Pregnant Diabetic Rats Fed the Antioxidant Butylated Hydroxytoluene Show Decreased Occurrence of Malformations in Offspring Ulf J. Eriksson and C. Martin Siman 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 [J-hydroxybu- tyrate 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 off- spring 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 nor- mal 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. Diabetes 45:1497-1502, 1996 From the Department of Medical Cell Biology, University of Uppsala, Uppsala, Sweden. Address correspondence and reprint requests to Dr. Ulf J. Eriksson, Department of Medical Cell Biology, University of Uppsala, Biomedicum, P.O. Box 571, S-751 23 Uppsala, Sweden. E-mail: ulf.eriksson@medcell- biol.uu.se. Received for publication 10 January 1996 and accepted in revised form 20 June 1996. ANOVA, analysis of variance; BHT, butylated hydroxytoluene; HPLC, high-pressure liquid chromotography; MD, manifestly diabetic rats fed a control diet; MDB, manifestly diabetic rats fed a BHT-supplemented diet; MDE, manifestly diabetic rats fed an ether-treated diet; N, normal rats fed a control diet; NB, normal rats fed a BHT-supplemented diet; NE, normal rats fed an ether-treated diet. M aternal diabetes during early pregnancy is associated with a considerable risk for mal- formations in the offspring. Good meta- bolic control of the maternal disease is con- sidered to diminish the risk of fetal dysmorphogenesis markedly. However, despite current intensive metabolic care of the pregnant diabetic mother, the malformation rate of the offspring of diabetic mothers is still twice that of the normal population (1-5). The mechanisms for dia- betes-induced embryonic maldevelopment remain largely unknown, although a number of hypotheses have been suggested during the last decade based on clinical and experimental findings (6,7). Several experimental studies have attempted to iden- tify causative teratological mechanisms in diabetic preg- nancy. Investigations using the whole embryo culture system have shown that the addition of the scavenging enzymes superoxide dismutase, catalase, or glutathione peroxidase can normalize the development of embryos exposed to a high glucose milieu (8). These results indi- cate that free oxygen radicals are involved in the terato- genic process. In subsequent studies, the mitochondria have been suggested as a possible source of the oxygen radicals (9,10). Alternatively, a decreased cellular antiox- idative status may constitute the basis for a relative excess of free oxygen radicals in the embryo exposed to a diabetic environment (11). The compound butylated hydroxytoluene (BHT) is an antioxidant that is commonly used as a preservative in lipid-containing products, such as stains and cosmetics, and as an additive to various foods. It has been demon- strated to have several positive therapeutic effects. BHT administration to animals has been shown to prevent sugar-induced cataracts (12,13), to block cholesterol- induced atherosclerosis (14), and to diminish tumorigen- esis in rats that have been exposed to carcinogenic com- pounds (15-17). Based on these findings, we aimed to study whether BHT administration to pregnant diabetic animals could have a protective effect on the develop- ment of their offspring. In the present study, BHT was fed to normal and diabetic rats by adding it to pelleted food at a concentration of 1%, and the offspring were com- pared with the offspring from normal and diabetic rats that were fed a control diet. After the interruption of ges- tation on day 20 of pregnancy, the effects on the mother and offspring were analyzed by determining the maternal DIABETES, VOL. 45, NOVEMBER 1996 1497