Developmental programming: Prenatal testosterone excess disrupts pancreatic islet developmental trajectory in female sheep.

Prenatal testosterone (T)- treated female sheep manifest juvenile insulin resistance, post-pubertal increase in insulin sensitivity and return to insulin resistance during adulthood. Since compensatory hyperinsulinemia is associated with insulin resistance, altered pancreatic islet ontogeny may contribute towards metabolic defects. To test this, pregnant sheep were treated with or without T propionate from days 30-90 of gestation and pancreas collected from female fetuses at gestational day 90 and female offspring at 21 months-of-age. Uterine (maternal) and umbilical (fetal) arterial blood insulin/glucose ratios were determined at gestational day 90. The morphological and functional changes in pancreatic islet were assessed through detection of 1) islet hormones (insulin, glucagon) and apoptotic beta cells at fetal day 90 and 2) islet hormones (insulin, glucagon and somatostatin), and pancreatic lipid and collagen accumulation in adults. At gestational day 90, T-treatment led to maternal but not fetal hyperinsulinemia, decrease in pancreatic/fetal weight ratio and alpha cells, and a trend for increase in beta cell apoptosis in fetal pancreas. Adult prenatal T-treated female sheep manifested 1) significant increase in beta cell size and a tendency for increase in insulin and somatostatin stained area and proportion of beta cells in the islet; and 2) significant increase in pancreatic islet collagen and a tendency towards increased lipid accumulation. Gestational T-treatment induced changes in pancreatic islet endocrine cells during both fetal and adult ages track the trajectory of hyperinsulinemic status with the increase in adult pancreatic collagen accumulation indicative of impending beta cell failure with chronic insulin resistance.

Gestational dexamethasone alters fetal neuroendocrine axis.

This study tested whether the maternal transport of dexamethasone (DEXA) may affect the development of the neuroendocrine system. DEXA (0.2mg/kg b.w., subcutaneous injection) was administered to pregnant rats from gestation day (GD) 1-20. In the DEXA-treated group, a decrease in maternal serum thyroxine (T4), triiodothyronine (T3), and increase in thyrotropin (TSH) levels (hypothyroid status) were observed at GDs 15 & 20 with respect to control group. The reverse pattern (hyperthyroid status) was observed in their fetuses at embryonic days (EDs) 15 & 20. Although the maternal body weight was diminished, the weight of the thyroid gland was increased at studied GDs as compared to the control group. The fetal growth retardation, hyperleptinemia, hyperinsulinism, and cytokines distortions (transforming growth factor-beta; TGF-ß, tumor necrosis factor-alpha; TNF-α, and interferon-γ; IFN-γ) were noticed at examined EDs if compared to the control group. Alternatively, the maternofetal thyroid dysfunctions due to the maternal DEXA administration attenuated the levels of fetal cerebral norepinephrine (NE) and epinephrine (E), and elevated the levels of dopamine (DA) and 5-hydroxytryptamine (5-HT) at considered days. These alterations were age-dependent and might damage the nerve transmission. Finally, maternal DEXA might act as neuroendocrine disruptor causing dyshormonogenesis and fetal cerebral dysfunction.

Impact of embryo number and periconceptional undernutrition on factors regulating adipogenesis, lipogenesis, and metabolism in adipose tissue in the sheep fetus.

Maternal undernutrition around the time of conception is associated with an increased risk of insulin resistance in adulthood. We hypothesized that maternal undernutrition during the periconceptional (PCUN: -60 to 7 days) and/or preimplantation (PIUN: 0-7 days) periods would result in a decrease in UCP1 expression and the abundance of insulin signaling molecules and an increase in the abundance of factors that regulate adipogenesis and lipogenesis in fetal perirenal adipose tissue (PAT) and that these effects would be different in singletons and twins. Maternal PCUN and PIUN resulted in a decrease in UCP1 expression in PAT, and PIUN resulted in higher circulating insulin concentrations, an increased abundance of pPKCζ and PDK4, and a decreased abundance of Akt1, phosphorylated mTOR, and PPARγ in PAT in singleton and twin fetuses. In singletons, there was also a decrease in the abundance of p110ß in PAT in the PCUN and PIUN groups and an increase in total AMPKα in PAT in the PIUN group. In twins, however, there was an increase in the abundance of mTOR in the PCUN group and an increase in PDK2 and decrease in total AMPKα in the PIUN group. Thus exposure to periconceptional undernutrition programs changes in the thermogenic capacity and the insulin and fatty acid oxidation signaling pathway in visceral fat, and these effects are different in singletons and twins. These findings are important, as the thermogenic capacity of brown fat and the insulin sensitivity of visceral fat are important determinants of the risk of developing obesity and an insulin resistance phenotype in later life.

Fetal anterior wall thickness and amniotic fluid insulin levels: an interdependence?

PURPOSE: Excessive fetal fat as the hallmark of GDM pregnancy complications is one consequence of fetal hyperinsulinism. Noninvasive methods for fetal surveillance and measurement of fetal fat are needed. The purpose of this study was to test the hypothesis that measurements of the fetal anterior abdominal wall thickness (AAWT) in women with GDM will allow early detection of fetal hyperinsulinism. MATERIALS AND METHODS: Amniocentesis was performed between 28 and 32 weeks of gestation (wks) in 220 women with GDM (diagnosed by 75 g oGTT at 24 to 28 wks). Amniotic fluid insulin levels (AFIL) were determined by a commercially available radioimmunoassay. Transabdominal ultrasound provided fetal biometric measurements following standard procedures and the AAWT including fetal skin and subcutaneous tissue at the time of amniocentesis. Maternal parameters (weight, BMI, oGTT blood glucose levels and mean daily blood glucose levels) were correlated with fetal biometric data and with AFIL. RESULTS: There was no difference in AAWT in women with GDM and no correlation with mean AFIL. AFIL also did not correlate with any other fetal measurement or with mean oGTT blood glucose levels. AFIL only showed a correlation with maternal weight (p = 0.02) and maternal BMI (p = 0.01). The correlation was present for values both before pregnancy and at the time of amniocentesis. CONCLUSION: In the early third trimester, AAWT measurements do not correlate with fetal insulin levels.

[The transgenerational mechanisms in developmental programming of metabolic diseases]. / Mecanismos transgeneracionales en el desarrollo de enfermedades metabólicas.

Human epidemiological and experimental animal studies have shown that suboptimal environments in the womb and during early neonatal life alter growth and may program offspring susceptibility to lifelong health problems. One of the most interesting and significant feature of developmental programming is the evidence that adverse consequences of altered intrauterine environments can be passed from first generation to second generation offspring. To obtain the transgenerational phenotype, a negative environment is required during fetal or early neonatal life, the physiologic phenotype or disease can be transmitted through the germ line and the subsequent generations are not directly exposed to the environmental factor. The hypothesis has become well accepted by compelling animal studies that define the outcome of specific challenges such as: 1) nutrient restriction or overfeeding during pregnancy and lactation; 2) uterine blood flow restriction; 3) fetal exposure to inappropriately high levels of glucocorticoids, and 4) experimental maternal diabetes. Maternal protein restriction in the rat adversely affects glucose metabolism of male and female second generation offspring in a gender and developmental time window-specific manner. Other studies have proved transgenerational passage of effects resulting from treatment of pregnant rats with dexamethasone by either maternal or paternal lines. First generation female diabetic offspring of F0 rats treated with streptozotocin during pregnancy had F2 offspring with altered glucose and carbohydrate metabolism. The studies suggest that the mechanisms involved in developmental programming are likely epigenetic rather than due to DNA sequence mutations. Many individuals all over the world experience undernutrition, stress, hyperglycemia and other negative environmental factors during pregnancy and/or lactation. Insult during this critical period of development may induce malprogramming and adversely alter not only the F1 generation but also future generations. Preventing or treating these conditions will help to minimize the risk of transmission of metabolic diseases to future generations.

Gestational diabetes mellitus: developments in diagnosis and treatment.

After many years of uncertainty regarding the true pathological nature of mild gestational diabetes and the possible benefits of treatment, the situation appears to have been resolved by the publication of the Australian Carbohydrate Intolerance Study in Pregnant Women (ACHOIS). It is now appropriate for obstetric units to review their treatment and screening programs for gestational diabetes mellitus. Furthermore, with the publication of the Metformin in Gestational Diabetes (MiG) trial, consideration should be given as to whether metformin should be the first choice when diet fails to maintain glycemic control.

Protein restriction during gestation and/or lactation causes adverse transgenerational effects on biometry and glucose metabolism in F1 and F2 progenies of rats.

Substantial evidence suggests that poor intrauterine milieu elicited by maternal nutritional disturbance may programme susceptibility in the fetus to later development of chronic diseases, such as obesity, hypertension, cardiovascular disease and diabetes. One of the most interesting features of fetal programming is the evidence from several studies that the consequences may not be limited to the first-generation offspring and that it can be passed transgenerationally. In the present study, female rats (F0) were fed either a normal-protein diet [control diet (C); 19 g of protein/100 g of diet] or a low-protein diet [restricted diet (R); 5 g of protein/100 g of diet]. The offspring were termed according to the period and the types of diet the dams were fed, i.e. CC, RC, CR and RR (first letter indicates the diet during gestation and the second the diet during lactation). At 3 months of age, F1 females were bred to proven males, outside the experiment, to produce F2 offspring. At weaning, F2 offspring were divided by gender. RC1 offspring (with the number indicating the filial generation) were born with low birthweight, but afterwards they had catch-up growth, reaching the weight of the CC1 offspring. The increased glycaemia in RC1 offspring was associated with insulin resistance. CR1 and RR1 offspring had impaired growth with no changes in glucose metabolism. RC2 offspring had high BM (body mass) at birth, which was sustained over the whole experiment in male offspring. The F2 generation had more alteration in glucose metabolism than the F1 generation. CR2 and RC2 offspring had hyperglycaemia accompanied by hyperinsulinaemia and insulin resistance in both genders. CR2 offspring had an increase in body adiposity with hyperleptinaemia. In conclusion, low protein during gestation improves BM, fat mass and growth rate in F1 rats, but has adverse effects on glucose and leptin metabolism, resulting in insulin resistance in adult F1 and F2 offspring. Low protein during lactation has adverse effects on glucose, insulin and leptin metabolism, resulting in insulin resistance in adult F2 offspring. These findings suggest that low protein during gestation and/or lactation can be passed transgenerationally to the second generation.

Developmental origins of obesity: a sympathoadrenal perspective.

Environmental exposures at crucial points in development permanently alter sympathoadrenal function in mammals. Both the sympathetic innervation of peripheral tissues and the responsiveness of sympathetic nerves and adrenal medulla to standard stimuli are susceptible to modification by exposures in early life. Several conditions studied in the laboratory, including environmental temperature, litter size and maternal nutrition, in addition to affecting sympathoadrenal function also produce larger, fatter offspring, raising the possibility that developmental programming of the sympathetic nervous system (SNS) may contribute to acquisition of an obese phenotype. The specific changes noted in all three circumstances include evidence of an increase in sympathetic innervation in pancreas and retroperitoneal fat. By contrast, SNS development is impaired in experimental models of intrauterine growth retardation. Although the physiological implications of increased sympathetic innervation in pancreas and retroperitoneal fat are not fully understood, these changes seen in animals reared at cool temperatures, in small litters or by mothers fed refined carbohydrate diets likely reflect an early enhancement of the offspring's capacity to take up and store glucose. If so, the tendency of these animals to gain weight and accumulate fat may represent an adaptive response to 'over-nutrition' in early life.

Maternal protein restriction leads to hyperinsulinemia and reduced insulin-signaling protein expression in 21-mo-old female rat offspring.

Human adult diseases such as cardiovascular disease, hypertension, and type 2 diabetes have been epidemiologically linked to poor fetal growth and development. Male offspring of rat dams fed a low-protein (LP) diet during pregnancy and lactation develop diabetes with concomitant alterations in their insulin-signaling mechanisms. Such associations have not been studied in female offspring. The aim of this study was to determine whether female LP offspring develop diabetes in later life. Control and LP female offspring groups were obtained from rat dams fed a control (20% protein) or an isocaloric (8% protein) diet, respectively, throughout pregnancy and lactation. Both groups were weaned and maintained on 20% normal laboratory chow until 21 mo of age when they underwent intravenous glucose tolerance testing (IVGTT). Fasting glucose was comparable between the two groups; however, LP fasting insulin was approximately twofold that of controls (P < 0.02). Glucose tolerance during IVGTT was comparable between the two groups; however, LP peak plasma insulin at 4 min was approximately threefold higher than in controls (P < 0.001). LP plasma insulin area under the curve was 1.9-fold higher than controls (P < 0.02). In Western blots, both muscle protein kinase C-zeta expression and p110beta-associated p85alpha in abdominal fat were reduced (P < 0.05) in LPs. Hyperinsulinemia in response to glucose challenge coupled with attenuation of certain insulin-signaling molecules imply the development of insulin resistance in LP muscle and fat. These observations suggest that intrauterine protein restriction leads to insulin resistance in females in old age and, hence, an increased risk of type 2 diabetes.

Beta-cell proliferation and apoptosis in the developing normal human pancreas and in hyperinsulinism of infancy.

Hyperinsulinism of infancy (HI), also known as persistent hyperinsulinemic hypoglycemia of infancy, is a rare genetic disorder that occurs in approximately 1 of 50,000 live births. Histologically, pancreases from HI patients can be divided into 2 major groups. In the first, diffuse HI, beta-cell distribution is similar to that seen in normal neonatal pancreas, whereas in the second, focal HI, there is a discrete region of beta-cell adenomatous hyperplasia. In most patients, the clinical course of the disease suggests a slow progressive loss of beta-cell function. Using double immunostaining, we examined the proportion of beta-cells undergoing proliferation and apoptosis during the development of the normal human pancreas and in pancreases from diffuse and focal HI patients. In the control samples, our findings show a progressive decrease in beta-cell proliferation from 3.2 +/- 0.5% between 17 and 32 weeks of gestation to 0.13 +/- 0.08% after 6 months of age. In contrast, frequency of apoptosis is low (0.6 +/- 0.2%) in weeks 17-32 of gestation, elevated (1.3 +/- 0.3% ) during the perinatal period, and again low (0.08 +/- 0.3%) after 6 months of age. HI beta-cells showed an increased frequency of proliferation, with focal lesions showing particularly high levels. Similarly, the proportion of apoptotic cells was increased in HI, although this reached statistical significance only after 3 months of age. In conclusion, we demonstrated that islet remodeling normally seen in the neonatal period may be primarily due to a wave of beta-cell apoptosis that occurs at that time. In HI, our findings of persistently increased beta-cell proliferation and apoptosis provide a possible mechanism to explain the histologic picture seen in diffuse disease. The slow progressive decrease in insulin secretion seen clinically in these patients suggests that the net effect of these phenomena may be loss of beta-cell mass.

What is the significance of macrosomia?

This commentary/review briefly considers the diverse criteria recommended for classification of overweight infants. Macrosomia continues to be a vexing problem for both obstetricians and pediatricians. Among the various techniques possible for use in assessing body composition, none are more practical than body weight relative to gestational age. The criteria for normative data from large populations are reviewed. The stringent definition, i.e., exceeding +2 SD of an appropriate normative population, is reaffirmed. Using these criteria, infants of diabetic mothers showed a significant relationship of body weight to fetal hyperinsulinemia.

Hyperinsulinemia and macrosomia in the fetus of the diabetic mother.

OBJECTIVE: To determine 1) whether macrosomia in the fetus of the diabetic mother is related to fetal hyperinsulinemia and 2) whether hyperinsulinemia and macrosomia are related to maternal metabolic control. RESEARCH DESIGN AND METHODS: Normal pregnant women (n = 95) were compared with insulin-treated pregnant women (n = 155), who were subdivided according to White's class, hypertension, and mode of delivery. All women were treated to achieve optimal metabolic control. HbA1c was determined at each visit. At delivery, umbilical plasma was analyzed for glucose, insulin antibodies, total insulin, free insulin, C-peptide, proinsulin components, and total and individual amino acids. RESULTS: Macrosomia, defined as > 2 standard deviation units (97.75%), was found in 10-27% of the diabetic groups. It was not related to maternal mass or size, but was significantly correlated with umbilical total insulin, free insulin, and C-peptide. Proinsulin components were not different among groups. Amino acids also were not different. Glycosylated hemoglobin was a weak predictor of birth weight and fetal hyperinsulinism. CONCLUSIONS: Macrosomia in the fetus of the diabetic mother remains inadequately explained. In a large population of pregnant women with strict metabolic control, macrosomia was mainly independent of glycosylated hemoglobin. Nevertheless, fetal hyperinsulinism remains the driving force for excessive fetal growth. The stimulus for fetal insulin excess in humans remains to be defined.

Theory of the etiology of human toxemia of pregnancy: fetal hyperinsulinemia as a compensatory response to decreased uterine blood flow.

Toxemia of pregnancy is a perplexing clinical problem that has defied accurate elucidation of its etiology because the disorder does not occur in undisturbed lower mammalian species that are currently used as animal models of reproductive physiology. We propose that toxemia of pregnancy occurs as the end stage human fetal-placental unit response to decreased maternal uterine blood flow, and that this fetal-placental unit response may be unique to the human species. The human fetus increases insulin secretion in response to progressive intrauterine asphyxia, which may result in decreased fetal-placental prostacyclin production (a vasodilator and inhibitor of platelet aggregation) and increased fetal-placental thromboxane A2 production (a vasoconstrictor). This could result in increased uteroplacental perfusion pressure, maternal hypertension, and increased maternal platelet aggregation. We also suggest that women who develop idiopathic toxemia of pregnancy are at increased risk for adult onset diabetes later on in life because they have a mild derangement in glucose-insulin homeostasis during their reproductive years that results in increased uterine vascular damage, that leads to decreased uterine blood flow, and ultimately the fetal hyperinsulinemia-prostaglandin pressor release mechanism. Therefore, prevention of toxemia may be possible by correction of mild derangements in glucose-insulin receptor homeostasis before conception occurs.

Fetal rat hyperinsulinism and hyperglucagonism: effects on hepatic ketogenesis, lipogenesis, and gluconeogenesis.

To study the direct effects of hyperglucagonism and hyperinsulinism (both with glucose excess) on fetal intermediary metabolism, rat liver explants from 19-day-gestated fetuses were maintained in culture for 48 h. The liver cubes were exposed to 0, 250, or 500 mU/ml porcine insulin or 5 micrograms/ml glucagon. In addition, lipogenesis from 3H2O was cumulated throughout the 48 h. Chronic hyperinsulinism in the fetal rat doubled hepatic lipogenesis and curtailed hepatic gluconeogenesis and ketogenesis by 80% and 50%, respectively. Chronic hyperglucagonism was without effect; however, the fetal liver did yet respond to 1 mM (Bu)2cAMP.

Experimental-induced hyperinsulinemia in a fetus and newborn rhesus monkey (Macaca mulatta).

An osmotically driven minipump continuously delivering 19 microU of pork insulin daily (6 microliter/day) was implanted subcutaneously into the upper thigh of a rhesus monkey fetus in utero at 122 days of gestation. A female infant weighing 408 g was delivered spontaneously and prematurely at 141 days of gestation. Within 6-12 hours of birth, she was in shock with signs of hypoglycemia. A radiograph of the chest showed normal lung aeration. Her blood glucose was undetectable (less than 1 mg/dl) and plasma insulin was 130 microU/ml at 12 hours. The minipump was removed, and the monkey was treated with 50% dextrose orally (2.5 g/kg body weight). The infant recovered and had a normal rate of growth thereafter. There was no neurological impairment consistent with hypoxia or hypoglycemia. Subsequent plasma glucose and insulin levels determined at various intervals were within normal limits.

Fetal hyperinsulinism in rhesus isoimmunization.

Analyses of peritoneal ascitic fluid obtained prior to intrauterine transfusion show that some babies with severe rhesus isoimmunization develop raised insulin levels up to a month before delivery. The glucose content of fetal ascitic fluid is usually only about 10 mg. per 100 ml. less than the glucose content of maternal plasma and there is no evidence that this relation is influenced by the fetal or maternal insulin level. The electrolyte content of fetal ascitic fluid is very similar to that of maternal plasma, but fluid from babies with hyperinsulinism has an unusually high calcium content.