant (LMWA) were found. Under these conditions we also found a decrease in vitamin C and vitamin E concentrations in the embryos, as measured by HPLC. In situ hybridization for SOD mRNA showed a marked reduction of SOD mRNA in the brain, spinal cord, heart and liver of embryos cultured in diabetic medium in comparison to controls. Following the addition of vitamins C and E to the diabetic culture medium, SOD and CAT activity, the concentrations of LMWA, the levels of vitamin C and E and the expression of SOD mRNA in the embryos and yolk sacs returned to normal.
Diabetic metabolic factors seem to have a direct effect on embryonic SOD gene and perhaps genes of other antioxidant enzymes, reducing embryonic endogenous antioxidant defense mechanism. This in turn may cause a depletion of the LMWA, such as vitamins C and E. The addition of these vitamins normalizes the embryonic antioxidant defense mechanism, reducing the damage caused by the diabetic environment.
Teratology 08/2001; 64(1):33-44.
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ABSTRACT: Reactive oxygen species (ROS) are involved in the etiology of numerous diseases and are suggested to be one of the mechanisms of action of several teratogens such as cocaine, high concentrations of glucose and ketone bodies. We studied the antioxidant capacity of 9.5-12.5 day old rat embryos and their yolk sacs both in vivo and in vitro. We measured the activity of superoxide dismutase (SOD) and the hydrogen peroxide removing activity (mainly due to catalase (CAT) and glutathione peroxidase (GSH -Px) and found significant activity of these enzymes already at day 9.5 in the embryos and their yolk sac, both in vivo and in vitro. A gradual increase in the activity was found with the advancement of embryonic age. The reducing power, that reflects the concentration of low molecular weight antioxidants (LMWA) was measured by cyclic voltammetry. LMWA were found in the embryos and their yolk sacs on days 9.5-11.5 of gestation with the peak potential of 0.56- 0.62 Volts. On day 12.5 an additional group of LMWA appeared at a peak potential of 0.95-0.97 Volts. There was a gradual increase in the concentration of LMWA with the increase in embryonic age. Generally, the concentration of LMWA was higher in the embryo than in its yolk sac but it was similar in vivo and in vitro at the same developmental stage. The gradual development of the embryonic antioxidant capacity implies that under normal conditions the developing embryo is capable of coping with oxidative stress, but this may fail under various pathological conditions, leading to embryonic damage.
Early pregnancy (Online) 05/2000; 4(2):110-23.
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ABSTRACT: A disturbed embryonic antioxidant defense mechanism may play a major role in diabetes-induced teratogenesis. We therefore studied the antioxidant capacity of 10.5-day-old rat embryos and their yolk sacs after culture for 28 hr in vitro under diabetic conditions (3 mg/ml glucose, 2 mg/ml beta-hydroxybutyrate (BHOB) and 10 microg/ml of acetoacetate), as compared with control embryos in vitro. We found a high rate of congenital anomalies, decreased growth and protein content, and a decrease in the activity of both superoxide dismutase (SOD) and catalase (CAT) under diabetic conditions, as compared with controls. The reducing power, which reflects the concentration and type of water-soluble and of lipid-soluble low-molecular-weight antioxidants (LMWA), was measured by cyclic voltammetry. Generally, LMWA were reduced in the embryos and yolk sacs under diabetic conditions. In the water-soluble fraction of control embryos and yolk sacs, two peak potentials were found, indicating two major groups of LMWA, while only one peak potential was found under diabetic conditions, indicating that an entire group of LMWA is missing. HPLC studies have demonstrated a decrease in vitamin C (water-soluble fraction) and in vitamin E (lipid-soluble fraction) under diabetic culture conditions, and an increase in uric acid. Generally, the concentration of LMWA was higher in the embryos than in the yolk sac. LMWA concentration, protein content, and antioxidant enzyme activity were lower in the malformed experimental embryos than in experimental embryos without anomalies. The addition of vitamins C and E to the diabetic culture medium abolished the deleterious effects of the diabetic serum on the embryos. The disturbed antioxidant defense mechanism under diabetic conditions may be explained, at least in part, by a direct effect of diabetic metabolic factors on the activity of antioxidant enzymes and on the concentration of reducing equivalents. This, in turn, may be embryotoxic.
Teratology 01/2000; 60(6):376-86.
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ABSTRACT: Serum from diabetic patients, as well as having high levels of glucose and ketone bodies, is known to have embryotoxic and teratogenic effects that play an important role in diabetes-induced teratology. We studied the effect of serum from women with gestational diabetes, who are not known to have a high incidence of malformations in their offspring, on the in vitro development of 10.5-day-old rat embryos. Results from these studies were then compared with those using serum from pregnant women with Type I diabetes, serum from pregnant women without diabetes, and normal rat serum. Serum from pregnant women with Type I diabetes caused abnormalities in 71% of the embryos in comparison with an incidence of 53.3% in embryos cultured in serum from women with gestational diabetes. Embryos cultured in serum from women without diabetes or in rat serum had a 9 and 4.2% incidence of defects, respectively. Diabetic serum also decreased the size of the embryos, the number of somites, yolk sac diameter, and the amount of protein in the embryos and their yolk sacs. This damage was more significant when embryos were cultured in Type I diabetic serum than in serum from patients with gestational diabetes. The levels of serum glucose, glycosylated haemoglobin, fructosamine, beta-hydroxybutyrate (beta-HOB) and acetoacetate were also higher in Type I diabetic serum than in serum from gestational diabetes. Significant ultrastructural damage was observed in the yolk sacs of embryos cultured in diabetic serum, with a reduction in the endocytic index. The fact that serum from women with gestational diabetes is teratogenic to early somite rat embryos supports the hypothesis that metabolic factors are responsible for diabetes-induced teratogenicity and that to prevent these defects it is essential to stabilize the diabetic state of the mother before, and during, early gestation.
Toxicology in Vitro 10/1995; 9(5):643-51. · 2.78 Impact Factor
