Dietary vitamin E prophylaxis and diabetic embryopathy: Morphologic and biochemical analysis

Objective: In this study we sought to determine whether dietary supplementation with vitamin E, a known antioxidant, would reduce the incidence of diabetic embryopathy in an in vivo rat model. Study Design: Eighty-day-old Sprague-Dawley rats were assigned to one of five groups: two control groups (groups 1 and 2) and three diabetic groups (groups 3, 4, and 5). One group of controls (group 2) and one group of diabetic rats (group 4) received dietary supplements of vitamin E (440 mg/day). The other three groups (groups 1, 3, and 5) received a normal diet only. Group 5 received insulin therapy to control glucose levels. On day 6 of gestation diabetes was induced in group 3, 4 and 5 with streptozotocin (65 mg/kg). Animals were killed on day 12; embryos were examined for size, protein content, evidence of malformations, and superoxide dismutase activity. Results: In both groups (groups 3 and 4) of diabetic rats the mean blood glucose level than was significantly higher in controls. Insulin-treated animals (group 5) had glucose levels that were comparable to those of controls. The unsupplemented diabetic group had a neural tube defect rate of 21.48%±9.6% (percentage of neural tube defects per rat) and a resorption rate of 21.37%±20.39% (percentage of resorptions per rat) as compared with rates in the supplemented diabetic group of 6.92%±4.08% and 2.17%±3.74%, respectively (p<0.01). Groups 1, 2, and 5 had similar neural tube defect rates (6.63%±5.0%, 5.01%±4.87%, and 3.55%±5.92%, respectively. Vitamin E levels, measured by high-performance liquid chromatography, were significantly higher in maternal serum and embryos in the supplemented groups (p<0.001) than in controls. Superoxide dismutase activity was reduced in the diabetes groups and was not affected by vitamin E therapy. Conclusions: Supplementation with the antioxidant vitamin E confers a significant protective effect against diabetic embryopathy and may potentially serve as a dietary prophylaxis in the future. We postulate that this protective effect is mediated by a reduction in the oxidative load induced by hyperglycemia.