Influence of maternal metabolism and parental genetics on fetal maldevelopment in diabetic rat pregnancy.

The purpose of this study was to investigate the influence of parental transgenerational genetics and maternal metabolic state on fetal maldevelopment in diabetic rat pregnancy. Rats from an inbred malformation-resistant (W) strain, and an inbred malformation-prone (L) strain, were cross-mated to produce two different F(1) hybrids, WL and LW. Normal (N) and manifestly diabetic (MD) WL and LW females were mated with normal males of the same F(1) generation to obtain WLWL and LWLW F(2) hybrids. Maternal diabetes increased malformation and resorption rates in both F(2) generations. MD-WLWL offspring had higher resorption rate but similar malformation rate compared with the MD-LWLW offspring. Malformed MD-WLWL offspring presented with 100% agnathia/micrognathia, whereas malformed MD-LWL offspring had 60% agnathia/micrognathia and 40% cleft lip and palate. The MD-WL dams showed increased ß-hydroxybutyrate levels and alterations in concentrations of several amino acids (taurine, asparagine, citrulline, cystine, glutamic acid, leucine, tyrosine, and tryptophan) compared with MD-LW dams. Fetal glyceraldehyde-3-phosphate dehydrogenase (Gapdh) activity and gene expression were more altered in MD-WLWL than MD-LWLW. Fetal gene expression of reactive oxygen species (ROS) scavenger enzymes was diminished in MD-WLWL compared with MD-LWLW. Glial cell line-derived neurotrophic factor and Ret proto-oncogene gene expression was decreased in both MD-WLWL and MD-LWLW fetuses, whereas increased bone morphogenetic protein 4 and decreased Sonic hedgehog homolog expression was found only in MD-LWLW fetuses. Despite identical autosomal genotypes, the WL and LW dams gave birth to offspring with markedly different malformation patterns. Together with fetal differences in enzymatic activity and expression of Gapdh, ROS scavengers, and developmental genes, these results may suggest a teratological mechanism in diabetic pregnancy influenced by maternal metabolism and parental strain epigenetics.

Genetic and environmental influence on diabetic rat embryopathy.

We assessed genetic and environmental influence on fetal outcome in diabetic rat pregnancy. Crossing normal (N) and manifestly diabetic (MD) Wistar Furth (W) and Sprague-Dawley (L) females with W or L males yielded four different fetal genotypes (WW, LL, WL, and LW) in N or MD rat pregnancies for studies. We also evaluated fetal outcome in litters with enhanced or diminished severity of maternal MD state, denoted MD(+)WL and MD(-)LW. The MDWW litters had less malformations and resorptions (0 and 19%) than the MDLL litters (17 and 30%). The MDWL litters (0 and 8%) were less maldeveloped than the MDLW litters (9 and 22%), whereas the MD(+)WL (3 and 23%) and MD(-)LW (1 and 17%) litters showed increased and decreased dysmorphogenesis (compared with MDWL and MDLW litters). The pregnant MDW rats had lower serum levels of glucose, fructosamine, and branched-chain amino acids than the pregnant MDL rats, whereas the pregnant MD(+)W and MD(-)L rats had levels comparable with those of the MDL and MDW rats, respectively. The 8-iso-PGF2α levels of the malformed MDLW offspring were increased compared with the nonmalformed MDLW offspring. Diabetes decreased fetal heart Ret and increased Bmp-4 gene expression in the MDLW offspring and caused decreased GDNF and Shh expression in the malformed fetal mandible of the MDLW offspring. We conclude that the fetal genome controls the embryonic dysmorphogenesis in diabetic pregnancy by instigating a threshold level for the teratological insult and that the maternal genome controls the teratogenic insult by (dys)regulating the maternal metabolism.

Altered uterine perfusion is involved in fetal outcome of diabetic rats.

Maternal diabetes affects the development of the offspring by altering the uterine environment. We aimed to investigate the extent to which the blood flow (measured as Tissue Perfusion Units; TPU) to implantation sites and the expression of developmentally important genes in the offspring are affected by maternal diabetes. We measured mRNA levels of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), Bcl-2 associated X protein (Bax), B-cell lymphoma protein (Bcl-2), tumor suppressor protein-53 (p53), paired box protein-3 (Pax-3) and vascular endothelial growth factor-A (Vegf-A). Moreover, we studied the effect on uterine blood flow (TPU) and the expression of the genes exerted by embryonic maldevelopment (malformation or resorption). Streptozotocin induced diabetic (D) and non-diabetic (N) pregnant rats were used in the study. Blood flow (TPU) to implantation sites was measured by a laser Doppler flow meter, and gene expression was analyzed by RT-PCR. Maternal diabetes caused increased blood flow (TPU) to implantation sites compared with normal pregnancy. Furthermore, implantation sites of D rats containing malformed offspring showed impaired growth and decreased blood flow (TPU) compared with their littermates at all gestational days. Resorbed offspring from both N and D rats displayed increased blood flow (TPU) compared with their non-resorbed littermates. Moreover, we found that maternal diabetes causes decreased expression of genes involved in the oxidative stress defense system (CuZnSOD in non-malformed D11 embryos, MnSOD at all gestational time points, ECSOD and Gpx-1 at GD11-GD15, CAT and Gpx-2 at GD15), decreased expression of Pax-3 at GD11, and increased expression of Vegf-A at all gestational time points. We conclude that both maternal metabolism and embryonic developmental state affect the blood flow (TPU) to the implantation site. Maternal diabetes causes decreased expression of anti-oxidative enzymes and enhanced angiogenesis in the offspring in rats.

Neurological and neuropsychological effects of low and moderate prenatal alcohol exposure.

Several explanations for the diverse results in research on foetal alcohol spectrum disorders or alcohol-related neurodevelopmental disorder might be at hand: timing, amount and patterns of alcohol exposure, as well as complex epigenetic responses. The genetic background of the offspring and its interaction with other prenatal and post-natal environmental cues are likely also of importance. In the present report, key findings about the possible effects of low and moderate doses of maternal alcohol intake on the neuropsychological development of the offspring are reviewed and plausible mechanisms discussed. Special focus is put on the serotonergic system within developmental and gene-environment frameworks. The review also suggests guidelines for future studies and also summarizes some of to-be-answered questions of relevance to clinical practice. Contradictory findings and paucity of studies on the effects of exposure to low alcohol levels during foetal life for the offspring's neuropsychological development call for large prospective studies, as well as for studies including neuroimaging and multi-omics analyses to dissect the neurobiological underpinnings of alcohol exposure-related phenotypes and to identify biomarkers. Finally, it remains to be investigated whether any safe threshold of alcohol drinking during pregnancy can be identified.

Suramin-restricted blood volume in the placenta of normal and diabetic rats is normalized by vitamin E treatment.

Previously maternal and fetal alterations resembling human pre-eclampsia were induced in pregnant rats by injections of the angiogenesis inhibitor Suramin. These alterations were aggravated by maternal diabetes and partly rectified by vitamin E supplementation. In the present study we evaluated the morphology of placentae and kidneys in this model. Non-diabetic and streptozotocin-induced diabetic pregnant rats of two rat strains (U and H) were treated with Suramin or saline, and given standard or vitamin E-enriched food. On gestational day 20 one placenta and the left kidney of the mother were collected for morphological and stereological analysis. In the placental trophospongium Suramin treatment caused cysts, which were further enhanced by maternal diabetes. Vitamin E treatment had no effect on the vacuolization. In the placental labyrinth of the non-diabetic rats Suramin treatment restricted maternal placental blood volume and increased the interface between maternal and fetal circulation. These changes were reversed by vitamin E treatment. Diabetes increased slightly the interface between the circulations in both rat strains. Suramin treatment decreased the interface, and vitamin E further decreased the interface in the diabetic U rats, whereas neither treatment affected the maternal-fetal interface in the diabetic H rats. The kidneys of Suramin-treated and diabetic rats were heavier compared to controls. Suramin treatment and maternal diabetes damaged renal glomeruli to a similar extent. Vitamin E treatment diminished the Suramin- and diabetes-induced glomerular damage in U rats, but not in H rats. The average cell count per glomerulus was decreased by Suramin in the U rats. Vitamin E treatment did not affect cell number per glomerulus in any group. We conclude that Suramin-injected pregnant rats constitute a valid animal model for placental dysfunction and pre-eclampsia, also from the histological perspective. The present work supports the notion that one important effect of untreated maternal diabetes may be impaired placentation, leading to oxidative stress, morphological damage, and compromised placental function.

Increase of bikunin and alpha1-microglobulin concentrations in urine of rats during pregnancy is due to decreased tubular reabsorption.

Bikunin and alpha1-microglobulin are two plasma proteins of about 25 kDa which are made in the liver from a common precursor. The concentration of bikunin in human urine has been shown to increase several fold during various conditions of stress. The mechanism behind this increase is unknown. We have studied pregnant rats and found that the bikunin and alpha1-microglobulin levels in their urine increased 3-fold towards the end of the pregnancy, whereas those of albumin and orosomucoid did not. There were no significant changes in either the bikunin/alpha1-microglobulin mRNA level or the concentrations of the two proteins in serum. These findings imply that the synthesis and the clearance rates of bikunin and alpha1-microglobulin are normal during pregnancy but that the tubular reabsorption of these proteins is decreased.

Vitamin E decreases the occurrence of malformations in the offspring of diabetic rats.

An association between excess oxygen radical activity and disturbed embryogenesis in diabetic pregnancy has been suggested. In the present study, the protective capacity of vitamin E with different treatment regimens was investigated in early and late pregnancy of streptozotocin-induced diabetic rats. Daily gavaging of 0.2 g/kg or 0.8 g/kg of vitamin E exerted moderate protective effects. In contrast, treatment with a diet enriched with 2% (wt/wt) of vitamin E, yielding an approximate daily dosage of 2 g/kg of vitamin E, clearly restored both embryonic and fetal morphology. High-performance liquid chromatography measurement showed that maternal diabetes decreased embryonic content of vitamin E. When pregnant diabetic animals were supplemented with vitamin E, increased concentrations of the vitamin were found in maternal, embryonic, and fetal tissues. Thus, despite marked accumulation of vitamin E in maternal tissues, the compound apparently reached the conceptus. Thiobarbituric acid reactive substances (TBARS) were estimated as a measure of lipid peroxidation, and no changes were observed in maternal tissue, embryonic tissue, placenta, and fetal brain in the untreated diabetic group. In contrast, a fivefold increase of TBARS was found in fetal liver, a rise that was reduced with vitamin E treatment of the diabetic pregnant rats and completely normalized with 2% vitamin E in the diet. Congenital malformations caused by experimental diabetes can be prevented by antioxidants in vivo. These findings further corroborate the notion that an imbalance in the metabolism of free oxygen radicals is involved in the embryonic maldevelopment of diabetic pregnancy, and suggest a direction for prophylactic treatment in the future.

Antioxidants diminish developmental damage induced by high glucose and cyclooxygenase inhibitors in rat embryos in vitro.

Previous studies have suggested that the metabolism of arachidonic acid and radical oxygen species (ROS) are altered in diabetes and that these disturbances may induce severe embryonic dysmorphogenesis in diabetic pregnancy. We tested this hypothesis by studying whether an inhibition of the rate-limiting enzyme of prostaglandin biosynthesis, cyclooxygenase (COX), caused developmental disturbances analogous to those seen in embryos exposed to high glucose concentration. Whether antioxidants could prevent such developmental alterations was also investigated. Whole embryo culture was used in which day-9 embryos were exposed to high concentrations of glucose, arachidonic acid, prostaglandin (PG)E2, COX inhibitors, and antioxidants for 48 h. Increased glucose concentration (from 10 to 30 mmol/l) caused embryonic dysmorphogenesis, and addition of either 60 pmol/l arachidonic acid or 280 nmol/l PGE2 largely protected the embryo from this maldevelopment. Furthermore, exposure to the COX inhibitors indomethacin (200 micromol/l) or acetylsalicylic acid (700 micromol/l) in 10 mmol/l glucose concentration yielded embryonic dysmorphogenesis similar to that caused by 30 mmol/l glucose. Supplementation of either arachidonic acid or PGE2 to the culture medium with COX inhibitors in low glucose rectified the embryonic development, and PGE2 supplementation also normalized the development of embryos cultured with COX inhibitors in high glucose concentration. Interestingly, the antioxidants superoxide dismutase (SOD) and N-acetylcysteine (NAC) were each able to diminish the dysmorphogenesis induced by the COX inhibitors, at doses previously shown to diminish glucose-induced embryonic damage in the same in vitro culture system. In conclusion, the present study shows that a high glucose concentration disturbs embryonic development and that this disturbance may be partly mediated via altered metabolism of arachidonic acid and ROS in the embryo.

Inhibition of N-acetylheparosan deacetylase in diabetic rats.

The effects on N-acetylheparosan deacetylase (N-deacetylase) activity exerted by poorly and well-regulated diabetes and variation of genetic background were investigated in insulin-treated streptozocin-induced diabetic rats of two different strains (H and U). N-deacetylase plays a key role in heparan sulfate biosynthesis, because N-deacetylation is a prerequisite for N- and further O-sulfation. Specific activity of the enzyme was reduced by 50% in poorly regulated diabetic rats compared with nondiabetic rats (P less than 0.001). The decrease in specific activity was accompanied by a reduction in the estimated KM from 34 +/- 3 to 27 +/- 4 mg/L (P less than 0.001). Optimal insulin treatment, leading to near normalization of blood glucose, prevented reduction in N-deacetylase activity. In rat strain U, however, a 20% reduction was found despite optimal insulin treatment (P = 0.01), and the nondiabetic animals of this strain had reduced N-deacetylase activity compared with nondiabetic rats from the H strain. This might suggest a genetic difference between the rat strains in the regulation of the enzyme activity. The diabetes-induced inhibition of N-deacetylase may have an important role in the pathogenesis of nephropathy and vascular complications in human diabetes mellitus.

Pregnant diabetic rats fed the antioxidant butylated hydroxytoluene show decreased occurrence of malformations in offspring.

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 beta-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.

Diabetes and embryonic malformations. Role of substrate-induced free-oxygen radical production for dysmorphogenesis in cultured rat embryos.

The aim of this study was to evaluate the role of free-oxygen radicals in the embryonic maldevelopment of diabetic pregnancy. Rat embryos cultured in vitro during early organogenesis showed growth retardation and severe malformations after exposure to 50 mM glucose, 3 mM PYR, 10 mM HBT, or 3 mM KIC. Combinations of 25 mM glucose, 2.5 mM HBT, and 1 mM KIC also elicited embryonic growth retardation and malformations. The deleterious effects on embryonic development by all agents were alleviated by addition of SOD to the culture media, which yielded increased enzyme activity in the embryos and their membranes. The endogenous SOD activity also increased in embryos subjected to a high concentration of glucose or PYR in the culture medium. Addition of the mitochondrial PYR transport inhibitor CHC to the culture media blocked the dysmorphogenesis caused by glucose and PYR, but was without effect on the teratogenic actions of HBT and KIC. These findings implicate the embryonic mitochondria as a likely site for enhanced substrate-induced production of free-oxygen radicals mediating the teratogenic effect of a diabetic environment. In particular, the teratogenic process in diabetic pregnancy may depend on an increased production of free-oxygen radicals in immature embryonic mitochondria in response to a metabolic overload. This notion implies that every oxidative substrate entering the mitochondrial metabolism in excess may induce embryonic malformations and emphasizes the need for an extended metabolic surveillance of pregnant diabetic women. Consequently, optimal metabolic control should aim at normalizing the maternal serum concentrations of all possible oxidative substrates.

Growth retardation during early organogenesis in embryos of experimentally diabetic rats.

Embryos from rats rendered diabetic with streptozotocin for 1 wk or more before conception were examined on day 11.5 of gestation (i.e., at the 26-29-somite stage of normal rat embryonic development). The studies were designed to assess whether poorly regulated maternal diabetes is associated with demonstrable abnormalities even during this early phase of embryogenesis. We found that manifest retardations in growth and development were invariably present as judged by significant reductions in crown-rump length and somite number, respectively. Total protein and DNA content of the embryos were also reduced, although not symmetrically, so that protein/DNA ratios were increased. Gross dysmorphogenic lesions in neural tissue disproportional to the overall growth retardation at 11.5 days could not be demonstrated. The findings suggest that maternal diabetes can compromise intra-uterine growth and development during the period preceding and coinciding with the establishment of circulation in the allantoic placenta. The possible multifactorial determinants remain to be elucidated. It also remains to be established whether the early embryotoxicity provides a setting conducive to the increased dysmorphogenesis that is traditionally recognized during the later stages of pregnancy complicated by diabetes.

Is there an animal model for gestational diabetes?

This article reviews the effects of pregnancy on carbohydrate metabolism and insulin production in the normal rat and discusses some animal models of potential value for the study of gestational diabetes mellitus (GDM). Against the background of current clinical and laboratory experiences it is suggested that GDM reflects a deficiency in islet B-cell proliferation in response to the increased insulin requirement during pregnancy. Although this hypothesis lends itself for testing in animal experiments, a suitable animal model for GDM needs to be described.

Increased accumulation of sorbitol in offspring of manifest diabetic rats.

The effects of maternal diabetes on somatic development and activity of the polyol pathway were investigated during early and late gestation in a rat model for diabetic pregnancy. We studied embryo-fetal growth, mortality, and malformation rate in the offspring of nondiabetic rats and in the offspring of diabetic rats either treated with an aldose reductase inhibitor during gestation or left untreated. The numbers of embryo-fetal resorptions and malformations were significantly increased in the diabetic groups compared with the controls despite maternal treatment with the aldose reductase inhibitor. The sorbitol content of embryos and membranes from the diabetic rats in early gestation was increased 3-5 times over the control values. Similarly, elevated sorbitol levels were observed in the fetal livers and placentas of the diabetic rats in late gestation. Administration of the aldose reductase inhibitor to the pregnant diabetic rats normalized the sorbitol levels in the embryos and their membranes, whereas the sorbitol contents of the fetal livers and placentas were significantly lowered but not completely corrected. Furthermore, in the diabetic groups, no differences in sorbitol levels could be demonstrated between malformed and nonmalformed offspring. The results of this study suggest that enhanced polyol metabolism leading to increased sorbitol accumulation is present in the embryos of diabetic mothers as early as organogenesis. This accumulation is apparently not a major factor in the early developmental disturbances (e.g., growth perturbations and congenital malformations) of diabetic pregnancy.

Effects of interrupted insulin treatment on fetal outcome of pregnant diabetic rats.

Streptozocin-induced diabetic female rats became normoglycemic after subcutaneous insertion of insulin-releasing osmotic minipumps. These female rats were mated with normal males from the same Sprague-Dawley substrain. In this substrain, the offspring of diabetic rats show a markedly increased congenital malformation rate compared with fetuses of nondiabetic rats. The pregnant diabetic rats were subjected to removal and insertion of pumps at defined gestational days that marked the beginning or end of a 2- or 4-day period of insulin withdrawal. Evaluation of the offspring on day 20 of pregnancy included fetal/placental weights, estimated number of implants, resorptions, and morphological assessment of congenital malformations. Resorptions occurred in all interruption groups, but malformations were found only in animals with insulin withdrawal on gestational days 4-8, 6-8, 6-10, 8-10, and 8-12. The highest resorption (42%) and malformation (17%) rates were found in the rats subjected to insulin withdrawal during gestational days 6-10. Because manifestly diabetic rats with no insulin treatment showed similar resorption (39%) and malformation (17%) rates, this study suggests that a teratogenic period in diabetic rat pregnancy occurs during gestational days 6-10, a period corresponding to postconceptional wk 2-4 in human pregnancy. Interruption of insulin treatment induced similar maternal weight loss and similar maternal serum concentrations of D-glucose, cholesterol, urea, and creatinine in rats with and without malformed offspring.(ABSTRACT TRUNCATED AT 250 WORDS)

Hyperglycemia-induced embryonic dysmorphogenesis correlates with genomic DNA mutation frequency in vitro and in vivo.

Congenital malformations affecting multiple organ systems are at least three times more common in infants of mothers with IDDM than in infants born to nondiabetic mothers. Numerous studies have confirmed the teratogenic effect of hyperglycemia on the developing embryo, although no direct mechanism has been determined. In this study, we aimed to correlate the frequency of lacI mutations with degree of hyperglycemic exposure and severity of malformations in mouse embryos from in vitro cultures. Day 8 transgenic mouse embryos cultured in 30 or 50 mmol/l glucose for 48 h exhibited a higher incidence of morphological abnormalities, as well as an increase in lacI mutation frequency, compared with embryos cultured in 10 mmol/l glucose with no abnormalities and a lower frequency of lacI mutations. We also used a transgenic lacI rat system to evaluate the relationship between abnormal embryonic development and DNA mutation frequency in day 11 embryos of severely diabetic rats (serum glucose >20 mmol/l). Compared with control embryos, the embryos from diabetic rats displayed significantly more malformations, shorter crown-rump lengths, fewer somites, and more than six times greater genomic DNA mutation frequency. Genetic analysis of the mutated lacI gene from both in vitro cultured mouse embryos and in vivo developed rat embryos revealed that the majority of mutations were due to base substitutions (transitions and transversions), but that the rate of large DNA mutations tended to increase in embryos exposed to a diabetic environment. Our results support the interrelationship between increased rates of congenital malformations and DNA mutations in the offspring of diabetic pregnancy.

Diabetes in pregnancy. Skeletal malformations in the offspring of diabetic rats after intermittent withdrawal of insulin in early gestation.

Precise timing of the teratogenic period in diabetic pregnancy is of clinical importance since correction of the glucose intolerance during this period may protect the offspring from malformations. An experimental approach to elucidate this problem with regard to skeletal development was made in groups of pregnant streptozotocin-diabetic rats (MDI), which were treated with daily insulin injections except for a 2-day period in the first half of pregnancy. The degree of metabolic derangement was estimated by measurements of serum glucose concentrations. During the insulin-free period, the rats showed severe hyperglycemia (greater than 20 mM) while during ongoing insulin treatment, only brief periods of hyper- or hypoglycemia were observed. Insulin treatment was withdrawn successively between gestational days 3 and 12. Control groups consisted of normal pregnant rats (N) or pregnant rats with manifest diabetes (MD) without insulin treatment. The serum glucose levels of the N animals were below 6 mM while those of the MD animals were above 25 mM throughout pregnancy. Skeletal malformations in the viable offspring were recorded on gestational day 20 after Alizarin staining of calcified ossification centers, which also allowed an estimate of skeletal development as a whole. Untreated diabetes in the MD rats induced a high rate of fetal resorptions, a decrease in fetal weight and viability, as well as retardation of skeletal development. Intermittent insulin treatment in the MDI rats ameliorated, but did not abolish, these changes. In the MD group 9 of 48 viable fetuses showed severe malformations of either the lower jaw (micrognathia) or of the lumbosacral region (caudal dysgenesis).(ABSTRACT TRUNCATED AT 250 WORDS)

Developmental damage, increased lipid peroxidation, diminished cyclooxygenase-2 gene expression, and lowered prostaglandin E2 levels in rat embryos exposed to a diabetic environment.

Previous experimental studies suggest that diabetic embryopathy is associated with an excess of radical oxygen species (ROS), as well as with a disturbance of prostaglandin (PG) metabolism. We aimed to investigate the relationship between these pathways and used hyperglycemia in vitro (embryo culture for 24-48 h) and maternal diabetes in vivo to affect embryonic development. Subsequently, we assessed lipid peroxidation and gene expression of cyclooxygenase (COX)-1 and -2 and measured the concentration of prostaglandin E2 (PGE2) in embryos and membranes. Both hyperglycemia in vitro and maternal diabetes in vivo caused embryonic dysmorphogenesis and increased embryonic levels of 8-epi-PGF2alpha, an indicator of lipid peroxidation. Addition of N-acetylcysteine (NAC) to the culture medium normalized the morphology and 8-epi-PGF2alpha concentration of the embryos exposed to high glucose. Neither hyperglycemia nor diabetes altered COX-1 expression, but embryonic COX-2 expression was diminished on gestational day 10. The PGE2 concentration of day 10 embryos and membranes was decreased after exposure to high glucose in vitro or diabetes in vivo. In vitro addition of NAC to high glucose cultures largely rectified morphology and restored PGE2 concentration, but without normalizing the COX-2 expression in embryos and membranes. Hyperglycemia/diabetes-induced downregulation of embryonic COX-2 gene expression may be a primary event in diabetic embryopathy, leading to lowered PGE2 levels and dysmorphogenesis. Antioxidant treatment does not prevent the decrease in COX-2 mRNA levels but restores PGE2 concentrations, suggesting that diabetes-induced oxidative stress aggravates the loss of COX-2 activity. This may explain in part the antiteratogenic effect of antioxidant treatment.

Maternal diabetes induces increased expression of extracellular matrix components in rat embryos.

The mechanisms responsible for the increased incidence of congenital malformations in offspring of diabetic mothers are poorly understood. Because the abnormal metabolic milieu of diabetes induces in the adult organism increased synthesis of basement membrane components, and these molecules play a prominent role in morphogenesis, we investigated whether maternal diabetes or high glucose levels disturb extracellular matrix synthesis in rat embryos. In gestational day 11 embryos, maternal diabetes induced a small but significant increase in laminin B1 (127 +/- 40% of control, mean +/- SD, P < 0.02) but not in fibronectin mRNA (101 +/- 26% of control). Day 12 embryos from diabetic mothers showed a larger increment in laminin B1 (179 +/- 91% of control, P < 0.02) and also an increase in fibronectin mRNA (172 +/- 73% of control, P < 0.02). A similar increase in the expression of fibronectin was observed in the kidneys and hearts of day 20 fetuses dissected from diabetic rats. High glucose levels mimicked in vitro the effects of maternal diabetes. Day 9 embryos cultured for 48 h in 50 mM D-glucose showed, akin to the day 11 embryos in vivo, an increase in laminin B1 mRNA (129 +/- 47% of control) and no changes in fibronectin mRNA (106 +/- 35% of control). The finding that maternal diabetes induces increased expression of extracellular matrix components in developing embryos establishes a link with the abnormalities occurring in the chronic complications of diabetes and proposes a new path of investigation for the mechanism of teratogenicity of the diabetic milieu.