The increased incidence of congenital malformations in diabetic pregnancy may be associated with an excess of free oxygen radicals in the embryo. We have previously blocked the dysmorphogenesis of rat embryos exposed to high glucose and β-hydroxybutyrate concentrations in vitro by increasing the antioxidant capacity of the conceptus. In the present study, we attempted to diminish the teratogenic process in vivo in a rat model of diabetic pregnancy. Thus, pregnant diabetic and normal rats were fed either a standard diet or a diet enriched with 1% of the antioxidant butylated hydroxytoluene (BHT). The fetuses of the diabetic rats were smaller than the fetuses of the normal rats (body weight 2.70 g vs. 3.68 g) when the mothers were fed a standard diet. The BHT diet increased the fetal weight in the offspring of diabetic rats (3.17 g), with no change in fetuses of the normal rats (3.65 g). The placentas of diabetic rats were heavier than the placentas of normal rats; this difference was not present in the BHT-fed rats. The BHT treatment had no effect on the rate of resorptions, which was increased in the diabetic rats compared with the normal rats. In contrast, the increased rate of congenital malformations in the offspring of diabetic rats (19%), compared with that in the normal rats (0%), was markedly decreased by the BHT diet (2.3%). No malformations were found in the normal rats treated with BHT. These data support the notion that an excess of free oxygen radicals in the embryo contributes to the teratogenic process of diabetic pregnancy and, thus, suggest an area for future preventive therapeutic treatment.

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