Fetal growth restriction and consequences for the offspring in animal models.

OBJECTIVE: In the present review we discuss rat models in which intra-uterine growth restriction is obtained through pharmacological (streptozotocin), dietary (global food restriction, low protein diet), or surgical (uterine artery ligation) manipulation of the maternal animal. METHODS: A MEDLINE search was performed on rat models of intrauterine growth restriction (IUGR), ie, streptozotocin, food restriction, low protein diet, or uterine artery ligation and pregnancy and fetal programming, long-term effects or adult offspring. RESULTS: We address the impact of the different maternal conditions for the fetal and neonatal development. The rat models we concentrate on were all associated with fetal hypoinsulinemia and intrauterine growth restriction. Both fetus and neonate adapt to the altered perinatal environment. Some of these adaptations may predispose the offspring to the development of insulin resistance, cardiovascular disease, obesity, and even overt diabetes in later life. CONCLUSION: The adaptations of the fetal metabolism to the altered intrauterine environment have consequences for the offspring, persisting into adulthood and into the next generation.

Lifetime consequences of abnormal fetal pancreatic development.

There is ample evidence that an adverse intrauterine environment has harmful consequences for health in later life. Maternal diabetes and experimentally induced hyperglycaemia result in asymmetric overgrowth, which is associated with an increased insulin secretion and hyperplasia of the insulin-producing B-cells in the fetuses. In adult life, a reduced insulin secretion is found. In contrast, intrauterine growth restriction is associated with low insulin secretion and a delayed development of the insulin-producing B-cells. These perinatal alterations may induce a deficient adaptation of the endocrine pancreas and insulin resistance in later life. Intrauterine growth restriction in human pregnancy is mainly due to a reduced uteroplacental blood flow or to maternal undernutrition or malnutrition. However, intrauterine growth restriction can be present in severe diabetes complicated by vasculopathy and nephropathy. In animal models, intrauterine growth retardation can be obtained through pharmacological (streptozotocin), dietary (semi-starvation, low protein diet) or surgical (intrauterine artery ligation) manipulation of the maternal animal. The endocrine pancreas and more specifically the insulin-producing B-cells play an important role in the adaptation to an adverse intrauterine milieu and the consequences in later life. The long-term consequences of an unfavourable intrauterine environment are of major importance worldwide. Concerted efforts are needed to explore how these long-term effects can be prevented. This review will consist of two parts. In the first part, we discuss the long-term consequences in relation to the development of the fetal endocrine pancreas and fetal growth in the human; in the second part, we focus on animal models with disturbed fetal and pancreatic development and the consequences for later life.

Long-term consequences for offspring of diabetes during pregnancy.

There is evidence that the diabetic intra-uterine environment has consequences for later life. Maternal diabetes mainly results in asymmetric macrosomia. This macrosomia is associated with an increased insulin secretion and overstimulation of the insulin producing B-cells during fetal life. In later life, a reduced insulin secretion is found. Intra-uterine growth restriction is present in severe maternal diabetes associated with vasculopathy. Intra-uterine growth restriction is associated with low insulin secretion and reduced development of the insulin receptors. In later life, these alterations can induce insulin resistance. The long-term consequences of an abnormal intra-uterine environment are of primary importance world-wide. Concentrated efforts are needed to explore how these long-term effects can be prevented.

Increase of the isoprostane 8-isoprostaglandin f2alpha in maternal and fetal blood of rats with streptozotocin-induced diabetes: evidence of lipid peroxidation.

OBJECTIVE: Pregnancy complicated by diabetes is associated with maternal complications and fetal abnormalities. Animal models of diabetes suggest that heightened free radical production may be implicated in the pathogenesis of this condition. The purpose of this investigation was to evaluate oxidative stress in plasma from diabetic rats and their fetuses through measurement of concentrations of 8-isoprostaglandin F(2alpha), a stable marker of lipid peroxidation. STUDY DESIGN: Diabetes was induced in virgin and pregnant rats with streptozotocin. Blood samples were collected after 20 days of diabetes. Adult and fetal plasma 8-isoprostaglandin F(2alpha) concentrations were determined by gas chromatography-mass spectroscopy. RESULTS: Significantly higher plasma 8-isoprostaglandin F(2alpha) concentrations were observed in the virgin rats with diabetes and in both the pregnant dams with diabetes and their fetuses when compared with their respective control groups without diabetes (P <.001). CONCLUSION: Oxidative stress was induced in both mother and fetus in rodent pregnancy complicated by diabetes. This finding may have implications for fetal dysmorphogenesis and in fetal programming for adulthood disease.

Raised saturated-fat intake worsens vascular function in virgin and pregnant offspring of streptozotocin-diabetic rats.

Adult offspring of severely diabetic pregnant rats are insulin resistant and display cardiovascular dysfunction. When pregnant they develop mild hyperglycaemia. Diets high in saturated fat have been implicated in the development of cardiovascular disease and vascular dysfunction. In the present study we have determined vascular function in small mesenteric arteries from offspring of normal (OC) and diabetic (OD) rats fed standard chow and offspring of diabetic rats fed a diet high in saturated fats (OD-HF) from weaning to adulthood, and throughout their subsequent pregnancies. OD rats displayed an increased sensitivity to noradrenaline (P < 0.05) and impaired sensitivity to the endothelium-dependent vasodilator, acetylcholine. The component of acetylcholine-induced relaxation attributable to endothelium-derived hyperpolarizing factor was reduced in OD-HF rats. Pregnant OD rats also demonstrated impaired maximum relaxation to acetylcholine (pregnant OD rats v. pregnant OC rats P < 0.05). In pregnant OD-HF rats noradrenaline sensitivity was enhanced and endothelium-dependent relaxation further reduced (pregnant OD-HF rats v. pregnant OC rats P < 0.001). The isoprostane, 8-epi-prostaglandin F2alpha, a marker of oxidative stress, was increased in pregnant OD rats (pregnant OD rats v. pregnant OC rats P

Maternal food restriction in the second half of pregnancy affects vascular function but not blood pressure of rat female offspring.

Food restriction during pregnancy in rats induces intrauterine growth retardation with consequences persisting into adulthood. In the present study we have investigated the hypothesis that malnutrition in pregnant rats may lead to altered cardiovascular function in adult female offspring. Perinatal growth retardation was induced by a 50% reduction of normal dietary intake in rats during the second half of pregnancy. Systolic and diastolic blood pressure values and heart rate were recorded in conscious female offspring (100 d old) using a femoral artery probe. No significant differences in heart rate, or in systolic and diastolic blood pressures were recorded between control offspring and offspring of nutritionally deprived rats. In order to ascertain whether cardiovascular variables in the offspring were influenced by lactation, subgroups of offspring from food-restricted dams were fostered with lactating dams fed on a normal diet. Blood pressure and heart rate were also found to be normal in these offspring. The rise in blood pressure associated with NO inhibition was similar in all groups. Isolated resistance artery function was assessed in vitro in offspring (100-120 d old) of a second group of semi-starved dams. Small mesenteric arteries from these animals showed reduced endothelium-dependent relaxation (to acetylcholine and bradykinin), but enhanced sensitivity to exogenous NO (sodium nitroprusside). We conclude that food restriction during the second half of pregnancy and/or lactation does not induce hypertension in adult offspring, but may effect subtle changes in vascular function.

Cholesterol-independent endothelial dysfunction in virgin and pregnant rats fed a diet high in saturated fat.

1. Western diets high in saturated fat are associated with an increased incidence of cardiovascular diseases. In this study we have evaluated vascular endothelial function and oxidative stress in virgin rats fed a normal (VC) or high in saturated fat diet (VHF) (20 % lard and corn oil w/w) from weaning until adulthood, and throughout subsequent pregnancy (PC and PHF, respectively). 2. The saturated fat diet was associated with enhanced noradrenaline sensitivity in small mesenteric arteries from VHF rats (VHF vs. VC, P < 0.05) and blunted endothelium-dependent relaxation in VHF and PHF rats (VHF vs. VC, P < 0.001; PHF vs. PC, P < 0.05). Endothelial dysfunction was attributable to a reduced nitric oxide component of relaxation in VHF rats, and blunted prostacyclin and endothelium-derived hyperpolarizing factor components in PHF rats. 3. Other than plasma cholesterol, which was reduced in VHF and PHF rats, plasma lipids were normal. Fasting plasma insulin and glucose concentrations were raised in VHF rats (P < 0.05) and the plasma marker of oxidative stress, 8-iso PGF2alpha, was increased in PHF animals (P < 0.01). 4. These findings suggest that endothelial dysfunction induced by a saturated fat diet is cholesterol independent and likely to be of different mechanistic origin in virgin and pregnant rats.

Streptozotocin diabetes in the pregnant rat induces cardiovascular dysfunction in adult offspring.

Severe diabetes in pregnant rats produces persistent metabolic consequences in adult offspring. This study investigated whether diabetes in pregnant rats could also lead to cardiovascular abnormalities in the adult offspring. Blood pressure, heart rate and in vitro vascular reactivity of small arteries were evaluated in female adult offspring of control rats and of rats rendered diabetic with streptozotocin. Rise in blood pressures were similar in both groups of offspring but heart rate was lower in the diabetic offspring (p < 0.05). The rise in blood pressure associated with infusion of a nitric oxide synthase inhibitor was similar in both groups, but the associated decrease in heart rate was more pronounced in diabetic offspring (p < 0.01). Small mesenteric arteries from this group showed enhanced sensitivity to noradrenaline (p < 0.05) and abnormal endothelium-dependent relaxation to acetylcholine (p < 0.01) and bradykinin (p < 0.05). Reduction in acetylcholine induced relaxation, reflected reduced synthesis of nitric oxide or a cyclooxygenase product and was not attributable to an endothelium-derived hyperpolarizing factor. Sensitivity to exogenous nitric oxide was normal. A subgroup of pups born to diabetic dams were suckled by control maternal dams and a subgroup of those born to controls by diabetic dams. Suckling was an important determinant of impaired growth; offspring of diabetic rats suckled by their own mother and those of control rats by diabetic dams showed impaired growth rates whereas growth of offspring of diabetic rats suckled by control dams paralleled those of control rats suckled by their own mother.

Fetal growth and long-term consequences in animal models of growth retardation.

Perturbations of the maternal environment involve an abnormal intrauterine milieu for the developing fetus. The altered fuel supply (depends on substrate availability, placental transport of nutrients and uteroplacental blood flow) from mother to fetus induces alterations in the development of the fetal endocrine pancreas and adaptations of the fetal metabolism to the altered intrauterine environment, resulting in intrauterine growth retardation. The alterations induced by maternal diabetes or maternal malnutrition (protein-calorie or protein deprivation) have consequences for the offspring, persisting into adulthood and into the next generation.

Fetal growth and consequences for later life.

There is evidence that an abnormal intrauterine environment has consequences for later life. Intrauterine growth retardation is associated with low insulin secretion during fetal life and probably a reduced development of insulin receptors. In later life these alterations can induce insulin resistance. Macrosomia is associated with an increased insulin secretion during fetal life and exhaustion of the insulin producing B cells. In later life a reduced insulin secretion is found. The working mechanisms have been explored in experimental studies. Normalisation of the diabetic intrauterine milieu can prevent consequences in later life. There are also indications that vascular changes in later life can be reduced by anti-oxidantia. In the human intrauterine growth retardation is related in later life with insulin resistance, vascular diseases and preeclampsia; macrosomia is related with gestational diabetes and breastcarcinoma.

Maternal semistarvation and streptozotocin-diabetes in rats have different effects on the in vivo glucose uptake by peripheral tissues in their female adult offspring.

Previous work in humans and rats has revealed a link between perinatal growth retardation and glucose intolerance in adulthood. Both maternal semistarvation and severe diabetes are accompanied by perinatal growth retardation in rats. In this study, we compared the effect of these conditions on tissue glucose uptake in their female offspring. Glucose uptake was measured as glucose metabolic index (GMI), using 2-deoxy-[1-3H]-glucose, in the postabsorptive state and during euglycemic hyperinsulinemia. The GMI was measured in insulin-sensitive tissues (5 skeletal muscles, diaphragm and white adipose tissue) and in two noninsulin-sensitive tissues (duodenum and brain) of adult offspring of normal dams, dams rendered diabetic with streptozotocin on d 11 of pregnancy, and dams fed half normal rations from d 11 of pregnancy. Whole-body insulin resistance, measured by decreased glucose infusion rate during hyperinsulinemia, was milder in offspring of semistarved rats (O-SR) than in offspring of diabetic rats (O-DR). The basal GMI did not differ among the three groups in any tissue except tibialis anterior; during hyperinsulinemia, GMI was significantly greater in the insulin-sensitive tissues of all three groups. GMI of skeletal muscles and adipose tissue during hyperinsulinemia did not differ between control rats and O-SR; in contrast, the GMI was 25-50% lower in skeletal muscles of O-DR during hyperinsulinemia than in those of control rats or O-SR. Thus, maternal semistarvation and diabetes have dissimilar effects on peripheral insulin sensitivity of the adult female offspring. Because both conditions are associated with perinatal growth retardation and fetal hypoinsulinemia, other mechanisms must be identified to explain impaired glucose uptake by skeletal muscles in the offspring of diabetic rats.

Insulin sensitivity in adult female rats subjected to malnutrition during the perinatal period.

OBJECTIVE: The purpose of the present study was to investigate insulin sensitivity in adult rats after perinatal malnutrition. METHODS: Wistar rats were food-restricted (about 50% of normal food intake) during pregnancy (group A) or during pregnancy and lactation (group B) and compared with rats fed ad libitum during pregnancy and lactation (group C). The insulin sensitivity in the adult female offspring was assessed with the hyperinsulinemic euglycemic clamp technique in combination with isotopic measurement of glucose turnover. Hepatic and peripheral insulin sensitivities were determined in the basal state and after 3, 10, or 50 mU/kg/minute insulin. RESULTS: Group A and group B rats had lower non-fasting plasma insulin levels (0.15 +/- 0.07 and 0.15 +/- 0.01 nmol/L, respectively) than group C rats (0.26 +/- 0.03 nmol/L) (P < .001). During hyperinsulinemia, the steady-state glucose infusion rate was lower in groups A and B, with 10 and 50 mU/kg/minute insulin, indicating insulin resistance. Hepatic glucose production in the basal state was normal, but its suppression by 10 and 50 mU/kg/minute insulin was dampened in group A and B rats, indicating decreased insulin responsiveness of the liver. Peripheral glucose utilization, however, in the basal state and during hyperinsulinemia remained normal in groups A and B. CONCLUSION: After perinatal malnutrition, adult rats have decreased plasma insulin concentrations and exhibit insulin resistance, with decreased insulin responsiveness of the liver.

The endocrine pancreas in nonimmune hydrops fetalis.

OBJECTIVE: Our purpose was to compare the endocrine pancreas of hydropic infants of immune and nonimmune origin. STUDY DESIGN: A quantitative morphologic study was performed on the pancreas in 10 infants with immune and nonimmune hydrops. The volume density of the endocrine pancreas in the gland was calculated, as was the numerical density of the endocrine cells in the islets. The percentage of the different cell types was measured on immunohistochemical stained slides. Ten normal infants were used as controls. RESULTS: An increased amount of endocrine tissue and an increased total number of islet cells of immune and nonimmune origin is present in hydropic infants. However, an increased proportion of the insulin-producing B cells is not present. CONCLUSIONS: The endocrine pancreas in hydrops fetalis of immune and nonimmune origin is equal, excluding hemolysis as the stimulating factor for equilibrated islet overgrowth. Metabolic stimuli, as seen in infants of diabetic mothers, are probably not involved, because they preferentially stimulate the insulin-producing B cells.

In vivo glucose utilization by individual tissues in virgin and pregnant offspring of severely diabetic rats.

Adult offspring of diabetic rats or SDF rats are characterized by insulin resistance in the liver and extrahepatic tissues; this insulin resistance does not worsen during pregnancy. In this study, we determined the glucose metabolic index in tissues of anesthetized virgin and pregnant control and SDF rats in basal conditions and during a euglycemic hyperinsulinemic clamp. Tissues comprised insulin-sensitive tissues (five skeletal muscles, diaphragm, and periovarian white adipose tissue) and control tissues (duodenum and cerebrum). In addition, this study measured the GMI of placenta and fetuses. In basal conditions, SDF rats showed a slight decrease (9-29%) in the GMI of skeletal muscles compared with control rats; it was not altered by pregnancy in any of the tissues. During physiological hyperinsulinemia, virgin SDF rats exhibited a 25-70% decrease in the GMI of skeletal muscles compared with control rats; this decrease was not observed in diaphragm, or in adipose tissue in which the GMI was found to be increased. During pregnancy, SDF rats did not show an additional drop in the GMI of skeletal muscles, whereas the GMI of both skeletal muscles and adipose tissue was clearly diminished (25-60%) in control rats. The GMI of skeletal muscles was therefore comparable in pregnant control rats and SDF rats. The placental, but not fetal, GMI was increased by 24% during hyperinsulinemia in control rats; the placental and fetal GMIs, in basal and hyperinsulinemic conditions, were similar in control rats and SDF rats. In conclusion, skeletal muscles, but not white adipose tissue, are involved in the peripheral insulin resistance of the SDF rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Absence of pregnancy-induced alterations in tissue insulin sensitivity in the offspring of diabetic rats.

We have previously demonstrated insulin resistance in the liver and peripheral tissues of the adult offspring of rats made diabetic with streptozotocin (SDF rats). In this study, a euglycaemic hyperinsulinaemic clamp was used to test the hypothesis that insulin resistance is further aggravated during pregnancy in SDF rats. Normal pregnancy was accompanied by a decrease in the sensitivity of the liver and peripheral tissues to insulin, with a normal responsiveness to insulin. In SDF rats no further decrease in the sensitivity of peripheral tissues to insulin occurred during pregnancy when compared with non-pregnant rats, and the dose-response curves of the glucose metabolic clearance rate during hyperinsulinaemia were similar in pregnant control and pregnant SDF rats. There was, however, a modest decrease in the sensitivity of the liver to insulin during pregnancy in SDF rats. The normal increase in plasma insulin levels during pregnancy was blunted in SDF rats: this resulted in increased glucose levels in maternal and fetal rats and increased fetal insulin concentrations, features compatible with mild 'gestation diabetes'. In conclusion, gestational diabetes develops in pregnant SDF rats, although there is no further deterioration in peripheral insulin resistance.

Metabolic alterations in adulthood after intrauterine development in mothers with mild diabetes.

We studied the long-term effects of maternal diabetes mellitus on the offspring of experimentally induced diabetic Wistar rats. When stressed by an intravenous glucose load, the adult female offspring had impaired glucose tolerance and developed gestational diabetes mellitus when pregnant. Our results show that even mild diabetes mellitus induces an abnormal intrauterine milieu that causes morphological and functional changes in fetal development with consequences for later life.

The effects of maternal diabetes on the offspring.

Diabetes in pregnancy has an influence on the development of the fetus. There are strong indications that the intrauterine diabetic milieu has long-lasting consequences. In the rat, mild diabetes during pregnancy induces decreased insulin secretion in later life, whereas severe diabetes is responsible for insulin resistance. In the human, data are available showing a long-term consequence in the offspring of type I diabetes and gestational diabetes mellitus.

Evidence for an insulin resistance in the adult offspring of pregnant streptozotocin-diabetic rats.

Our previous work has suggested the presence of an insulin resistance in the adult offspring of streptozotocin-diabetic pregnant rats. In this study we used the euglycaemic hyperinsulinaemic clamp technique with an isotope-dilution method to define and quantify this postulated insulin resistance in adult offspring of streptozotocin-diabetic rats. Under basal conditions, these rats had a lower body weight than control rats, but their glucose and insulin concentrations were normal. During the hyperinsulinaemic clamp, the steady-state glucose infusion rate was significantly lower in the offspring of streptozotocin-diabetic rats than in both age- and weight-matched controls, indicating insulin resistance. Basal peripheral tissue glucose utilization was normal in the offspring of streptozotocin-diabetic rats, but the dose-response curve was shifted to the right:insulin concentrations causing half-maximal stimulation of glucose utilization were increased by about 60% in the offspring of diabetic rats; the maximal stimulation of glucose utilization, however, was unaltered. Basal hepatic glucose production was normal, but again, half-maximal suppression of glucose production occurred at insulin concentrations 50% higher than in control rats; in addition, the maximal suppression of glucose production was significantly decreased, even at insulin concentrations of 5700 microU/ml. These data are evidence for an insulin resistance in the adult offspring of streptozotocin-diabetic rats, characterized by: (1) a decreased insulin sensitivity by peripheral glucose-utilizing tissues, and, (2) a decreased sensitivity and responsiveness of the liver.